Add initial Microsoft Teams support

Documentation on https://github.com/42wim/matterbridge/wiki/MS-Teams-setup

9 files changed, 4374 insertions, 0 deletions

diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/README.md b/vendor/github.com/yaegashi/msgraph.go/jsonx/README.md
new file mode 100644
index 00000000..575ce781
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/README.md
@@ -0,0 +1,55 @@
+# jsonx
+
+It's modified version of [encoding/json](https://golang.org/pkg/encoding/json/)
+which enables extra map field (with `jsonx:"true"` tag) to catch all other fields not declared in the struct.
+
+`jsonx` is a code name for internal use
+and not related to [JSONx](https://tools.ietf.org/html/draft-rsalz-jsonx-00).
+
+Example ([Run on playgroud](https://play.golang.org/p/TZi0JeHYG69))
+```go
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/yaegashi/msgraph.go/jsonx"
+)
+
+type Extra struct {
+	X     string
+	Y     int
+	Extra map[string]interface{} `json:"-" jsonx:"true"`
+}
+
+func main() {
+	var x1, x2 Extra
+	b := []byte(`{"X":"123","Y":123,"A":"123","B":123}`)
+	fmt.Printf("\nUnmarshal input: %s\n", string(b))
+	json.Unmarshal(b, &x1)
+	fmt.Printf(" json.Unmarshal: %#v\n", x1)
+	jsonx.Unmarshal(b, &x2)
+	fmt.Printf("jsonx.Unmarshal: %#v\n", x2)
+
+	x := Extra{X: "456", Y: 456, Extra: map[string]interface{}{"A": "456", "B": 456}}
+	fmt.Printf("\nMarshal input: %#v\n", x)
+	b1, _ := json.Marshal(x)
+	fmt.Printf(" json.Marshal: %s\n", string(b1))
+	b2, _ := jsonx.Marshal(x)
+	fmt.Printf("jsonx.Marshal: %s\n", string(b2))
+}
+```
+
+Result
+
+```text
+Unmarshal input: {"X":"123","Y":123,"A":"123","B":123}
+ json.Unmarshal: main.Extra{X:"123", Y:123, Extra:map[string]interface {}(nil)}
+jsonx.Unmarshal: main.Extra{X:"123", Y:123, Extra:map[string]interface {}{"A":"123", "B":123}}
+
+Marshal input: main.Extra{X:"456", Y:456, Extra:map[string]interface {}{"A":"456", "B":456}}
+ json.Marshal: {"X":"456","Y":456}
+jsonx.Marshal: {"X":"456","Y":456,"A":"456","B":456}
+```
+
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/decode.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/decode.go
new file mode 100644
index 00000000..081d7ad0
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/decode.go
@@ -0,0 +1,1376 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Represents JSON data structure using native Go types: booleans, floats,
+// strings, arrays, and maps.
+
+package jsonx
+
+import (
+	"encoding"
+	"encoding/base64"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+	"unicode"
+	"unicode/utf16"
+	"unicode/utf8"
+)
+
+// Unmarshal parses the JSON-encoded data and stores the result
+// in the value pointed to by v. If v is nil or not a pointer,
+// Unmarshal returns an InvalidUnmarshalError.
+//
+// Unmarshal uses the inverse of the encodings that
+// Marshal uses, allocating maps, slices, and pointers as necessary,
+// with the following additional rules:
+//
+// To unmarshal JSON into a pointer, Unmarshal first handles the case of
+// the JSON being the JSON literal null. In that case, Unmarshal sets
+// the pointer to nil. Otherwise, Unmarshal unmarshals the JSON into
+// the value pointed at by the pointer. If the pointer is nil, Unmarshal
+// allocates a new value for it to point to.
+//
+// To unmarshal JSON into a value implementing the Unmarshaler interface,
+// Unmarshal calls that value's UnmarshalJSON method, including
+// when the input is a JSON null.
+// Otherwise, if the value implements encoding.TextUnmarshaler
+// and the input is a JSON quoted string, Unmarshal calls that value's
+// UnmarshalText method with the unquoted form of the string.
+//
+// To unmarshal JSON into a struct, Unmarshal matches incoming object
+// keys to the keys used by Marshal (either the struct field name or its tag),
+// preferring an exact match but also accepting a case-insensitive match. By
+// default, object keys which don't have a corresponding struct field are
+// ignored (see Decoder.DisallowUnknownFields for an alternative).
+//
+// To unmarshal JSON into an interface value,
+// Unmarshal stores one of these in the interface value:
+//
+//	bool, for JSON booleans
+//	float64, for JSON numbers
+//	string, for JSON strings
+//	[]interface{}, for JSON arrays
+//	map[string]interface{}, for JSON objects
+//	nil for JSON null
+//
+// To unmarshal a JSON array into a slice, Unmarshal resets the slice length
+// to zero and then appends each element to the slice.
+// As a special case, to unmarshal an empty JSON array into a slice,
+// Unmarshal replaces the slice with a new empty slice.
+//
+// To unmarshal a JSON array into a Go array, Unmarshal decodes
+// JSON array elements into corresponding Go array elements.
+// If the Go array is smaller than the JSON array,
+// the additional JSON array elements are discarded.
+// If the JSON array is smaller than the Go array,
+// the additional Go array elements are set to zero values.
+//
+// To unmarshal a JSON object into a map, Unmarshal first establishes a map to
+// use. If the map is nil, Unmarshal allocates a new map. Otherwise Unmarshal
+// reuses the existing map, keeping existing entries. Unmarshal then stores
+// key-value pairs from the JSON object into the map. The map's key type must
+// either be a string, an integer, or implement encoding.TextUnmarshaler.
+//
+// If a JSON value is not appropriate for a given target type,
+// or if a JSON number overflows the target type, Unmarshal
+// skips that field and completes the unmarshaling as best it can.
+// If no more serious errors are encountered, Unmarshal returns
+// an UnmarshalTypeError describing the earliest such error. In any
+// case, it's not guaranteed that all the remaining fields following
+// the problematic one will be unmarshaled into the target object.
+//
+// The JSON null value unmarshals into an interface, map, pointer, or slice
+// by setting that Go value to nil. Because null is often used in JSON to mean
+// ``not present,'' unmarshaling a JSON null into any other Go type has no effect
+// on the value and produces no error.
+//
+// When unmarshaling quoted strings, invalid UTF-8 or
+// invalid UTF-16 surrogate pairs are not treated as an error.
+// Instead, they are replaced by the Unicode replacement
+// character U+FFFD.
+//
+func Unmarshal(data []byte, v interface{}) error {
+	// Check for well-formedness.
+	// Avoids filling out half a data structure
+	// before discovering a JSON syntax error.
+	var d decodeState
+	err := checkValid(data, &d.scan)
+	if err != nil {
+		return err
+	}
+
+	d.init(data)
+	return d.unmarshal(v)
+}
+
+// Unmarshaler is the interface implemented by types
+// that can unmarshal a JSON description of themselves.
+// The input can be assumed to be a valid encoding of
+// a JSON value. UnmarshalJSON must copy the JSON data
+// if it wishes to retain the data after returning.
+//
+// By convention, to approximate the behavior of Unmarshal itself,
+// Unmarshalers implement UnmarshalJSON([]byte("null")) as a no-op.
+type Unmarshaler interface {
+	UnmarshalJSON([]byte) error
+}
+
+// An UnmarshalTypeError describes a JSON value that was
+// not appropriate for a value of a specific Go type.
+type UnmarshalTypeError struct {
+	Value  string       // description of JSON value - "bool", "array", "number -5"
+	Type   reflect.Type // type of Go value it could not be assigned to
+	Offset int64        // error occurred after reading Offset bytes
+	Struct string       // name of the struct type containing the field
+	Field  string       // the full path from root node to the field
+}
+
+func (e *UnmarshalTypeError) Error() string {
+	if e.Struct != "" || e.Field != "" {
+		return "json: cannot unmarshal " + e.Value + " into Go struct field " + e.Struct + "." + e.Field + " of type " + e.Type.String()
+	}
+	return "json: cannot unmarshal " + e.Value + " into Go value of type " + e.Type.String()
+}
+
+// An UnmarshalFieldError describes a JSON object key that
+// led to an unexported (and therefore unwritable) struct field.
+//
+// Deprecated: No longer used; kept for compatibility.
+type UnmarshalFieldError struct {
+	Key   string
+	Type  reflect.Type
+	Field reflect.StructField
+}
+
+func (e *UnmarshalFieldError) Error() string {
+	return "json: cannot unmarshal object key " + strconv.Quote(e.Key) + " into unexported field " + e.Field.Name + " of type " + e.Type.String()
+}
+
+// An InvalidUnmarshalError describes an invalid argument passed to Unmarshal.
+// (The argument to Unmarshal must be a non-nil pointer.)
+type InvalidUnmarshalError struct {
+	Type reflect.Type
+}
+
+func (e *InvalidUnmarshalError) Error() string {
+	if e.Type == nil {
+		return "json: Unmarshal(nil)"
+	}
+
+	if e.Type.Kind() != reflect.Ptr {
+		return "json: Unmarshal(non-pointer " + e.Type.String() + ")"
+	}
+	return "json: Unmarshal(nil " + e.Type.String() + ")"
+}
+
+func (d *decodeState) unmarshal(v interface{}) error {
+	rv := reflect.ValueOf(v)
+	if rv.Kind() != reflect.Ptr || rv.IsNil() {
+		return &InvalidUnmarshalError{reflect.TypeOf(v)}
+	}
+
+	d.scan.reset()
+	d.scanWhile(scanSkipSpace)
+	// We decode rv not rv.Elem because the Unmarshaler interface
+	// test must be applied at the top level of the value.
+	err := d.value(rv)
+	if err != nil {
+		return d.addErrorContext(err)
+	}
+	return d.savedError
+}
+
+// A Number represents a JSON number literal.
+type Number string
+
+// String returns the literal text of the number.
+func (n Number) String() string { return string(n) }
+
+// Float64 returns the number as a float64.
+func (n Number) Float64() (float64, error) {
+	return strconv.ParseFloat(string(n), 64)
+}
+
+// Int64 returns the number as an int64.
+func (n Number) Int64() (int64, error) {
+	return strconv.ParseInt(string(n), 10, 64)
+}
+
+// isValidNumber reports whether s is a valid JSON number literal.
+func isValidNumber(s string) bool {
+	// This function implements the JSON numbers grammar.
+	// See https://tools.ietf.org/html/rfc7159#section-6
+	// and https://json.org/number.gif
+
+	if s == "" {
+		return false
+	}
+
+	// Optional -
+	if s[0] == '-' {
+		s = s[1:]
+		if s == "" {
+			return false
+		}
+	}
+
+	// Digits
+	switch {
+	default:
+		return false
+
+	case s[0] == '0':
+		s = s[1:]
+
+	case '1' <= s[0] && s[0] <= '9':
+		s = s[1:]
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+		}
+	}
+
+	// . followed by 1 or more digits.
+	if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' {
+		s = s[2:]
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+		}
+	}
+
+	// e or E followed by an optional - or + and
+	// 1 or more digits.
+	if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
+		s = s[1:]
+		if s[0] == '+' || s[0] == '-' {
+			s = s[1:]
+			if s == "" {
+				return false
+			}
+		}
+		for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+			s = s[1:]
+		}
+	}
+
+	// Make sure we are at the end.
+	return s == ""
+}
+
+// decodeState represents the state while decoding a JSON value.
+type decodeState struct {
+	data         []byte
+	off          int // next read offset in data
+	opcode       int // last read result
+	scan         scanner
+	errorContext struct { // provides context for type errors
+		Struct     reflect.Type
+		FieldStack []string
+	}
+	savedError            error
+	useNumber             bool
+	disallowUnknownFields bool
+}
+
+// readIndex returns the position of the last byte read.
+func (d *decodeState) readIndex() int {
+	return d.off - 1
+}
+
+// phasePanicMsg is used as a panic message when we end up with something that
+// shouldn't happen. It can indicate a bug in the JSON decoder, or that
+// something is editing the data slice while the decoder executes.
+const phasePanicMsg = "JSON decoder out of sync - data changing underfoot?"
+
+func (d *decodeState) init(data []byte) *decodeState {
+	d.data = data
+	d.off = 0
+	d.savedError = nil
+	d.errorContext.Struct = nil
+
+	// Reuse the allocated space for the FieldStack slice.
+	d.errorContext.FieldStack = d.errorContext.FieldStack[:0]
+	return d
+}
+
+// saveError saves the first err it is called with,
+// for reporting at the end of the unmarshal.
+func (d *decodeState) saveError(err error) {
+	if d.savedError == nil {
+		d.savedError = d.addErrorContext(err)
+	}
+}
+
+// addErrorContext returns a new error enhanced with information from d.errorContext
+func (d *decodeState) addErrorContext(err error) error {
+	if d.errorContext.Struct != nil || len(d.errorContext.FieldStack) > 0 {
+		switch err := err.(type) {
+		case *UnmarshalTypeError:
+			err.Struct = d.errorContext.Struct.Name()
+			err.Field = strings.Join(d.errorContext.FieldStack, ".")
+			return err
+		}
+	}
+	return err
+}
+
+// skip scans to the end of what was started.
+func (d *decodeState) skip() {
+	s, data, i := &d.scan, d.data, d.off
+	depth := len(s.parseState)
+	for {
+		op := s.step(s, data[i])
+		i++
+		if len(s.parseState) < depth {
+			d.off = i
+			d.opcode = op
+			return
+		}
+	}
+}
+
+// scanNext processes the byte at d.data[d.off].
+func (d *decodeState) scanNext() {
+	if d.off < len(d.data) {
+		d.opcode = d.scan.step(&d.scan, d.data[d.off])
+		d.off++
+	} else {
+		d.opcode = d.scan.eof()
+		d.off = len(d.data) + 1 // mark processed EOF with len+1
+	}
+}
+
+// scanWhile processes bytes in d.data[d.off:] until it
+// receives a scan code not equal to op.
+func (d *decodeState) scanWhile(op int) {
+	s, data, i := &d.scan, d.data, d.off
+	for i < len(data) {
+		newOp := s.step(s, data[i])
+		i++
+		if newOp != op {
+			d.opcode = newOp
+			d.off = i
+			return
+		}
+	}
+
+	d.off = len(data) + 1 // mark processed EOF with len+1
+	d.opcode = d.scan.eof()
+}
+
+// rescanLiteral is similar to scanWhile(scanContinue), but it specialises the
+// common case where we're decoding a literal. The decoder scans the input
+// twice, once for syntax errors and to check the length of the value, and the
+// second to perform the decoding.
+//
+// Only in the second step do we use decodeState to tokenize literals, so we
+// know there aren't any syntax errors. We can take advantage of that knowledge,
+// and scan a literal's bytes much more quickly.
+func (d *decodeState) rescanLiteral() {
+	data, i := d.data, d.off
+Switch:
+	switch data[i-1] {
+	case '"': // string
+		for ; i < len(data); i++ {
+			switch data[i] {
+			case '\\':
+				i++ // escaped char
+			case '"':
+				i++ // tokenize the closing quote too
+				break Switch
+			}
+		}
+	case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-': // number
+		for ; i < len(data); i++ {
+			switch data[i] {
+			case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+				'.', 'e', 'E', '+', '-':
+			default:
+				break Switch
+			}
+		}
+	case 't': // true
+		i += len("rue")
+	case 'f': // false
+		i += len("alse")
+	case 'n': // null
+		i += len("ull")
+	}
+	if i < len(data) {
+		d.opcode = stateEndValue(&d.scan, data[i])
+	} else {
+		d.opcode = scanEnd
+	}
+	d.off = i + 1
+}
+
+// value consumes a JSON value from d.data[d.off-1:], decoding into v, and
+// reads the following byte ahead. If v is invalid, the value is discarded.
+// The first byte of the value has been read already.
+func (d *decodeState) value(v reflect.Value) error {
+	switch d.opcode {
+	default:
+		panic(phasePanicMsg)
+
+	case scanBeginArray:
+		if v.IsValid() {
+			if err := d.array(v); err != nil {
+				return err
+			}
+		} else {
+			d.skip()
+		}
+		d.scanNext()
+
+	case scanBeginObject:
+		if v.IsValid() {
+			if err := d.object(v); err != nil {
+				return err
+			}
+		} else {
+			d.skip()
+		}
+		d.scanNext()
+
+	case scanBeginLiteral:
+		// All bytes inside literal return scanContinue op code.
+		start := d.readIndex()
+		d.rescanLiteral()
+
+		if v.IsValid() {
+			if err := d.literalStore(d.data[start:d.readIndex()], v, false); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+type unquotedValue struct{}
+
+// valueQuoted is like value but decodes a
+// quoted string literal or literal null into an interface value.
+// If it finds anything other than a quoted string literal or null,
+// valueQuoted returns unquotedValue{}.
+func (d *decodeState) valueQuoted() interface{} {
+	switch d.opcode {
+	default:
+		panic(phasePanicMsg)
+
+	case scanBeginArray, scanBeginObject:
+		d.skip()
+		d.scanNext()
+
+	case scanBeginLiteral:
+		v := d.literalInterface()
+		switch v.(type) {
+		case nil, string:
+			return v
+		}
+	}
+	return unquotedValue{}
+}
+
+// indirect walks down v allocating pointers as needed,
+// until it gets to a non-pointer.
+// if it encounters an Unmarshaler, indirect stops and returns that.
+// if decodingNull is true, indirect stops at the last pointer so it can be set to nil.
+func indirect(v reflect.Value, decodingNull bool) (Unmarshaler, encoding.TextUnmarshaler, reflect.Value) {
+	// Issue #24153 indicates that it is generally not a guaranteed property
+	// that you may round-trip a reflect.Value by calling Value.Addr().Elem()
+	// and expect the value to still be settable for values derived from
+	// unexported embedded struct fields.
+	//
+	// The logic below effectively does this when it first addresses the value
+	// (to satisfy possible pointer methods) and continues to dereference
+	// subsequent pointers as necessary.
+	//
+	// After the first round-trip, we set v back to the original value to
+	// preserve the original RW flags contained in reflect.Value.
+	v0 := v
+	haveAddr := false
+
+	// If v is a named type and is addressable,
+	// start with its address, so that if the type has pointer methods,
+	// we find them.
+	if v.Kind() != reflect.Ptr && v.Type().Name() != "" && v.CanAddr() {
+		haveAddr = true
+		v = v.Addr()
+	}
+	for {
+		// Load value from interface, but only if the result will be
+		// usefully addressable.
+		if v.Kind() == reflect.Interface && !v.IsNil() {
+			e := v.Elem()
+			if e.Kind() == reflect.Ptr && !e.IsNil() && (!decodingNull || e.Elem().Kind() == reflect.Ptr) {
+				haveAddr = false
+				v = e
+				continue
+			}
+		}
+
+		if v.Kind() != reflect.Ptr {
+			break
+		}
+
+		if v.Elem().Kind() != reflect.Ptr && decodingNull && v.CanSet() {
+			break
+		}
+
+		// Prevent infinite loop if v is an interface pointing to its own address:
+		//     var v interface{}
+		//     v = &v
+		if v.Elem().Kind() == reflect.Interface && v.Elem().Elem() == v {
+			v = v.Elem()
+			break
+		}
+		if v.IsNil() {
+			v.Set(reflect.New(v.Type().Elem()))
+		}
+		if v.Type().NumMethod() > 0 && v.CanInterface() {
+			if u, ok := v.Interface().(Unmarshaler); ok {
+				return u, nil, reflect.Value{}
+			}
+			if !decodingNull {
+				if u, ok := v.Interface().(encoding.TextUnmarshaler); ok {
+					return nil, u, reflect.Value{}
+				}
+			}
+		}
+
+		if haveAddr {
+			v = v0 // restore original value after round-trip Value.Addr().Elem()
+			haveAddr = false
+		} else {
+			v = v.Elem()
+		}
+	}
+	return nil, nil, v
+}
+
+// array consumes an array from d.data[d.off-1:], decoding into v.
+// The first byte of the array ('[') has been read already.
+func (d *decodeState) array(v reflect.Value) error {
+	// Check for unmarshaler.
+	u, ut, pv := indirect(v, false)
+	if u != nil {
+		start := d.readIndex()
+		d.skip()
+		return u.UnmarshalJSON(d.data[start:d.off])
+	}
+	if ut != nil {
+		d.saveError(&UnmarshalTypeError{Value: "array", Type: v.Type(), Offset: int64(d.off)})
+		d.skip()
+		return nil
+	}
+	v = pv
+
+	// Check type of target.
+	switch v.Kind() {
+	case reflect.Interface:
+		if v.NumMethod() == 0 {
+			// Decoding into nil interface? Switch to non-reflect code.
+			ai := d.arrayInterface()
+			v.Set(reflect.ValueOf(ai))
+			return nil
+		}
+		// Otherwise it's invalid.
+		fallthrough
+	default:
+		d.saveError(&UnmarshalTypeError{Value: "array", Type: v.Type(), Offset: int64(d.off)})
+		d.skip()
+		return nil
+	case reflect.Array, reflect.Slice:
+		break
+	}
+
+	i := 0
+	for {
+		// Look ahead for ] - can only happen on first iteration.
+		d.scanWhile(scanSkipSpace)
+		if d.opcode == scanEndArray {
+			break
+		}
+
+		// Get element of array, growing if necessary.
+		if v.Kind() == reflect.Slice {
+			// Grow slice if necessary
+			if i >= v.Cap() {
+				newcap := v.Cap() + v.Cap()/2
+				if newcap < 4 {
+					newcap = 4
+				}
+				newv := reflect.MakeSlice(v.Type(), v.Len(), newcap)
+				reflect.Copy(newv, v)
+				v.Set(newv)
+			}
+			if i >= v.Len() {
+				v.SetLen(i + 1)
+			}
+		}
+
+		if i < v.Len() {
+			// Decode into element.
+			if err := d.value(v.Index(i)); err != nil {
+				return err
+			}
+		} else {
+			// Ran out of fixed array: skip.
+			if err := d.value(reflect.Value{}); err != nil {
+				return err
+			}
+		}
+		i++
+
+		// Next token must be , or ].
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode == scanEndArray {
+			break
+		}
+		if d.opcode != scanArrayValue {
+			panic(phasePanicMsg)
+		}
+	}
+
+	if i < v.Len() {
+		if v.Kind() == reflect.Array {
+			// Array. Zero the rest.
+			z := reflect.Zero(v.Type().Elem())
+			for ; i < v.Len(); i++ {
+				v.Index(i).Set(z)
+			}
+		} else {
+			v.SetLen(i)
+		}
+	}
+	if i == 0 && v.Kind() == reflect.Slice {
+		v.Set(reflect.MakeSlice(v.Type(), 0, 0))
+	}
+	return nil
+}
+
+var nullLiteral = []byte("null")
+var textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+
+// object consumes an object from d.data[d.off-1:], decoding into v.
+// The first byte ('{') of the object has been read already.
+func (d *decodeState) object(v reflect.Value) error {
+	// Check for unmarshaler.
+	u, ut, pv := indirect(v, false)
+	if u != nil {
+		start := d.readIndex()
+		d.skip()
+		return u.UnmarshalJSON(d.data[start:d.off])
+	}
+	if ut != nil {
+		d.saveError(&UnmarshalTypeError{Value: "object", Type: v.Type(), Offset: int64(d.off)})
+		d.skip()
+		return nil
+	}
+	v = pv
+	t := v.Type()
+
+	// Decoding into nil interface? Switch to non-reflect code.
+	if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
+		oi := d.objectInterface()
+		v.Set(reflect.ValueOf(oi))
+		return nil
+	}
+
+	var fields structFields
+
+	// Check type of target:
+	//   struct or
+	//   map[T1]T2 where T1 is string, an integer type,
+	//             or an encoding.TextUnmarshaler
+	switch v.Kind() {
+	case reflect.Map:
+		// Map key must either have string kind, have an integer kind,
+		// or be an encoding.TextUnmarshaler.
+		switch t.Key().Kind() {
+		case reflect.String,
+			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		default:
+			if !reflect.PtrTo(t.Key()).Implements(textUnmarshalerType) {
+				d.saveError(&UnmarshalTypeError{Value: "object", Type: t, Offset: int64(d.off)})
+				d.skip()
+				return nil
+			}
+		}
+		if v.IsNil() {
+			v.Set(reflect.MakeMap(t))
+		}
+	case reflect.Struct:
+		fields = cachedTypeFields(t)
+		// ok
+	default:
+		d.saveError(&UnmarshalTypeError{Value: "object", Type: t, Offset: int64(d.off)})
+		d.skip()
+		return nil
+	}
+
+	var mapElem, extraMapElem reflect.Value
+	origErrorContext := d.errorContext
+
+	for {
+		// Read opening " of string key or closing }.
+		d.scanWhile(scanSkipSpace)
+		if d.opcode == scanEndObject {
+			// closing } - can only happen on first iteration.
+			break
+		}
+		if d.opcode != scanBeginLiteral {
+			panic(phasePanicMsg)
+		}
+
+		// Read key.
+		start := d.readIndex()
+		d.rescanLiteral()
+		item := d.data[start:d.readIndex()]
+		key, ok := unquoteBytes(item)
+		if !ok {
+			panic(phasePanicMsg)
+		}
+
+		// Figure out field corresponding to key.
+		var subv, mapv reflect.Value
+		destring := false // whether the value is wrapped in a string to be decoded first
+
+		if v.Kind() == reflect.Map {
+			elemType := t.Elem()
+			if !mapElem.IsValid() {
+				mapElem = reflect.New(elemType).Elem()
+			} else {
+				mapElem.Set(reflect.Zero(elemType))
+			}
+			subv = mapElem
+			mapv = v
+		} else {
+			var f, extraf *field
+			if i, ok := fields.nameIndex[string(key)]; ok {
+				// Found an exact name match.
+				f = &fields.list[i]
+			} else {
+				// Fall back to the expensive case-insensitive
+				// linear search.
+				for i := range fields.list {
+					ff := &fields.list[i]
+					if ff.equalFold(ff.nameBytes, key) {
+						f = ff
+						break
+					}
+					if ff.extra && extraf == nil {
+						extraf = ff
+					}
+				}
+			}
+			if f == nil {
+				f = extraf
+			}
+			if f != nil {
+				subv = v
+				destring = f.quoted
+				for _, i := range f.index {
+					if subv.Kind() == reflect.Ptr {
+						if subv.IsNil() {
+							// If a struct embeds a pointer to an unexported type,
+							// it is not possible to set a newly allocated value
+							// since the field is unexported.
+							//
+							// See https://golang.org/issue/21357
+							if !subv.CanSet() {
+								d.saveError(fmt.Errorf("json: cannot set embedded pointer to unexported struct: %v", subv.Type().Elem()))
+								// Invalidate subv to ensure d.value(subv) skips over
+								// the JSON value without assigning it to subv.
+								subv = reflect.Value{}
+								destring = false
+								break
+							}
+							subv.Set(reflect.New(subv.Type().Elem()))
+						}
+						subv = subv.Elem()
+					}
+					subv = subv.Field(i)
+				}
+				if f == extraf {
+					// subv is extra map
+					mapv = subv
+					if mapv.IsNil() {
+						mapv.Set(reflect.MakeMap(mapv.Type()))
+					}
+					elemType := mapv.Type().Elem()
+					if !extraMapElem.IsValid() {
+						extraMapElem = reflect.New(elemType).Elem()
+					} else {
+						extraMapElem.Set(reflect.Zero(elemType))
+					}
+					subv = extraMapElem
+				}
+				d.errorContext.FieldStack = append(d.errorContext.FieldStack, f.name)
+				d.errorContext.Struct = t
+			} else if d.disallowUnknownFields {
+				d.saveError(fmt.Errorf("json: unknown field %q", key))
+			}
+		}
+
+		// Read : before value.
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode != scanObjectKey {
+			panic(phasePanicMsg)
+		}
+		d.scanWhile(scanSkipSpace)
+
+		if destring {
+			switch qv := d.valueQuoted().(type) {
+			case nil:
+				if err := d.literalStore(nullLiteral, subv, false); err != nil {
+					return err
+				}
+			case string:
+				if err := d.literalStore([]byte(qv), subv, true); err != nil {
+					return err
+				}
+			default:
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal unquoted value into %v", subv.Type()))
+			}
+		} else {
+			if err := d.value(subv); err != nil {
+				return err
+			}
+		}
+
+		// Write value back to map;
+		// if using struct, subv points into struct already.
+		if mapv.IsValid() {
+			kt := mapv.Type().Key()
+			var kv reflect.Value
+			switch {
+			case kt.Kind() == reflect.String:
+				kv = reflect.ValueOf(key).Convert(kt)
+			case reflect.PtrTo(kt).Implements(textUnmarshalerType):
+				kv = reflect.New(kt)
+				if err := d.literalStore(item, kv, true); err != nil {
+					return err
+				}
+				kv = kv.Elem()
+			default:
+				switch kt.Kind() {
+				case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+					s := string(key)
+					n, err := strconv.ParseInt(s, 10, 64)
+					if err != nil || reflect.Zero(kt).OverflowInt(n) {
+						d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: kt, Offset: int64(start + 1)})
+						break
+					}
+					kv = reflect.ValueOf(n).Convert(kt)
+				case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+					s := string(key)
+					n, err := strconv.ParseUint(s, 10, 64)
+					if err != nil || reflect.Zero(kt).OverflowUint(n) {
+						d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: kt, Offset: int64(start + 1)})
+						break
+					}
+					kv = reflect.ValueOf(n).Convert(kt)
+				default:
+					panic("json: Unexpected key type") // should never occur
+				}
+			}
+			if kv.IsValid() {
+				mapv.SetMapIndex(kv, subv)
+			}
+		}
+
+		// Next token must be , or }.
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		// Reset errorContext to its original state.
+		// Keep the same underlying array for FieldStack, to reuse the
+		// space and avoid unnecessary allocs.
+		d.errorContext.FieldStack = d.errorContext.FieldStack[:len(origErrorContext.FieldStack)]
+		d.errorContext.Struct = origErrorContext.Struct
+		if d.opcode == scanEndObject {
+			break
+		}
+		if d.opcode != scanObjectValue {
+			panic(phasePanicMsg)
+		}
+	}
+	return nil
+}
+
+// convertNumber converts the number literal s to a float64 or a Number
+// depending on the setting of d.useNumber.
+func (d *decodeState) convertNumber(s string) (interface{}, error) {
+	if d.useNumber {
+		return Number(s), nil
+	}
+	f, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return nil, &UnmarshalTypeError{Value: "number " + s, Type: reflect.TypeOf(0.0), Offset: int64(d.off)}
+	}
+	return f, nil
+}
+
+var numberType = reflect.TypeOf(Number(""))
+
+// literalStore decodes a literal stored in item into v.
+//
+// fromQuoted indicates whether this literal came from unwrapping a
+// string from the ",string" struct tag option. this is used only to
+// produce more helpful error messages.
+func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool) error {
+	// Check for unmarshaler.
+	if len(item) == 0 {
+		//Empty string given
+		d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+		return nil
+	}
+	isNull := item[0] == 'n' // null
+	u, ut, pv := indirect(v, isNull)
+	if u != nil {
+		return u.UnmarshalJSON(item)
+	}
+	if ut != nil {
+		if item[0] != '"' {
+			if fromQuoted {
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+				return nil
+			}
+			val := "number"
+			switch item[0] {
+			case 'n':
+				val = "null"
+			case 't', 'f':
+				val = "bool"
+			}
+			d.saveError(&UnmarshalTypeError{Value: val, Type: v.Type(), Offset: int64(d.readIndex())})
+			return nil
+		}
+		s, ok := unquoteBytes(item)
+		if !ok {
+			if fromQuoted {
+				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
+			}
+			panic(phasePanicMsg)
+		}
+		return ut.UnmarshalText(s)
+	}
+
+	v = pv
+
+	switch c := item[0]; c {
+	case 'n': // null
+		// The main parser checks that only true and false can reach here,
+		// but if this was a quoted string input, it could be anything.
+		if fromQuoted && string(item) != "null" {
+			d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			break
+		}
+		switch v.Kind() {
+		case reflect.Interface, reflect.Ptr, reflect.Map, reflect.Slice:
+			v.Set(reflect.Zero(v.Type()))
+			// otherwise, ignore null for primitives/string
+		}
+	case 't', 'f': // true, false
+		value := item[0] == 't'
+		// The main parser checks that only true and false can reach here,
+		// but if this was a quoted string input, it could be anything.
+		if fromQuoted && string(item) != "true" && string(item) != "false" {
+			d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			break
+		}
+		switch v.Kind() {
+		default:
+			if fromQuoted {
+				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
+			} else {
+				d.saveError(&UnmarshalTypeError{Value: "bool", Type: v.Type(), Offset: int64(d.readIndex())})
+			}
+		case reflect.Bool:
+			v.SetBool(value)
+		case reflect.Interface:
+			if v.NumMethod() == 0 {
+				v.Set(reflect.ValueOf(value))
+			} else {
+				d.saveError(&UnmarshalTypeError{Value: "bool", Type: v.Type(), Offset: int64(d.readIndex())})
+			}
+		}
+
+	case '"': // string
+		s, ok := unquoteBytes(item)
+		if !ok {
+			if fromQuoted {
+				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
+			}
+			panic(phasePanicMsg)
+		}
+		switch v.Kind() {
+		default:
+			d.saveError(&UnmarshalTypeError{Value: "string", Type: v.Type(), Offset: int64(d.readIndex())})
+		case reflect.Slice:
+			if v.Type().Elem().Kind() != reflect.Uint8 {
+				d.saveError(&UnmarshalTypeError{Value: "string", Type: v.Type(), Offset: int64(d.readIndex())})
+				break
+			}
+			b := make([]byte, base64.StdEncoding.DecodedLen(len(s)))
+			n, err := base64.StdEncoding.Decode(b, s)
+			if err != nil {
+				d.saveError(err)
+				break
+			}
+			v.SetBytes(b[:n])
+		case reflect.String:
+			v.SetString(string(s))
+		case reflect.Interface:
+			if v.NumMethod() == 0 {
+				v.Set(reflect.ValueOf(string(s)))
+			} else {
+				d.saveError(&UnmarshalTypeError{Value: "string", Type: v.Type(), Offset: int64(d.readIndex())})
+			}
+		}
+
+	default: // number
+		if c != '-' && (c < '0' || c > '9') {
+			if fromQuoted {
+				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
+			}
+			panic(phasePanicMsg)
+		}
+		s := string(item)
+		switch v.Kind() {
+		default:
+			if v.Kind() == reflect.String && v.Type() == numberType {
+				v.SetString(s)
+				if !isValidNumber(s) {
+					return fmt.Errorf("json: invalid number literal, trying to unmarshal %q into Number", item)
+				}
+				break
+			}
+			if fromQuoted {
+				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
+			}
+			d.saveError(&UnmarshalTypeError{Value: "number", Type: v.Type(), Offset: int64(d.readIndex())})
+		case reflect.Interface:
+			n, err := d.convertNumber(s)
+			if err != nil {
+				d.saveError(err)
+				break
+			}
+			if v.NumMethod() != 0 {
+				d.saveError(&UnmarshalTypeError{Value: "number", Type: v.Type(), Offset: int64(d.readIndex())})
+				break
+			}
+			v.Set(reflect.ValueOf(n))
+
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			n, err := strconv.ParseInt(s, 10, 64)
+			if err != nil || v.OverflowInt(n) {
+				d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: v.Type(), Offset: int64(d.readIndex())})
+				break
+			}
+			v.SetInt(n)
+
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+			n, err := strconv.ParseUint(s, 10, 64)
+			if err != nil || v.OverflowUint(n) {
+				d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: v.Type(), Offset: int64(d.readIndex())})
+				break
+			}
+			v.SetUint(n)
+
+		case reflect.Float32, reflect.Float64:
+			n, err := strconv.ParseFloat(s, v.Type().Bits())
+			if err != nil || v.OverflowFloat(n) {
+				d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: v.Type(), Offset: int64(d.readIndex())})
+				break
+			}
+			v.SetFloat(n)
+		}
+	}
+	return nil
+}
+
+// The xxxInterface routines build up a value to be stored
+// in an empty interface. They are not strictly necessary,
+// but they avoid the weight of reflection in this common case.
+
+// valueInterface is like value but returns interface{}
+func (d *decodeState) valueInterface() (val interface{}) {
+	switch d.opcode {
+	default:
+		panic(phasePanicMsg)
+	case scanBeginArray:
+		val = d.arrayInterface()
+		d.scanNext()
+	case scanBeginObject:
+		val = d.objectInterface()
+		d.scanNext()
+	case scanBeginLiteral:
+		val = d.literalInterface()
+	}
+	return
+}
+
+// arrayInterface is like array but returns []interface{}.
+func (d *decodeState) arrayInterface() []interface{} {
+	var v = make([]interface{}, 0)
+	for {
+		// Look ahead for ] - can only happen on first iteration.
+		d.scanWhile(scanSkipSpace)
+		if d.opcode == scanEndArray {
+			break
+		}
+
+		v = append(v, d.valueInterface())
+
+		// Next token must be , or ].
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode == scanEndArray {
+			break
+		}
+		if d.opcode != scanArrayValue {
+			panic(phasePanicMsg)
+		}
+	}
+	return v
+}
+
+// objectInterface is like object but returns map[string]interface{}.
+func (d *decodeState) objectInterface() map[string]interface{} {
+	m := make(map[string]interface{})
+	for {
+		// Read opening " of string key or closing }.
+		d.scanWhile(scanSkipSpace)
+		if d.opcode == scanEndObject {
+			// closing } - can only happen on first iteration.
+			break
+		}
+		if d.opcode != scanBeginLiteral {
+			panic(phasePanicMsg)
+		}
+
+		// Read string key.
+		start := d.readIndex()
+		d.rescanLiteral()
+		item := d.data[start:d.readIndex()]
+		key, ok := unquote(item)
+		if !ok {
+			panic(phasePanicMsg)
+		}
+
+		// Read : before value.
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode != scanObjectKey {
+			panic(phasePanicMsg)
+		}
+		d.scanWhile(scanSkipSpace)
+
+		// Read value.
+		m[key] = d.valueInterface()
+
+		// Next token must be , or }.
+		if d.opcode == scanSkipSpace {
+			d.scanWhile(scanSkipSpace)
+		}
+		if d.opcode == scanEndObject {
+			break
+		}
+		if d.opcode != scanObjectValue {
+			panic(phasePanicMsg)
+		}
+	}
+	return m
+}
+
+// literalInterface consumes and returns a literal from d.data[d.off-1:] and
+// it reads the following byte ahead. The first byte of the literal has been
+// read already (that's how the caller knows it's a literal).
+func (d *decodeState) literalInterface() interface{} {
+	// All bytes inside literal return scanContinue op code.
+	start := d.readIndex()
+	d.rescanLiteral()
+
+	item := d.data[start:d.readIndex()]
+
+	switch c := item[0]; c {
+	case 'n': // null
+		return nil
+
+	case 't', 'f': // true, false
+		return c == 't'
+
+	case '"': // string
+		s, ok := unquote(item)
+		if !ok {
+			panic(phasePanicMsg)
+		}
+		return s
+
+	default: // number
+		if c != '-' && (c < '0' || c > '9') {
+			panic(phasePanicMsg)
+		}
+		n, err := d.convertNumber(string(item))
+		if err != nil {
+			d.saveError(err)
+		}
+		return n
+	}
+}
+
+// getu4 decodes \uXXXX from the beginning of s, returning the hex value,
+// or it returns -1.
+func getu4(s []byte) rune {
+	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
+		return -1
+	}
+	var r rune
+	for _, c := range s[2:6] {
+		switch {
+		case '0' <= c && c <= '9':
+			c = c - '0'
+		case 'a' <= c && c <= 'f':
+			c = c - 'a' + 10
+		case 'A' <= c && c <= 'F':
+			c = c - 'A' + 10
+		default:
+			return -1
+		}
+		r = r*16 + rune(c)
+	}
+	return r
+}
+
+// unquote converts a quoted JSON string literal s into an actual string t.
+// The rules are different than for Go, so cannot use strconv.Unquote.
+func unquote(s []byte) (t string, ok bool) {
+	s, ok = unquoteBytes(s)
+	t = string(s)
+	return
+}
+
+func unquoteBytes(s []byte) (t []byte, ok bool) {
+	if len(s) < 2 || s[0] != '"' || s[len(s)-1] != '"' {
+		return
+	}
+	s = s[1 : len(s)-1]
+
+	// Check for unusual characters. If there are none,
+	// then no unquoting is needed, so return a slice of the
+	// original bytes.
+	r := 0
+	for r < len(s) {
+		c := s[r]
+		if c == '\\' || c == '"' || c < ' ' {
+			break
+		}
+		if c < utf8.RuneSelf {
+			r++
+			continue
+		}
+		rr, size := utf8.DecodeRune(s[r:])
+		if rr == utf8.RuneError && size == 1 {
+			break
+		}
+		r += size
+	}
+	if r == len(s) {
+		return s, true
+	}
+
+	b := make([]byte, len(s)+2*utf8.UTFMax)
+	w := copy(b, s[0:r])
+	for r < len(s) {
+		// Out of room? Can only happen if s is full of
+		// malformed UTF-8 and we're replacing each
+		// byte with RuneError.
+		if w >= len(b)-2*utf8.UTFMax {
+			nb := make([]byte, (len(b)+utf8.UTFMax)*2)
+			copy(nb, b[0:w])
+			b = nb
+		}
+		switch c := s[r]; {
+		case c == '\\':
+			r++
+			if r >= len(s) {
+				return
+			}
+			switch s[r] {
+			default:
+				return
+			case '"', '\\', '/', '\'':
+				b[w] = s[r]
+				r++
+				w++
+			case 'b':
+				b[w] = '\b'
+				r++
+				w++
+			case 'f':
+				b[w] = '\f'
+				r++
+				w++
+			case 'n':
+				b[w] = '\n'
+				r++
+				w++
+			case 'r':
+				b[w] = '\r'
+				r++
+				w++
+			case 't':
+				b[w] = '\t'
+				r++
+				w++
+			case 'u':
+				r--
+				rr := getu4(s[r:])
+				if rr < 0 {
+					return
+				}
+				r += 6
+				if utf16.IsSurrogate(rr) {
+					rr1 := getu4(s[r:])
+					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
+						// A valid pair; consume.
+						r += 6
+						w += utf8.EncodeRune(b[w:], dec)
+						break
+					}
+					// Invalid surrogate; fall back to replacement rune.
+					rr = unicode.ReplacementChar
+				}
+				w += utf8.EncodeRune(b[w:], rr)
+			}
+
+		// Quote, control characters are invalid.
+		case c == '"', c < ' ':
+			return
+
+		// ASCII
+		case c < utf8.RuneSelf:
+			b[w] = c
+			r++
+			w++
+
+		// Coerce to well-formed UTF-8.
+		default:
+			rr, size := utf8.DecodeRune(s[r:])
+			r += size
+			w += utf8.EncodeRune(b[w:], rr)
+		}
+	}
+	return b[0:w], true
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/encode.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/encode.go
new file mode 100644
index 00000000..7c155502
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/encode.go
@@ -0,0 +1,1317 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package json implements encoding and decoding of JSON as defined in
+// RFC 7159. The mapping between JSON and Go values is described
+// in the documentation for the Marshal and Unmarshal functions.
+//
+// See "JSON and Go" for an introduction to this package:
+// https://golang.org/doc/articles/json_and_go.html
+package jsonx
+
+import (
+	"bytes"
+	"encoding"
+	"encoding/base64"
+	"fmt"
+	"math"
+	"reflect"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"unicode"
+	"unicode/utf8"
+)
+
+// Marshal returns the JSON encoding of v.
+//
+// Marshal traverses the value v recursively.
+// If an encountered value implements the Marshaler interface
+// and is not a nil pointer, Marshal calls its MarshalJSON method
+// to produce JSON. If no MarshalJSON method is present but the
+// value implements encoding.TextMarshaler instead, Marshal calls
+// its MarshalText method and encodes the result as a JSON string.
+// The nil pointer exception is not strictly necessary
+// but mimics a similar, necessary exception in the behavior of
+// UnmarshalJSON.
+//
+// Otherwise, Marshal uses the following type-dependent default encodings:
+//
+// Boolean values encode as JSON booleans.
+//
+// Floating point, integer, and Number values encode as JSON numbers.
+//
+// String values encode as JSON strings coerced to valid UTF-8,
+// replacing invalid bytes with the Unicode replacement rune.
+// So that the JSON will be safe to embed inside HTML <script> tags,
+// the string is encoded using HTMLEscape,
+// which replaces "<", ">", "&", U+2028, and U+2029 are escaped
+// to "\u003c","\u003e", "\u0026", "\u2028", and "\u2029".
+// This replacement can be disabled when using an Encoder,
+// by calling SetEscapeHTML(false).
+//
+// Array and slice values encode as JSON arrays, except that
+// []byte encodes as a base64-encoded string, and a nil slice
+// encodes as the null JSON value.
+//
+// Struct values encode as JSON objects.
+// Each exported struct field becomes a member of the object, using the
+// field name as the object key, unless the field is omitted for one of the
+// reasons given below.
+//
+// The encoding of each struct field can be customized by the format string
+// stored under the "json" key in the struct field's tag.
+// The format string gives the name of the field, possibly followed by a
+// comma-separated list of options. The name may be empty in order to
+// specify options without overriding the default field name.
+//
+// The "omitempty" option specifies that the field should be omitted
+// from the encoding if the field has an empty value, defined as
+// false, 0, a nil pointer, a nil interface value, and any empty array,
+// slice, map, or string.
+//
+// As a special case, if the field tag is "-", the field is always omitted.
+// Note that a field with name "-" can still be generated using the tag "-,".
+//
+// Examples of struct field tags and their meanings:
+//
+//   // Field appears in JSON as key "myName".
+//   Field int `json:"myName"`
+//
+//   // Field appears in JSON as key "myName" and
+//   // the field is omitted from the object if its value is empty,
+//   // as defined above.
+//   Field int `json:"myName,omitempty"`
+//
+//   // Field appears in JSON as key "Field" (the default), but
+//   // the field is skipped if empty.
+//   // Note the leading comma.
+//   Field int `json:",omitempty"`
+//
+//   // Field is ignored by this package.
+//   Field int `json:"-"`
+//
+//   // Field appears in JSON as key "-".
+//   Field int `json:"-,"`
+//
+// The "string" option signals that a field is stored as JSON inside a
+// JSON-encoded string. It applies only to fields of string, floating point,
+// integer, or boolean types. This extra level of encoding is sometimes used
+// when communicating with JavaScript programs:
+//
+//    Int64String int64 `json:",string"`
+//
+// The key name will be used if it's a non-empty string consisting of
+// only Unicode letters, digits, and ASCII punctuation except quotation
+// marks, backslash, and comma.
+//
+// Anonymous struct fields are usually marshaled as if their inner exported fields
+// were fields in the outer struct, subject to the usual Go visibility rules amended
+// as described in the next paragraph.
+// An anonymous struct field with a name given in its JSON tag is treated as
+// having that name, rather than being anonymous.
+// An anonymous struct field of interface type is treated the same as having
+// that type as its name, rather than being anonymous.
+//
+// The Go visibility rules for struct fields are amended for JSON when
+// deciding which field to marshal or unmarshal. If there are
+// multiple fields at the same level, and that level is the least
+// nested (and would therefore be the nesting level selected by the
+// usual Go rules), the following extra rules apply:
+//
+// 1) Of those fields, if any are JSON-tagged, only tagged fields are considered,
+// even if there are multiple untagged fields that would otherwise conflict.
+//
+// 2) If there is exactly one field (tagged or not according to the first rule), that is selected.
+//
+// 3) Otherwise there are multiple fields, and all are ignored; no error occurs.
+//
+// Handling of anonymous struct fields is new in Go 1.1.
+// Prior to Go 1.1, anonymous struct fields were ignored. To force ignoring of
+// an anonymous struct field in both current and earlier versions, give the field
+// a JSON tag of "-".
+//
+// Map values encode as JSON objects. The map's key type must either be a
+// string, an integer type, or implement encoding.TextMarshaler. The map keys
+// are sorted and used as JSON object keys by applying the following rules,
+// subject to the UTF-8 coercion described for string values above:
+//   - keys of any string type are used directly
+//   - encoding.TextMarshalers are marshaled
+//   - integer keys are converted to strings
+//
+// Pointer values encode as the value pointed to.
+// A nil pointer encodes as the null JSON value.
+//
+// Interface values encode as the value contained in the interface.
+// A nil interface value encodes as the null JSON value.
+//
+// Channel, complex, and function values cannot be encoded in JSON.
+// Attempting to encode such a value causes Marshal to return
+// an UnsupportedTypeError.
+//
+// JSON cannot represent cyclic data structures and Marshal does not
+// handle them. Passing cyclic structures to Marshal will result in
+// an infinite recursion.
+//
+func Marshal(v interface{}) ([]byte, error) {
+	e := newEncodeState()
+
+	err := e.marshal(v, encOpts{escapeHTML: true})
+	if err != nil {
+		return nil, err
+	}
+	buf := append([]byte(nil), e.Bytes()...)
+
+	e.Reset()
+	encodeStatePool.Put(e)
+
+	return buf, nil
+}
+
+// MarshalIndent is like Marshal but applies Indent to format the output.
+// Each JSON element in the output will begin on a new line beginning with prefix
+// followed by one or more copies of indent according to the indentation nesting.
+func MarshalIndent(v interface{}, prefix, indent string) ([]byte, error) {
+	b, err := Marshal(v)
+	if err != nil {
+		return nil, err
+	}
+	var buf bytes.Buffer
+	err = Indent(&buf, b, prefix, indent)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+// HTMLEscape appends to dst the JSON-encoded src with <, >, &, U+2028 and U+2029
+// characters inside string literals changed to \u003c, \u003e, \u0026, \u2028, \u2029
+// so that the JSON will be safe to embed inside HTML <script> tags.
+// For historical reasons, web browsers don't honor standard HTML
+// escaping within <script> tags, so an alternative JSON encoding must
+// be used.
+func HTMLEscape(dst *bytes.Buffer, src []byte) {
+	// The characters can only appear in string literals,
+	// so just scan the string one byte at a time.
+	start := 0
+	for i, c := range src {
+		if c == '<' || c == '>' || c == '&' {
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			dst.WriteString(`\u00`)
+			dst.WriteByte(hex[c>>4])
+			dst.WriteByte(hex[c&0xF])
+			start = i + 1
+		}
+		// Convert U+2028 and U+2029 (E2 80 A8 and E2 80 A9).
+		if c == 0xE2 && i+2 < len(src) && src[i+1] == 0x80 && src[i+2]&^1 == 0xA8 {
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			dst.WriteString(`\u202`)
+			dst.WriteByte(hex[src[i+2]&0xF])
+			start = i + 3
+		}
+	}
+	if start < len(src) {
+		dst.Write(src[start:])
+	}
+}
+
+// Marshaler is the interface implemented by types that
+// can marshal themselves into valid JSON.
+type Marshaler interface {
+	MarshalJSON() ([]byte, error)
+}
+
+// An UnsupportedTypeError is returned by Marshal when attempting
+// to encode an unsupported value type.
+type UnsupportedTypeError struct {
+	Type reflect.Type
+}
+
+func (e *UnsupportedTypeError) Error() string {
+	return "json: unsupported type: " + e.Type.String()
+}
+
+type UnsupportedValueError struct {
+	Value reflect.Value
+	Str   string
+}
+
+func (e *UnsupportedValueError) Error() string {
+	return "json: unsupported value: " + e.Str
+}
+
+// Before Go 1.2, an InvalidUTF8Error was returned by Marshal when
+// attempting to encode a string value with invalid UTF-8 sequences.
+// As of Go 1.2, Marshal instead coerces the string to valid UTF-8 by
+// replacing invalid bytes with the Unicode replacement rune U+FFFD.
+//
+// Deprecated: No longer used; kept for compatibility.
+type InvalidUTF8Error struct {
+	S string // the whole string value that caused the error
+}
+
+func (e *InvalidUTF8Error) Error() string {
+	return "json: invalid UTF-8 in string: " + strconv.Quote(e.S)
+}
+
+// A MarshalerError represents an error from calling a MarshalJSON or MarshalText method.
+type MarshalerError struct {
+	Type reflect.Type
+	Err  error
+}
+
+func (e *MarshalerError) Error() string {
+	return "json: error calling MarshalJSON for type " + e.Type.String() + ": " + e.Err.Error()
+}
+
+func (e *MarshalerError) Unwrap() error { return e.Err }
+
+var hex = "0123456789abcdef"
+
+// An encodeState encodes JSON into a bytes.Buffer.
+type encodeState struct {
+	bytes.Buffer // accumulated output
+	scratch      [64]byte
+}
+
+var encodeStatePool sync.Pool
+
+func newEncodeState() *encodeState {
+	if v := encodeStatePool.Get(); v != nil {
+		e := v.(*encodeState)
+		e.Reset()
+		return e
+	}
+	return new(encodeState)
+}
+
+// jsonError is an error wrapper type for internal use only.
+// Panics with errors are wrapped in jsonError so that the top-level recover
+// can distinguish intentional panics from this package.
+type jsonError struct{ error }
+
+func (e *encodeState) marshal(v interface{}, opts encOpts) (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if je, ok := r.(jsonError); ok {
+				err = je.error
+			} else {
+				panic(r)
+			}
+		}
+	}()
+	e.reflectValue(reflect.ValueOf(v), opts)
+	return nil
+}
+
+// error aborts the encoding by panicking with err wrapped in jsonError.
+func (e *encodeState) error(err error) {
+	panic(jsonError{err})
+}
+
+func isEmptyValue(v reflect.Value) bool {
+	switch v.Kind() {
+	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
+		return v.Len() == 0
+	case reflect.Bool:
+		return !v.Bool()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return v.Int() == 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return v.Uint() == 0
+	case reflect.Float32, reflect.Float64:
+		return v.Float() == 0
+	case reflect.Interface, reflect.Ptr:
+		return v.IsNil()
+	}
+	return false
+}
+
+func (e *encodeState) reflectValue(v reflect.Value, opts encOpts) {
+	valueEncoder(v)(e, v, opts)
+}
+
+type encOpts struct {
+	// quoted causes primitive fields to be encoded inside JSON strings.
+	quoted bool
+	// escapeHTML causes '<', '>', and '&' to be escaped in JSON strings.
+	escapeHTML bool
+}
+
+type encoderFunc func(e *encodeState, v reflect.Value, opts encOpts)
+
+var encoderCache sync.Map // map[reflect.Type]encoderFunc
+
+func valueEncoder(v reflect.Value) encoderFunc {
+	if !v.IsValid() {
+		return invalidValueEncoder
+	}
+	return typeEncoder(v.Type())
+}
+
+func typeEncoder(t reflect.Type) encoderFunc {
+	if fi, ok := encoderCache.Load(t); ok {
+		return fi.(encoderFunc)
+	}
+
+	// To deal with recursive types, populate the map with an
+	// indirect func before we build it. This type waits on the
+	// real func (f) to be ready and then calls it. This indirect
+	// func is only used for recursive types.
+	var (
+		wg sync.WaitGroup
+		f  encoderFunc
+	)
+	wg.Add(1)
+	fi, loaded := encoderCache.LoadOrStore(t, encoderFunc(func(e *encodeState, v reflect.Value, opts encOpts) {
+		wg.Wait()
+		f(e, v, opts)
+	}))
+	if loaded {
+		return fi.(encoderFunc)
+	}
+
+	// Compute the real encoder and replace the indirect func with it.
+	f = newTypeEncoder(t, true)
+	wg.Done()
+	encoderCache.Store(t, f)
+	return f
+}
+
+var (
+	marshalerType     = reflect.TypeOf((*Marshaler)(nil)).Elem()
+	textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+)
+
+// newTypeEncoder constructs an encoderFunc for a type.
+// The returned encoder only checks CanAddr when allowAddr is true.
+func newTypeEncoder(t reflect.Type, allowAddr bool) encoderFunc {
+	if t.Implements(marshalerType) {
+		return marshalerEncoder
+	}
+	if t.Kind() != reflect.Ptr && allowAddr && reflect.PtrTo(t).Implements(marshalerType) {
+		return newCondAddrEncoder(addrMarshalerEncoder, newTypeEncoder(t, false))
+	}
+
+	if t.Implements(textMarshalerType) {
+		return textMarshalerEncoder
+	}
+	if t.Kind() != reflect.Ptr && allowAddr && reflect.PtrTo(t).Implements(textMarshalerType) {
+		return newCondAddrEncoder(addrTextMarshalerEncoder, newTypeEncoder(t, false))
+	}
+
+	switch t.Kind() {
+	case reflect.Bool:
+		return boolEncoder
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return intEncoder
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return uintEncoder
+	case reflect.Float32:
+		return float32Encoder
+	case reflect.Float64:
+		return float64Encoder
+	case reflect.String:
+		return stringEncoder
+	case reflect.Interface:
+		return interfaceEncoder
+	case reflect.Struct:
+		return newStructEncoder(t)
+	case reflect.Map:
+		return newMapEncoder(t)
+	case reflect.Slice:
+		return newSliceEncoder(t)
+	case reflect.Array:
+		return newArrayEncoder(t)
+	case reflect.Ptr:
+		return newPtrEncoder(t)
+	default:
+		return unsupportedTypeEncoder
+	}
+}
+
+func invalidValueEncoder(e *encodeState, v reflect.Value, _ encOpts) {
+	e.WriteString("null")
+}
+
+func marshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.Kind() == reflect.Ptr && v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	m, ok := v.Interface().(Marshaler)
+	if !ok {
+		e.WriteString("null")
+		return
+	}
+	b, err := m.MarshalJSON()
+	if err == nil {
+		// copy JSON into buffer, checking validity.
+		err = compact(&e.Buffer, b, opts.escapeHTML)
+	}
+	if err != nil {
+		e.error(&MarshalerError{v.Type(), err})
+	}
+}
+
+func addrMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	va := v.Addr()
+	if va.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	m := va.Interface().(Marshaler)
+	b, err := m.MarshalJSON()
+	if err == nil {
+		// copy JSON into buffer, checking validity.
+		err = compact(&e.Buffer, b, opts.escapeHTML)
+	}
+	if err != nil {
+		e.error(&MarshalerError{v.Type(), err})
+	}
+}
+
+func textMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.Kind() == reflect.Ptr && v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	m := v.Interface().(encoding.TextMarshaler)
+	b, err := m.MarshalText()
+	if err != nil {
+		e.error(&MarshalerError{v.Type(), err})
+	}
+	e.stringBytes(b, opts.escapeHTML)
+}
+
+func addrTextMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	va := v.Addr()
+	if va.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	m := va.Interface().(encoding.TextMarshaler)
+	b, err := m.MarshalText()
+	if err != nil {
+		e.error(&MarshalerError{v.Type(), err})
+	}
+	e.stringBytes(b, opts.escapeHTML)
+}
+
+func boolEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+	if v.Bool() {
+		e.WriteString("true")
+	} else {
+		e.WriteString("false")
+	}
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+}
+
+func intEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	b := strconv.AppendInt(e.scratch[:0], v.Int(), 10)
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+	e.Write(b)
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+}
+
+func uintEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	b := strconv.AppendUint(e.scratch[:0], v.Uint(), 10)
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+	e.Write(b)
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+}
+
+type floatEncoder int // number of bits
+
+func (bits floatEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	f := v.Float()
+	if math.IsInf(f, 0) || math.IsNaN(f) {
+		e.error(&UnsupportedValueError{v, strconv.FormatFloat(f, 'g', -1, int(bits))})
+	}
+
+	// Convert as if by ES6 number to string conversion.
+	// This matches most other JSON generators.
+	// See golang.org/issue/6384 and golang.org/issue/14135.
+	// Like fmt %g, but the exponent cutoffs are different
+	// and exponents themselves are not padded to two digits.
+	b := e.scratch[:0]
+	abs := math.Abs(f)
+	fmt := byte('f')
+	// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
+	if abs != 0 {
+		if bits == 64 && (abs < 1e-6 || abs >= 1e21) || bits == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
+			fmt = 'e'
+		}
+	}
+	b = strconv.AppendFloat(b, f, fmt, -1, int(bits))
+	if fmt == 'e' {
+		// clean up e-09 to e-9
+		n := len(b)
+		if n >= 4 && b[n-4] == 'e' && b[n-3] == '-' && b[n-2] == '0' {
+			b[n-2] = b[n-1]
+			b = b[:n-1]
+		}
+	}
+
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+	e.Write(b)
+	if opts.quoted {
+		e.WriteByte('"')
+	}
+}
+
+var (
+	float32Encoder = (floatEncoder(32)).encode
+	float64Encoder = (floatEncoder(64)).encode
+)
+
+func stringEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.Type() == numberType {
+		numStr := v.String()
+		// In Go1.5 the empty string encodes to "0", while this is not a valid number literal
+		// we keep compatibility so check validity after this.
+		if numStr == "" {
+			numStr = "0" // Number's zero-val
+		}
+		if !isValidNumber(numStr) {
+			e.error(fmt.Errorf("json: invalid number literal %q", numStr))
+		}
+		e.WriteString(numStr)
+		return
+	}
+	if opts.quoted {
+		sb, err := Marshal(v.String())
+		if err != nil {
+			e.error(err)
+		}
+		e.string(string(sb), opts.escapeHTML)
+	} else {
+		e.string(v.String(), opts.escapeHTML)
+	}
+}
+
+func interfaceEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	e.reflectValue(v.Elem(), opts)
+}
+
+func unsupportedTypeEncoder(e *encodeState, v reflect.Value, _ encOpts) {
+	e.error(&UnsupportedTypeError{v.Type()})
+}
+
+type structEncoder struct {
+	fields structFields
+}
+
+type structFields struct {
+	list      []field
+	nameIndex map[string]int
+}
+
+func (se structEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	next := byte('{')
+FieldLoop:
+	for i := range se.fields.list {
+		f := &se.fields.list[i]
+
+		// Find the nested struct field by following f.index.
+		fv := v
+		for _, i := range f.index {
+			if fv.Kind() == reflect.Ptr {
+				if fv.IsNil() {
+					continue FieldLoop
+				}
+				fv = fv.Elem()
+			}
+			fv = fv.Field(i)
+		}
+
+		if f.omitEmpty && isEmptyValue(fv) {
+			continue
+		}
+		if f.extra {
+			keys := fv.MapKeys()
+			sv := make([]reflectWithString, len(keys))
+			for i, v := range keys {
+				sv[i].v = v
+				if err := sv[i].resolve(); err != nil {
+					e.error(&MarshalerError{v.Type(), err})
+				}
+			}
+			sort.Slice(sv, func(i, j int) bool { return sv[i].s < sv[j].s })
+			elemEnc := typeEncoder(fv.Type().Elem())
+			for _, kv := range sv {
+				e.WriteByte(next)
+				next = ','
+				e.string(kv.s, opts.escapeHTML)
+				e.WriteByte(':')
+				elemEnc(e, fv.MapIndex(kv.v), opts)
+			}
+			continue
+		}
+		e.WriteByte(next)
+		next = ','
+		if opts.escapeHTML {
+			e.WriteString(f.nameEscHTML)
+		} else {
+			e.WriteString(f.nameNonEsc)
+		}
+		opts.quoted = f.quoted
+		f.encoder(e, fv, opts)
+	}
+	if next == '{' {
+		e.WriteString("{}")
+	} else {
+		e.WriteByte('}')
+	}
+}
+
+func newStructEncoder(t reflect.Type) encoderFunc {
+	se := structEncoder{fields: cachedTypeFields(t)}
+	return se.encode
+}
+
+type mapEncoder struct {
+	elemEnc encoderFunc
+}
+
+func (me mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	e.WriteByte('{')
+
+	// Extract and sort the keys.
+	keys := v.MapKeys()
+	sv := make([]reflectWithString, len(keys))
+	for i, v := range keys {
+		sv[i].v = v
+		if err := sv[i].resolve(); err != nil {
+			e.error(&MarshalerError{v.Type(), err})
+		}
+	}
+	sort.Slice(sv, func(i, j int) bool { return sv[i].s < sv[j].s })
+
+	for i, kv := range sv {
+		if i > 0 {
+			e.WriteByte(',')
+		}
+		e.string(kv.s, opts.escapeHTML)
+		e.WriteByte(':')
+		me.elemEnc(e, v.MapIndex(kv.v), opts)
+	}
+	e.WriteByte('}')
+}
+
+func newMapEncoder(t reflect.Type) encoderFunc {
+	switch t.Key().Kind() {
+	case reflect.String,
+		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+	default:
+		if !t.Key().Implements(textMarshalerType) {
+			return unsupportedTypeEncoder
+		}
+	}
+	me := mapEncoder{typeEncoder(t.Elem())}
+	return me.encode
+}
+
+func encodeByteSlice(e *encodeState, v reflect.Value, _ encOpts) {
+	if v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	s := v.Bytes()
+	e.WriteByte('"')
+	encodedLen := base64.StdEncoding.EncodedLen(len(s))
+	if encodedLen <= len(e.scratch) {
+		// If the encoded bytes fit in e.scratch, avoid an extra
+		// allocation and use the cheaper Encoding.Encode.
+		dst := e.scratch[:encodedLen]
+		base64.StdEncoding.Encode(dst, s)
+		e.Write(dst)
+	} else if encodedLen <= 1024 {
+		// The encoded bytes are short enough to allocate for, and
+		// Encoding.Encode is still cheaper.
+		dst := make([]byte, encodedLen)
+		base64.StdEncoding.Encode(dst, s)
+		e.Write(dst)
+	} else {
+		// The encoded bytes are too long to cheaply allocate, and
+		// Encoding.Encode is no longer noticeably cheaper.
+		enc := base64.NewEncoder(base64.StdEncoding, e)
+		enc.Write(s)
+		enc.Close()
+	}
+	e.WriteByte('"')
+}
+
+// sliceEncoder just wraps an arrayEncoder, checking to make sure the value isn't nil.
+type sliceEncoder struct {
+	arrayEnc encoderFunc
+}
+
+func (se sliceEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	se.arrayEnc(e, v, opts)
+}
+
+func newSliceEncoder(t reflect.Type) encoderFunc {
+	// Byte slices get special treatment; arrays don't.
+	if t.Elem().Kind() == reflect.Uint8 {
+		p := reflect.PtrTo(t.Elem())
+		if !p.Implements(marshalerType) && !p.Implements(textMarshalerType) {
+			return encodeByteSlice
+		}
+	}
+	enc := sliceEncoder{newArrayEncoder(t)}
+	return enc.encode
+}
+
+type arrayEncoder struct {
+	elemEnc encoderFunc
+}
+
+func (ae arrayEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	e.WriteByte('[')
+	n := v.Len()
+	for i := 0; i < n; i++ {
+		if i > 0 {
+			e.WriteByte(',')
+		}
+		ae.elemEnc(e, v.Index(i), opts)
+	}
+	e.WriteByte(']')
+}
+
+func newArrayEncoder(t reflect.Type) encoderFunc {
+	enc := arrayEncoder{typeEncoder(t.Elem())}
+	return enc.encode
+}
+
+type ptrEncoder struct {
+	elemEnc encoderFunc
+}
+
+func (pe ptrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	pe.elemEnc(e, v.Elem(), opts)
+}
+
+func newPtrEncoder(t reflect.Type) encoderFunc {
+	enc := ptrEncoder{typeEncoder(t.Elem())}
+	return enc.encode
+}
+
+type condAddrEncoder struct {
+	canAddrEnc, elseEnc encoderFunc
+}
+
+func (ce condAddrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	if v.CanAddr() {
+		ce.canAddrEnc(e, v, opts)
+	} else {
+		ce.elseEnc(e, v, opts)
+	}
+}
+
+// newCondAddrEncoder returns an encoder that checks whether its value
+// CanAddr and delegates to canAddrEnc if so, else to elseEnc.
+func newCondAddrEncoder(canAddrEnc, elseEnc encoderFunc) encoderFunc {
+	enc := condAddrEncoder{canAddrEnc: canAddrEnc, elseEnc: elseEnc}
+	return enc.encode
+}
+
+func isValidTag(s string) bool {
+	if s == "" {
+		return false
+	}
+	for _, c := range s {
+		switch {
+		case strings.ContainsRune("!#$%&()*+-./:<=>?@[]^_{|}~ ", c):
+			// Backslash and quote chars are reserved, but
+			// otherwise any punctuation chars are allowed
+			// in a tag name.
+		case !unicode.IsLetter(c) && !unicode.IsDigit(c):
+			return false
+		}
+	}
+	return true
+}
+
+func typeByIndex(t reflect.Type, index []int) reflect.Type {
+	for _, i := range index {
+		if t.Kind() == reflect.Ptr {
+			t = t.Elem()
+		}
+		t = t.Field(i).Type
+	}
+	return t
+}
+
+type reflectWithString struct {
+	v reflect.Value
+	s string
+}
+
+func (w *reflectWithString) resolve() error {
+	if w.v.Kind() == reflect.String {
+		w.s = w.v.String()
+		return nil
+	}
+	if tm, ok := w.v.Interface().(encoding.TextMarshaler); ok {
+		buf, err := tm.MarshalText()
+		w.s = string(buf)
+		return err
+	}
+	switch w.v.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		w.s = strconv.FormatInt(w.v.Int(), 10)
+		return nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		w.s = strconv.FormatUint(w.v.Uint(), 10)
+		return nil
+	}
+	panic("unexpected map key type")
+}
+
+// NOTE: keep in sync with stringBytes below.
+func (e *encodeState) string(s string, escapeHTML bool) {
+	e.WriteByte('"')
+	start := 0
+	for i := 0; i < len(s); {
+		if b := s[i]; b < utf8.RuneSelf {
+			if htmlSafeSet[b] || (!escapeHTML && safeSet[b]) {
+				i++
+				continue
+			}
+			if start < i {
+				e.WriteString(s[start:i])
+			}
+			e.WriteByte('\\')
+			switch b {
+			case '\\', '"':
+				e.WriteByte(b)
+			case '\n':
+				e.WriteByte('n')
+			case '\r':
+				e.WriteByte('r')
+			case '\t':
+				e.WriteByte('t')
+			default:
+				// This encodes bytes < 0x20 except for \t, \n and \r.
+				// If escapeHTML is set, it also escapes <, >, and &
+				// because they can lead to security holes when
+				// user-controlled strings are rendered into JSON
+				// and served to some browsers.
+				e.WriteString(`u00`)
+				e.WriteByte(hex[b>>4])
+				e.WriteByte(hex[b&0xF])
+			}
+			i++
+			start = i
+			continue
+		}
+		c, size := utf8.DecodeRuneInString(s[i:])
+		if c == utf8.RuneError && size == 1 {
+			if start < i {
+				e.WriteString(s[start:i])
+			}
+			e.WriteString(`\ufffd`)
+			i += size
+			start = i
+			continue
+		}
+		// U+2028 is LINE SEPARATOR.
+		// U+2029 is PARAGRAPH SEPARATOR.
+		// They are both technically valid characters in JSON strings,
+		// but don't work in JSONP, which has to be evaluated as JavaScript,
+		// and can lead to security holes there. It is valid JSON to
+		// escape them, so we do so unconditionally.
+		// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
+		if c == '\u2028' || c == '\u2029' {
+			if start < i {
+				e.WriteString(s[start:i])
+			}
+			e.WriteString(`\u202`)
+			e.WriteByte(hex[c&0xF])
+			i += size
+			start = i
+			continue
+		}
+		i += size
+	}
+	if start < len(s) {
+		e.WriteString(s[start:])
+	}
+	e.WriteByte('"')
+}
+
+// NOTE: keep in sync with string above.
+func (e *encodeState) stringBytes(s []byte, escapeHTML bool) {
+	e.WriteByte('"')
+	start := 0
+	for i := 0; i < len(s); {
+		if b := s[i]; b < utf8.RuneSelf {
+			if htmlSafeSet[b] || (!escapeHTML && safeSet[b]) {
+				i++
+				continue
+			}
+			if start < i {
+				e.Write(s[start:i])
+			}
+			e.WriteByte('\\')
+			switch b {
+			case '\\', '"':
+				e.WriteByte(b)
+			case '\n':
+				e.WriteByte('n')
+			case '\r':
+				e.WriteByte('r')
+			case '\t':
+				e.WriteByte('t')
+			default:
+				// This encodes bytes < 0x20 except for \t, \n and \r.
+				// If escapeHTML is set, it also escapes <, >, and &
+				// because they can lead to security holes when
+				// user-controlled strings are rendered into JSON
+				// and served to some browsers.
+				e.WriteString(`u00`)
+				e.WriteByte(hex[b>>4])
+				e.WriteByte(hex[b&0xF])
+			}
+			i++
+			start = i
+			continue
+		}
+		c, size := utf8.DecodeRune(s[i:])
+		if c == utf8.RuneError && size == 1 {
+			if start < i {
+				e.Write(s[start:i])
+			}
+			e.WriteString(`\ufffd`)
+			i += size
+			start = i
+			continue
+		}
+		// U+2028 is LINE SEPARATOR.
+		// U+2029 is PARAGRAPH SEPARATOR.
+		// They are both technically valid characters in JSON strings,
+		// but don't work in JSONP, which has to be evaluated as JavaScript,
+		// and can lead to security holes there. It is valid JSON to
+		// escape them, so we do so unconditionally.
+		// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
+		if c == '\u2028' || c == '\u2029' {
+			if start < i {
+				e.Write(s[start:i])
+			}
+			e.WriteString(`\u202`)
+			e.WriteByte(hex[c&0xF])
+			i += size
+			start = i
+			continue
+		}
+		i += size
+	}
+	if start < len(s) {
+		e.Write(s[start:])
+	}
+	e.WriteByte('"')
+}
+
+// A field represents a single field found in a struct.
+type field struct {
+	name      string
+	nameBytes []byte                 // []byte(name)
+	equalFold func(s, t []byte) bool // bytes.EqualFold or equivalent
+
+	nameNonEsc  string // `"` + name + `":`
+	nameEscHTML string // `"` + HTMLEscape(name) + `":`
+
+	tag       bool
+	index     []int
+	typ       reflect.Type
+	omitEmpty bool
+	extra     bool
+	quoted    bool
+
+	encoder encoderFunc
+}
+
+// byIndex sorts field by index sequence.
+type byIndex []field
+
+func (x byIndex) Len() int { return len(x) }
+
+func (x byIndex) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+
+func (x byIndex) Less(i, j int) bool {
+	for k, xik := range x[i].index {
+		if k >= len(x[j].index) {
+			return false
+		}
+		if xik != x[j].index[k] {
+			return xik < x[j].index[k]
+		}
+	}
+	return len(x[i].index) < len(x[j].index)
+}
+
+// typeFields returns a list of fields that JSON should recognize for the given type.
+// The algorithm is breadth-first search over the set of structs to include - the top struct
+// and then any reachable anonymous structs.
+func typeFields(t reflect.Type) structFields {
+	// Anonymous fields to explore at the current level and the next.
+	current := []field{}
+	next := []field{{typ: t}}
+
+	// Count of queued names for current level and the next.
+	var count, nextCount map[reflect.Type]int
+
+	// Types already visited at an earlier level.
+	visited := map[reflect.Type]bool{}
+
+	// Fields found.
+	var fields []field
+
+	// Buffer to run HTMLEscape on field names.
+	var nameEscBuf bytes.Buffer
+
+	for len(next) > 0 {
+		current, next = next, current[:0]
+		count, nextCount = nextCount, map[reflect.Type]int{}
+
+		for _, f := range current {
+			if visited[f.typ] {
+				continue
+			}
+			visited[f.typ] = true
+
+			// Scan f.typ for fields to include.
+			for i := 0; i < f.typ.NumField(); i++ {
+				sf := f.typ.Field(i)
+				isUnexported := sf.PkgPath != ""
+				if sf.Anonymous {
+					t := sf.Type
+					if t.Kind() == reflect.Ptr {
+						t = t.Elem()
+					}
+					if isUnexported && t.Kind() != reflect.Struct {
+						// Ignore embedded fields of unexported non-struct types.
+						continue
+					}
+					// Do not ignore embedded fields of unexported struct types
+					// since they may have exported fields.
+				} else if isUnexported {
+					// Ignore unexported non-embedded fields.
+					continue
+				}
+				tag := sf.Tag.Get("json")
+				tagx := sf.Tag.Get("jsonx")
+				if tag == "-" && tagx == "" {
+					continue
+				}
+				if tagx != "" {
+					tag = ""
+				}
+				name, opts := parseTag(tag)
+				if !isValidTag(name) {
+					name = ""
+				}
+				index := make([]int, len(f.index)+1)
+				copy(index, f.index)
+				index[len(f.index)] = i
+
+				ft := sf.Type
+				if ft.Name() == "" && ft.Kind() == reflect.Ptr {
+					// Follow pointer.
+					ft = ft.Elem()
+				}
+
+				// Only maps can be extra.
+				extra := false
+				if tagx != "" {
+					switch ft.Kind() {
+					case reflect.Map:
+						extra = true
+					default:
+						continue
+					}
+				}
+
+				// Only strings, floats, integers, and booleans can be quoted.
+				quoted := false
+				if opts.Contains("string") {
+					switch ft.Kind() {
+					case reflect.Bool,
+						reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+						reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
+						reflect.Float32, reflect.Float64,
+						reflect.String:
+						quoted = true
+					}
+				}
+
+				// Record found field and index sequence.
+				if name != "" || !sf.Anonymous || ft.Kind() != reflect.Struct {
+					tagged := name != ""
+					if name == "" {
+						name = sf.Name
+					}
+					field := field{
+						name:      name,
+						tag:       tagged,
+						index:     index,
+						typ:       ft,
+						omitEmpty: opts.Contains("omitempty"),
+						extra:     extra,
+						quoted:    quoted,
+					}
+					field.nameBytes = []byte(field.name)
+					field.equalFold = foldFunc(field.nameBytes)
+
+					// Build nameEscHTML and nameNonEsc ahead of time.
+					nameEscBuf.Reset()
+					nameEscBuf.WriteString(`"`)
+					HTMLEscape(&nameEscBuf, field.nameBytes)
+					nameEscBuf.WriteString(`":`)
+					field.nameEscHTML = nameEscBuf.String()
+					field.nameNonEsc = `"` + field.name + `":`
+
+					fields = append(fields, field)
+					if count[f.typ] > 1 {
+						// If there were multiple instances, add a second,
+						// so that the annihilation code will see a duplicate.
+						// It only cares about the distinction between 1 or 2,
+						// so don't bother generating any more copies.
+						fields = append(fields, fields[len(fields)-1])
+					}
+					continue
+				}
+
+				// Record new anonymous struct to explore in next round.
+				nextCount[ft]++
+				if nextCount[ft] == 1 {
+					next = append(next, field{name: ft.Name(), index: index, typ: ft})
+				}
+			}
+		}
+	}
+
+	sort.Slice(fields, func(i, j int) bool {
+		x := fields
+		// sort field by name, breaking ties with depth, then
+		// breaking ties with "name came from json tag", then
+		// breaking ties with index sequence.
+		if x[i].name != x[j].name {
+			return x[i].name < x[j].name
+		}
+		if len(x[i].index) != len(x[j].index) {
+			return len(x[i].index) < len(x[j].index)
+		}
+		if x[i].tag != x[j].tag {
+			return x[i].tag
+		}
+		return byIndex(x).Less(i, j)
+	})
+
+	// Delete all fields that are hidden by the Go rules for embedded fields,
+	// except that fields with JSON tags are promoted.
+
+	// The fields are sorted in primary order of name, secondary order
+	// of field index length. Loop over names; for each name, delete
+	// hidden fields by choosing the one dominant field that survives.
+	out := fields[:0]
+	for advance, i := 0, 0; i < len(fields); i += advance {
+		// One iteration per name.
+		// Find the sequence of fields with the name of this first field.
+		fi := fields[i]
+		name := fi.name
+		for advance = 1; i+advance < len(fields); advance++ {
+			fj := fields[i+advance]
+			if fj.name != name {
+				break
+			}
+		}
+		if advance == 1 { // Only one field with this name
+			out = append(out, fi)
+			continue
+		}
+		dominant, ok := dominantField(fields[i : i+advance])
+		if ok {
+			out = append(out, dominant)
+		}
+	}
+
+	fields = out
+	sort.Sort(byIndex(fields))
+
+	for i := range fields {
+		f := &fields[i]
+		f.encoder = typeEncoder(typeByIndex(t, f.index))
+	}
+	nameIndex := make(map[string]int, len(fields))
+	for i, field := range fields {
+		nameIndex[field.name] = i
+	}
+	return structFields{fields, nameIndex}
+}
+
+// dominantField looks through the fields, all of which are known to
+// have the same name, to find the single field that dominates the
+// others using Go's embedding rules, modified by the presence of
+// JSON tags. If there are multiple top-level fields, the boolean
+// will be false: This condition is an error in Go and we skip all
+// the fields.
+func dominantField(fields []field) (field, bool) {
+	// The fields are sorted in increasing index-length order, then by presence of tag.
+	// That means that the first field is the dominant one. We need only check
+	// for error cases: two fields at top level, either both tagged or neither tagged.
+	if len(fields) > 1 && len(fields[0].index) == len(fields[1].index) && fields[0].tag == fields[1].tag {
+		return field{}, false
+	}
+	return fields[0], true
+}
+
+var fieldCache sync.Map // map[reflect.Type]structFields
+
+// cachedTypeFields is like typeFields but uses a cache to avoid repeated work.
+func cachedTypeFields(t reflect.Type) structFields {
+	if f, ok := fieldCache.Load(t); ok {
+		return f.(structFields)
+	}
+	f, _ := fieldCache.LoadOrStore(t, typeFields(t))
+	return f.(structFields)
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/fold.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/fold.go
new file mode 100644
index 00000000..316ea018
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/fold.go
@@ -0,0 +1,143 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonx
+
+import (
+	"bytes"
+	"unicode/utf8"
+)
+
+const (
+	caseMask     = ^byte(0x20) // Mask to ignore case in ASCII.
+	kelvin       = '\u212a'
+	smallLongEss = '\u017f'
+)
+
+// foldFunc returns one of four different case folding equivalence
+// functions, from most general (and slow) to fastest:
+//
+// 1) bytes.EqualFold, if the key s contains any non-ASCII UTF-8
+// 2) equalFoldRight, if s contains special folding ASCII ('k', 'K', 's', 'S')
+// 3) asciiEqualFold, no special, but includes non-letters (including _)
+// 4) simpleLetterEqualFold, no specials, no non-letters.
+//
+// The letters S and K are special because they map to 3 runes, not just 2:
+//  * S maps to s and to U+017F 'ſ' Latin small letter long s
+//  * k maps to K and to U+212A 'K' Kelvin sign
+// See https://play.golang.org/p/tTxjOc0OGo
+//
+// The returned function is specialized for matching against s and
+// should only be given s. It's not curried for performance reasons.
+func foldFunc(s []byte) func(s, t []byte) bool {
+	nonLetter := false
+	special := false // special letter
+	for _, b := range s {
+		if b >= utf8.RuneSelf {
+			return bytes.EqualFold
+		}
+		upper := b & caseMask
+		if upper < 'A' || upper > 'Z' {
+			nonLetter = true
+		} else if upper == 'K' || upper == 'S' {
+			// See above for why these letters are special.
+			special = true
+		}
+	}
+	if special {
+		return equalFoldRight
+	}
+	if nonLetter {
+		return asciiEqualFold
+	}
+	return simpleLetterEqualFold
+}
+
+// equalFoldRight is a specialization of bytes.EqualFold when s is
+// known to be all ASCII (including punctuation), but contains an 's',
+// 'S', 'k', or 'K', requiring a Unicode fold on the bytes in t.
+// See comments on foldFunc.
+func equalFoldRight(s, t []byte) bool {
+	for _, sb := range s {
+		if len(t) == 0 {
+			return false
+		}
+		tb := t[0]
+		if tb < utf8.RuneSelf {
+			if sb != tb {
+				sbUpper := sb & caseMask
+				if 'A' <= sbUpper && sbUpper <= 'Z' {
+					if sbUpper != tb&caseMask {
+						return false
+					}
+				} else {
+					return false
+				}
+			}
+			t = t[1:]
+			continue
+		}
+		// sb is ASCII and t is not. t must be either kelvin
+		// sign or long s; sb must be s, S, k, or K.
+		tr, size := utf8.DecodeRune(t)
+		switch sb {
+		case 's', 'S':
+			if tr != smallLongEss {
+				return false
+			}
+		case 'k', 'K':
+			if tr != kelvin {
+				return false
+			}
+		default:
+			return false
+		}
+		t = t[size:]
+
+	}
+	if len(t) > 0 {
+		return false
+	}
+	return true
+}
+
+// asciiEqualFold is a specialization of bytes.EqualFold for use when
+// s is all ASCII (but may contain non-letters) and contains no
+// special-folding letters.
+// See comments on foldFunc.
+func asciiEqualFold(s, t []byte) bool {
+	if len(s) != len(t) {
+		return false
+	}
+	for i, sb := range s {
+		tb := t[i]
+		if sb == tb {
+			continue
+		}
+		if ('a' <= sb && sb <= 'z') || ('A' <= sb && sb <= 'Z') {
+			if sb&caseMask != tb&caseMask {
+				return false
+			}
+		} else {
+			return false
+		}
+	}
+	return true
+}
+
+// simpleLetterEqualFold is a specialization of bytes.EqualFold for
+// use when s is all ASCII letters (no underscores, etc) and also
+// doesn't contain 'k', 'K', 's', or 'S'.
+// See comments on foldFunc.
+func simpleLetterEqualFold(s, t []byte) bool {
+	if len(s) != len(t) {
+		return false
+	}
+	for i, b := range s {
+		if b&caseMask != t[i]&caseMask {
+			return false
+		}
+	}
+	return true
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/indent.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/indent.go
new file mode 100644
index 00000000..15d95cd1
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/indent.go
@@ -0,0 +1,141 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonx
+
+import "bytes"
+
+// Compact appends to dst the JSON-encoded src with
+// insignificant space characters elided.
+func Compact(dst *bytes.Buffer, src []byte) error {
+	return compact(dst, src, false)
+}
+
+func compact(dst *bytes.Buffer, src []byte, escape bool) error {
+	origLen := dst.Len()
+	var scan scanner
+	scan.reset()
+	start := 0
+	for i, c := range src {
+		if escape && (c == '<' || c == '>' || c == '&') {
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			dst.WriteString(`\u00`)
+			dst.WriteByte(hex[c>>4])
+			dst.WriteByte(hex[c&0xF])
+			start = i + 1
+		}
+		// Convert U+2028 and U+2029 (E2 80 A8 and E2 80 A9).
+		if c == 0xE2 && i+2 < len(src) && src[i+1] == 0x80 && src[i+2]&^1 == 0xA8 {
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			dst.WriteString(`\u202`)
+			dst.WriteByte(hex[src[i+2]&0xF])
+			start = i + 3
+		}
+		v := scan.step(&scan, c)
+		if v >= scanSkipSpace {
+			if v == scanError {
+				break
+			}
+			if start < i {
+				dst.Write(src[start:i])
+			}
+			start = i + 1
+		}
+	}
+	if scan.eof() == scanError {
+		dst.Truncate(origLen)
+		return scan.err
+	}
+	if start < len(src) {
+		dst.Write(src[start:])
+	}
+	return nil
+}
+
+func newline(dst *bytes.Buffer, prefix, indent string, depth int) {
+	dst.WriteByte('\n')
+	dst.WriteString(prefix)
+	for i := 0; i < depth; i++ {
+		dst.WriteString(indent)
+	}
+}
+
+// Indent appends to dst an indented form of the JSON-encoded src.
+// Each element in a JSON object or array begins on a new,
+// indented line beginning with prefix followed by one or more
+// copies of indent according to the indentation nesting.
+// The data appended to dst does not begin with the prefix nor
+// any indentation, to make it easier to embed inside other formatted JSON data.
+// Although leading space characters (space, tab, carriage return, newline)
+// at the beginning of src are dropped, trailing space characters
+// at the end of src are preserved and copied to dst.
+// For example, if src has no trailing spaces, neither will dst;
+// if src ends in a trailing newline, so will dst.
+func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
+	origLen := dst.Len()
+	var scan scanner
+	scan.reset()
+	needIndent := false
+	depth := 0
+	for _, c := range src {
+		scan.bytes++
+		v := scan.step(&scan, c)
+		if v == scanSkipSpace {
+			continue
+		}
+		if v == scanError {
+			break
+		}
+		if needIndent && v != scanEndObject && v != scanEndArray {
+			needIndent = false
+			depth++
+			newline(dst, prefix, indent, depth)
+		}
+
+		// Emit semantically uninteresting bytes
+		// (in particular, punctuation in strings) unmodified.
+		if v == scanContinue {
+			dst.WriteByte(c)
+			continue
+		}
+
+		// Add spacing around real punctuation.
+		switch c {
+		case '{', '[':
+			// delay indent so that empty object and array are formatted as {} and [].
+			needIndent = true
+			dst.WriteByte(c)
+
+		case ',':
+			dst.WriteByte(c)
+			newline(dst, prefix, indent, depth)
+
+		case ':':
+			dst.WriteByte(c)
+			dst.WriteByte(' ')
+
+		case '}', ']':
+			if needIndent {
+				// suppress indent in empty object/array
+				needIndent = false
+			} else {
+				depth--
+				newline(dst, prefix, indent, depth)
+			}
+			dst.WriteByte(c)
+
+		default:
+			dst.WriteByte(c)
+		}
+	}
+	if scan.eof() == scanError {
+		dst.Truncate(origLen)
+		return scan.err
+	}
+	return nil
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/scanner.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/scanner.go
new file mode 100644
index 00000000..780c5e45
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/scanner.go
@@ -0,0 +1,573 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonx
+
+// JSON value parser state machine.
+// Just about at the limit of what is reasonable to write by hand.
+// Some parts are a bit tedious, but overall it nicely factors out the
+// otherwise common code from the multiple scanning functions
+// in this package (Compact, Indent, checkValid, etc).
+//
+// This file starts with two simple examples using the scanner
+// before diving into the scanner itself.
+
+import "strconv"
+
+// Valid reports whether data is a valid JSON encoding.
+func Valid(data []byte) bool {
+	return checkValid(data, &scanner{}) == nil
+}
+
+// checkValid verifies that data is valid JSON-encoded data.
+// scan is passed in for use by checkValid to avoid an allocation.
+func checkValid(data []byte, scan *scanner) error {
+	scan.reset()
+	for _, c := range data {
+		scan.bytes++
+		if scan.step(scan, c) == scanError {
+			return scan.err
+		}
+	}
+	if scan.eof() == scanError {
+		return scan.err
+	}
+	return nil
+}
+
+// A SyntaxError is a description of a JSON syntax error.
+type SyntaxError struct {
+	msg    string // description of error
+	Offset int64  // error occurred after reading Offset bytes
+}
+
+func (e *SyntaxError) Error() string { return e.msg }
+
+// A scanner is a JSON scanning state machine.
+// Callers call scan.reset() and then pass bytes in one at a time
+// by calling scan.step(&scan, c) for each byte.
+// The return value, referred to as an opcode, tells the
+// caller about significant parsing events like beginning
+// and ending literals, objects, and arrays, so that the
+// caller can follow along if it wishes.
+// The return value scanEnd indicates that a single top-level
+// JSON value has been completed, *before* the byte that
+// just got passed in.  (The indication must be delayed in order
+// to recognize the end of numbers: is 123 a whole value or
+// the beginning of 12345e+6?).
+type scanner struct {
+	// The step is a func to be called to execute the next transition.
+	// Also tried using an integer constant and a single func
+	// with a switch, but using the func directly was 10% faster
+	// on a 64-bit Mac Mini, and it's nicer to read.
+	step func(*scanner, byte) int
+
+	// Reached end of top-level value.
+	endTop bool
+
+	// Stack of what we're in the middle of - array values, object keys, object values.
+	parseState []int
+
+	// Error that happened, if any.
+	err error
+
+	// total bytes consumed, updated by decoder.Decode
+	bytes int64
+}
+
+// These values are returned by the state transition functions
+// assigned to scanner.state and the method scanner.eof.
+// They give details about the current state of the scan that
+// callers might be interested to know about.
+// It is okay to ignore the return value of any particular
+// call to scanner.state: if one call returns scanError,
+// every subsequent call will return scanError too.
+const (
+	// Continue.
+	scanContinue     = iota // uninteresting byte
+	scanBeginLiteral        // end implied by next result != scanContinue
+	scanBeginObject         // begin object
+	scanObjectKey           // just finished object key (string)
+	scanObjectValue         // just finished non-last object value
+	scanEndObject           // end object (implies scanObjectValue if possible)
+	scanBeginArray          // begin array
+	scanArrayValue          // just finished array value
+	scanEndArray            // end array (implies scanArrayValue if possible)
+	scanSkipSpace           // space byte; can skip; known to be last "continue" result
+
+	// Stop.
+	scanEnd   // top-level value ended *before* this byte; known to be first "stop" result
+	scanError // hit an error, scanner.err.
+)
+
+// These values are stored in the parseState stack.
+// They give the current state of a composite value
+// being scanned. If the parser is inside a nested value
+// the parseState describes the nested state, outermost at entry 0.
+const (
+	parseObjectKey   = iota // parsing object key (before colon)
+	parseObjectValue        // parsing object value (after colon)
+	parseArrayValue         // parsing array value
+)
+
+// reset prepares the scanner for use.
+// It must be called before calling s.step.
+func (s *scanner) reset() {
+	s.step = stateBeginValue
+	s.parseState = s.parseState[0:0]
+	s.err = nil
+	s.endTop = false
+}
+
+// eof tells the scanner that the end of input has been reached.
+// It returns a scan status just as s.step does.
+func (s *scanner) eof() int {
+	if s.err != nil {
+		return scanError
+	}
+	if s.endTop {
+		return scanEnd
+	}
+	s.step(s, ' ')
+	if s.endTop {
+		return scanEnd
+	}
+	if s.err == nil {
+		s.err = &SyntaxError{"unexpected end of JSON input", s.bytes}
+	}
+	return scanError
+}
+
+// pushParseState pushes a new parse state p onto the parse stack.
+func (s *scanner) pushParseState(p int) {
+	s.parseState = append(s.parseState, p)
+}
+
+// popParseState pops a parse state (already obtained) off the stack
+// and updates s.step accordingly.
+func (s *scanner) popParseState() {
+	n := len(s.parseState) - 1
+	s.parseState = s.parseState[0:n]
+	if n == 0 {
+		s.step = stateEndTop
+		s.endTop = true
+	} else {
+		s.step = stateEndValue
+	}
+}
+
+func isSpace(c byte) bool {
+	return c == ' ' || c == '\t' || c == '\r' || c == '\n'
+}
+
+// stateBeginValueOrEmpty is the state after reading `[`.
+func stateBeginValueOrEmpty(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	if c == ']' {
+		return stateEndValue(s, c)
+	}
+	return stateBeginValue(s, c)
+}
+
+// stateBeginValue is the state at the beginning of the input.
+func stateBeginValue(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	switch c {
+	case '{':
+		s.step = stateBeginStringOrEmpty
+		s.pushParseState(parseObjectKey)
+		return scanBeginObject
+	case '[':
+		s.step = stateBeginValueOrEmpty
+		s.pushParseState(parseArrayValue)
+		return scanBeginArray
+	case '"':
+		s.step = stateInString
+		return scanBeginLiteral
+	case '-':
+		s.step = stateNeg
+		return scanBeginLiteral
+	case '0': // beginning of 0.123
+		s.step = state0
+		return scanBeginLiteral
+	case 't': // beginning of true
+		s.step = stateT
+		return scanBeginLiteral
+	case 'f': // beginning of false
+		s.step = stateF
+		return scanBeginLiteral
+	case 'n': // beginning of null
+		s.step = stateN
+		return scanBeginLiteral
+	}
+	if '1' <= c && c <= '9' { // beginning of 1234.5
+		s.step = state1
+		return scanBeginLiteral
+	}
+	return s.error(c, "looking for beginning of value")
+}
+
+// stateBeginStringOrEmpty is the state after reading `{`.
+func stateBeginStringOrEmpty(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	if c == '}' {
+		n := len(s.parseState)
+		s.parseState[n-1] = parseObjectValue
+		return stateEndValue(s, c)
+	}
+	return stateBeginString(s, c)
+}
+
+// stateBeginString is the state after reading `{"key": value,`.
+func stateBeginString(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
+		return scanSkipSpace
+	}
+	if c == '"' {
+		s.step = stateInString
+		return scanBeginLiteral
+	}
+	return s.error(c, "looking for beginning of object key string")
+}
+
+// stateEndValue is the state after completing a value,
+// such as after reading `{}` or `true` or `["x"`.
+func stateEndValue(s *scanner, c byte) int {
+	n := len(s.parseState)
+	if n == 0 {
+		// Completed top-level before the current byte.
+		s.step = stateEndTop
+		s.endTop = true
+		return stateEndTop(s, c)
+	}
+	if c <= ' ' && isSpace(c) {
+		s.step = stateEndValue
+		return scanSkipSpace
+	}
+	ps := s.parseState[n-1]
+	switch ps {
+	case parseObjectKey:
+		if c == ':' {
+			s.parseState[n-1] = parseObjectValue
+			s.step = stateBeginValue
+			return scanObjectKey
+		}
+		return s.error(c, "after object key")
+	case parseObjectValue:
+		if c == ',' {
+			s.parseState[n-1] = parseObjectKey
+			s.step = stateBeginString
+			return scanObjectValue
+		}
+		if c == '}' {
+			s.popParseState()
+			return scanEndObject
+		}
+		return s.error(c, "after object key:value pair")
+	case parseArrayValue:
+		if c == ',' {
+			s.step = stateBeginValue
+			return scanArrayValue
+		}
+		if c == ']' {
+			s.popParseState()
+			return scanEndArray
+		}
+		return s.error(c, "after array element")
+	}
+	return s.error(c, "")
+}
+
+// stateEndTop is the state after finishing the top-level value,
+// such as after reading `{}` or `[1,2,3]`.
+// Only space characters should be seen now.
+func stateEndTop(s *scanner, c byte) int {
+	if !isSpace(c) {
+		// Complain about non-space byte on next call.
+		s.error(c, "after top-level value")
+	}
+	return scanEnd
+}
+
+// stateInString is the state after reading `"`.
+func stateInString(s *scanner, c byte) int {
+	if c == '"' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	if c == '\\' {
+		s.step = stateInStringEsc
+		return scanContinue
+	}
+	if c < 0x20 {
+		return s.error(c, "in string literal")
+	}
+	return scanContinue
+}
+
+// stateInStringEsc is the state after reading `"\` during a quoted string.
+func stateInStringEsc(s *scanner, c byte) int {
+	switch c {
+	case 'b', 'f', 'n', 'r', 't', '\\', '/', '"':
+		s.step = stateInString
+		return scanContinue
+	case 'u':
+		s.step = stateInStringEscU
+		return scanContinue
+	}
+	return s.error(c, "in string escape code")
+}
+
+// stateInStringEscU is the state after reading `"\u` during a quoted string.
+func stateInStringEscU(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInStringEscU1
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU1 is the state after reading `"\u1` during a quoted string.
+func stateInStringEscU1(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInStringEscU12
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU12 is the state after reading `"\u12` during a quoted string.
+func stateInStringEscU12(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInStringEscU123
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU123 is the state after reading `"\u123` during a quoted string.
+func stateInStringEscU123(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+		s.step = stateInString
+		return scanContinue
+	}
+	// numbers
+	return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateNeg is the state after reading `-` during a number.
+func stateNeg(s *scanner, c byte) int {
+	if c == '0' {
+		s.step = state0
+		return scanContinue
+	}
+	if '1' <= c && c <= '9' {
+		s.step = state1
+		return scanContinue
+	}
+	return s.error(c, "in numeric literal")
+}
+
+// state1 is the state after reading a non-zero integer during a number,
+// such as after reading `1` or `100` but not `0`.
+func state1(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		s.step = state1
+		return scanContinue
+	}
+	return state0(s, c)
+}
+
+// state0 is the state after reading `0` during a number.
+func state0(s *scanner, c byte) int {
+	if c == '.' {
+		s.step = stateDot
+		return scanContinue
+	}
+	if c == 'e' || c == 'E' {
+		s.step = stateE
+		return scanContinue
+	}
+	return stateEndValue(s, c)
+}
+
+// stateDot is the state after reading the integer and decimal point in a number,
+// such as after reading `1.`.
+func stateDot(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		s.step = stateDot0
+		return scanContinue
+	}
+	return s.error(c, "after decimal point in numeric literal")
+}
+
+// stateDot0 is the state after reading the integer, decimal point, and subsequent
+// digits of a number, such as after reading `3.14`.
+func stateDot0(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		return scanContinue
+	}
+	if c == 'e' || c == 'E' {
+		s.step = stateE
+		return scanContinue
+	}
+	return stateEndValue(s, c)
+}
+
+// stateE is the state after reading the mantissa and e in a number,
+// such as after reading `314e` or `0.314e`.
+func stateE(s *scanner, c byte) int {
+	if c == '+' || c == '-' {
+		s.step = stateESign
+		return scanContinue
+	}
+	return stateESign(s, c)
+}
+
+// stateESign is the state after reading the mantissa, e, and sign in a number,
+// such as after reading `314e-` or `0.314e+`.
+func stateESign(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		s.step = stateE0
+		return scanContinue
+	}
+	return s.error(c, "in exponent of numeric literal")
+}
+
+// stateE0 is the state after reading the mantissa, e, optional sign,
+// and at least one digit of the exponent in a number,
+// such as after reading `314e-2` or `0.314e+1` or `3.14e0`.
+func stateE0(s *scanner, c byte) int {
+	if '0' <= c && c <= '9' {
+		return scanContinue
+	}
+	return stateEndValue(s, c)
+}
+
+// stateT is the state after reading `t`.
+func stateT(s *scanner, c byte) int {
+	if c == 'r' {
+		s.step = stateTr
+		return scanContinue
+	}
+	return s.error(c, "in literal true (expecting 'r')")
+}
+
+// stateTr is the state after reading `tr`.
+func stateTr(s *scanner, c byte) int {
+	if c == 'u' {
+		s.step = stateTru
+		return scanContinue
+	}
+	return s.error(c, "in literal true (expecting 'u')")
+}
+
+// stateTru is the state after reading `tru`.
+func stateTru(s *scanner, c byte) int {
+	if c == 'e' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	return s.error(c, "in literal true (expecting 'e')")
+}
+
+// stateF is the state after reading `f`.
+func stateF(s *scanner, c byte) int {
+	if c == 'a' {
+		s.step = stateFa
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 'a')")
+}
+
+// stateFa is the state after reading `fa`.
+func stateFa(s *scanner, c byte) int {
+	if c == 'l' {
+		s.step = stateFal
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 'l')")
+}
+
+// stateFal is the state after reading `fal`.
+func stateFal(s *scanner, c byte) int {
+	if c == 's' {
+		s.step = stateFals
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 's')")
+}
+
+// stateFals is the state after reading `fals`.
+func stateFals(s *scanner, c byte) int {
+	if c == 'e' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	return s.error(c, "in literal false (expecting 'e')")
+}
+
+// stateN is the state after reading `n`.
+func stateN(s *scanner, c byte) int {
+	if c == 'u' {
+		s.step = stateNu
+		return scanContinue
+	}
+	return s.error(c, "in literal null (expecting 'u')")
+}
+
+// stateNu is the state after reading `nu`.
+func stateNu(s *scanner, c byte) int {
+	if c == 'l' {
+		s.step = stateNul
+		return scanContinue
+	}
+	return s.error(c, "in literal null (expecting 'l')")
+}
+
+// stateNul is the state after reading `nul`.
+func stateNul(s *scanner, c byte) int {
+	if c == 'l' {
+		s.step = stateEndValue
+		return scanContinue
+	}
+	return s.error(c, "in literal null (expecting 'l')")
+}
+
+// stateError is the state after reaching a syntax error,
+// such as after reading `[1}` or `5.1.2`.
+func stateError(s *scanner, c byte) int {
+	return scanError
+}
+
+// error records an error and switches to the error state.
+func (s *scanner) error(c byte, context string) int {
+	s.step = stateError
+	s.err = &SyntaxError{"invalid character " + quoteChar(c) + " " + context, s.bytes}
+	return scanError
+}
+
+// quoteChar formats c as a quoted character literal
+func quoteChar(c byte) string {
+	// special cases - different from quoted strings
+	if c == '\'' {
+		return `'\''`
+	}
+	if c == '"' {
+		return `'"'`
+	}
+
+	// use quoted string with different quotation marks
+	s := strconv.Quote(string(c))
+	return "'" + s[1:len(s)-1] + "'"
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/stream.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/stream.go
new file mode 100644
index 00000000..0f00c037
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/stream.go
@@ -0,0 +1,507 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonx
+
+import (
+	"bytes"
+	"errors"
+	"io"
+)
+
+// A Decoder reads and decodes JSON values from an input stream.
+type Decoder struct {
+	r       io.Reader
+	buf     []byte
+	d       decodeState
+	scanp   int   // start of unread data in buf
+	scanned int64 // amount of data already scanned
+	scan    scanner
+	err     error
+
+	tokenState int
+	tokenStack []int
+}
+
+// NewDecoder returns a new decoder that reads from r.
+//
+// The decoder introduces its own buffering and may
+// read data from r beyond the JSON values requested.
+func NewDecoder(r io.Reader) *Decoder {
+	return &Decoder{r: r}
+}
+
+// UseNumber causes the Decoder to unmarshal a number into an interface{} as a
+// Number instead of as a float64.
+func (dec *Decoder) UseNumber() { dec.d.useNumber = true }
+
+// DisallowUnknownFields causes the Decoder to return an error when the destination
+// is a struct and the input contains object keys which do not match any
+// non-ignored, exported fields in the destination.
+func (dec *Decoder) DisallowUnknownFields() { dec.d.disallowUnknownFields = true }
+
+// Decode reads the next JSON-encoded value from its
+// input and stores it in the value pointed to by v.
+//
+// See the documentation for Unmarshal for details about
+// the conversion of JSON into a Go value.
+func (dec *Decoder) Decode(v interface{}) error {
+	if dec.err != nil {
+		return dec.err
+	}
+
+	if err := dec.tokenPrepareForDecode(); err != nil {
+		return err
+	}
+
+	if !dec.tokenValueAllowed() {
+		return &SyntaxError{msg: "not at beginning of value", Offset: dec.offset()}
+	}
+
+	// Read whole value into buffer.
+	n, err := dec.readValue()
+	if err != nil {
+		return err
+	}
+	dec.d.init(dec.buf[dec.scanp : dec.scanp+n])
+	dec.scanp += n
+
+	// Don't save err from unmarshal into dec.err:
+	// the connection is still usable since we read a complete JSON
+	// object from it before the error happened.
+	err = dec.d.unmarshal(v)
+
+	// fixup token streaming state
+	dec.tokenValueEnd()
+
+	return err
+}
+
+// Buffered returns a reader of the data remaining in the Decoder's
+// buffer. The reader is valid until the next call to Decode.
+func (dec *Decoder) Buffered() io.Reader {
+	return bytes.NewReader(dec.buf[dec.scanp:])
+}
+
+// readValue reads a JSON value into dec.buf.
+// It returns the length of the encoding.
+func (dec *Decoder) readValue() (int, error) {
+	dec.scan.reset()
+
+	scanp := dec.scanp
+	var err error
+Input:
+	// help the compiler see that scanp is never negative, so it can remove
+	// some bounds checks below.
+	for scanp >= 0 {
+
+		// Look in the buffer for a new value.
+		for ; scanp < len(dec.buf); scanp++ {
+			c := dec.buf[scanp]
+			dec.scan.bytes++
+			switch dec.scan.step(&dec.scan, c) {
+			case scanEnd:
+				break Input
+			case scanEndObject, scanEndArray:
+				// scanEnd is delayed one byte.
+				// We might block trying to get that byte from src,
+				// so instead invent a space byte.
+				if stateEndValue(&dec.scan, ' ') == scanEnd {
+					scanp++
+					break Input
+				}
+			case scanError:
+				dec.err = dec.scan.err
+				return 0, dec.scan.err
+			}
+		}
+
+		// Did the last read have an error?
+		// Delayed until now to allow buffer scan.
+		if err != nil {
+			if err == io.EOF {
+				if dec.scan.step(&dec.scan, ' ') == scanEnd {
+					break Input
+				}
+				if nonSpace(dec.buf) {
+					err = io.ErrUnexpectedEOF
+				}
+			}
+			dec.err = err
+			return 0, err
+		}
+
+		n := scanp - dec.scanp
+		err = dec.refill()
+		scanp = dec.scanp + n
+	}
+	return scanp - dec.scanp, nil
+}
+
+func (dec *Decoder) refill() error {
+	// Make room to read more into the buffer.
+	// First slide down data already consumed.
+	if dec.scanp > 0 {
+		dec.scanned += int64(dec.scanp)
+		n := copy(dec.buf, dec.buf[dec.scanp:])
+		dec.buf = dec.buf[:n]
+		dec.scanp = 0
+	}
+
+	// Grow buffer if not large enough.
+	const minRead = 512
+	if cap(dec.buf)-len(dec.buf) < minRead {
+		newBuf := make([]byte, len(dec.buf), 2*cap(dec.buf)+minRead)
+		copy(newBuf, dec.buf)
+		dec.buf = newBuf
+	}
+
+	// Read. Delay error for next iteration (after scan).
+	n, err := dec.r.Read(dec.buf[len(dec.buf):cap(dec.buf)])
+	dec.buf = dec.buf[0 : len(dec.buf)+n]
+
+	return err
+}
+
+func nonSpace(b []byte) bool {
+	for _, c := range b {
+		if !isSpace(c) {
+			return true
+		}
+	}
+	return false
+}
+
+// An Encoder writes JSON values to an output stream.
+type Encoder struct {
+	w          io.Writer
+	err        error
+	escapeHTML bool
+
+	indentBuf    *bytes.Buffer
+	indentPrefix string
+	indentValue  string
+}
+
+// NewEncoder returns a new encoder that writes to w.
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{w: w, escapeHTML: true}
+}
+
+// Encode writes the JSON encoding of v to the stream,
+// followed by a newline character.
+//
+// See the documentation for Marshal for details about the
+// conversion of Go values to JSON.
+func (enc *Encoder) Encode(v interface{}) error {
+	if enc.err != nil {
+		return enc.err
+	}
+	e := newEncodeState()
+	err := e.marshal(v, encOpts{escapeHTML: enc.escapeHTML})
+	if err != nil {
+		return err
+	}
+
+	// Terminate each value with a newline.
+	// This makes the output look a little nicer
+	// when debugging, and some kind of space
+	// is required if the encoded value was a number,
+	// so that the reader knows there aren't more
+	// digits coming.
+	e.WriteByte('\n')
+
+	b := e.Bytes()
+	if enc.indentPrefix != "" || enc.indentValue != "" {
+		if enc.indentBuf == nil {
+			enc.indentBuf = new(bytes.Buffer)
+		}
+		enc.indentBuf.Reset()
+		err = Indent(enc.indentBuf, b, enc.indentPrefix, enc.indentValue)
+		if err != nil {
+			return err
+		}
+		b = enc.indentBuf.Bytes()
+	}
+	if _, err = enc.w.Write(b); err != nil {
+		enc.err = err
+	}
+	encodeStatePool.Put(e)
+	return err
+}
+
+// SetIndent instructs the encoder to format each subsequent encoded
+// value as if indented by the package-level function Indent(dst, src, prefix, indent).
+// Calling SetIndent("", "") disables indentation.
+func (enc *Encoder) SetIndent(prefix, indent string) {
+	enc.indentPrefix = prefix
+	enc.indentValue = indent
+}
+
+// SetEscapeHTML specifies whether problematic HTML characters
+// should be escaped inside JSON quoted strings.
+// The default behavior is to escape &, <, and > to \u0026, \u003c, and \u003e
+// to avoid certain safety problems that can arise when embedding JSON in HTML.
+//
+// In non-HTML settings where the escaping interferes with the readability
+// of the output, SetEscapeHTML(false) disables this behavior.
+func (enc *Encoder) SetEscapeHTML(on bool) {
+	enc.escapeHTML = on
+}
+
+// RawMessage is a raw encoded JSON value.
+// It implements Marshaler and Unmarshaler and can
+// be used to delay JSON decoding or precompute a JSON encoding.
+type RawMessage []byte
+
+// MarshalJSON returns m as the JSON encoding of m.
+func (m RawMessage) MarshalJSON() ([]byte, error) {
+	if m == nil {
+		return []byte("null"), nil
+	}
+	return m, nil
+}
+
+// UnmarshalJSON sets *m to a copy of data.
+func (m *RawMessage) UnmarshalJSON(data []byte) error {
+	if m == nil {
+		return errors.New("json.RawMessage: UnmarshalJSON on nil pointer")
+	}
+	*m = append((*m)[0:0], data...)
+	return nil
+}
+
+var _ Marshaler = (*RawMessage)(nil)
+var _ Unmarshaler = (*RawMessage)(nil)
+
+// A Token holds a value of one of these types:
+//
+//	Delim, for the four JSON delimiters [ ] { }
+//	bool, for JSON booleans
+//	float64, for JSON numbers
+//	Number, for JSON numbers
+//	string, for JSON string literals
+//	nil, for JSON null
+//
+type Token interface{}
+
+const (
+	tokenTopValue = iota
+	tokenArrayStart
+	tokenArrayValue
+	tokenArrayComma
+	tokenObjectStart
+	tokenObjectKey
+	tokenObjectColon
+	tokenObjectValue
+	tokenObjectComma
+)
+
+// advance tokenstate from a separator state to a value state
+func (dec *Decoder) tokenPrepareForDecode() error {
+	// Note: Not calling peek before switch, to avoid
+	// putting peek into the standard Decode path.
+	// peek is only called when using the Token API.
+	switch dec.tokenState {
+	case tokenArrayComma:
+		c, err := dec.peek()
+		if err != nil {
+			return err
+		}
+		if c != ',' {
+			return &SyntaxError{"expected comma after array element", dec.offset()}
+		}
+		dec.scanp++
+		dec.tokenState = tokenArrayValue
+	case tokenObjectColon:
+		c, err := dec.peek()
+		if err != nil {
+			return err
+		}
+		if c != ':' {
+			return &SyntaxError{"expected colon after object key", dec.offset()}
+		}
+		dec.scanp++
+		dec.tokenState = tokenObjectValue
+	}
+	return nil
+}
+
+func (dec *Decoder) tokenValueAllowed() bool {
+	switch dec.tokenState {
+	case tokenTopValue, tokenArrayStart, tokenArrayValue, tokenObjectValue:
+		return true
+	}
+	return false
+}
+
+func (dec *Decoder) tokenValueEnd() {
+	switch dec.tokenState {
+	case tokenArrayStart, tokenArrayValue:
+		dec.tokenState = tokenArrayComma
+	case tokenObjectValue:
+		dec.tokenState = tokenObjectComma
+	}
+}
+
+// A Delim is a JSON array or object delimiter, one of [ ] { or }.
+type Delim rune
+
+func (d Delim) String() string {
+	return string(d)
+}
+
+// Token returns the next JSON token in the input stream.
+// At the end of the input stream, Token returns nil, io.EOF.
+//
+// Token guarantees that the delimiters [ ] { } it returns are
+// properly nested and matched: if Token encounters an unexpected
+// delimiter in the input, it will return an error.
+//
+// The input stream consists of basic JSON values—bool, string,
+// number, and null—along with delimiters [ ] { } of type Delim
+// to mark the start and end of arrays and objects.
+// Commas and colons are elided.
+func (dec *Decoder) Token() (Token, error) {
+	for {
+		c, err := dec.peek()
+		if err != nil {
+			return nil, err
+		}
+		switch c {
+		case '[':
+			if !dec.tokenValueAllowed() {
+				return dec.tokenError(c)
+			}
+			dec.scanp++
+			dec.tokenStack = append(dec.tokenStack, dec.tokenState)
+			dec.tokenState = tokenArrayStart
+			return Delim('['), nil
+
+		case ']':
+			if dec.tokenState != tokenArrayStart && dec.tokenState != tokenArrayComma {
+				return dec.tokenError(c)
+			}
+			dec.scanp++
+			dec.tokenState = dec.tokenStack[len(dec.tokenStack)-1]
+			dec.tokenStack = dec.tokenStack[:len(dec.tokenStack)-1]
+			dec.tokenValueEnd()
+			return Delim(']'), nil
+
+		case '{':
+			if !dec.tokenValueAllowed() {
+				return dec.tokenError(c)
+			}
+			dec.scanp++
+			dec.tokenStack = append(dec.tokenStack, dec.tokenState)
+			dec.tokenState = tokenObjectStart
+			return Delim('{'), nil
+
+		case '}':
+			if dec.tokenState != tokenObjectStart && dec.tokenState != tokenObjectComma {
+				return dec.tokenError(c)
+			}
+			dec.scanp++
+			dec.tokenState = dec.tokenStack[len(dec.tokenStack)-1]
+			dec.tokenStack = dec.tokenStack[:len(dec.tokenStack)-1]
+			dec.tokenValueEnd()
+			return Delim('}'), nil
+
+		case ':':
+			if dec.tokenState != tokenObjectColon {
+				return dec.tokenError(c)
+			}
+			dec.scanp++
+			dec.tokenState = tokenObjectValue
+			continue
+
+		case ',':
+			if dec.tokenState == tokenArrayComma {
+				dec.scanp++
+				dec.tokenState = tokenArrayValue
+				continue
+			}
+			if dec.tokenState == tokenObjectComma {
+				dec.scanp++
+				dec.tokenState = tokenObjectKey
+				continue
+			}
+			return dec.tokenError(c)
+
+		case '"':
+			if dec.tokenState == tokenObjectStart || dec.tokenState == tokenObjectKey {
+				var x string
+				old := dec.tokenState
+				dec.tokenState = tokenTopValue
+				err := dec.Decode(&x)
+				dec.tokenState = old
+				if err != nil {
+					return nil, err
+				}
+				dec.tokenState = tokenObjectColon
+				return x, nil
+			}
+			fallthrough
+
+		default:
+			if !dec.tokenValueAllowed() {
+				return dec.tokenError(c)
+			}
+			var x interface{}
+			if err := dec.Decode(&x); err != nil {
+				return nil, err
+			}
+			return x, nil
+		}
+	}
+}
+
+func (dec *Decoder) tokenError(c byte) (Token, error) {
+	var context string
+	switch dec.tokenState {
+	case tokenTopValue:
+		context = " looking for beginning of value"
+	case tokenArrayStart, tokenArrayValue, tokenObjectValue:
+		context = " looking for beginning of value"
+	case tokenArrayComma:
+		context = " after array element"
+	case tokenObjectKey:
+		context = " looking for beginning of object key string"
+	case tokenObjectColon:
+		context = " after object key"
+	case tokenObjectComma:
+		context = " after object key:value pair"
+	}
+	return nil, &SyntaxError{"invalid character " + quoteChar(c) + context, dec.offset()}
+}
+
+// More reports whether there is another element in the
+// current array or object being parsed.
+func (dec *Decoder) More() bool {
+	c, err := dec.peek()
+	return err == nil && c != ']' && c != '}'
+}
+
+func (dec *Decoder) peek() (byte, error) {
+	var err error
+	for {
+		for i := dec.scanp; i < len(dec.buf); i++ {
+			c := dec.buf[i]
+			if isSpace(c) {
+				continue
+			}
+			dec.scanp = i
+			return c, nil
+		}
+		// buffer has been scanned, now report any error
+		if err != nil {
+			return 0, err
+		}
+		err = dec.refill()
+	}
+}
+
+func (dec *Decoder) offset() int64 {
+	return dec.scanned + int64(dec.scanp)
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/tables.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/tables.go
new file mode 100644
index 00000000..cb994a3e
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/tables.go
@@ -0,0 +1,218 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonx
+
+import "unicode/utf8"
+
+// safeSet holds the value true if the ASCII character with the given array
+// position can be represented inside a JSON string without any further
+// escaping.
+//
+// All values are true except for the ASCII control characters (0-31), the
+// double quote ("), and the backslash character ("\").
+var safeSet = [utf8.RuneSelf]bool{
+	' ':      true,
+	'!':      true,
+	'"':      false,
+	'#':      true,
+	'$':      true,
+	'%':      true,
+	'&':      true,
+	'\'':     true,
+	'(':      true,
+	')':      true,
+	'*':      true,
+	'+':      true,
+	',':      true,
+	'-':      true,
+	'.':      true,
+	'/':      true,
+	'0':      true,
+	'1':      true,
+	'2':      true,
+	'3':      true,
+	'4':      true,
+	'5':      true,
+	'6':      true,
+	'7':      true,
+	'8':      true,
+	'9':      true,
+	':':      true,
+	';':      true,
+	'<':      true,
+	'=':      true,
+	'>':      true,
+	'?':      true,
+	'@':      true,
+	'A':      true,
+	'B':      true,
+	'C':      true,
+	'D':      true,
+	'E':      true,
+	'F':      true,
+	'G':      true,
+	'H':      true,
+	'I':      true,
+	'J':      true,
+	'K':      true,
+	'L':      true,
+	'M':      true,
+	'N':      true,
+	'O':      true,
+	'P':      true,
+	'Q':      true,
+	'R':      true,
+	'S':      true,
+	'T':      true,
+	'U':      true,
+	'V':      true,
+	'W':      true,
+	'X':      true,
+	'Y':      true,
+	'Z':      true,
+	'[':      true,
+	'\\':     false,
+	']':      true,
+	'^':      true,
+	'_':      true,
+	'`':      true,
+	'a':      true,
+	'b':      true,
+	'c':      true,
+	'd':      true,
+	'e':      true,
+	'f':      true,
+	'g':      true,
+	'h':      true,
+	'i':      true,
+	'j':      true,
+	'k':      true,
+	'l':      true,
+	'm':      true,
+	'n':      true,
+	'o':      true,
+	'p':      true,
+	'q':      true,
+	'r':      true,
+	's':      true,
+	't':      true,
+	'u':      true,
+	'v':      true,
+	'w':      true,
+	'x':      true,
+	'y':      true,
+	'z':      true,
+	'{':      true,
+	'|':      true,
+	'}':      true,
+	'~':      true,
+	'\u007f': true,
+}
+
+// htmlSafeSet holds the value true if the ASCII character with the given
+// array position can be safely represented inside a JSON string, embedded
+// inside of HTML <script> tags, without any additional escaping.
+//
+// All values are true except for the ASCII control characters (0-31), the
+// double quote ("), the backslash character ("\"), HTML opening and closing
+// tags ("<" and ">"), and the ampersand ("&").
+var htmlSafeSet = [utf8.RuneSelf]bool{
+	' ':      true,
+	'!':      true,
+	'"':      false,
+	'#':      true,
+	'$':      true,
+	'%':      true,
+	'&':      false,
+	'\'':     true,
+	'(':      true,
+	')':      true,
+	'*':      true,
+	'+':      true,
+	',':      true,
+	'-':      true,
+	'.':      true,
+	'/':      true,
+	'0':      true,
+	'1':      true,
+	'2':      true,
+	'3':      true,
+	'4':      true,
+	'5':      true,
+	'6':      true,
+	'7':      true,
+	'8':      true,
+	'9':      true,
+	':':      true,
+	';':      true,
+	'<':      false,
+	'=':      true,
+	'>':      false,
+	'?':      true,
+	'@':      true,
+	'A':      true,
+	'B':      true,
+	'C':      true,
+	'D':      true,
+	'E':      true,
+	'F':      true,
+	'G':      true,
+	'H':      true,
+	'I':      true,
+	'J':      true,
+	'K':      true,
+	'L':      true,
+	'M':      true,
+	'N':      true,
+	'O':      true,
+	'P':      true,
+	'Q':      true,
+	'R':      true,
+	'S':      true,
+	'T':      true,
+	'U':      true,
+	'V':      true,
+	'W':      true,
+	'X':      true,
+	'Y':      true,
+	'Z':      true,
+	'[':      true,
+	'\\':     false,
+	']':      true,
+	'^':      true,
+	'_':      true,
+	'`':      true,
+	'a':      true,
+	'b':      true,
+	'c':      true,
+	'd':      true,
+	'e':      true,
+	'f':      true,
+	'g':      true,
+	'h':      true,
+	'i':      true,
+	'j':      true,
+	'k':      true,
+	'l':      true,
+	'm':      true,
+	'n':      true,
+	'o':      true,
+	'p':      true,
+	'q':      true,
+	'r':      true,
+	's':      true,
+	't':      true,
+	'u':      true,
+	'v':      true,
+	'w':      true,
+	'x':      true,
+	'y':      true,
+	'z':      true,
+	'{':      true,
+	'|':      true,
+	'}':      true,
+	'~':      true,
+	'\u007f': true,
+}
diff --git a/vendor/github.com/yaegashi/msgraph.go/jsonx/tags.go b/vendor/github.com/yaegashi/msgraph.go/jsonx/tags.go
new file mode 100644
index 00000000..e524e12e
--- /dev/null
+++ b/vendor/github.com/yaegashi/msgraph.go/jsonx/tags.go
@@ -0,0 +1,44 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package jsonx
+
+import (
+	"strings"
+)
+
+// tagOptions is the string following a comma in a struct field's "json"
+// tag, or the empty string. It does not include the leading comma.
+type tagOptions string
+
+// parseTag splits a struct field's json tag into its name and
+// comma-separated options.
+func parseTag(tag string) (string, tagOptions) {
+	if idx := strings.Index(tag, ","); idx != -1 {
+		return tag[:idx], tagOptions(tag[idx+1:])
+	}
+	return tag, tagOptions("")
+}
+
+// Contains reports whether a comma-separated list of options
+// contains a particular substr flag. substr must be surrounded by a
+// string boundary or commas.
+func (o tagOptions) Contains(optionName string) bool {
+	if len(o) == 0 {
+		return false
+	}
+	s := string(o)
+	for s != "" {
+		var next string
+		i := strings.Index(s, ",")
+		if i >= 0 {
+			s, next = s[:i], s[i+1:]
+		}
+		if s == optionName {
+			return true
+		}
+		s = next
+	}
+	return false
+}