Initial QSfera import

Server/vendor/github.com/prometheus/alertmanager/matcher/parse/token.go

@@ -0,0 +1,104 @@
+// Copyright 2023 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package parse
+
+import (
+	"errors"
+	"fmt"
+	"slices"
+	"strconv"
+	"unicode/utf8"
+)
+
+type tokenKind int
+
+const (
+	tokenEOF tokenKind = iota
+	tokenOpenBrace
+	tokenCloseBrace
+	tokenComma
+	tokenEquals
+	tokenNotEquals
+	tokenMatches
+	tokenNotMatches
+	tokenQuoted
+	tokenUnquoted
+)
+
+func (k tokenKind) String() string {
+	switch k {
+	case tokenOpenBrace:
+		return "OpenBrace"
+	case tokenCloseBrace:
+		return "CloseBrace"
+	case tokenComma:
+		return "Comma"
+	case tokenEquals:
+		return "Equals"
+	case tokenNotEquals:
+		return "NotEquals"
+	case tokenMatches:
+		return "Matches"
+	case tokenNotMatches:
+		return "NotMatches"
+	case tokenQuoted:
+		return "Quoted"
+	case tokenUnquoted:
+		return "Unquoted"
+	default:
+		return "EOF"
+	}
+}
+
+type token struct {
+	kind  tokenKind
+	value string
+	position
+}
+
+// isEOF returns true if the token is an end of file token.
+func (t token) isEOF() bool {
+	return t.kind == tokenEOF
+}
+
+// isOneOf returns true if the token is one of the specified kinds.
+func (t token) isOneOf(kinds ...tokenKind) bool {
+	return slices.Contains(kinds, t.kind)
+}
+
+// unquote the value in token. If unquoted returns it unmodified.
+func (t token) unquote() (string, error) {
+	if t.kind == tokenQuoted {
+		unquoted, err := strconv.Unquote(t.value)
+		if err != nil {
+			return "", err
+		}
+		if !utf8.ValidString(unquoted) {
+			return "", errors.New("quoted string contains invalid UTF-8 code points")
+		}
+		return unquoted, nil
+	}
+	return t.value, nil
+}
+
+func (t token) String() string {
+	return fmt.Sprintf("(%s) '%s'", t.kind, t.value)
+}
+
+type position struct {
+	offsetStart int // The start position in the input.
+	offsetEnd   int // The end position in the input.
+	columnStart int // The column number.
+	columnEnd   int // The end of the column.
+}