func _peek_char(port Obj) Obj {
if is_immediate(port) {
panic("bad type")
}
switch v := (*port).(type) {
case *InputPort:
if v.is_binary {
panic("bad port type")
}
for !utf8.FullRune(v.lookahead[0:v.lookahead_valid]) {
n, err := io.ReadFull(v.r,
v.lookahead[v.lookahead_valid:v.lookahead_valid+1])
v.lookahead_valid += n
switch {
case err == os.EOF:
return Eof
case err != nil:
panic("I/O read error")
}
}
cp, _ := utf8.DecodeRune(v.lookahead[0:v.lookahead_valid])
return Make_char(cp)
}
panic("bad type")
}
// ReadRune returns the next UTF-8 encoded code point from the
// io.Reader inside r.
func (r *readRune) ReadRune() (rune int, size int, err os.Error) {
r.buf[0], err = r.readByte()
if err != nil {
return 0, 0, err
}
if r.buf[0] < utf8.RuneSelf { // fast check for common ASCII case
rune = int(r.buf[0])
return
}
var n int
for n = 1; !utf8.FullRune(r.buf[0:n]); n++ {
r.buf[n], err = r.readByte()
if err != nil {
if err == os.EOF {
err = nil
break
}
return
}
}
rune, size = utf8.DecodeRune(r.buf[0:n])
if size < n { // an error
r.unread(r.buf[size:n])
}
return
}
// next reads and returns the next Unicode character. It is designed such
// that only a minimal amount of work needs to be done in the common ASCII
// case (one test to check for both ASCII and end-of-buffer, and one test
// to check for newlines).
func (s *Scanner) next() int {
ch := int(s.srcBuf[s.srcPos])
if ch >= utf8.RuneSelf {
// uncommon case: not ASCII or not enough bytes
for s.srcPos+utf8.UTFMax > s.srcEnd && !utf8.FullRune(s.srcBuf[s.srcPos:s.srcEnd]) {
// not enough bytes: read some more, but first
// save away token text if any
if s.tokPos >= 0 {
s.tokBuf.Write(s.srcBuf[s.tokPos:s.srcPos])
s.tokPos = 0
}
// move unread bytes to beginning of buffer
copy(s.srcBuf[0:], s.srcBuf[s.srcPos:s.srcEnd])
s.srcBufOffset += s.srcPos
// read more bytes
i := s.srcEnd - s.srcPos
n, err := s.src.Read(s.srcBuf[i:bufLen])
s.srcEnd = i + n
s.srcPos = 0
s.srcBuf[s.srcEnd] = utf8.RuneSelf // sentinel
if err != nil {
if s.srcEnd == 0 {
return EOF
}
if err != os.EOF {
s.error(err.String())
break
}
}
}
// at least one byte
ch = int(s.srcBuf[s.srcPos])
if ch >= utf8.RuneSelf {
// uncommon case: not ASCII
var width int
ch, width = utf8.DecodeRune(s.srcBuf[s.srcPos:s.srcEnd])
if ch == utf8.RuneError && width == 1 {
s.error("illegal UTF-8 encoding")
}
s.srcPos += width - 1
}
}
s.srcPos++
s.column++
switch ch {
case 0:
// implementation restriction for compatibility with other tools
s.error("illegal character NUL")
case '\n':
s.line++
s.column = 0
}
return ch
}
// ReadRune reads a single UTF-8 encoded Unicode character and returns the
// rune and its size in bytes.
func (b *Reader) ReadRune() (rune int, size int, err os.Error) {
for b.r+utf8.UTFMax > b.w && !utf8.FullRune(b.buf[b.r:b.w]) && b.err == nil {
b.fill()
}
if b.r == b.w {
return 0, 0, b.err
}
rune, size = int(b.buf[b.r]), 1
if rune >= 0x80 {
rune, size = utf8.DecodeRune(b.buf[b.r:b.w])
}
b.r += size
b.lastbyte = int(b.buf[b.r-1])
return rune, size, nil
}
// next reads and returns the next Unicode character. It is designed such
// that only a minimal amount of work needs to be done in the common ASCII
// case (one test to check for both ASCII and end-of-buffer, and one test
// to check for newlines).
func (s *Scanner) next() int {
ch := int(s.srcBuf[s.srcPos])
if ch >= utf8.RuneSelf {
// uncommon case: not ASCII or not enough bytes
for s.srcPos+utf8.UTFMax > s.srcEnd && !utf8.FullRune(s.srcBuf[s.srcPos:s.srcEnd]) {
// not enough bytes: read some more, but first
// save away token text if any
if s.tokPos >= 0 {
s.tokBuf.Write(s.srcBuf[s.tokPos:s.srcPos])
s.tokPos = 0
}
// move unread bytes to beginning of buffer
copy(s.srcBuf[0:], s.srcBuf[s.srcPos:s.srcEnd])
s.srcBufOffset += s.srcPos
// read more bytes
i := s.srcEnd - s.srcPos
n, err := s.src.Read(s.srcBuf[i:bufLen])
s.srcEnd = i + n
s.srcPos = 0
s.srcBuf[s.srcEnd] = utf8.RuneSelf // sentinel
if err != nil {
if s.srcEnd == 0 {
return EOF
}
s.error(err.String())
break
}
}
// at least one byte
ch = int(s.srcBuf[s.srcPos])
if ch >= utf8.RuneSelf {
// uncommon case: not ASCII
var width int
ch, width = utf8.DecodeRune(s.srcBuf[s.srcPos:s.srcEnd])
s.srcPos += width - 1
}
}
s.srcPos++
s.column++
if ch == '\n' {
s.line++
s.column = 0
}
return ch
}
// ReadRune reads a single UTF-8 encoded Unicode character and returns the
// rune and its size in bytes.
func (b *Reader) ReadRune() (r rune, size int, err error) {
for b.r+utf8.UTFMax > b.w && !utf8.FullRune(b.buf[b.r:b.w]) && b.err == nil {
b.fill()
}
b.lastRuneSize = -1
if b.r == b.w {
return 0, 0, b.readErr()
}
r, size = rune(b.buf[b.r]), 1
if r >= 0x80 {
r, size = utf8.DecodeRune(b.buf[b.r:b.w])
}
b.r += size
b.lastByte = int(b.buf[b.r-1])
b.lastRuneSize = size
return r, size, nil
}
func isText(b []byte) bool {
for len(b) > 0 && utf8.FullRune(b) {
if rune, size := utf8.DecodeRune(b); size == 1 && rune == utf8.RuneError {
return false
} else {
if 0x80 <= rune && rune <= 0x9F {
return false
}
if rune < ' ' {
switch rune {
case '\n', '\r', '\t':
default:
return false
}
}
b = b[size:]
}
}
return true
}
// Heuristic: b is text if it is valid UTF-8 and doesn't
// contain any unprintable ASCII or Unicode characters.
func isText(b []byte) bool {
for len(b) > 0 && utf8.FullRune(b) {
rune, size := utf8.DecodeRune(b)
if size == 1 && rune == utf8.RuneError {
// decoding error
return false
}
if 0x7F <= rune && rune <= 0x9F {
return false
}
if rune < ' ' {
switch rune {
case '\n', '\r', '\t':
// okay
default:
// binary garbage
return false
}
}
b = b[size:]
}
return true
}
// next reads and returns the next Unicode character. It is designed such
// that only a minimal amount of work needs to be done in the common ASCII
// case (one test to check for both ASCII and end-of-buffer, and one test
// to check for newlines).
func (s *Scanner) next() rune {
ch, width := rune(s.srcBuf[s.srcPos]), 1
if ch >= utf8.RuneSelf {
// uncommon case: not ASCII or not enough bytes
for s.srcPos+utf8.UTFMax > s.srcEnd && !utf8.FullRune(s.srcBuf[s.srcPos:s.srcEnd]) {
// not enough bytes: read some more, but first
// save away token text if any
if s.tokPos >= 0 {
s.tokBuf.Write(s.srcBuf[s.tokPos:s.srcPos])
s.tokPos = 0
// s.tokEnd is set by Scan()
}
// move unread bytes to beginning of buffer
copy(s.srcBuf[0:], s.srcBuf[s.srcPos:s.srcEnd])
s.srcBufOffset += s.srcPos
// read more bytes
// (an io.Reader must return os.EOF when it reaches
// the end of what it is reading - simply returning
// n == 0 will make this loop retry forever; but the
// error is in the reader implementation in that case)
i := s.srcEnd - s.srcPos
n, err := s.src.Read(s.srcBuf[i:bufLen])
s.srcPos = 0
s.srcEnd = i + n
s.srcBuf[s.srcEnd] = utf8.RuneSelf // sentinel
if err != nil {
if s.srcEnd == 0 {
if s.lastCharLen > 0 {
// previous character was not EOF
s.column++
}
s.lastCharLen = 0
return EOF
}
if err != io.EOF {
s.error(err.Error())
}
// If err == EOF, we won't be getting more
// bytes; break to avoid infinite loop. If
// err is something else, we don't know if
// we can get more bytes; thus also break.
break
}
}
// at least one byte
ch = rune(s.srcBuf[s.srcPos])
if ch >= utf8.RuneSelf {
// uncommon case: not ASCII
ch, width = utf8.DecodeRune(s.srcBuf[s.srcPos:s.srcEnd])
if ch == utf8.RuneError && width == 1 {
// advance for correct error position
s.srcPos += width
s.lastCharLen = width
s.column++
s.error("illegal UTF-8 encoding")
return ch
}
}
}
// advance
s.srcPos += width
s.lastCharLen = width
s.column++
// special situations
switch ch {
case 0:
// implementation restriction for compatibility with other tools
s.error("illegal character NUL")
case '\n':
s.line++
s.lastLineLen = s.column
s.column = 0
}
return ch
}
