bump irc-go to v0.1.0

vendor/github.com/ergochat/irc-go/ircmsg/userhost.go

@@ -0,0 +1,61 @@
+// written by Daniel Oaks <daniel@danieloaks.net>
+// released under the ISC license
+
+package ircmsg
+
+import (
+	"errors"
+	"strings"
+)
+
+var (
+	MalformedNUH = errors.New("NUH is malformed")
+)
+
+// NUH holds a parsed name!user@host source ("prefix") of an IRC message.
+// The Name member will be either a nickname (in the case of a user-initiated
+// message) or a server name (in the case of a server-initiated numeric,
+// command, or NOTICE).
+type NUH struct {
+	Name string
+	User string
+	Host string
+}
+
+// ParseNUH parses a NUH source of an IRC message into its constituent parts;
+// name (nickname or server name), username, and hostname.
+func ParseNUH(in string) (out NUH, err error) {
+	if len(in) == 0 {
+		return out, MalformedNUH
+	}
+
+	hostStart := strings.IndexByte(in, '@')
+	if hostStart != -1 {
+		out.Host = in[hostStart+1:]
+		in = in[:hostStart]
+	}
+	userStart := strings.IndexByte(in, '!')
+	if userStart != -1 {
+		out.User = in[userStart+1:]
+		in = in[:userStart]
+	}
+	out.Name = in
+
+	return
+}
+
+// Canonical returns the canonical string representation of the NUH.
+func (nuh *NUH) Canonical() (result string) {
+	var out strings.Builder
+	out.Grow(len(nuh.Name) + len(nuh.User) + len(nuh.Host) + 2)
+	out.WriteString(nuh.Name)
+	if len(nuh.User) != 0 {
+		out.WriteByte('!')
+		out.WriteString(nuh.User)
+	}
+	if len(nuh.Host) != 0 {
+		out.WriteByte('@')
+		out.WriteString(nuh.Host)
+	}
+	return out.String()
+}