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scanner: more internal renamings

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This commit is contained in:
Fatih Arslan 2015-10-06 19:59:12 +03:00
parent 3631451bd2
commit b5330a1d78
1 changed files with 14 additions and 14 deletions
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28
scanner/scanner.go
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@ -17,14 +17,12 @@ const eof = rune(0)
// Scanner defines a lexical scanner // Scanner defines a lexical scanner
type Scanner struct { type Scanner struct {
src *bytes.Buffer buf *bytes.Buffer // Source buffer for advancing and scanning
src []byte // Source buffer for immutable access
// Source Buffer
srcBuf []byte
// Source Position // Source Position
srcPos Position // current position srcPos Position // current position
prevPos Position // previous position prevPos Position // previous position, used for peek() method
lastCharLen int // length of last character in bytes lastCharLen int // length of last character in bytes
lastLineLen int // length of last line in characters (for correct column reporting) lastLineLen int // length of last line in characters (for correct column reporting)
@ -49,10 +47,13 @@ type Scanner struct {
// NewScanner returns a new instance of Scanner. // NewScanner returns a new instance of Scanner.
func NewScanner(src []byte) *Scanner { func NewScanner(src []byte) *Scanner {
// even though we accept a src, we read from a io.Reader compatible type
// (*bytes.Buffer). So in the future we might easily change it to streaming
// read.
b := bytes.NewBuffer(src) b := bytes.NewBuffer(src)
s := &Scanner{ s := &Scanner{
src: b, buf: b,
srcBuf: src, // immutable src src: src,
} }
// srcPosition always starts with 1 // srcPosition always starts with 1
@ -63,8 +64,7 @@ func NewScanner(src []byte) *Scanner {
// next reads the next rune from the bufferred reader. Returns the rune(0) if // next reads the next rune from the bufferred reader. Returns the rune(0) if
// an error occurs (or io.EOF is returned). // an error occurs (or io.EOF is returned).
func (s *Scanner) next() rune { func (s *Scanner) next() rune {
ch, size, err := s.buf.ReadRune()
ch, size, err := s.src.ReadRune()
if err != nil { if err != nil {
// advance for error reporting // advance for error reporting
s.srcPos.Column++ s.srcPos.Column++
@ -101,7 +101,7 @@ func (s *Scanner) next() rune {
// unread // unread
func (s *Scanner) unread() { func (s *Scanner) unread() {
if err := s.src.UnreadRune(); err != nil { if err := s.buf.UnreadRune(); err != nil {
panic(err) // this is user fault, we should catch it panic(err) // this is user fault, we should catch it
} }
s.srcPos = s.prevPos // put back last position s.srcPos = s.prevPos // put back last position
@ -109,12 +109,12 @@ func (s *Scanner) unread() {
// peek returns the next rune without advancing the reader. // peek returns the next rune without advancing the reader.
func (s *Scanner) peek() rune { func (s *Scanner) peek() rune {
peek, _, err := s.src.ReadRune() peek, _, err := s.buf.ReadRune()
if err != nil { if err != nil {
return eof return eof
} }
s.src.UnreadRune() s.buf.UnreadRune()
return peek return peek
} }
@ -208,7 +208,7 @@ func (s *Scanner) TokenText() string {
// part of the token text was saved in tokBuf: save the rest in // part of the token text was saved in tokBuf: save the rest in
// tokBuf as well and return its content // tokBuf as well and return its content
s.tokBuf.Write(s.srcBuf[s.tokStart:s.tokEnd]) s.tokBuf.Write(s.src[s.tokStart:s.tokEnd])
s.tokStart = s.tokEnd // ensure idempotency of TokenText() call s.tokStart = s.tokEnd // ensure idempotency of TokenText() call
return s.tokBuf.String() return s.tokBuf.String()
} }
@ -446,7 +446,7 @@ func (s *Scanner) scanIdentifier() string {
} }
s.unread() // we got identifier, put back latest char s.unread() // we got identifier, put back latest char
return string(s.srcBuf[offs:s.srcPos.Offset]) return string(s.src[offs:s.srcPos.Offset])
} }
// recentPosition returns the position of the character immediately after the // recentPosition returns the position of the character immediately after the