wave/cpplexer/token_cache.hpp

0001 /*=============================================================================
0002     Boost.Wave: A Standard compliant C++ preprocessor library
0003
0004     http://www.boost.org/
0005
0006     Copyright (c) 2001-2012 Hartmut Kaiser. Distributed under the Boost
0007     Software License, Version 1.0. (See accompanying file
0008     LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 =============================================================================*/
0010
0011 #if !defined(BOOST_TOKEN_CACHE_HPP_4D2320B7_1D56_4113_A114_397E70FA438C_INCLUDED)
0012 #define BOOST_TOKEN_CACHE_HPP_4D2320B7_1D56_4113_A114_397E70FA438C_INCLUDED
0013
0014 #include <vector>
0015
0016 #include <boost/wave/wave_config.hpp>
0017 #include <boost/wave/token_ids.hpp>
0018
0019 // this must occur after all of the includes and before any code appears
0020 #ifdef BOOST_HAS_ABI_HEADERS
0021 #include BOOST_ABI_PREFIX
0022 #endif
0023
0024 ///////////////////////////////////////////////////////////////////////////////
0025 namespace boost {
0026 namespace wave {
0027 namespace cpplexer {
0028
0029 ///////////////////////////////////////////////////////////////////////////////
0030 //
0031 //  The token_cache template is used to cache the tokens corresponding to the
0032 //  keywords, operators and other constant language elements.
0033 //
0034 //  This avoids repeated construction of these tokens, which is especially
0035 //  effective when used in conjunction with a copy on write string
0036 //  implementation (COW string).
0037 //
0038 ///////////////////////////////////////////////////////////////////////////////
0039 template <typename StringT>
0040 class token_cache
0041 {
0042 public:
0043     token_cache()
0044     :   cache(T_LAST_TOKEN - T_FIRST_TOKEN)
0045     {
0046         typename std::vector<StringT>::iterator it = cache.begin();
0047         for (unsigned int i = T_FIRST_TOKEN; i < T_LAST_TOKEN;  ++i, ++it)
0048         {
0049             *it = StringT(boost::wave::get_token_value(token_id(i)));
0050         }
0051     }
0052
0053     StringT const &get_token_value(token_id id) const
0054     {
0055         return cache[BASEID_FROM_TOKEN(id) - T_FIRST_TOKEN];
0056     }
0057
0058 private:
0059     std::vector<StringT> cache;
0060 };
0061
0062 ///////////////////////////////////////////////////////////////////////////////
0063 }   // namespace cpplexer
0064 }   // namespace wave
0065 }   // namespace boost
0066
0067 // the suffix header occurs after all of the code
0068 #ifdef BOOST_HAS_ABI_HEADERS
0069 #include BOOST_ABI_SUFFIX
0070 #endif
0071
0072 #endif // !defined(BOOST_TOKEN_CACHE_HPP_4D2320B7_1D56_4113_A114_397E70FA438C_INCLUDED)