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, 119 insertions, 0 deletions

diff --git a/vendor/github.com/d5/tengo/objects/char.go b/vendor/github.com/d5/tengo/objects/char.go
new file mode 100644
index 00000000..4458bd12
--- /dev/null
+++ b/vendor/github.com/d5/tengo/objects/char.go
@@ -0,0 +1,119 @@
+package objects
+
+import (
+	"github.com/d5/tengo/compiler/token"
+)
+
+// Char represents a character value.
+type Char struct {
+	Value rune
+}
+
+func (o *Char) String() string {
+	return string(o.Value)
+}
+
+// TypeName returns the name of the type.
+func (o *Char) TypeName() string {
+	return "char"
+}
+
+// BinaryOp returns another object that is the result of
+// a given binary operator and a right-hand side object.
+func (o *Char) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	switch rhs := rhs.(type) {
+	case *Char:
+		switch op {
+		case token.Add:
+			r := o.Value + rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Sub:
+			r := o.Value - rhs.Value
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Less:
+			if o.Value < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if o.Value > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if o.Value <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if o.Value >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	case *Int:
+		switch op {
+		case token.Add:
+			r := o.Value + rune(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Sub:
+			r := o.Value - rune(rhs.Value)
+			if r == o.Value {
+				return o, nil
+			}
+			return &Char{Value: r}, nil
+		case token.Less:
+			if int64(o.Value) < rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.Greater:
+			if int64(o.Value) > rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.LessEq:
+			if int64(o.Value) <= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		case token.GreaterEq:
+			if int64(o.Value) >= rhs.Value {
+				return TrueValue, nil
+			}
+			return FalseValue, nil
+		}
+	}
+
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *Char) Copy() Object {
+	return &Char{Value: o.Value}
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *Char) IsFalsy() bool {
+	return o.Value == 0
+}
+
+// Equals returns true if the value of the type
+// is equal to the value of another object.
+func (o *Char) Equals(x Object) bool {
+	t, ok := x.(*Char)
+	if !ok {
+		return false
+	}
+
+	return o.Value == t.Value
+}