func compileSyntax(re *syntax.Regexp, expr string, longest bool) (*Regexp, error) {
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,
onepass: compileOnePass(prog),
numSubexp: maxCap,
subexpNames: capNames,
cond: prog.StartCond(),
longest: longest,
}
if regexp.onepass == notOnePass {
regexp.prefix, regexp.prefixComplete = prog.Prefix()
} else {
regexp.prefix, regexp.prefixComplete, regexp.prefixEnd = onePassPrefix(prog)
}
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
}
