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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 
     41 namespace JSC {
     42 
     43     class EvalCodeCache {
     44     public:
     45         PassRefPtr<EvalExecutable> get(ExecState* exec, const UString& evalSource, ScopeChainNode* scopeChain, JSValue& exceptionValue)
     46         {
     47             RefPtr<EvalExecutable> evalExecutable;
     48 
     49             if (evalSource.size() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject())
     50                 evalExecutable = m_cacheMap.get(evalSource.rep());
     51 
     52             if (!evalExecutable) {
     53                 evalExecutable = EvalExecutable::create(exec, makeSource(evalSource));
     54                 exceptionValue = evalExecutable->compile(exec, scopeChain);
     55                 if (exceptionValue)
     56                     return 0;
     57 
     58                 if (evalSource.size() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject() && m_cacheMap.size() < maxCacheEntries)
     59                     m_cacheMap.set(evalSource.rep(), evalExecutable);
     60             }
     61 
     62             return evalExecutable.release();
     63         }
     64 
     65         bool isEmpty() const { return m_cacheMap.isEmpty(); }
     66 
     67     private:
     68         static const int maxCacheableSourceLength = 256;
     69         static const int maxCacheEntries = 64;
     70 
     71         typedef HashMap<RefPtr<UString::Rep>, RefPtr<EvalExecutable> > EvalCacheMap;
     72         EvalCacheMap m_cacheMap;
     73     };
     74 
     75 } // namespace JSC
     76 
     77 #endif // EvalCodeCache_h
     78