72 lines
1.4 KiB
Go
72 lines
1.4 KiB
Go
package wavefront
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import (
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"bufio"
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"io"
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)
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// Lexical Point Scanner
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type PointScanner struct {
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r *bufio.Reader
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}
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func NewScanner(r io.Reader) *PointScanner {
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return &PointScanner{r: bufio.NewReader(r)}
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}
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// read reads the next rune from the buffered reader.
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// Returns rune(0) if an error occurs (or io.EOF is returned).
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func (s *PointScanner) read() rune {
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ch, _, err := s.r.ReadRune()
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if err != nil {
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return eof
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}
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return ch
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}
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// unread places the previously read rune back on the reader.
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func (s *PointScanner) unread() {
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_ = s.r.UnreadRune()
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}
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// Scan returns the next token and literal value.
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func (s *PointScanner) Scan() (Token, string) {
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// Read the next rune
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ch := s.read()
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if isWhitespace(ch) {
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return WS, string(ch)
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} else if isLetter(ch) {
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return LETTER, string(ch)
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} else if isNumber(ch) {
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return NUMBER, string(ch)
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} else if isDelta(ch) {
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return DELTA, string(ch)
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}
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// Otherwise read the individual character.
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switch ch {
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case eof:
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return EOF, ""
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case '\n':
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return NEWLINE, string(ch)
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case '.':
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return DOT, string(ch)
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case '-':
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return MINUS_SIGN, string(ch)
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case '_':
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return UNDERSCORE, string(ch)
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case '/':
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return SLASH, string(ch)
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case '\\':
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return BACKSLASH, string(ch)
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case ',':
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return COMMA, string(ch)
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case '"':
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return QUOTES, string(ch)
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case '=':
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return EQUALS, string(ch)
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}
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return ILLEGAL, string(ch)
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}
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