Current File : //usr/share/doc/re2c/examples/go/submatch/03_posix.re
//go:generate re2go $INPUT -o $OUTPUT
package main
import "reflect"
// Maximum number of capturing groups among all rules.
/*!maxnmatch:re2c*/
type SemVer struct { major, minor, patch int }
func s2n(s string) int { // convert pre-parsed string to a number
n := 0
for _, c := range s { n = n*10 + int(c-'0') }
return n
}
func parse(str string) *SemVer {
var cur, mar int
// Allocate memory for capturing parentheses (twice the number of groups).
yypmatch := make([]int, YYMAXNMATCH*2)
var yynmatch int
// Autogenerated tag variables used by the lexer to track tag values.
/*!stags:re2c format = '\tvar @@ int\n'; */
/*!re2c
re2c:yyfill:enable = 0;
re2c:define:YYCTYPE = byte;
re2c:define:YYPEEK = "str[cur]";
re2c:define:YYSKIP = "cur += 1";
re2c:define:YYBACKUP = "mar = cur";
re2c:define:YYRESTORE = "cur = mar";
re2c:define:YYSTAGP = "@@{tag} = cur";
re2c:define:YYSTAGN = "@@{tag} = -1";
re2c:define:YYSHIFTSTAG = "@@{tag} += @@{shift}";
re2c:posix-captures = 1;
num = [0-9]+;
(num) "." (num) ("." num)? [\x00] {
// `yynmatch` is the number of capturing groups
if yynmatch != 4 { panic("expected 4 submatch groups") }
// Even `yypmatch` values are for opening parentheses, odd values
// are for closing parentheses, the first group is the whole match.
major := s2n(str[yypmatch[2]:yypmatch[3]])
minor := s2n(str[yypmatch[4]:yypmatch[5]])
patch := 0
if yypmatch[6] != -1 { patch = s2n(str[yypmatch[6]+1:yypmatch[7]]) }
return &SemVer{major, minor, patch}
}
* { return nil }
*/
}
func main() {
assert_eq := func(x, y *SemVer) {
if !reflect.DeepEqual(x, y) { panic("error") }
}
assert_eq(parse("23.34\000"), &SemVer{23, 34, 0})
assert_eq(parse("1.2.9999\000"), &SemVer{1, 2, 9999})
assert_eq(parse("1.a\000"), nil)
}
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