Command parsers plan 1

server/command/parsers.go

@@ -0,0 +1,72 @@
+package command
+
+import (
+	"io"
+	"strconv"
+	"strings"
+
+	pk "github.com/Tnze/go-mc/net/packet"
+)
+
+type StringParser struct {
+	Format int32
+	V      string
+}
+
+func (s StringParser) WriteTo(w io.Writer) (int64, error) {
+	return pk.Tuple{
+		pk.Identifier("brigadier:string"),
+		pk.VarInt(s.Format),
+	}.WriteTo(w)
+}
+
+func (s StringParser) Parse(cmd string) (token string, value interface{}, err error) {
+	switch s.Format {
+	case 2: // Greedy Phrase
+		return cmd, cmd, nil
+	case 1: // Quotable Phrase
+		if len(cmd) > 0 && cmd[0] == '"' {
+			var sb strings.Builder
+			var isEscaping bool
+			for i, v := range cmd[1:] {
+				if isEscaping {
+					isEscaping = false
+					switch v {
+					case '\\':
+						sb.WriteRune('\\')
+					case '"':
+						sb.WriteRune('"')
+					}
+				} else if v == '\\' {
+					isEscaping = true
+				} else if v == '"' {
+					return cmd[:i], sb.String(), nil
+				} else {
+					sb.WriteRune(v)
+				}
+			}
+			return "", nil, ParseErr{
+				Pos: len(cmd) - 1,
+				Err: "expected '\"'",
+			}
+		}
+		fallthrough
+	case 0: // Single Word
+		i := strings.IndexAny(cmd, "\t\n\v\f\r ")
+		if i == -1 {
+			return cmd, cmd, nil
+		}
+		return cmd[:i], cmd[:i], nil
+	default:
+		panic("StringParser: unknown format 0x" + strconv.FormatInt(int64(s.Format), 16))
+	}
+}
+
+type ParseErr struct {
+	Pos int
+	Err string
+}
+
+func (p ParseErr) Error() string {
+	return p.Err
+}