irc-go/ircmsg/tags.go

// written by Daniel Oaks <daniel@danieloaks.net>
// released under the CC0 Public Domain license

package ircmsg

// ValToEscape contains the IRCv3 Tag Escapes and how characters map to them.
var ValToEscape = map[byte]byte{
	';':  ':',
	' ':  's',
	'\\': '\\',
	'\r': 'r',
	'\n': 'n',
}

// EscapeToVal contains the IRCv3 Tag Escapes and how they map to characters.
var EscapeToVal = map[byte]byte{
	':':  ';',
	's':  ' ',
	'\\': '\\',
	'r':  '\r',
	'n':  '\n',
}

// EscapeTagValue takes a value, and returns an escaped message tag value.
func EscapeTagValue(in string) string {
	out := ""

	for len(in) > 0 {
		val, exists := ValToEscape[in[0]]
		if exists == true {
			out += "\\" + string(val)
		} else {
			out += string(in[0])
		}
		in = in[1:]
	}

	return out
}

// UnescapeTagValue takes an escaped message tag value, and returns the raw value.
func UnescapeTagValue(in string) string {
	out := ""

	for len(in) > 0 {
		if in[0] == '\\' && len(in) > 1 {
			val, exists := EscapeToVal[in[1]]
			if exists == true {
				out += "\\" + string(val)
			} else {
				out += string(in[1])
			}
			in = in[2:]
		} else {
			out += string(in[0])
			in = in[1:]
		}
	}

	return out
}

// TagValue represents the value of a tag. This is because tags may have
// no value at all or just an empty value, and this can represent both
// using the HasValue attribute.
type TagValue struct {
	HasValue bool
	Value    string
}

// NoTagValue returns an empty TagValue.
func NoTagValue() TagValue {
	var tag TagValue
	tag.HasValue = false
	return tag
}

// MakeTagValue returns a TagValue with a defined value.
func MakeTagValue(value string) TagValue {
	var tag TagValue
	tag.HasValue = true
	tag.Value = value
	return tag
}

// MakeTags simplifies tag creation for new messages.
//
// For example: MakeTags("intent", "PRIVMSG", "account", "bunny", "noval", nil)
func MakeTags(values ...interface{}) *map[string]TagValue {
	var tags map[string]TagValue
	tags = make(map[string]TagValue)

	for len(values) > 1 {
		tag := values[0].(string)
		value := values[1]
		var val TagValue

		if value == nil {
			val = NoTagValue()
		} else {
			val = MakeTagValue(value.(string))
		}

		tags[tag] = val

		values = values[2:]
	}

	return &tags
}