diff options
Diffstat (limited to 'libgo/go/text/scanner/scanner.go')
| -rw-r--r-- | libgo/go/text/scanner/scanner.go | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/libgo/go/text/scanner/scanner.go b/libgo/go/text/scanner/scanner.go index db7ca73c68d..5199ee4fc7d 100644 --- a/libgo/go/text/scanner/scanner.go +++ b/libgo/go/text/scanner/scanner.go @@ -11,7 +11,7 @@ // By default, a Scanner skips white space and Go comments and recognizes all // literals as defined by the Go language specification. It may be // customized to recognize only a subset of those literals and to recognize -// different white space characters. +// different identifier and white space characters. // // Basic usage pattern: // @@ -34,8 +34,6 @@ import ( "unicode/utf8" ) -// TODO(gri): Consider changing this to use the new (token) Position package. - // A source position is represented by a Position value. // A position is valid if Line > 0. type Position struct { @@ -68,6 +66,12 @@ func (pos Position) String() string { // // ScanIdents | ScanInts | SkipComments // +// With the exceptions of comments, which are skipped if SkipComments is +// set, unrecognized tokens are not ignored. Instead, the scanner simply +// returns the respective individual characters (or possibly sub-tokens). +// For instance, if the mode is ScanIdents (not ScanStrings), the string +// "foo" is scanned as the token sequence '"' Ident '"'. +// const ( ScanIdents = 1 << -Ident ScanInts = 1 << -Int @@ -164,6 +168,13 @@ type Scanner struct { // for values ch > ' '). The field may be changed at any time. Whitespace uint64 + // IsIdentRune is a predicate controlling the characters accepted + // as the ith rune in an identifier. The set of valid characters + // must not intersect with the set of white space characters. + // If no IsIdentRune function is set, regular Go identifiers are + // accepted instead. The field may be changed at any time. + IsIdentRune func(ch rune, i int) bool + // Start position of most recently scanned token; set by Scan. // Calling Init or Next invalidates the position (Line == 0). // The Filename field is always left untouched by the Scanner. @@ -334,9 +345,17 @@ func (s *Scanner) error(msg string) { fmt.Fprintf(os.Stderr, "%s: %s\n", pos, msg) } +func (s *Scanner) isIdentRune(ch rune, i int) bool { + if s.IsIdentRune != nil { + return s.IsIdentRune(ch, i) + } + return ch == '_' || unicode.IsLetter(ch) || unicode.IsDigit(ch) && i > 0 +} + func (s *Scanner) scanIdentifier() rune { - ch := s.next() // read character after first '_' or letter - for ch == '_' || unicode.IsLetter(ch) || unicode.IsDigit(ch) { + // we know the zero'th rune is OK; start scanning at the next one + ch := s.next() + for i := 1; s.isIdentRune(ch, i); i++ { ch = s.next() } return ch @@ -563,7 +582,7 @@ redo: // determine token value tok := ch switch { - case unicode.IsLetter(ch) || ch == '_': + case s.isIdentRune(ch, 0): if s.Mode&ScanIdents != 0 { tok = Ident ch = s.scanIdentifier() |