compilation-cache.h.svn-base

Google浏览器V8内核代码

// Copyright 2008 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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#ifndef V8_COMPILATION_CACHE_H_
#define V8_COMPILATION_CACHE_H_

namespace v8 { namespace internal {


// The compilation cache keeps function boilerplates for compiled
// scripts and evals. The boilerplates are looked up using the source
// string as the key.
class CompilationCache {
 public:
  // The same source code string has different compiled code for
  // scripts and evals. Internally, we use separate caches to avoid
  // getting the wrong kind of entry when looking up.
  enum Entry {
    SCRIPT,
    EVAL_GLOBAL,
    EVAL_CONTEXTUAL
  };

  // Finds the script function boilerplate for a source
  // string. Returns an empty handle if the cache doesn't contain a
  // script for the given source string with the right origin.
  static Handle<JSFunction> LookupScript(Handle<String> source,
                                         Handle<Object> name,
                                         int line_offset,
                                         int column_offset);

  // Finds the function boilerplate for a source string for
  // eval. Returns an empty handle if the cache doesn't contain a
  // script for the given source string.
  static Handle<JSFunction> LookupEval(Handle<String> source,
                                       Entry entry);

  // Associate the (source, kind) pair to the boilerplate. This may
  // overwrite an existing mapping.
  static void Associate(Handle<String> source,
                        Entry entry,
                        Handle<JSFunction> boilerplate);

  // Clear the cache - also used to initialize the cache at startup.
  static void Clear();

  // GC support.
  static void Iterate(ObjectVisitor* v);

  // Notify the cache that a mark-sweep garbage collection is about to
  // take place. This is used to retire entries from the cache to
  // avoid keeping them alive too long without using them. For now, we
  // just clear the cache but we should consider are more
  // sophisticated LRU scheme.
  static void MarkCompactPrologue() { Clear(); }
};


} }  // namespace v8::internal

#endif  // V8_COMPILATION_CACHE_H_