Add scripting (tengo) support for every incoming message (#731)

TengoModifyMessage allows you to specify the location of a tengo (https://github.com/d5/tengo/) script.
This script will receive every incoming message and can be used to modify the Username and the Text of that message.
The script will have the following global variables:
to modify: msgUsername and msgText
to read: msgChannel and msgAccount

The script is reloaded on every message, so you can modify the script on the fly.

Example script can be found in https://github.com/42wim/matterbridge/tree/master/gateway/bench.tengo
and https://github.com/42wim/matterbridge/tree/master/contrib/example.tengo

The example below will check if the text contains blah and if so, it'll replace the text and the username of that message.
text := import("text")
if text.re_match("blah",msgText) {
    msgText="replaced by this"
    msgUsername="fakeuser"
}

More information about tengo on: https://github.com/d5/tengo/blob/master/docs/tutorial.md and
https://github.com/d5/tengo/blob/master/docs/stdlib.md

1 files changed, 105 insertions, 0 deletions

diff --git a/vendor/github.com/d5/tengo/objects/immutable_map.go b/vendor/github.com/d5/tengo/objects/immutable_map.go
new file mode 100644
index 00000000..8f58701b
--- /dev/null
+++ b/vendor/github.com/d5/tengo/objects/immutable_map.go
@@ -0,0 +1,105 @@
+package objects
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/d5/tengo/compiler/token"
+)
+
+// ImmutableMap represents an immutable map object.
+type ImmutableMap struct {
+	Value map[string]Object
+}
+
+// TypeName returns the name of the type.
+func (o *ImmutableMap) TypeName() string {
+	return "immutable-map"
+}
+
+func (o *ImmutableMap) String() string {
+	var pairs []string
+	for k, v := range o.Value {
+		pairs = append(pairs, fmt.Sprintf("%s: %s", k, v.String()))
+	}
+
+	return fmt.Sprintf("{%s}", strings.Join(pairs, ", "))
+}
+
+// BinaryOp returns another object that is the result of
+// a given binary operator and a right-hand side object.
+func (o *ImmutableMap) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *ImmutableMap) Copy() Object {
+	c := make(map[string]Object)
+	for k, v := range o.Value {
+		c[k] = v.Copy()
+	}
+
+	return &Map{Value: c}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *ImmutableMap) IsFalsy() bool {
+	return len(o.Value) == 0
+}
+
+// IndexGet returns the value for the given key.
+func (o *ImmutableMap) IndexGet(index Object) (res Object, err error) {
+	strIdx, ok := ToString(index)
+	if !ok {
+		err = ErrInvalidIndexType
+		return
+	}
+
+	val, ok := o.Value[strIdx]
+	if !ok {
+		val = UndefinedValue
+	}
+
+	return val, nil
+}
+
+// Equals returns true if the value of the type
+// is equal to the value of another object.
+func (o *ImmutableMap) Equals(x Object) bool {
+	var xVal map[string]Object
+	switch x := x.(type) {
+	case *Map:
+		xVal = x.Value
+	case *ImmutableMap:
+		xVal = x.Value
+	default:
+		return false
+	}
+
+	if len(o.Value) != len(xVal) {
+		return false
+	}
+
+	for k, v := range o.Value {
+		tv := xVal[k]
+		if !v.Equals(tv) {
+			return false
+		}
+	}
+
+	return true
+}
+
+// Iterate creates an immutable map iterator.
+func (o *ImmutableMap) Iterate() Iterator {
+	var keys []string
+	for k := range o.Value {
+		keys = append(keys, k)
+	}
+
+	return &MapIterator{
+		v: o.Value,
+		k: keys,
+		l: len(keys),
+	}
+}