1/*
2 * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
14 *     its contributors may be used to endorse or promote products derived
15 *     from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef EvalCodeCache_h
30#define EvalCodeCache_h
31
32#include "Executable.h"
33#include "JSGlobalObject.h"
34#include "SourceCode.h"
35#include <wtf/HashMap.h>
36#include <wtf/RefPtr.h>
37#include <wtf/text/StringHash.h>
38
39namespace JSC {
40
41    class SlotVisitor;
42
43    class EvalCodeCache {
44    public:
45        EvalExecutable* tryGet(bool inStrictContext, const String& evalSource, JSScope* scope)
46        {
47            if (!inStrictContext && evalSource.length() < maxCacheableSourceLength && scope->begin()->isVariableObject())
48                return m_cacheMap.get(evalSource.impl()).get();
49            return 0;
50        }
51
52        EvalExecutable* getSlow(ExecState* exec, ScriptExecutable* owner, bool inStrictContext, const String& evalSource, JSScope* scope)
53        {
54            EvalExecutable* evalExecutable = EvalExecutable::create(exec, makeSource(evalSource), inStrictContext);
55            if (!evalExecutable)
56                return 0;
57
58            if (!inStrictContext && evalSource.length() < maxCacheableSourceLength && scope->begin()->isVariableObject() && m_cacheMap.size() < maxCacheEntries)
59                m_cacheMap.set(evalSource.impl(), WriteBarrier<EvalExecutable>(exec->vm(), owner, evalExecutable));
60
61            return evalExecutable;
62        }
63
64        bool isEmpty() const { return m_cacheMap.isEmpty(); }
65
66        void visitAggregate(SlotVisitor&);
67
68        void clear()
69        {
70            m_cacheMap.clear();
71        }
72
73    private:
74        static const unsigned maxCacheableSourceLength = 256;
75        static const int maxCacheEntries = 64;
76
77        typedef HashMap<RefPtr<StringImpl>, WriteBarrier<EvalExecutable>> EvalCacheMap;
78        EvalCacheMap m_cacheMap;
79    };
80
81} // namespace JSC
82
83#endif // EvalCodeCache_h
84