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 EvalCodeCache {

    45     public:

    46         PassRefPtr<EvalExecutable> get(ExecState* exec, const UString& evalSource, ScopeChainNode* scopeChain, JSValue& exceptionValue)

    47         {

    48             RefPtr<EvalExecutable> evalExecutable;

    49 

    50             if (evalSource.size() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject())

    51                 evalExecutable = m_cacheMap.get(evalSource.rep());

    52 

    53             if (!evalExecutable) {

    54                 evalExecutable = EvalExecutable::create(exec, makeSource(evalSource));

    55                 exceptionValue = evalExecutable->compile(exec, scopeChain);

    56                 if (exceptionValue)

    57                     return 0;

    58 

    59                 if (evalSource.size() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject() && m_cacheMap.size() < maxCacheEntries)

    60                     m_cacheMap.set(evalSource.rep(), evalExecutable);

    61             }

    62 

    63             return evalExecutable.release();

    64         }

    65 

    66         bool isEmpty() const { return m_cacheMap.isEmpty(); }

    67 

    68     private:

    69         static const unsigned maxCacheableSourceLength = 256;

    70         static const int maxCacheEntries = 64;

    71 

    72         typedef HashMap<RefPtr<UString::Rep>, RefPtr<EvalExecutable> > EvalCacheMap;

    73         EvalCacheMap m_cacheMap;

    74     };

    75 

    76 } // namespace JSC

    77 

    78 #endif // EvalCodeCache_h