//go:generate re2go $INPUT -o $OUTPUT package main import "testing" // Expects a null-terminated string. func lex(str string) int { var cursor, marker int limit := len(str) - 1 // limit points at the terminating null count := 0 loop: /*!re2c re2c:yyfill:enable = 0; re2c:eof = 0; re2c:define:YYCTYPE = byte; re2c:define:YYPEEK = "str[cursor]"; re2c:define:YYSKIP = "cursor += 1"; re2c:define:YYBACKUP = "marker = cursor"; re2c:define:YYRESTORE = "cursor = marker"; re2c:define:YYLESSTHAN = "limit <= cursor"; * { return -1 } $ { return count } ['] ([^'\\] | [\\][^])* ['] { count += 1; goto loop } [ ]+ { goto loop } */ } func TestLex(t *testing.T) { var tests = []struct { res int str string }{ {0, "\000"}, {3, "'qu\000tes' 'are' 'fine: \\'' \000"}, {-1, "'unterminated\\'\000"}, } for _, x := range tests { t.Run(x.str, func(t *testing.T) { res := lex(x.str) if res != x.res { t.Errorf("got %d, want %d", res, x.res) } }) } }