nativestring.java

java中比较著名的js引擎当属mozilla开源的rhino

            /* Don't delimit whitespace at end of string. */
            if (i == length)
                return -1;

            /* Skip over the non-whitespace chars. */
            while (i < length
                   && !Character.isWhitespace(target.charAt(i)))
                i++;

            /* Now skip the next run of whitespace. */
            int j = i;
            while (j < length && Character.isWhitespace(target.charAt(j)))
                j++;

            /* Update matchlen to count delimiter chars. */
            matchlen[0] = j - i;
            return i;
        }

        /*
         * Stop if past end of string.  If at end of string, we will
         * return target length, so that
         *
         *  "ab,".split(',') => new Array("ab", "")
         *
         * and the resulting array converts back to the string "ab,"
         * for symmetry.  NB: This differs from perl, which drops the
         * trailing empty substring if the LIMIT argument is omitted.
         */
        if (i > length)
            return -1;

        /*
         * Match a regular expression against the separator at or
         * above index i.  Return -1 at end of string instead of
         * trying for a match, so we don't get stuck in a loop.
         */
        if (re != null) {
            return reProxy.find_split(cx, scope, target, separator, re,
                                      ip, matchlen, matched, parensp);
        }

        /*
         * Deviate from ECMA by never splitting an empty string by any separator
         * string into a non-empty array (an array of length 1 that contains the
         * empty string).
         */
        if (version != Context.VERSION_DEFAULT && version < Context.VERSION_1_3
            && length == 0)
            return -1;

        /*
         * Special case: if sep is the empty string, split str into
         * one character substrings.  Let our caller worry about
         * whether to split once at end of string into an empty
         * substring.
         *
         * For 1.2 compatibility, at the end of the string, we return the length as
         * the result, and set the separator length to 1 -- this allows the caller
         * to include an additional null string at the end of the substring list.
         */
        if (separator.length() == 0) {
            if (version == Context.VERSION_1_2) {
                if (i == length) {
                    matchlen[0] = 1;
                    return i;
                }
                return i + 1;
            }
            return (i == length) ? -1 : i + 1;
        }

        /* Punt to j.l.s.indexOf; return target length if separator is
         * not found.
         */
        if (ip[0] >= length)
            return length;

        i = target.indexOf(separator, ip[0]);

        return (i != -1) ? i : length;
    }

    /*
     * See ECMA 15.5.4.8.  Modified to match JS 1.2 - optionally takes
     * a limit argument and accepts a regular expression as the split
     * argument.
     */
    private static Object js_split(Context cx, Scriptable scope,
                                   String target, Object[] args)
    {
        // create an empty Array to return;
        Scriptable top = getTopLevelScope(scope);
        Scriptable result = ScriptRuntime.newObject(cx, top, "Array", null);

        // return an array consisting of the target if no separator given
        // don't check against undefined, because we want
        // 'fooundefinedbar'.split(void 0) to split to ['foo', 'bar']
        if (args.length < 1) {
            result.put(0, result, target);
            return result;
        }

        // Use the second argument as the split limit, if given.
        boolean limited = (args.length > 1) && (args[1] != Undefined.instance);
        long limit = 0;  // Initialize to avoid warning.
        if (limited) {
            /* Clamp limit between 0 and 1 + string length. */
            limit = ScriptRuntime.toUint32(args[1]);
            if (limit > target.length())
                limit = 1 + target.length();
        }

        String separator = null;
        int[] matchlen = new int[1];
        Scriptable re = null;
        RegExpProxy reProxy = null;
        if (args[0] instanceof Scriptable) {
            reProxy = ScriptRuntime.getRegExpProxy(cx);
            if (reProxy != null) {
                Scriptable test = (Scriptable)args[0];
                if (reProxy.isRegExp(test)) {
                    re = test;
                }
            }
        }
        if (re == null) {
            separator = ScriptRuntime.toString(args[0]);
            matchlen[0] = separator.length();
        }

        // split target with separator or re
        int[] ip = { 0 };
        int match;
        int len = 0;
        boolean[] matched = { false };
        String[][] parens = { null };
        int version = cx.getLanguageVersion();
        while ((match = find_split(cx, scope, target, separator, version,
                                   reProxy, re, ip, matchlen, matched, parens))
               >= 0)
        {
            if ((limited && len >= limit) || (match > target.length()))
                break;

            String substr;
            if (target.length() == 0)
                substr = target;
            else
                substr = target.substring(ip[0], match);

            result.put(len, result, substr);
            len++;
        /*
         * Imitate perl's feature of including parenthesized substrings
         * that matched part of the delimiter in the new array, after the
         * split substring that was delimited.
         */
            if (re != null && matched[0] == true) {
                int size = parens[0].length;
                for (int num = 0; num < size; num++) {
                    if (limited && len >= limit)
                        break;
                    result.put(len, result, parens[0][num]);
                    len++;
                }
                matched[0] = false;
            }
            ip[0] = match + matchlen[0];

            if (version < Context.VERSION_1_3
                && version != Context.VERSION_DEFAULT)
            {
        /*
         * Deviate from ECMA to imitate Perl, which omits a final
         * split unless a limit argument is given and big enough.
         */
                if (!limited && ip[0] == target.length())
                    break;
            }
        }
        return result;
    }

    /*
     * See ECMA 15.5.4.15
     */
    private static String js_substring(Context cx, String target,
                                       Object[] args)
    {
        int length = target.length();
        double start = ScriptRuntime.toInteger(args, 0);
        double end;

        if (start < 0)
            start = 0;
        else if (start > length)
            start = length;

        if (args.length <= 1 || args[1] == Undefined.instance) {
            end = length;
        } else {
            end = ScriptRuntime.toInteger(args[1]);
            if (end < 0)
                end = 0;
            else if (end > length)
                end = length;

            // swap if end < start
            if (end < start) {
                if (cx.getLanguageVersion() != Context.VERSION_1_2) {
                    double temp = start;
                    start = end;
                    end = temp;
                } else {
                    // Emulate old JDK1.0 java.lang.String.substring()
                    end = start;
                }
            }
        }
        return target.substring((int)start, (int)end);
    }

    int getLength() {
        return string.length();
    }

    /*
     * Non-ECMA methods.
     */
    private static String js_substr(String target, Object[] args) {
        if (args.length < 1)
            return target;

        double begin = ScriptRuntime.toInteger(args[0]);
        double end;
        int length = target.length();

        if (begin < 0) {
            begin += length;
            if (begin < 0)
                begin = 0;
        } else if (begin > length) {
            begin = length;
        }

        if (args.length == 1) {
            end = length;
        } else {
            end = ScriptRuntime.toInteger(args[1]);
            if (end < 0)
                end = 0;
            end += begin;
            if (end > length)
                end = length;
        }

        return target.substring((int)begin, (int)end);
    }

    /*
     * Python-esque sequence operations.
     */
    private static String js_concat(String target, Object[] args) {
        int N = args.length;
        if (N == 0) { return target; }
        else if (N == 1) {
            String arg = ScriptRuntime.toString(args[0]);
            return target.concat(arg);
        }

        // Find total capacity for the final string to avoid unnecessary
        // re-allocations in StringBuffer
        int size = target.length();
        String[] argsAsStrings = new String[N];
        for (int i = 0; i != N; ++i) {
            String s = ScriptRuntime.toString(args[i]);
            argsAsStrings[i] = s;
            size += s.length();
        }

        StringBuffer result = new StringBuffer(size);
        result.append(target);
        for (int i = 0; i != N; ++i) {
            result.append(argsAsStrings[i]);
        }
        return result.toString();
    }

    private static String js_slice(String target, Object[] args) {
        if (args.length != 0) {
            double begin = ScriptRuntime.toInteger(args[0]);
            double end;
            int length = target.length();
            if (begin < 0) {
                begin += length;
                if (begin < 0)
                    begin = 0;
            } else if (begin > length) {
                begin = length;
            }

            if (args.length == 1) {
                end = length;
            } else {
                end = ScriptRuntime.toInteger(args[1]);
                if (end < 0) {
                    end += length;
                    if (end < 0)
                        end = 0;
                } else if (end > length) {
                    end = length;
                }
                if (end < begin)
                    end = begin;
            }
            return target.substring((int)begin, (int)end);
        }
        return target;
    }

// #string_id_map#

    protected int findPrototypeId(String s)
    {
        int id;
// #generated# Last update: 2004-03-17 13:44:29 CET
        L0: { id = 0; String X = null; int c;
            L: switch (s.length()) {
            case 3: c=s.charAt(2);
                if (c=='b') { if (s.charAt(0)=='s' && s.charAt(1)=='u') {id=Id_sub; break L0;} }
                else if (c=='g') { if (s.charAt(0)=='b' && s.charAt(1)=='i') {id=Id_big; break L0;} }
                else if (c=='p') { if (s.charAt(0)=='s' && s.charAt(1)=='u') {id=Id_sup; break L0;} }
                break L;
            case 4: c=s.charAt(0);
                if (c=='b') { X="bold";id=Id_bold; }
                else if (c=='l') { X="link";id=Id_link; }
                break L;
            case 5: switch (s.charAt(4)) {
                case 'd': X="fixed";id=Id_fixed; break L;
                case 'e': X="slice";id=Id_slice; break L;
                case 'h': X="match";id=Id_match; break L;
                case 'k': X="blink";id=Id_blink; break L;
                case 'l': X="small";id=Id_small; break L;
                case 't': X="split";id=Id_split; break L;
                } break L;
            case 6: switch (s.charAt(1)) {
                case 'e': X="search";id=Id_search; break L;
                case 'h': X="charAt";id=Id_charAt; break L;
                case 'n': X="anchor";id=Id_anchor; break L;
                case 'o': X="concat";id=Id_concat; break L;
                case 'q': X="equals";id=Id_equals; break L;
                case 't': X="strike";id=Id_strike; break L;
                case 'u': X="substr";id=Id_substr; break L;
                } break L;
            case 7: switch (s.charAt(1)) {
                case 'a': X="valueOf";id=Id_valueOf; break L;
                case 'e': X="replace";id=Id_replace; break L;
                case 'n': X="indexOf";id=Id_indexOf; break L;
                case 't': X="italics";id=Id_italics; break L;
                } break L;
            case 8: c=s.charAt(4);
                if (c=='r') { X="toString";id=Id_toString; }
                else if (c=='s') { X="fontsize";id=Id_fontsize; }
                else if (c=='u') { X="toSource";id=Id_toSource; }
                break L;
            case 9: c=s.charAt(0);
                if (c=='f') { X="fontcolor";id=Id_fontcolor; }
                else if (c=='s') { X="substring";id=Id_substring; }
                break L;
            case 10: X="charCodeAt";id=Id_charCodeAt; break L;
            case 11: switch (s.charAt(2)) {
                case 'L': X="toLowerCase";id=Id_toLowerCase; break L;
                case 'U': X="toUpperCase";id=Id_toUpperCase; break L;
                case 'n': X="constructor";id=Id_constructor; break L;
                case 's': X="lastIndexOf";id=Id_lastIndexOf; break L;
                } break L;
            case 16: X="equalsIgnoreCase";id=Id_equalsIgnoreCase; break L;
            }
            if (X!=null && X!=s && !X.equals(s)) id = 0;
        }
// #/generated#
        return id;
    }

    private static final int
        ConstructorId_fromCharCode   = -1,

        Id_constructor               = 1,
        Id_toString                  = 2,
        Id_toSource                  = 3,
        Id_valueOf                   = 4,
        Id_charAt                    = 5,
        Id_charCodeAt                = 6,
        Id_indexOf                   = 7,
        Id_lastIndexOf               = 8,
        Id_split                     = 9,
        Id_substring                 = 10,
        Id_toLowerCase               = 11,
        Id_toUpperCase               = 12,
        Id_substr                    = 13,
        Id_concat                    = 14,
        Id_slice                     = 15,
        Id_bold                      = 16,
        Id_italics                   = 17,
        Id_fixed                     = 18,
        Id_strike                    = 19,
        Id_small                     = 20,
        Id_big                       = 21,
        Id_blink                     = 22,
        Id_sup                       = 23,
        Id_sub                       = 24,
        Id_fontsize                  = 25,
        Id_fontcolor                 = 26,
        Id_link                      = 27,
        Id_anchor                    = 28,
        Id_equals                    = 29,
        Id_equalsIgnoreCase          = 30,
        Id_match                     = 31,
        Id_search                    = 32,
        Id_replace                   = 33,

        MAX_PROTOTYPE_ID             = 33;

// #/string_id_map#

    private String string;
}