select

/*
 *  call-seq:
 *     mtch.select{|obj| block}   => array
 *  
 *  Returns an array containing match strings for which <em>block</em>
 *  gives <code>true</code>.  MatchData#select will be removed from Ruby 1.9.
 *     
 *     m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
 *     p m.select{|x| /X/ =~ x}   #=> ["HX1138", "X"]
 */

static VALUE
match_select(argc, argv, match)
    int argc;
    VALUE *argv;
    VALUE match;
{
    if (argc > 0) {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
    }
    else {
        struct re_registers *regs;
        VALUE target;
        VALUE result = rb_ary_new();
        int i;
        int taint = OBJ_TAINTED(match);

        match_check(match);
        regs = RMATCH(match)->regs;
        target = RMATCH(match)->str;

        for (i=0; i<regs->num_regs; i++) {
            VALUE str = rb_str_substr(target, regs->beg[i], regs->end[i]-regs->beg[i]);
            if (taint) OBJ_TAINT(str);
            if (RTEST(rb_yield(str))) {
                rb_ary_push(result, str);
            }
        }
        return result;
    }
}