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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 Computer, 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 "Nodes.h"
35 #include "Parser.h"
36 #include "SourceCode.h"
37 #include "UString.h"
38 #include <wtf/HashMap.h>
39 #include <wtf/RefPtr.h>
40 #include <wtf/text/StringHash.h>
41 
42 namespace JSC {
43 
44     class MarkStack;
45 
46     class EvalCodeCache {
47     public:
get(ExecState * exec,ScriptExecutable * owner,bool inStrictContext,const UString & evalSource,ScopeChainNode * scopeChain,JSValue & exceptionValue)48         EvalExecutable* get(ExecState* exec, ScriptExecutable* owner, bool inStrictContext, const UString& evalSource, ScopeChainNode* scopeChain, JSValue& exceptionValue)
49         {
50             EvalExecutable* evalExecutable = 0;
51 
52             if (!inStrictContext && evalSource.length() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject())
53                 evalExecutable = m_cacheMap.get(evalSource.impl()).get();
54 
55             if (!evalExecutable) {
56                 evalExecutable = EvalExecutable::create(exec, makeSource(evalSource), inStrictContext);
57                 exceptionValue = evalExecutable->compile(exec, scopeChain);
58                 if (exceptionValue)
59                     return 0;
60 
61                 if (!inStrictContext && evalSource.length() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject() && m_cacheMap.size() < maxCacheEntries)
62                     m_cacheMap.set(evalSource.impl(), WriteBarrier<EvalExecutable>(exec->globalData(), owner, evalExecutable));
63             }
64 
65             return evalExecutable;
66         }
67 
isEmpty()68         bool isEmpty() const { return m_cacheMap.isEmpty(); }
69 
70         void markAggregate(MarkStack&);
71 
72     private:
73         static const unsigned maxCacheableSourceLength = 256;
74         static const int maxCacheEntries = 64;
75 
76         typedef HashMap<RefPtr<StringImpl>, WriteBarrier<EvalExecutable> > EvalCacheMap;
77         EvalCacheMap m_cacheMap;
78     };
79 
80 } // namespace JSC
81 
82 #endif // EvalCodeCache_h
83