Release catalyst

caql/unquote.go

@@ -0,0 +1,79 @@
+// Adapted from https://github.com/golang/go
+// Original License:
+//
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the https://go.dev/LICENSE file.
+
+package caql
+
+import (
+	"strconv"
+	"strings"
+	"unicode/utf8"
+)
+
+// unquote interprets s as a single-quoted, double-quoted,
+// or backquoted string literal, returning the string value
+// that s quotes.
+func unquote(s string) (string, error) {
+	n := len(s)
+	if n < 2 {
+		return "", strconv.ErrSyntax
+	}
+	quote := s[0]
+	if quote != s[n-1] {
+		return "", strconv.ErrSyntax
+	}
+	s = s[1 : n-1]
+
+	if quote == '`' {
+		if strings.ContainsRune(s, '`') {
+			return "", strconv.ErrSyntax
+		}
+		if strings.ContainsRune(s, '\r') {
+			// -1 because we know there is at least one \r to remove.
+			buf := make([]byte, 0, len(s)-1)
+			for i := 0; i < len(s); i++ {
+				if s[i] != '\r' {
+					buf = append(buf, s[i])
+				}
+			}
+			return string(buf), nil
+		}
+		return s, nil
+	}
+	if quote != '"' && quote != '\'' {
+		return "", strconv.ErrSyntax
+	}
+	if strings.ContainsRune(s, '\n') {
+		return "", strconv.ErrSyntax
+	}
+
+	// Is it trivial? Avoid allocation.
+	if !strings.ContainsRune(s, '\\') && !strings.ContainsRune(s, rune(quote)) {
+		switch quote {
+		case '"', '\'':
+			if utf8.ValidString(s) {
+				return s, nil
+			}
+		}
+	}
+
+	var runeTmp [utf8.UTFMax]byte
+	buf := make([]byte, 0, 3*len(s)/2) // Try to avoid more allocations.
+	for len(s) > 0 {
+		c, multibyte, ss, err := strconv.UnquoteChar(s, quote)
+		if err != nil {
+			return "", err
+		}
+		s = ss
+		if c < utf8.RuneSelf || !multibyte {
+			buf = append(buf, byte(c))
+		} else {
+			n := utf8.EncodeRune(runeTmp[:], c)
+			buf = append(buf, runeTmp[:n]...)
+		}
+	}
+	return string(buf), nil
+}