nativestring.java

這是一個javascript 的 interpreter是了解 web browser的好材料

    
              case Id_blink:
                return tagify(thisObj, "blink", null, null);
    
              case Id_sup:
                return tagify(thisObj, "sup", null, null);
    
              case Id_sub:
                return tagify(thisObj, "sub", null, null);
    
              case Id_fontsize:
                return tagify(thisObj, "font", "size", args);
    
              case Id_fontcolor:
                return tagify(thisObj, "font", "color", args);
    
              case Id_link:
                return tagify(thisObj, "a", "href", args);
    
              case Id_anchor:
                return tagify(thisObj, "a", "name", args);
    
              case Id_equals:
              case Id_equalsIgnoreCase: {
                String s1 = ScriptRuntime.toString(thisObj);
                String s2 = ScriptRuntime.toString(args, 0);
                return ScriptRuntime.wrapBoolean(
                    (id == Id_equals) ? s1.equals(s2) 
                                      : s1.equalsIgnoreCase(s2));
              }
                  
              case Id_match:
              case Id_search:
              case Id_replace:
                {
                    int actionType;
                    if (id == Id_match) {
                        actionType = RegExpProxy.RA_MATCH;
                    } else if (id == Id_search) {
                        actionType = RegExpProxy.RA_SEARCH;
                    } else {
                        actionType = RegExpProxy.RA_REPLACE;
                    }
                    return ScriptRuntime.checkRegExpProxy(cx).
                        action(cx, scope, thisObj, args, actionType);
                }
                // ECMA-262 1 5.5.4.9
              case Id_localeCompare:
                {
                    // For now, create and configure a collator instance. I can't
                    // actually imagine that this'd be slower than caching them
                    // a la ClassCache, so we aren't trying to outsmart ourselves
                    // with a caching mechanism for now.
                    Collator collator = Collator.getInstance(cx.getLocale());
                    collator.setStrength(Collator.IDENTICAL);
                    collator.setDecomposition(Collator.CANONICAL_DECOMPOSITION);
                    return ScriptRuntime.wrapNumber(collator.compare(
                            ScriptRuntime.toString(thisObj), 
                            ScriptRuntime.toString(args, 0)));
                }
              case Id_toLocaleLowerCase:
                {
                    return ScriptRuntime.toString(thisObj)
                            .toLowerCase(cx.getLocale());
                }
              case Id_toLocaleUpperCase:
                {
                    return ScriptRuntime.toString(thisObj)
                            .toUpperCase(cx.getLocale());
                }
            }
            throw new IllegalArgumentException(String.valueOf(id));
        }
    }

    private static NativeString realThis(Scriptable thisObj, IdFunctionObject f)
    {
        if (!(thisObj instanceof NativeString))
            throw incompatibleCallError(f);
        return (NativeString)thisObj;
    }

    /*
     * HTML composition aids.
     */
    private static String tagify(Object thisObj, String tag,
                                 String attribute, Object[] args)
    {
        String str = ScriptRuntime.toString(thisObj);
        StringBuffer result = new StringBuffer();
        result.append('<');
        result.append(tag);
        if (attribute != null) {
            result.append(' ');
            result.append(attribute);
            result.append("=\"");
            result.append(ScriptRuntime.toString(args, 0));
            result.append('"');
        }
        result.append('>');
        result.append(str);
        result.append("</");
        result.append(tag);
        result.append('>');
        return result.toString();
    }

    public String toString() {
        return string;
    }

    /* Make array-style property lookup work for strings.
     * XXX is this ECMA?  A version check is probably needed. In js too.
     */
    public Object get(int index, Scriptable start) {
        if (0 <= index && index < string.length()) {
            return string.substring(index, index + 1);
        }
        return super.get(index, start);
    }

    public void put(int index, Scriptable start, Object value) {
        if (0 <= index && index < string.length()) {
            return;
        }
        super.put(index, start, value);
    }

    /*
     *
     * See ECMA 15.5.4.6.  Uses Java String.indexOf()
     * OPT to add - BMH searching from jsstr.c.
     */
    private static int js_indexOf(String target, Object[] args) {
        String search = ScriptRuntime.toString(args, 0);
        double begin = ScriptRuntime.toInteger(args, 1);

        if (begin > target.length()) {
            return -1;
        } else {
            if (begin < 0)
                begin = 0;
            return target.indexOf(search, (int)begin);
        }
    }

    /*
     *
     * See ECMA 15.5.4.7
     *
     */
    private static int js_lastIndexOf(String target, Object[] args) {
        String search = ScriptRuntime.toString(args, 0);
        double end = ScriptRuntime.toNumber(args, 1);

        if (end != end || end > target.length())
            end = target.length();
        else if (end < 0)
            end = 0;

        return target.lastIndexOf(search, (int)end);
    }

    /*
     * Used by js_split to find the next split point in target,
     * starting at offset ip and looking either for the given
     * separator substring, or for the next re match.  ip and
     * matchlen must be reference variables (assumed to be arrays of
     * length 1) so they can be updated in the leading whitespace or
     * re case.
     *
     * Return -1 on end of string, >= 0 for a valid index of the next
     * separator occurrence if found, or the string length if no
     * separator is found.
     */
    private static int find_split(Context cx, Scriptable scope, String target,
                                  String separator, int version,
                                  RegExpProxy reProxy, Scriptable re,
                                  int[] ip, int[] matchlen, boolean[] matched,
                                  String[][] parensp)
    {
        int i = ip[0];
        int length = target.length();

        /*
         * Perl4 special case for str.split(' '), only if the user has selected
         * JavaScript1.2 explicitly.  Split on whitespace, and skip leading w/s.
         * Strange but true, apparently modeled after awk.
         */
        if (version == Context.VERSION_1_2 &&
            re == null && separator.length() == 1 && separator.charAt(0) == ' ')
        {
            /* Skip leading whitespace if at front of str. */
            if (i == 0) {
                while (i < length && Character.isWhitespace(target.charAt(i)))
                    i++;
                ip[0] = i;
            }

            /* 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();