bytecode/EvalCodeCache.h

   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 "JSGlobalObject.h"
  33 #include "Nodes.h"
  34 #include "Parser.h"
  35 #include "SourceCode.h"
  36 #include "UString.h"
  37 #include <wtf/HashMap.h>
  38 #include <wtf/RefPtr.h>
  39
  40 namespace JSC {
  41
  42     class EvalCodeCache {
  43     public:
  44         PassRefPtr<EvalNode> get(ExecState* exec, const UString& evalSource, ScopeChainNode* scopeChain, JSValue& exceptionValue)
  45         {
  46             RefPtr<EvalNode> evalNode;
  47
  48             if (evalSource.size() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject())
  49                 evalNode = m_cacheMap.get(evalSource.rep());
  50
  51             if (!evalNode) {
  52                 int errorLine;
  53                 UString errorMessage;
  54
  55                 SourceCode source = makeSource(evalSource);
  56                 evalNode = exec->globalData().parser->parse<EvalNode>(exec, exec->dynamicGlobalObject()->debugger(), source, &errorLine, &errorMessage);
  57                 if (evalNode) {
  58                     if (evalSource.size() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject() && m_cacheMap.size() < maxCacheEntries)
  59                         m_cacheMap.set(evalSource.rep(), evalNode);
  60                 } else {
  61                     exceptionValue = Error::create(exec, SyntaxError, errorMessage, errorLine, source.provider()->asID(), 0);
  62                     return 0;
  63                 }
  64             }
  65
  66             return evalNode.release();
  67         }
  68
  69         bool isEmpty() const { return m_cacheMap.isEmpty(); }
  70
  71         void mark()
  72         {
  73             EvalCacheMap::iterator end = m_cacheMap.end();
  74             for (EvalCacheMap::iterator ptr = m_cacheMap.begin(); ptr != end; ++ptr)
  75                 ptr->second->mark();
  76         }
  77     private:
  78         static const int maxCacheableSourceLength = 256;
  79         static const int maxCacheEntries = 64;
  80
  81         typedef HashMap<RefPtr<UString::Rep>, RefPtr<EvalNode> > EvalCacheMap;
  82         EvalCacheMap m_cacheMap;
  83     };
  84
  85 } // namespace JSC
  86
  87 #endif // EvalCodeCache_h