CircularQueue.hpp

Go to the documentation of this file.

#ifndef INC_CircularQueue_hpp__
#define INC_CircularQueue_hpp__
 
/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/license.html
 *
 * $Id: //depot/code/org.antlr/release/antlr-2.7.7/lib/cpp/antlr/CircularQueue.hpp#2 $
 */
 
#include <antlr/config.hpp>
#include <antlr/Token.hpp>
#include <vector>
#include <cassert>
 
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
namespace antlr {
#endif
 
// Resize every 5000 items
#define OFFSET_MAX_RESIZE 5000
 
template <class T>
class ANTLR_API CircularQueue {
public:
   CircularQueue()
   : storage()
   , m_offset(0)
   {
   }
   ~CircularQueue()
   {
   }

   inline void clear( void )
   {
      m_offset = 0;
      storage.clear();
   }

   inline T elementAt( size_t idx ) const
   {
      return storage[idx+m_offset];
   }
   void removeFirst()
   {
      if (m_offset >= OFFSET_MAX_RESIZE)
      {
         storage.erase( storage.begin(), storage.begin() + m_offset + 1 );
         m_offset = 0;
      }
      else
         ++m_offset;
   }
   inline void removeItems( size_t nb )
   {
      // it would be nice if we would not get called with nb > entries
      // (or to be precise when entries() == 0)
      // This case is possible when lexer/parser::recover() calls
      // consume+consumeUntil when the queue is empty.
      // In recover the consume says to prepare to read another
      // character/token. Then in the subsequent consumeUntil the
      // LA() call will trigger
      // syncConsume which calls this method *before* the same queue
      // has been sufficiently filled.
      if( nb > entries() )
         nb = entries();
 
      if (m_offset >= OFFSET_MAX_RESIZE)
      {
         storage.erase( storage.begin(), storage.begin() + m_offset + nb );
         m_offset = 0;
      }
      else
         m_offset += nb;
   }
   inline void append(const T& t)
   {
      storage.push_back(t);
   }
   inline size_t entries() const
   {
      return storage.size() - m_offset;
   }
 
private:
   ANTLR_USE_NAMESPACE(std)vector<T> storage;
   size_t m_offset;
 
   CircularQueue(const CircularQueue&);
   const CircularQueue& operator=(const CircularQueue&);
};
 
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
}
#endif
 
#endif //INC_CircularQueue_hpp__