encoding/json: scanner: use byte, more consistent

The fields step and redoState of struct scanner are now defined as
`func(s *scanner, c byte) int` instead of
`func(s *scanner, c int) int`, since bytes are sufficient.
Further changes improve the consistency in the scanner.go file.

Change-Id: Ifb85f2130d728d2b936d79914d87a1f0b5c6ee7d
Reviewed-on: https://go-review.googlesource.com/14801Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/encoding/json/decode.go

@@ -241,7 +241,7 @@ func (d *decodeState) scanWhile(op int) int {
 			newOp = d.scan.eof()
 			d.off = len(d.data) + 1 // mark processed EOF with len+1
 		} else {
-			c := int(d.data[d.off])
+			c := d.data[d.off]
 			d.off++
 			newOp = d.scan.step(&d.scan, c)
 		}

src/encoding/json/decode_test.go

@@ -716,7 +716,7 @@ func TestErrorMessageFromMisusedString(t *testing.T) {
 }
 
 func noSpace(c rune) rune {
-	if isSpace(c) {
+	if isSpace(byte(c)) { //only used for ascii
 		return -1
 	}
 	return c

src/encoding/json/indent.go

@@ -36,7 +36,7 @@ func compact(dst *bytes.Buffer, src []byte, escape bool) error {
 			dst.WriteByte(hex[src[i+2]&0xF])
 			start = i + 3
 		}
-		v := scan.step(&scan, int(c))
+		v := scan.step(&scan, c)
 		if v >= scanSkipSpace {
 			if v == scanError {
 				break
@@ -80,7 +80,7 @@ func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
 	depth := 0
 	for _, c := range src {
 		scan.bytes++
-		v := scan.step(&scan, int(c))
+		v := scan.step(&scan, c)
 		if v == scanSkipSpace {
 			continue
 		}

src/encoding/json/scanner.go

@@ -21,7 +21,7 @@ func checkValid(data []byte, scan *scanner) error {
 	scan.reset()
 	for _, c := range data {
 		scan.bytes++
-		if scan.step(scan, int(c)) == scanError {
+		if scan.step(scan, c) == scanError {
 			return scan.err
 		}
 	}
@@ -37,7 +37,7 @@ func checkValid(data []byte, scan *scanner) error {
 func nextValue(data []byte, scan *scanner) (value, rest []byte, err error) {
 	scan.reset()
 	for i, c := range data {
-		v := scan.step(scan, int(c))
+		v := scan.step(scan, c)
 		if v >= scanEndObject {
 			switch v {
 			// probe the scanner with a space to determine whether we will
@@ -50,7 +50,7 @@ func nextValue(data []byte, scan *scanner) (value, rest []byte, err error) {
 			case scanError:
 				return nil, nil, scan.err
 			case scanEnd:
-				return data[0:i], data[i:], nil
+				return data[:i], data[i:], nil
 			}
 		}
 	}
@@ -85,7 +85,7 @@ type scanner struct {
 	// Also tried using an integer constant and a single func
 	// with a switch, but using the func directly was 10% faster
 	// on a 64-bit Mac Mini, and it's nicer to read.
-	step func(*scanner, int) int
+	step func(*scanner, byte) int
 
 	// Reached end of top-level value.
 	endTop bool
@@ -99,7 +99,7 @@ type scanner struct {
 	// 1-byte redo (see undo method)
 	redo      bool
 	redoCode  int
-	redoState func(*scanner, int) int
+	redoState func(*scanner, byte) int
 
 	// total bytes consumed, updated by decoder.Decode
 	bytes int64
@@ -188,13 +188,13 @@ func (s *scanner) popParseState() {
 	}
 }
 
-func isSpace(c rune) bool {
+func isSpace(c byte) bool {
 	return c == ' ' || c == '\t' || c == '\r' || c == '\n'
 }
 
 // stateBeginValueOrEmpty is the state after reading `[`.
-func stateBeginValueOrEmpty(s *scanner, c int) int {
-	if c <= ' ' && isSpace(rune(c)) {
+func stateBeginValueOrEmpty(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
 		return scanSkipSpace
 	}
 	if c == ']' {
@@ -204,8 +204,8 @@ func stateBeginValueOrEmpty(s *scanner, c int) int {
 }
 
 // stateBeginValue is the state at the beginning of the input.
-func stateBeginValue(s *scanner, c int) int {
-	if c <= ' ' && isSpace(rune(c)) {
+func stateBeginValue(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
 		return scanSkipSpace
 	}
 	switch c {
@@ -244,8 +244,8 @@ func stateBeginValue(s *scanner, c int) int {
 }
 
 // stateBeginStringOrEmpty is the state after reading `{`.
-func stateBeginStringOrEmpty(s *scanner, c int) int {
-	if c <= ' ' && isSpace(rune(c)) {
+func stateBeginStringOrEmpty(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
 		return scanSkipSpace
 	}
 	if c == '}' {
@@ -257,8 +257,8 @@ func stateBeginStringOrEmpty(s *scanner, c int) int {
 }
 
 // stateBeginString is the state after reading `{"key": value,`.
-func stateBeginString(s *scanner, c int) int {
-	if c <= ' ' && isSpace(rune(c)) {
+func stateBeginString(s *scanner, c byte) int {
+	if c <= ' ' && isSpace(c) {
 		return scanSkipSpace
 	}
 	if c == '"' {
@@ -270,7 +270,7 @@ func stateBeginString(s *scanner, c int) int {
 
 // stateEndValue is the state after completing a value,
 // such as after reading `{}` or `true` or `["x"`.
-func stateEndValue(s *scanner, c int) int {
+func stateEndValue(s *scanner, c byte) int {
 	n := len(s.parseState)
 	if n == 0 {
 		// Completed top-level before the current byte.
@@ -278,7 +278,7 @@ func stateEndValue(s *scanner, c int) int {
 		s.endTop = true
 		return stateEndTop(s, c)
 	}
-	if c <= ' ' && isSpace(rune(c)) {
+	if c <= ' ' && isSpace(c) {
 		s.step = stateEndValue
 		return scanSkipSpace
 	}
@@ -319,7 +319,7 @@ func stateEndValue(s *scanner, c int) int {
 // stateEndTop is the state after finishing the top-level value,
 // such as after reading `{}` or `[1,2,3]`.
 // Only space characters should be seen now.
-func stateEndTop(s *scanner, c int) int {
+func stateEndTop(s *scanner, c byte) int {
 	if c != ' ' && c != '\t' && c != '\r' && c != '\n' {
 		// Complain about non-space byte on next call.
 		s.error(c, "after top-level value")
@@ -328,7 +328,7 @@ func stateEndTop(s *scanner, c int) int {
 }
 
 // stateInString is the state after reading `"`.
-func stateInString(s *scanner, c int) int {
+func stateInString(s *scanner, c byte) int {
 	if c == '"' {
 		s.step = stateEndValue
 		return scanContinue
@@ -344,13 +344,12 @@ func stateInString(s *scanner, c int) int {
 }
 
 // stateInStringEsc is the state after reading `"\` during a quoted string.
-func stateInStringEsc(s *scanner, c int) int {
+func stateInStringEsc(s *scanner, c byte) int {
 	switch c {
 	case 'b', 'f', 'n', 'r', 't', '\\', '/', '"':
 		s.step = stateInString
 		return scanContinue
-	}
-	if c == 'u' {
+	case 'u':
 		s.step = stateInStringEscU
 		return scanContinue
 	}
@@ -358,7 +357,7 @@ func stateInStringEsc(s *scanner, c int) int {
 }
 
 // stateInStringEscU is the state after reading `"\u` during a quoted string.
-func stateInStringEscU(s *scanner, c int) int {
+func stateInStringEscU(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
 		s.step = stateInStringEscU1
 		return scanContinue
@@ -368,7 +367,7 @@ func stateInStringEscU(s *scanner, c int) int {
 }
 
 // stateInStringEscU1 is the state after reading `"\u1` during a quoted string.
-func stateInStringEscU1(s *scanner, c int) int {
+func stateInStringEscU1(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
 		s.step = stateInStringEscU12
 		return scanContinue
@@ -378,7 +377,7 @@ func stateInStringEscU1(s *scanner, c int) int {
 }
 
 // stateInStringEscU12 is the state after reading `"\u12` during a quoted string.
-func stateInStringEscU12(s *scanner, c int) int {
+func stateInStringEscU12(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
 		s.step = stateInStringEscU123
 		return scanContinue
@@ -388,7 +387,7 @@ func stateInStringEscU12(s *scanner, c int) int {
 }
 
 // stateInStringEscU123 is the state after reading `"\u123` during a quoted string.
-func stateInStringEscU123(s *scanner, c int) int {
+func stateInStringEscU123(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
 		s.step = stateInString
 		return scanContinue
@@ -398,7 +397,7 @@ func stateInStringEscU123(s *scanner, c int) int {
 }
 
 // stateNeg is the state after reading `-` during a number.
-func stateNeg(s *scanner, c int) int {
+func stateNeg(s *scanner, c byte) int {
 	if c == '0' {
 		s.step = state0
 		return scanContinue
@@ -412,7 +411,7 @@ func stateNeg(s *scanner, c int) int {
 
 // state1 is the state after reading a non-zero integer during a number,
 // such as after reading `1` or `100` but not `0`.
-func state1(s *scanner, c int) int {
+func state1(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' {
 		s.step = state1
 		return scanContinue
@@ -421,7 +420,7 @@ func state1(s *scanner, c int) int {
 }
 
 // state0 is the state after reading `0` during a number.
-func state0(s *scanner, c int) int {
+func state0(s *scanner, c byte) int {
 	if c == '.' {
 		s.step = stateDot
 		return scanContinue
@@ -435,7 +434,7 @@ func state0(s *scanner, c int) int {
 
 // stateDot is the state after reading the integer and decimal point in a number,
 // such as after reading `1.`.
-func stateDot(s *scanner, c int) int {
+func stateDot(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' {
 		s.step = stateDot0
 		return scanContinue
@@ -445,9 +444,8 @@ func stateDot(s *scanner, c int) int {
 
 // stateDot0 is the state after reading the integer, decimal point, and subsequent
 // digits of a number, such as after reading `3.14`.
-func stateDot0(s *scanner, c int) int {
+func stateDot0(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' {
-		s.step = stateDot0
 		return scanContinue
 	}
 	if c == 'e' || c == 'E' {
@@ -459,12 +457,8 @@ func stateDot0(s *scanner, c int) int {
 
 // stateE is the state after reading the mantissa and e in a number,
 // such as after reading `314e` or `0.314e`.
-func stateE(s *scanner, c int) int {
-	if c == '+' {
-		s.step = stateESign
-		return scanContinue
-	}
-	if c == '-' {
+func stateE(s *scanner, c byte) int {
+	if c == '+' || c == '-' {
 		s.step = stateESign
 		return scanContinue
 	}
@@ -473,7 +467,7 @@ func stateE(s *scanner, c int) int {
 
 // stateESign is the state after reading the mantissa, e, and sign in a number,
 // such as after reading `314e-` or `0.314e+`.
-func stateESign(s *scanner, c int) int {
+func stateESign(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' {
 		s.step = stateE0
 		return scanContinue
@@ -484,16 +478,15 @@ func stateESign(s *scanner, c int) int {
 // stateE0 is the state after reading the mantissa, e, optional sign,
 // and at least one digit of the exponent in a number,
 // such as after reading `314e-2` or `0.314e+1` or `3.14e0`.
-func stateE0(s *scanner, c int) int {
+func stateE0(s *scanner, c byte) int {
 	if '0' <= c && c <= '9' {
-		s.step = stateE0
 		return scanContinue
 	}
 	return stateEndValue(s, c)
 }
 
 // stateT is the state after reading `t`.
-func stateT(s *scanner, c int) int {
+func stateT(s *scanner, c byte) int {
 	if c == 'r' {
 		s.step = stateTr
 		return scanContinue
@@ -502,7 +495,7 @@ func stateT(s *scanner, c int) int {
 }
 
 // stateTr is the state after reading `tr`.
-func stateTr(s *scanner, c int) int {
+func stateTr(s *scanner, c byte) int {
 	if c == 'u' {
 		s.step = stateTru
 		return scanContinue
@@ -511,7 +504,7 @@ func stateTr(s *scanner, c int) int {
 }
 
 // stateTru is the state after reading `tru`.
-func stateTru(s *scanner, c int) int {
+func stateTru(s *scanner, c byte) int {
 	if c == 'e' {
 		s.step = stateEndValue
 		return scanContinue
@@ -520,7 +513,7 @@ func stateTru(s *scanner, c int) int {
 }
 
 // stateF is the state after reading `f`.
-func stateF(s *scanner, c int) int {
+func stateF(s *scanner, c byte) int {
 	if c == 'a' {
 		s.step = stateFa
 		return scanContinue
@@ -529,7 +522,7 @@ func stateF(s *scanner, c int) int {
 }
 
 // stateFa is the state after reading `fa`.
-func stateFa(s *scanner, c int) int {
+func stateFa(s *scanner, c byte) int {
 	if c == 'l' {
 		s.step = stateFal
 		return scanContinue
@@ -538,7 +531,7 @@ func stateFa(s *scanner, c int) int {
 }
 
 // stateFal is the state after reading `fal`.
-func stateFal(s *scanner, c int) int {
+func stateFal(s *scanner, c byte) int {
 	if c == 's' {
 		s.step = stateFals
 		return scanContinue
@@ -547,7 +540,7 @@ func stateFal(s *scanner, c int) int {
 }
 
 // stateFals is the state after reading `fals`.
-func stateFals(s *scanner, c int) int {
+func stateFals(s *scanner, c byte) int {
 	if c == 'e' {
 		s.step = stateEndValue
 		return scanContinue
@@ -556,7 +549,7 @@ func stateFals(s *scanner, c int) int {
 }
 
 // stateN is the state after reading `n`.
-func stateN(s *scanner, c int) int {
+func stateN(s *scanner, c byte) int {
 	if c == 'u' {
 		s.step = stateNu
 		return scanContinue
@@ -565,7 +558,7 @@ func stateN(s *scanner, c int) int {
 }
 
 // stateNu is the state after reading `nu`.
-func stateNu(s *scanner, c int) int {
+func stateNu(s *scanner, c byte) int {
 	if c == 'l' {
 		s.step = stateNul
 		return scanContinue
@@ -574,7 +567,7 @@ func stateNu(s *scanner, c int) int {
 }
 
 // stateNul is the state after reading `nul`.
-func stateNul(s *scanner, c int) int {
+func stateNul(s *scanner, c byte) int {
 	if c == 'l' {
 		s.step = stateEndValue
 		return scanContinue
@@ -584,19 +577,19 @@ func stateNul(s *scanner, c int) int {
 
 // stateError is the state after reaching a syntax error,
 // such as after reading `[1}` or `5.1.2`.
-func stateError(s *scanner, c int) int {
+func stateError(s *scanner, c byte) int {
 	return scanError
 }
 
 // error records an error and switches to the error state.
-func (s *scanner) error(c int, context string) int {
+func (s *scanner) error(c byte, context string) int {
 	s.step = stateError
 	s.err = &SyntaxError{"invalid character " + quoteChar(c) + " " + context, s.bytes}
 	return scanError
 }
 
 // quoteChar formats c as a quoted character literal
-func quoteChar(c int) string {
+func quoteChar(c byte) string {
 	// special cases - different from quoted strings
 	if c == '\'' {
 		return `'\''`
@@ -623,7 +616,7 @@ func (s *scanner) undo(scanCode int) {
 }
 
 // stateRedo helps implement the scanner's 1-byte undo.
-func stateRedo(s *scanner, c int) int {
+func stateRedo(s *scanner, c byte) int {
 	s.redo = false
 	s.step = s.redoState
 	return s.redoCode

src/encoding/json/stream.go

@@ -90,7 +90,7 @@ Input:
 		// Look in the buffer for a new value.
 		for i, c := range dec.buf[scanp:] {
 			dec.scan.bytes++
-			v := dec.scan.step(&dec.scan, int(c))
+			v := dec.scan.step(&dec.scan, c)
 			if v == scanEnd {
 				scanp += i
 				break Input
@@ -157,7 +157,7 @@ func (dec *Decoder) refill() error {
 
 func nonSpace(b []byte) bool {
 	for _, c := range b {
-		if !isSpace(rune(c)) {
+		if !isSpace(c) {
 			return true
 		}
 	}
@@ -433,7 +433,7 @@ func (dec *Decoder) tokenError(c byte) (Token, error) {
 	case tokenObjectComma:
 		context = " after object key:value pair"
 	}
-	return nil, &SyntaxError{"invalid character " + quoteChar(int(c)) + " " + context, 0}
+	return nil, &SyntaxError{"invalid character " + quoteChar(c) + " " + context, 0}
 }
 
 // More reports whether there is another element in the
@@ -448,7 +448,7 @@ func (dec *Decoder) peek() (byte, error) {
 	for {
 		for i := dec.scanp; i < len(dec.buf); i++ {
 			c := dec.buf[i]
-			if isSpace(rune(c)) {
+			if isSpace(c) {
 				continue
 			}
 			dec.scanp = i