reorganize parsing code

src/irc/parse.go

@@ -0,0 +1,88 @@
+package irc
+
+import (
+	"strconv"
+	"strings"
+)
+
+func parseArg(line string) (string, string) {
+	if line == "" {
+		return "", ""
+	}
+
+	if strings.HasPrefix(line, ":") {
+		return line[1:], ""
+	}
+
+	parts := strings.SplitN(line, " ", 2)
+	arg := parts[0]
+	rest := ""
+	if len(parts) > 1 {
+		rest = parts[1]
+	}
+	return arg, rest
+}
+
+func parseLine(line string) (string, []string) {
+	args := make([]string, 0)
+	for arg, rest := parseArg(line); arg != ""; arg, rest = parseArg(rest) {
+		args = append(args, arg)
+	}
+	return args[0], args[1:]
+}
+
+var commands = map[string]func([]string) Message {
+	"NICK": NewNickMessage,
+	"PING": NewPingMessage,
+	"QUIT": NewQuitMessage,
+	"USER": NewUserMessage,
+}
+
+func ParseMessage(line string) Message {
+	command, args := parseLine(line)
+	constructor, ok := commands[command]
+	var msg Message
+	if ok {
+		msg = constructor(args)
+	}
+	if msg == nil {
+		msg = &UnknownMessage{command}
+	}
+	return msg
+}
+
+// []string => Message constructors
+
+func NewNickMessage(args []string) Message {
+	if len(args) != 1 {
+		return nil
+	}
+	return &NickMessage{args[0]}
+}
+
+func NewPingMessage(args []string) Message {
+	return &PingMessage{}
+}
+
+func NewQuitMessage(args []string) Message {
+	msg := QuitMessage{}
+	if len(args) > 0 {
+		msg.message = args[0]
+	}
+	return &msg
+}
+
+func NewUserMessage(args []string) Message {
+	if len(args) != 4 {
+		return nil
+	}
+	msg := new(UserMessage)
+	msg.user = args[0]
+	mode, err := strconv.ParseUint(args[1], 10, 8)
+	if err == nil {
+		msg.mode = uint8(mode)
+	}
+	msg.unused = args[2]
+	msg.realname = args[3]
+	return msg
+}