src/main/java/com/basistech/tclre/Lex.java
void lexstart() throws RegexException {
        prefixes();         /* may turn on new type bits etc. */

        if (0 != (v.cflags & Flags.REG_QUOTE)) {
            assert 0 == (v.cflags & (Flags.REG_ADVANCED | Flags.REG_EXPANDED | Flags.REG_NEWLINE));
            intocon(L_Q);
        } else if (0 != (v.cflags & Flags.REG_EXTENDED)) {
            assert 0 == (v.cflags & Flags.REG_QUOTE);
            intocon(L_ERE);
        } else {
            assert 0 == (v.cflags & (Flags.REG_QUOTE | Flags.REG_ADVF));
            intocon(L_BRE);
        }

        v.nexttype = Compiler.EMPTY;        /* remember we were at the start */
        next();         /* set up the first token */
    }
void lexstart() throws RegexException {
        prefixes();         /* may turn on new type bits etc. */

        if (0 != (v.cflags & Flags.REG_QUOTE)) {
            assert 0 == (v.cflags & (Flags.REG_ADVANCED | Flags.REG_EXPANDED | Flags.REG_NEWLINE));
            intocon(L_Q);
        } else if (0 != (v.cflags & Flags.REG_EXTENDED)) {
            assert 0 == (v.cflags & Flags.REG_QUOTE);
            intocon(L_ERE);
        } else {
            assert 0 == (v.cflags & (Flags.REG_QUOTE | Flags.REG_ADVF));
            intocon(L_BRE);
        }

        v.nexttype = Compiler.EMPTY;        /* remember we were at the start */
        next();         /* set up the first token */
    }
lexstart - set up lexical stuff, scan leading options