nativearray.java

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

        return result;
    }

    private Scriptable js_slice(Context cx, Scriptable thisObj,
                                Object[] args)
    {
        Scriptable scope = getTopLevelScope(this);
        Scriptable result = ScriptRuntime.newObject(cx, scope, "Array", null);
        long length = getLengthProperty(cx, thisObj);

        long begin, end;
        if (args.length == 0) {
            begin = 0;
            end = length;
        } else {
            begin = toSliceIndex(ScriptRuntime.toInteger(args[0]), length);
            if (args.length == 1) {
                end = length;
            } else {
                end = toSliceIndex(ScriptRuntime.toInteger(args[1]), length);
            }
        }

        for (long slot = begin; slot < end; slot++) {
            Object temp = getElem(cx, thisObj, slot);
            setElem(cx, result, slot - begin, temp);
        }

        return result;
    }

    private static long toSliceIndex(double value, long length) {
        long result;
        if (value < 0.0) {
            if (value + length < 0.0) {
                result = 0;
            } else {
                result = (long)(value + length);
            }
        } else if (value > length) {
            result = length;
        } else {
            result = (long)value;
        }
        return result;
    }

    /**
     * Implements the methods "indexOf" and "lastIndexOf".
     */
    private Object indexOfHelper(Context cx, Scriptable thisObj,
                                 Object[] args, boolean isLast)
    {
        Object compareTo = args.length > 0 ? args[0] : Undefined.instance;
        long length = getLengthProperty(cx, thisObj);
        long start;
        if (isLast) {
            // lastIndexOf
            /*
             * From http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Objects:Array:lastIndexOf
             * The index at which to start searching backwards. Defaults to the
             * array's length, i.e. the whole array will be searched. If the
             * index is greater than or equal to the length of the array, the
             * whole array will be searched. If negative, it is taken as the
             * offset from the end of the array. Note that even when the index
             * is negative, the array is still searched from back to front. If
             * the calculated index is less than 0, -1 is returned, i.e. the
             * array will not be searched.
             */
            if (args.length < 2) {
                // default
                start = length-1;
            } else {
                start = ScriptRuntime.toInt32(ScriptRuntime.toNumber(args[1]));
                if (start >= length)
                    start = length-1;
                else if (start < 0)
                    start += length;
                // Note that start may be negative, but that's okay
                // as the result of -1 will fall out from the code below
            }
        } else {
            // indexOf
            /*
             * From http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Objects:Array:indexOf
             * The index at which to begin the search. Defaults to 0, i.e. the
             * whole array will be searched. If the index is greater than or
             * equal to the length of the array, -1 is returned, i.e. the array
             * will not be searched. If negative, it is taken as the offset from
             * the end of the array. Note that even when the index is negative,
             * the array is still searched from front to back. If the calculated
             * index is less than 0, the whole array will be searched.
             */
            if (args.length < 2) {
                // default
                start = 0;
            } else {
                start = ScriptRuntime.toInt32(ScriptRuntime.toNumber(args[1]));
                if (start < 0) {
                    start += length;
                    if (start < 0)
                        start = 0;
                }
                // Note that start may be > length-1, but that's okay
                // as the result of -1 will fall out from the code below
            }
        }
        if (thisObj instanceof NativeArray) {
            NativeArray na = (NativeArray) thisObj;
            if (na.denseOnly) {
                if (isLast) {
                  for (int i=(int)start; i >= 0; i--) {
                      if (na.dense[i] != Scriptable.NOT_FOUND &&
                          ScriptRuntime.shallowEq(na.dense[i], compareTo))
                      {
                          return new Long(i);
                      }
                  }
                } else {
                  for (int i=(int)start; i < length; i++) {
                      if (na.dense[i] != Scriptable.NOT_FOUND &&
                          ScriptRuntime.shallowEq(na.dense[i], compareTo))
                      {
                          return new Long(i);
                      }
                  }
                }
                return NEGATIVE_ONE;
            }
        }
        if (isLast) {
          for (long i=start; i >= 0; i--) {
              if (ScriptRuntime.shallowEq(getElem(cx, thisObj, i), compareTo)) {
                  return new Long(i);
              }
          }
        } else {
          for (long i=start; i < length; i++) {
              if (ScriptRuntime.shallowEq(getElem(cx, thisObj, i), compareTo)) {
                  return new Long(i);
              }
          }
        }
        return NEGATIVE_ONE;
    }

    /**
     * Implements the methods "every", "filter", "forEach", "map", and "some".
     */
    private Object iterativeMethod(Context cx, int id, Scriptable scope, 
                                   Scriptable thisObj, Object[] args)
    {
        Object callbackArg = args.length > 0 ? args[0] : Undefined.instance;
        if (callbackArg == null || !(callbackArg instanceof Function)) {
            throw ScriptRuntime.notFunctionError(
                     ScriptRuntime.toString(callbackArg));
        }
        Function f = (Function) callbackArg;
        Scriptable parent = ScriptableObject.getTopLevelScope(f);
        Scriptable thisArg;
        if (args.length < 2 || args[1] == null || args[1] == Undefined.instance)
        {
            thisArg = parent;
        } else {
            thisArg = ScriptRuntime.toObject(cx, scope, args[1]);
        }
        long length = getLengthProperty(cx, thisObj);
        Scriptable array = ScriptRuntime.newObject(cx, scope, "Array", null);
        long j=0;
        for (long i=0; i < length; i++) {
            Object[] innerArgs = new Object[3];
            Object elem = (i > Integer.MAX_VALUE)
                ? ScriptableObject.getProperty(thisObj, Long.toString(i))
                : ScriptableObject.getProperty(thisObj, (int)i);
            if (elem == Scriptable.NOT_FOUND) {
                continue;
            }
            innerArgs[0] = elem;
            innerArgs[1] = new Long(i);
            innerArgs[2] = thisObj;
            Object result = f.call(cx, parent, thisArg, innerArgs);
            switch (id) {
              case Id_every:
                if (!ScriptRuntime.toBoolean(result))
                    return Boolean.FALSE;
                break;
              case Id_filter:
                if (ScriptRuntime.toBoolean(result))
                  setElem(cx, array, j++, innerArgs[0]);
                break;
              case Id_forEach:
                break;
              case Id_map:
                setElem(cx, array, i, result);
                break;
              case Id_some:
                if (ScriptRuntime.toBoolean(result))
                    return Boolean.TRUE;
                break;
            }
        }
        switch (id) {
          case Id_every:
            return Boolean.TRUE;
          case Id_filter:
          case Id_map:
            return array;
          case Id_some:
            return Boolean.FALSE;
          case Id_forEach:
          default:
            return Undefined.instance;
        }
    }

// #string_id_map#

    protected int findPrototypeId(String s)
    {
        int id;
// #generated# Last update: 2005-09-26 15:47:42 EDT
        L0: { id = 0; String X = null; int c;
            L: switch (s.length()) {
            case 3: c=s.charAt(0);
                if (c=='m') { if (s.charAt(2)=='p' && s.charAt(1)=='a') {id=Id_map; break L0;} }
                else if (c=='p') { if (s.charAt(2)=='p' && s.charAt(1)=='o') {id=Id_pop; break L0;} }
                break L;
            case 4: switch (s.charAt(2)) {
                case 'i': X="join";id=Id_join; break L;
                case 'm': X="some";id=Id_some; break L;
                case 'r': X="sort";id=Id_sort; break L;
                case 's': X="push";id=Id_push; break L;
                } break L;
            case 5: c=s.charAt(1);
                if (c=='h') { X="shift";id=Id_shift; }
                else if (c=='l') { X="slice";id=Id_slice; }
                else if (c=='v') { X="every";id=Id_every; }
                break L;
            case 6: c=s.charAt(0);
                if (c=='c') { X="concat";id=Id_concat; }
                else if (c=='f') { X="filter";id=Id_filter; }
                else if (c=='s') { X="splice";id=Id_splice; }
                break L;
            case 7: switch (s.charAt(0)) {
                case 'f': X="forEach";id=Id_forEach; break L;
                case 'i': X="indexOf";id=Id_indexOf; break L;
                case 'r': X="reverse";id=Id_reverse; break L;
                case 'u': X="unshift";id=Id_unshift; break L;
                } break L;
            case 8: c=s.charAt(3);
                if (c=='o') { X="toSource";id=Id_toSource; }
                else if (c=='t') { X="toString";id=Id_toString; }
                break L;
            case 11: c=s.charAt(0);
                if (c=='c') { X="constructor";id=Id_constructor; }
                else if (c=='l') { X="lastIndexOf";id=Id_lastIndexOf; }
                break L;
            case 14: X="toLocaleString";id=Id_toLocaleString; break L;
            }
            if (X!=null && X!=s && !X.equals(s)) id = 0;
        }
// #/generated#
        return id;
    }
    
    private static final int
        Id_constructor          = 1,
        Id_toString             = 2,
        Id_toLocaleString       = 3,
        Id_toSource             = 4,
        Id_join                 = 5,
        Id_reverse              = 6,
        Id_sort                 = 7,
        Id_push                 = 8,
        Id_pop                  = 9,
        Id_shift                = 10,
        Id_unshift              = 11,
        Id_splice               = 12,
        Id_concat               = 13,
        Id_slice                = 14,
        Id_indexOf              = 15,
        Id_lastIndexOf          = 16,
        Id_every                = 17,
        Id_filter               = 18,
        Id_forEach              = 19,
        Id_map                  = 20,
        Id_some                 = 21,

        MAX_PROTOTYPE_ID        = 21;

// #/string_id_map#
    
    private static final int
        ConstructorId_join                 = -Id_join,
        ConstructorId_reverse              = -Id_reverse,
        ConstructorId_sort                 = -Id_sort,
        ConstructorId_push                 = -Id_push,
        ConstructorId_pop                  = -Id_pop,
        ConstructorId_shift                = -Id_shift,
        ConstructorId_unshift              = -Id_unshift,
        ConstructorId_splice               = -Id_splice,
        ConstructorId_concat               = -Id_concat,
        ConstructorId_slice                = -Id_slice,
        ConstructorId_indexOf              = -Id_indexOf,
        ConstructorId_lastIndexOf          = -Id_lastIndexOf,
        ConstructorId_every                = -Id_every,
        ConstructorId_filter               = -Id_filter,
        ConstructorId_forEach              = -Id_forEach,
        ConstructorId_map                  = -Id_map,
        ConstructorId_some                 = -Id_some;

    /**
     * Internal representation of the JavaScript array's length property.
     */
    private long length;

    /**
     * Fast storage for dense arrays. Sparse arrays will use the superclass's
     * hashtable storage scheme.
     */
    private Object[] dense;

    /**
     * True if all numeric properties are stored in <code>dense</code>.
     */
    private boolean denseOnly;

    /**
     * The maximum size of <code>dense</code> that will be allocated initially.
     */
    private static int maximumInitialCapacity = 10000;

    /**
     * The default capacity for <code>dense</code>.
     */
    private static final int DEFAULT_INITIAL_CAPACITY = 10;

    /**
     * The factor to grow <code>dense</code> by.
     */
    private static final double GROW_FACTOR = 1.5;
    private static final int MAX_PRE_GROW_SIZE = (int)(Integer.MAX_VALUE / GROW_FACTOR);
}