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/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