ceph/src/boost/libs/wave/samples/advanced_hooks/advanced_hooks.hpp

   1 /*=============================================================================
   2     Boost.Wave: A Standard compliant C++ preprocessor library
   3     http://www.boost.org/
   4
   5     Copyright (c) 2001-2010 Hartmut Kaiser. Distributed under the Boost
   6     Software License, Version 1.0. (See accompanying file
   7     LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   8 =============================================================================*/
   9
  10 #if !defined(BOOST_WAVE_ADVANCED_PREPROCESSING_HOOKS_INCLUDED)
  11 #define BOOST_WAVE_ADVANCED_PREPROCESSING_HOOKS_INCLUDED
  12
  13 #include <cstdio>
  14 #include <ostream>
  15 #include <string>
  16
  17 #include <boost/assert.hpp>
  18 #include <boost/config.hpp>
  19
  20 #include <boost/wave/token_ids.hpp>
  21 #include <boost/wave/util/macro_helpers.hpp>
  22 #include <boost/wave/preprocessing_hooks.hpp>
  23
  24 ///////////////////////////////////////////////////////////////////////////////
  25 //
  26 //  The advanced_preprocessing_hooks policy class is used to register some
  27 //  of the more advanced (and probably more rarely used hooks with the Wave
  28 //  library.
  29 //
  30 //  This policy type is used as a template parameter to the boost::wave::context<>
  31 //  object.
  32 //
  33 ///////////////////////////////////////////////////////////////////////////////
  34 class advanced_preprocessing_hooks
  35 :   public boost::wave::context_policies::default_preprocessing_hooks
  36 {
  37 public:
  38     advanced_preprocessing_hooks() : need_comment(true) {}
  39
  40     ///////////////////////////////////////////////////////////////////////////
  41     //
  42     //  The function 'found_directive' is called, whenever a preprocessor
  43     //  directive was encountered, but before the corresponding action is
  44     //  executed.
  45     //
  46     //  The parameter 'ctx' is a reference to the context object used for
  47     //  instantiating the preprocessing iterators by the user.
  48     //
  49     //  The parameter 'directive' is a reference to the token holding the
  50     //  preprocessing directive.
  51     //
  52     ///////////////////////////////////////////////////////////////////////////
  53     template <typename ContextT, typename TokenT>
  54     bool
  55     found_directive(ContextT const& ctx, TokenT const& directive)
  56     {
  57         // print the commented conditional directives
  58         using namespace boost::wave;
  59         token_id id = token_id(directive);
  60         switch (id) {
  61         case T_PP_IFDEF:
  62         case T_PP_IFNDEF:
  63         case T_PP_IF:
  64         case T_PP_ELIF:
  65             std::cout << "// " << directive.get_value() << " ";
  66             need_comment = false;
  67             break;
  68
  69         case T_PP_ELSE:
  70         case T_PP_ENDIF:
  71             std::cout << "// " << directive.get_value() << std::endl;
  72             need_comment = true;
  73             break;
  74
  75         default:
  76             break;
  77         }
  78
  79         return false;
  80     }
  81
  82     ///////////////////////////////////////////////////////////////////////////
  83     //
  84     //  The function 'evaluated_conditional_expression' is called, whenever a
  85     //  conditional preprocessing expression was evaluated (the expression
  86     //  given to a #if, #elif, #ifdef or #ifndef directive)
  87     //
  88     //  The parameter 'ctx' is a reference to the context object used for
  89     //  instantiating the preprocessing iterators by the user.
  90     //
  91     //  The parameter 'expression' holds the non-expanded token sequence
  92     //  comprising the evaluated expression.
  93     //
  94     //  The parameter expression_value contains the result of the evaluation of
  95     //  the expression in the current preprocessing context.
  96     //
  97     //  The return value defines, whether the given expression has to be
  98     //  evaluated again, allowing to decide which of the conditional branches
  99     //  should be expanded. You need to return 'true' from this hook function
 100     //  to force the expression to be re-evaluated.
 101     //
 102     ///////////////////////////////////////////////////////////////////////////
 103     template <typename ContextT, typename TokenT, typename ContainerT>
 104     bool
 105     evaluated_conditional_expression(ContextT const &ctx,
 106         TokenT const& directive, ContainerT const& expression,
 107         bool expression_value)
 108     {
 109         // print the conditional expressions
 110         std::cout << boost::wave::util::impl::as_string(expression) << std::endl;
 111         need_comment = true;
 112         return false;          // ok to continue, do not re-evaluate expression
 113     }
 114
 115     ///////////////////////////////////////////////////////////////////////////
 116     //
 117     //  The function 'skipped_token' is called, whenever a token is about to be
 118     //  skipped due to a false preprocessor condition (code fragments to be
 119     //  skipped inside the not evaluated conditional #if/#else/#endif branches).
 120     //
 121     //  The parameter 'ctx' is a reference to the context object used for
 122     //  instantiating the preprocessing iterators by the user.
 123     //
 124     //  The parameter 'token' refers to the token to be skipped.
 125     //
 126     ///////////////////////////////////////////////////////////////////////////
 127     template <typename ContextT, typename TokenT>
 128     void
 129     skipped_token(ContextT const& ctx, TokenT const& token)
 130     {
 131         // prepend a comment at the beginning of all skipped lines
 132         using namespace boost::wave;
 133         if (need_comment && token_id(token) != T_SPACE) {
 134             std::cout << "// ";
 135             need_comment = false;
 136         }
 137         std::cout << token.get_value();
 138         if (token_id(token) == T_NEWLINE || token_id(token) == T_CPPCOMMENT)
 139             need_comment = true;
 140     }
 141
 142 private:
 143     bool need_comment;
 144 };
 145
 146 #endif // !defined(BOOST_WAVE_ADVANCED_PREPROCESSING_HOOKS_INCLUDED)