Copy unquoteBytes from encoding/json and use it for UnmarshalText

decode_unmarshal_text.go

@@ -2,6 +2,9 @@ package json
 
 import (
 	"encoding"
+	"unicode"
+	"unicode/utf16"
+	"unicode/utf8"
 	"unsafe"
 )
 
@@ -20,6 +23,9 @@ func (d *unmarshalTextDecoder) decodeStream(s *stream, p uintptr) error {
 		return err
 	}
 	src := s.buf[start:s.cursor]
+	if s, ok := unquoteBytes(src); ok {
+		src = s
+	}
 	v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 		typ: d.typ,
 		ptr: unsafe.Pointer(p),
@@ -38,6 +44,9 @@ func (d *unmarshalTextDecoder) decode(buf []byte, cursor int64, p uintptr) (int6
 		return 0, err
 	}
 	src := buf[start:end]
+	if s, ok := unquoteBytes(src); ok {
+		src = s
+	}
 	v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 		typ: d.typ,
 		ptr: unsafe.Pointer(p),
@@ -47,3 +56,140 @@ func (d *unmarshalTextDecoder) decode(buf []byte, cursor int64, p uintptr) (int6
 	}
 	return end, nil
 }
+
+func unquoteBytes(s []byte) (t []byte, ok bool) {
+	length := len(s)
+	if length < 2 || s[0] != '"' || s[length-1] != '"' {
+		return
+	}
+	s = s[1 : length-1]
+	length -= 2
+
+	// Check for unusual characters. If there are none,
+	// then no unquoting is needed, so return a slice of the
+	// original bytes.
+	r := 0
+	for r < length {
+		c := s[r]
+		if c == '\\' || c == '"' || c < ' ' {
+			break
+		}
+		if c < utf8.RuneSelf {
+			r++
+			continue
+		}
+		rr, size := utf8.DecodeRune(s[r:])
+		if rr == utf8.RuneError && size == 1 {
+			break
+		}
+		r += size
+	}
+	if r == length {
+		return s, true
+	}
+
+	b := make([]byte, length+2*utf8.UTFMax)
+	w := copy(b, s[0:r])
+	for r < length {
+		// Out of room? Can only happen if s is full of
+		// malformed UTF-8 and we're replacing each
+		// byte with RuneError.
+		if w >= len(b)-2*utf8.UTFMax {
+			nb := make([]byte, (len(b)+utf8.UTFMax)*2)
+			copy(nb, b[0:w])
+			b = nb
+		}
+		switch c := s[r]; {
+		case c == '\\':
+			r++
+			if r >= length {
+				return
+			}
+			switch s[r] {
+			default:
+				return
+			case '"', '\\', '/', '\'':
+				b[w] = s[r]
+				r++
+				w++
+			case 'b':
+				b[w] = '\b'
+				r++
+				w++
+			case 'f':
+				b[w] = '\f'
+				r++
+				w++
+			case 'n':
+				b[w] = '\n'
+				r++
+				w++
+			case 'r':
+				b[w] = '\r'
+				r++
+				w++
+			case 't':
+				b[w] = '\t'
+				r++
+				w++
+			case 'u':
+				r--
+				rr := getu4(s[r:])
+				if rr < 0 {
+					return
+				}
+				r += 6
+				if utf16.IsSurrogate(rr) {
+					rr1 := getu4(s[r:])
+					if dec := utf16.DecodeRune(rr, rr1); dec != unicode.ReplacementChar {
+						// A valid pair; consume.
+						r += 6
+						w += utf8.EncodeRune(b[w:], dec)
+						break
+					}
+					// Invalid surrogate; fall back to replacement rune.
+					rr = unicode.ReplacementChar
+				}
+				w += utf8.EncodeRune(b[w:], rr)
+			}
+
+		// Quote, control characters are invalid.
+		case c == '"', c < ' ':
+			return
+
+		// ASCII
+		case c < utf8.RuneSelf:
+			b[w] = c
+			r++
+			w++
+
+		// Coerce to well-formed UTF-8.
+		default:
+			rr, size := utf8.DecodeRune(s[r:])
+			r += size
+			w += utf8.EncodeRune(b[w:], rr)
+		}
+	}
+	return b[0:w], true
+}
+
+func getu4(s []byte) rune {
+	if len(s) < 6 || s[0] != '\\' || s[1] != 'u' {
+		return -1
+	}
+	var r rune
+	for _, c := range s[2:6] {
+		switch {
+		case '0' <= c && c <= '9':
+			c = c - '0'
+		case 'a' <= c && c <= 'f':
+			c = c - 'a' + 10
+		case 'A' <= c && c <= 'F':
+			c = c - 'A' + 10
+		default:
+			return -1
+		}
+		r = r*16 + rune(c)
+	}
+	return r
+}