nativeregexp.java

java中比较著名的js引擎当属mozilla开源的rhino

     */

    private static void doFlat(CompilerState state, char c)
    {
        state.result = new RENode(REOP_FLAT);
        state.result.chr = c;
        state.result.length = 1;
        state.result.flatIndex = -1;
        state.progLength += 3;
    }

    private static int
    getDecimalValue(char c, CompilerState state, int maxValue,
                    String overflowMessageId)
    {
        boolean overflow = false;
        int start = state.cp;
        char[] src = state.cpbegin;
        int value = c - '0';
        for (; state.cp != state.cpend; ++state.cp) {
            c = src[state.cp];
            if (!isDigit(c)) {
                break;
            }
            if (!overflow) {
                int digit = c - '0';
                if (value < (maxValue - digit) / 10) {
                    value = value * 10 + digit;
                } else {
                    overflow = true;
                    value = maxValue;
                }
            }
        }
        if (overflow) {
            reportError(overflowMessageId,
                        String.valueOf(src, start, state.cp - start));
        }
        return value;
    }

    private static boolean
    parseTerm(CompilerState state)
    {
        char[] src = state.cpbegin;
        char c = src[state.cp++];
        int nDigits = 2;
        int parenBaseCount = state.parenCount;
        int num, tmp;
        RENode term;
        int termStart;
        int ocp = state.cp;

        switch (c) {
        /* assertions and atoms */
        case '^':
            state.result = new RENode(REOP_BOL);
            state.progLength++;
            return true;
        case '$':
            state.result = new RENode(REOP_EOL);
            state.progLength++;
            return true;
        case '\\':
            if (state.cp < state.cpend) {
                c = src[state.cp++];
                switch (c) {
                /* assertion escapes */
                case 'b' :
                    state.result = new RENode(REOP_WBDRY);
                    state.progLength++;
                    return true;
                case 'B':
                    state.result = new RENode(REOP_WNONBDRY);
                    state.progLength++;
                    return true;
                /* Decimal escape */
                case '0':
/*
 * Under 'strict' ECMA 3, we interpret \0 as NUL and don't accept octal.
 * However, (XXX and since Rhino doesn't have a 'strict' mode) we'll just
 * behave the old way for compatibility reasons.
 * (see http://bugzilla.mozilla.org/show_bug.cgi?id=141078)
 *
 */
                    /* octal escape */
                    num = 0;
                    while (state.cp < state.cpend) {
                        c = src[state.cp];
                        if ((c >= '0') && (c <= '7')) {
                            state.cp++;
                            tmp = 8 * num + (c - '0');
                            if (tmp > 0377)
                                break;
                            num = tmp;
                        }
                        else
                            break;
                    }
                    c = (char)(num);
                    doFlat(state, c);
                    break;
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                    termStart = state.cp - 1;
                    num = getDecimalValue(c, state, 0xFFFF,
                                          "msg.overlarge.backref");
                    /*
                     * n > 9 and > count of parentheses,
                     * then treat as octal instead.
                     */
                    if ((num > 9) && (num > state.parenCount)) {
                        state.cp = termStart;
                        num = 0;
                        while (state.cp < state.cpend) {
                            c = src[state.cp];
                            if ((c >= '0') && (c <= '7')) {
                                state.cp++;
                                tmp = 8 * num + (c - '0');
                                if (tmp > 0377)
                                    break;
                                num = tmp;
                            }
                            else
                                break;
                        }
                        c = (char)(num);
                        doFlat(state, c);
                        break;
                    }
                    /* otherwise, it's a back-reference */
                    state.result = new RENode(REOP_BACKREF);
                    state.result.parenIndex = num - 1;
                    state.progLength += 3;
                    break;
                /* Control escape */
                case 'f':
                    c = 0xC;
                    doFlat(state, c);
                    break;
                case 'n':
                    c = 0xA;
                    doFlat(state, c);
                    break;
                case 'r':
                    c = 0xD;
                    doFlat(state, c);
                    break;
                case 't':
                    c = 0x9;
                    doFlat(state, c);
                    break;
                case 'v':
                    c = 0xB;
                    doFlat(state, c);
                    break;
                /* Control letter */
                case 'c':
                    if (((state.cp + 1) < state.cpend) &&
                                        Character.isLetter(src[state.cp + 1]))
                        c = (char)(src[state.cp++] & 0x1F);
                    else {
                        /* back off to accepting the original '\' as a literal */
                        --state.cp;
                        c = '\\';
                    }
                    doFlat(state, c);
                    break;
                /* UnicodeEscapeSequence */
                case 'u':
                    nDigits += 2;
                    // fall thru...
                /* HexEscapeSequence */
                case 'x':
                    {
                        int n = 0;
                        int i;
                        for (i = 0; (i < nDigits)
                                && (state.cp < state.cpend); i++) {
                            int digit;
                            c = src[state.cp++];
                            n = Kit.xDigitToInt(c, n);
                            if (n < 0) {
                                // Back off to accepting the original
                                // 'u' or 'x' as a literal
                                state.cp -= (i + 2);
                                n = src[state.cp++];
                                break;
                            }
                        }
                        c = (char)(n);
                    }
                    doFlat(state, c);
                    break;
                /* Character class escapes */
                case 'd':
                    state.result = new RENode(REOP_DIGIT);
                    state.progLength++;
                    break;
                case 'D':
                    state.result = new RENode(REOP_NONDIGIT);
                    state.progLength++;
                    break;
                case 's':
                    state.result = new RENode(REOP_SPACE);
                    state.progLength++;
                    break;
                case 'S':
                    state.result = new RENode(REOP_NONSPACE);
                    state.progLength++;
                    break;
                case 'w':
                    state.result = new RENode(REOP_ALNUM);
                    state.progLength++;
                    break;
                case 'W':
                    state.result = new RENode(REOP_NONALNUM);
                    state.progLength++;
                    break;
                /* IdentityEscape */
                default:
                    state.result = new RENode(REOP_FLAT);
                    state.result.chr = c;
                    state.result.length = 1;
                    state.result.flatIndex = state.cp - 1;
                    state.progLength += 3;
                    break;
                }
                break;
            }
            else {
                /* a trailing '\' is an error */
                reportError("msg.trail.backslash", "");
                return false;
            }
        case '(': {
            RENode result = null;
            termStart = state.cp;
            if (state.cp + 1 < state.cpend && src[state.cp] == '?'
                && ((c = src[state.cp + 1]) == '=' || c == '!' || c == ':'))
            {
                state.cp += 2;
                if (c == '=') {
                    result = new RENode(REOP_ASSERT);
                    /* ASSERT, <next>, ... ASSERTTEST */
                    state.progLength += 4;
                } else if (c == '!') {
                    result = new RENode(REOP_ASSERT_NOT);
                    /* ASSERTNOT, <next>, ... ASSERTNOTTEST */
                    state.progLength += 4;
                }
            } else {
                result = new RENode(REOP_LPAREN);
                /* LPAREN, <index>, ... RPAREN, <index> */
                state.progLength += 6;
                result.parenIndex = state.parenCount++;
            }
            ++state.parenNesting;
            if (!parseDisjunction(state))
                return false;
            if (state.cp == state.cpend || src[state.cp] != ')') {
                reportError("msg.unterm.paren", "");
                return false;
            }
            ++state.cp;
            --state.parenNesting;
            if (result != null) {
                result.kid = state.result;
                state.result = result;
            }
            break;
        }
        case ')':
          reportError("msg.re.unmatched.right.paren", "");
          return false;
        case '[':
            state.result = new RENode(REOP_CLASS);
            termStart = state.cp;
            state.result.startIndex = termStart;
            while (true) {
                if (state.cp == state.cpend) {
                    reportError("msg.unterm.class", "");
                    return false;
                }
                if (src[state.cp] == '\\')
                    state.cp++;
                else {
                    if (src[state.cp] == ']') {
                        state.result.kidlen = state.cp - termStart;
                        break;
                    }
                }
                state.cp++;
            }
            state.result.index = state.classCount++;
            /*
             * Call calculateBitmapSize now as we want any errors it finds
             * to be reported during the parse phase, not at execution.
             */
            if (!calculateBitmapSize(state, state.result, src, termStart, state.cp++))
                return false;
            state.progLength += 3; /* CLASS, <index> */
            break;

        case '.':
            state.result = new RENode(REOP_DOT);
            state.progLength++;
            break;
        case '*':
        case '+':
        case '?':
            reportError("msg.bad.quant", String.valueOf(src[state.cp - 1]));
            return false;
        default:
            state.result = new RENode(REOP_FLAT);
            state.result.chr = c;
            state.result.length = 1;
            state.result.flatIndex = state.cp - 1;
            state.progLength += 3;
            break;
        }

        term = state.result;
        if (state.cp == state.cpend) {
            return true;
        }
        boolean hasQ = false;
        switch (src[state.cp]) {
            case '+':
                state.result = new RENode(REOP_QUANT);
                state.result.min = 1;
                state.result.max = -1;
                /* <PLUS>, <parencount>, <parenindex>, <next> ... <ENDCHILD> */
                state.progLength += 8;
                hasQ = true;
                break;
            case '*':
                state.result = new RENode(REOP_QUANT);
                state.result.min = 0;
                state.result.max = -1;
                /* <STAR>, <parencount>, <parenindex>, <next> ... <ENDCHILD> */
                state.progLength += 8;
                hasQ = true;
                break;
            case '?':
                state.result = new RENode(REOP_QUANT);
                state.result.min = 0;
                state.result.max = 1;