func compileReverse(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
re, err := syntax.Parse(expr, mode)
if err != nil {
return nil, err
}
maxCap := re.MaxCap()
capNames := re.CapNames()
// Reverse it, using our own reversal function that we hope work as it shoudl, but
// this is just based on a frivolous comment found on the internet.. I don't reallt know
// the theory of regexps
re.Reverse()
re = re.Simplify()
prog, err := syntax.Compile(re)
if err != nil {
return nil, err
}
regexp := &Regexp{
expr: expr,
prog: prog,
numSubexp: maxCap,
subexpNames: capNames,
cond: prog.StartCond(),
longest: longest,
}
regexp.prefix, regexp.prefixComplete = prog.Prefix()
if regexp.prefix != "" {
// TODO(rsc): Remove this allocation by adding
// IndexString to package bytes.
regexp.PrefixBytes = []byte(regexp.prefix)
regexp.prefixRune, _ = utf8.DecodeRuneInString(regexp.prefix)
}
return regexp, nil
}
func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
re, err := syntax.Parse(expr, mode)
if err != nil {
return nil, err
}
maxCap := re.MaxCap()
capNames := re.CapNames()
re = re.Simplify()
prog, err := syntax.Compile(re)
if err != nil {
return nil, err
}
regexp := &Regexp{
expr: expr,
prog: prog,
numSubexp: maxCap,
subexpNames: capNames,
cond: prog.StartCond(),
longest: longest,
}
regexp.prefix, regexp.prefixComplete = prog.Prefix()
if regexp.prefix != "" {
// TODO(rsc): Remove this allocation by adding
// IndexString to package bytes.
regexp.PrefixBytes = []byte(regexp.prefix)
regexp.prefixRune, _ = utf8.DecodeRuneInString(regexp.prefix)
}
return regexp, nil
}