gecko/js/src/jsarray.h

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
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 * Contributor(s):
 *
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
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#ifndef jsarray_h___
#define jsarray_h___
/*
 * JS Array interface.
 */
#include "jsprvtd.h"
#include "jspubtd.h"
#include "jsatom.h"
#include "jsobj.h"
#include "jsstr.h"

/* Small arrays are dense, no matter what. */
const uintN MIN_SPARSE_INDEX = 256;

inline JSObject::EnsureDenseResult
JSObject::ensureDenseArrayElements(JSContext *cx, uintN index, uintN extra)
{
    JS_ASSERT(isDenseArray());
    uintN currentCapacity = numSlots();

    uintN requiredCapacity;
    if (extra == 1) {
        /* Optimize for the common case. */
        if (index < currentCapacity)
            return ED_OK;
        requiredCapacity = index + 1;
        if (requiredCapacity == 0) {
            /* Overflow. */
            return ED_SPARSE;
        }
    } else {
        requiredCapacity = index + extra;
        if (requiredCapacity < index) {
            /* Overflow. */
            return ED_SPARSE;
        }
        if (requiredCapacity <= currentCapacity)
            return ED_OK;
    }

    /*
     * We use the extra argument also as a hint about number of non-hole
     * elements to be inserted.
     */
    if (requiredCapacity > MIN_SPARSE_INDEX &&
        willBeSparseDenseArray(requiredCapacity, extra)) {
        return ED_SPARSE;
    }
    return growSlots(cx, requiredCapacity) ? ED_OK : ED_FAILED;
}

extern bool
js_StringIsIndex(JSLinearString *str, jsuint *indexp);

inline JSBool
js_IdIsIndex(jsid id, jsuint *indexp)
{
    if (JSID_IS_INT(id)) {
        jsint i;
        i = JSID_TO_INT(id);
        if (i < 0)
            return JS_FALSE;
        *indexp = (jsuint)i;
        return JS_TRUE;
    }

    if (JS_UNLIKELY(!JSID_IS_STRING(id)))
        return JS_FALSE;

    return js_StringIsIndex(JSID_TO_ATOM(id), indexp);
}

extern js::Class js_ArrayClass, js_SlowArrayClass;

inline bool
JSObject::isDenseArray() const
{
    return getClass() == &js_ArrayClass;
}

inline bool
JSObject::isSlowArray() const
{
    return getClass() == &js_SlowArrayClass;
}

inline bool
JSObject::isArray() const
{
    return isDenseArray() || isSlowArray();
}

/*
 * Dense arrays are not native -- aobj->isNative() for a dense array aobj
 * results in false, meaning aobj->map does not point to a js::Shape.
 *
 * But Array methods are called via aobj.sort(), e.g., and the interpreter and
 * the trace recorder must consult the property cache in order to perform well.
 * The cache works only for native objects.
 *
 * Therefore the interpreter (js_Interpret in JSOP_GETPROP and JSOP_CALLPROP)
 * and js_GetPropertyHelper use this inline function to skip up one link in the
 * prototype chain when obj is a dense array, in order to find a native object
 * (to wit, Array.prototype) in which to probe for cached methods.
 *
 * Note that setting aobj.__proto__ for a dense array aobj turns aobj into a
 * slow array, avoiding the neede to skip.
 *
 * Callers of js_GetProtoIfDenseArray must take care to use the original object
 * (obj) for the |this| value of a getter, setter, or method call (bug 476447).
 */
static JS_INLINE JSObject *
js_GetProtoIfDenseArray(JSObject *obj)
{
    return obj->isDenseArray() ? obj->getProto() : obj;
}

extern JSObject *
js_InitArrayClass(JSContext *cx, JSObject *obj);

extern bool
js_InitContextBusyArrayTable(JSContext *cx);

namespace js
{

/* Create a dense array with no capacity allocated, length set to 0. */
extern JSObject * JS_FASTCALL
NewDenseEmptyArray(JSContext *cx, JSObject *proto=NULL);

/* Create a dense array with length and capacity == 'length'. */
extern JSObject * JS_FASTCALL
NewDenseAllocatedArray(JSContext *cx, uint length, JSObject *proto=NULL);

/*
 * Create a dense array with a set length, but without allocating space for the
 * contents. This is useful, e.g., when accepting length from the user.
 */
extern JSObject * JS_FASTCALL
NewDenseUnallocatedArray(JSContext *cx, uint length, JSObject *proto=NULL);

/* Create a dense array with a copy of vp. */
extern JSObject *
NewDenseCopiedArray(JSContext *cx, uint length, Value *vp, JSObject *proto=NULL);

/* Create a sparse array. */
extern JSObject *
NewSlowEmptyArray(JSContext *cx);

}

extern JSBool
js_GetLengthProperty(JSContext *cx, JSObject *obj, jsuint *lengthp);

extern JSBool
js_SetLengthProperty(JSContext *cx, JSObject *obj, jsdouble length);

extern JSBool
js_HasLengthProperty(JSContext *cx, JSObject *obj, jsuint *lengthp);

extern JSBool JS_FASTCALL
js_IndexToId(JSContext *cx, jsuint index, jsid *idp);

namespace js {

/*
 * This function assumes 'length' is effectively the result of calling
 * js_GetLengthProperty on aobj.
 */
extern bool
GetElements(JSContext *cx, JSObject *aobj, jsuint length, js::Value *vp);

}

/*
 * JS-specific merge sort function.
 */
typedef JSBool (*JSComparator)(void *arg, const void *a, const void *b,
                               int *result);

enum JSMergeSortElemType {
    JS_SORTING_VALUES,
    JS_SORTING_GENERIC
};

/*
 * NB: vec is the array to be sorted, tmp is temporary space at least as big
 * as vec. Both should be GC-rooted if appropriate.
 *
 * isValue should true iff vec points to an array of js::Value
 *
 * The sorted result is in vec. vec may be in an inconsistent state if the
 * comparator function cmp returns an error inside a comparison, so remember
 * to check the return value of this function.
 */
extern bool
js_MergeSort(void *vec, size_t nel, size_t elsize, JSComparator cmp,
             void *arg, void *tmp, JSMergeSortElemType elemType);

/*
 * The Array.prototype.sort fast-native entry point is exported for joined
 * function optimization in js{interp,tracer}.cpp.
 */
namespace js {
extern JSBool
array_sort(JSContext *cx, uintN argc, js::Value *vp);
}

#ifdef DEBUG
extern JSBool
js_ArrayInfo(JSContext *cx, uintN argc, jsval *vp);
#endif

extern JSBool
js_ArrayCompPush(JSContext *cx, JSObject *obj, const js::Value &vp);

/*
 * Fast dense-array-to-buffer conversion for use by canvas.
 *
 * If the array is a dense array, fill [offset..offset+count] values into
 * destination, assuming that types are consistent.  Return JS_TRUE if
 * successful, otherwise JS_FALSE -- note that the destination buffer may be
 * modified even if JS_FALSE is returned (e.g. due to finding an inappropriate
 * type later on in the array).  If JS_FALSE is returned, no error conditions
 * or exceptions are set on the context.
 *
 * This method succeeds if each element of the array is an integer or a double.
 * Values outside the 0-255 range are clamped to that range.  Double values are
 * converted to integers in this range by clamping and then rounding to
 * nearest, ties to even.
 */

JS_FRIEND_API(JSBool)
js_CoerceArrayToCanvasImageData(JSObject *obj, jsuint offset, jsuint count,
                                JSUint8 *dest);

JSBool
js_PrototypeHasIndexedProperties(JSContext *cx, JSObject *obj);

/*
 * Utility to access the value from the id returned by array_lookupProperty.
 */
JSBool
js_GetDenseArrayElementValue(JSContext *cx, JSObject *obj, jsid id,
                             js::Value *vp);

/* Array constructor native. Exposed only so the JIT can know its address. */
JSBool
js_Array(JSContext *cx, uintN argc, js::Value *vp);

/*
 * Makes a fast clone of a dense array as long as the array only contains
 * primitive values.
 *
 * If the return value is JS_FALSE then clone will not be set.
 *
 * If the return value is JS_TRUE then clone will either be set to the address
 * of a new JSObject or to NULL if the array was not dense or contained values
 * that were not primitives.
 */
JS_FRIEND_API(JSBool)
js_CloneDensePrimitiveArray(JSContext *cx, JSObject *obj, JSObject **clone);

/*
 * Returns JS_TRUE if the given object is a dense array that contains only
 * primitive values.
 */
JS_FRIEND_API(JSBool)
js_IsDensePrimitiveArray(JSObject *obj);

extern JSBool JS_FASTCALL
js_EnsureDenseArrayCapacity(JSContext *cx, JSObject *obj, jsint i);

#endif /* jsarray_h___ */