comparison DEPENDENCIES/generic/include/boost/spirit/home/lex/lexer/lexertl/token.hpp @ 16:2665513ce2d3

Add boost headers

+//  Copyright (c) 2001-2011 Hartmut Kaiser
+// 
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying 
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#if !defined(BOOST_SPIRIT_LEX_TOKEN_FEB_10_2008_0751PM)
+#define BOOST_SPIRIT_LEX_TOKEN_FEB_10_2008_0751PM
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/config.hpp>
+#include <boost/detail/workaround.hpp>
+#include <boost/spirit/home/qi/detail/assign_to.hpp>
+#include <boost/spirit/home/support/attributes.hpp>
+#include <boost/spirit/home/support/argument.hpp>
+#include <boost/spirit/home/support/detail/lexer/generator.hpp>
+#include <boost/spirit/home/support/detail/lexer/rules.hpp>
+#include <boost/spirit/home/support/detail/lexer/consts.hpp>
+#include <boost/spirit/home/support/utree/utree_traits_fwd.hpp>
+#include <boost/spirit/home/lex/lexer/terminals.hpp>
+#include <boost/fusion/include/vector.hpp>
+#include <boost/fusion/include/at.hpp>
+#include <boost/fusion/include/value_at.hpp>
+#include <boost/detail/iterator.hpp>
+#include <boost/variant.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/vector.hpp>
+#include <boost/mpl/is_sequence.hpp>
+#include <boost/mpl/begin.hpp>
+#include <boost/mpl/insert.hpp>
+#include <boost/mpl/vector.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/or.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/range/iterator_range.hpp>
+#if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+#include <boost/static_assert.hpp>
+#endif
+
+#if defined(BOOST_SPIRIT_DEBUG)
+#include <iosfwd>
+#endif
+
+namespace boost { namespace spirit { namespace lex { namespace lexertl
+{ 
+    ///////////////////////////////////////////////////////////////////////////
+    //
+    //  The token is the type of the objects returned by default by the 
+    //  iterator.
+    //
+    //    template parameters:
+    //        Iterator        The type of the iterator used to access the
+    //                        underlying character stream.
+    //        AttributeTypes  A mpl sequence containing the types of all 
+    //                        required different token values to be supported 
+    //                        by this token type.
+    //        HasState        A mpl::bool_ indicating, whether this token type
+    //                        should support lexer states.
+    //        Idtype          The type to use for the token id (defaults to 
+    //                        std::size_t).
+    //
+    //  It is possible to use other token types with the spirit::lex 
+    //  framework as well. If you plan to use a different type as your token 
+    //  type, you'll need to expose the following things from your token type 
+    //  to make it compatible with spirit::lex:
+    //
+    //    typedefs
+    //        iterator_type   The type of the iterator used to access the
+    //                        underlying character stream.
+    //
+    //        id_type         The type of the token id used.
+    //
+    //    methods
+    //        default constructor
+    //                        This should initialize the token as an end of 
+    //                        input token.
+    //        constructors    The prototype of the other required 
+    //                        constructors should be:
+    //
+    //              token(int)
+    //                        This constructor should initialize the token as 
+    //                        an invalid token (not carrying any specific 
+    //                        values)
+    //
+    //              where:  the int is used as a tag only and its value is 
+    //                      ignored
+    //
+    //                        and:
+    //
+    //              token(Idtype id, std::size_t state, 
+    //                    iterator_type first, iterator_type last);
+    //
+    //              where:  id:           token id
+    //                      state:        lexer state this token was matched in
+    //                      first, last:  pair of iterators marking the matched 
+    //                                    range in the underlying input stream 
+    //
+    //        accessors
+    //              id()      return the token id of the matched input sequence
+    //              id(newid) set the token id of the token instance
+    //
+    //              state()   return the lexer state this token was matched in
+    //
+    //              value()   return the token value
+    //
+    //  Additionally, you will have to implement a couple of helper functions
+    //  in the same namespace as the token type: a comparison operator==() to 
+    //  compare your token instances, a token_is_valid() function and different 
+    //  specializations of the Spirit customization point 
+    //  assign_to_attribute_from_value as shown below.
+    //
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Iterator = char const*
+      , typename AttributeTypes = mpl::vector0<>
+      , typename HasState = mpl::true_
+      , typename Idtype = std::size_t> 
+    struct token;
+
+    ///////////////////////////////////////////////////////////////////////////
+    //  This specialization of the token type doesn't contain any item data and
+    //  doesn't support working with lexer states.
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Iterator, typename Idtype>
+    struct token<Iterator, lex::omit, mpl::false_, Idtype>
+    {
+        typedef Iterator iterator_type;
+        typedef mpl::false_ has_state;
+        typedef Idtype id_type;
+        typedef unused_type token_value_type;
+
+        //  default constructed tokens correspond to EOI tokens
+        token() : id_(id_type(boost::lexer::npos)) {}
+
+        //  construct an invalid token
+        explicit token(int) : id_(id_type(0)) {}
+
+        token(id_type id, std::size_t) : id_(id) {}
+
+        token(id_type id, std::size_t, token_value_type)
+          : id_(id) {}
+
+        token_value_type& value() { static token_value_type u; return u; }
+        token_value_type const& value() const { return unused; }
+
+#if defined(BOOST_SPIRIT_DEBUG)
+        token(id_type id, std::size_t, Iterator const& first
+              , Iterator const& last)
+          : matched_(first, last)
+          , id_(id) {}
+#else
+        token(id_type id, std::size_t, Iterator const&, Iterator const&)
+          : id_(id) {}
+#endif
+
+        //  this default conversion operator is needed to allow the direct 
+        //  usage of tokens in conjunction with the primitive parsers defined 
+        //  in Qi
+        operator id_type() const { return id_; }
+
+        //  Retrieve or set the token id of this token instance. 
+        id_type id() const { return id_; }
+        void id(id_type newid) { id_ = newid; }
+
+        std::size_t state() const { return 0; }   // always '0' (INITIAL state)
+
+        bool is_valid() const 
+        { 
+            return 0 != id_ && id_type(boost::lexer::npos) != id_; 
+        }
+
+#if defined(BOOST_SPIRIT_DEBUG)
+#if BOOST_WORKAROUND(BOOST_MSVC, == 1600)
+        // workaround for MSVC10 which has problems copying a default 
+        // constructed iterator_range
+        token& operator= (token const& rhs)
+        {
+            if (this != &rhs) 
+            {
+                id_ = rhs.id_;
+                if (is_valid()) 
+                    matched_ = rhs.matched_;
+            }
+            return *this;
+        }
+#endif
+        std::pair<Iterator, Iterator> matched_;
+#endif
+
+    protected:
+        id_type id_;            // token id, 0 if nothing has been matched
+    };
+
+#if defined(BOOST_SPIRIT_DEBUG)
+    template <typename Char, typename Traits, typename Iterator
+      , typename AttributeTypes, typename HasState, typename Idtype> 
+    inline std::basic_ostream<Char, Traits>& 
+    operator<< (std::basic_ostream<Char, Traits>& os
+      , token<Iterator, AttributeTypes, HasState, Idtype> const& t)
+    {
+        if (t.is_valid()) {
+            Iterator end = t.matched_.second;
+            for (Iterator it = t.matched_.first; it != end; ++it)
+                os << *it;
+        }
+        else {
+            os << "<invalid token>";
+        }
+        return os;
+    }
+#endif
+
+    ///////////////////////////////////////////////////////////////////////////
+    //  This specialization of the token type doesn't contain any item data but
+    //  supports working with lexer states.
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Iterator, typename Idtype>
+    struct token<Iterator, lex::omit, mpl::true_, Idtype>
+      : token<Iterator, lex::omit, mpl::false_, Idtype>
+    {
+    private:
+        typedef token<Iterator, lex::omit, mpl::false_, Idtype> base_type;
+
+    public:
+        typedef typename base_type::id_type id_type;
+        typedef Iterator iterator_type;
+        typedef mpl::true_ has_state;
+        typedef unused_type token_value_type;
+
+        //  default constructed tokens correspond to EOI tokens
+        token() : state_(boost::lexer::npos) {}
+
+        //  construct an invalid token
+        explicit token(int) : base_type(0), state_(boost::lexer::npos) {}
+
+        token(id_type id, std::size_t state)
+          : base_type(id, boost::lexer::npos), state_(state) {}
+
+        token(id_type id, std::size_t state, token_value_type)
+          : base_type(id, boost::lexer::npos, unused)
+          , state_(state) {}
+
+        token(id_type id, std::size_t state
+              , Iterator const& first, Iterator const& last)
+          : base_type(id, boost::lexer::npos, first, last)
+          , state_(state) {}
+
+        std::size_t state() const { return state_; }
+
+#if defined(BOOST_SPIRIT_DEBUG) && BOOST_WORKAROUND(BOOST_MSVC, == 1600)
+        // workaround for MSVC10 which has problems copying a default 
+        // constructed iterator_range
+        token& operator= (token const& rhs)
+        {
+            if (this != &rhs) 
+            {
+                this->base_type::operator=(static_cast<base_type const&>(rhs));
+                state_ = rhs.state_;
+            }
+            return *this;
+        }
+#endif
+
+    protected:
+        std::size_t state_;      // lexer state this token was matched in
+    };
+
+    ///////////////////////////////////////////////////////////////////////////
+    //  The generic version of the token type derives from the 
+    //  specialization above and adds a single data member holding the item 
+    //  data carried by the token instance.
+    ///////////////////////////////////////////////////////////////////////////
+    namespace detail
+    {
+        ///////////////////////////////////////////////////////////////////////
+        //  Meta-function to calculate the type of the variant data item to be 
+        //  stored with each token instance.
+        //
+        //  Note: The iterator pair needs to be the first type in the list of 
+        //        types supported by the generated variant type (this is being 
+        //        used to identify whether the stored data item in a particular 
+        //        token instance needs to be converted from the pair of 
+        //        iterators (see the first of the assign_to_attribute_from_value 
+        //        specializations below).
+        ///////////////////////////////////////////////////////////////////////
+        template <typename IteratorPair, typename AttributeTypes>
+        struct token_value_typesequence
+        {
+            typedef typename mpl::insert<
+                AttributeTypes
+              , typename mpl::begin<AttributeTypes>::type
+              , IteratorPair
+            >::type sequence_type;
+            typedef typename make_variant_over<sequence_type>::type type;
+        };
+
+        ///////////////////////////////////////////////////////////////////////
+        //  The type of the data item stored with a token instance is defined 
+        //  by the template parameter 'AttributeTypes' and may be:
+        //  
+        //     lex::omit:         no data item is stored with the token 
+        //                        instance (this is handled by the 
+        //                        specializations of the token class
+        //                        below)
+        //     mpl::vector0<>:    each token instance stores a pair of 
+        //                        iterators pointing to the matched input 
+        //                        sequence
+        //     mpl::vector<...>:  each token instance stores a variant being 
+        //                        able to store the pair of iterators pointing 
+        //                        to the matched input sequence, or any of the 
+        //                        types a specified in the mpl::vector<>
+        //
+        //  All this is done to ensure the token type is as small (in terms 
+        //  of its byte-size) as possible.
+        ///////////////////////////////////////////////////////////////////////
+        template <typename IteratorPair, typename AttributeTypes>
+        struct token_value_type
+          : mpl::eval_if<
+                mpl::or_<
+                    is_same<AttributeTypes, mpl::vector0<> >
+                  , is_same<AttributeTypes, mpl::vector<> > >
+              , mpl::identity<IteratorPair>
+              , token_value_typesequence<IteratorPair, AttributeTypes> >
+        {};
+    }
+
+    template <typename Iterator, typename AttributeTypes, typename HasState
+      , typename Idtype>
+    struct token : token<Iterator, lex::omit, HasState, Idtype>
+    {
+    private: // precondition assertions
+#if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+        BOOST_STATIC_ASSERT((mpl::is_sequence<AttributeTypes>::value || 
+                            is_same<AttributeTypes, lex::omit>::value));
+#endif
+        typedef token<Iterator, lex::omit, HasState, Idtype> base_type;
+
+    protected: 
+        //  If no additional token value types are given, the the token will 
+        //  hold the plain pair of iterators pointing to the matched range
+        //  in the underlying input sequence. Otherwise the token value is 
+        //  stored as a variant and will again hold the pair of iterators but
+        //  is able to hold any of the given data types as well. The conversion 
+        //  from the iterator pair to the required data type is done when it is
+        //  accessed for the first time.
+        typedef iterator_range<Iterator> iterpair_type;
+
+    public:
+        typedef typename base_type::id_type id_type;
+        typedef typename detail::token_value_type<
+            iterpair_type, AttributeTypes
+        >::type token_value_type;
+
+        typedef Iterator iterator_type;
+
+        //  default constructed tokens correspond to EOI tokens
+        token() : value_(iterpair_type(iterator_type(), iterator_type())) {}
+
+        //  construct an invalid token
+        explicit token(int)
+          : base_type(0)
+          , value_(iterpair_type(iterator_type(), iterator_type())) {}
+
+        token(id_type id, std::size_t state, token_value_type const& value)
+          : base_type(id, state, value)
+          , value_(value) {}
+
+        token(id_type id, std::size_t state, Iterator const& first
+              , Iterator const& last)
+          : base_type(id, state, first, last)
+          , value_(iterpair_type(first, last)) {}
+
+        token_value_type& value() { return value_; }
+        token_value_type const& value() const { return value_; }
+
+#if BOOST_WORKAROUND(BOOST_MSVC, == 1600)
+        // workaround for MSVC10 which has problems copying a default 
+        // constructed iterator_range
+        token& operator= (token const& rhs)
+        {
+            if (this != &rhs) 
+            {
+                this->base_type::operator=(static_cast<base_type const&>(rhs));
+                if (this->is_valid()) 
+                    value_ = rhs.value_;
+            }
+            return *this;
+        }
+#endif
+
+    protected:
+        token_value_type value_; // token value, by default a pair of iterators
+    };
+
+    ///////////////////////////////////////////////////////////////////////////
+    //  tokens are considered equal, if their id's match (these are unique)
+    template <typename Iterator, typename AttributeTypes, typename HasState
+      , typename Idtype>
+    inline bool 
+    operator== (token<Iterator, AttributeTypes, HasState, Idtype> const& lhs, 
+                token<Iterator, AttributeTypes, HasState, Idtype> const& rhs)
+    {
+        return lhs.id() == rhs.id();
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    //  This overload is needed by the multi_pass/functor_input_policy to 
+    //  validate a token instance. It has to be defined in the same namespace 
+    //  as the token class itself to allow ADL to find it.
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Iterator, typename AttributeTypes, typename HasState
+      , typename Idtype>
+    inline bool 
+    token_is_valid(token<Iterator, AttributeTypes, HasState, Idtype> const& t)
+    {
+        return t.is_valid();
+    }
+}}}}
+
+namespace boost { namespace spirit { namespace traits
+{
+    ///////////////////////////////////////////////////////////////////////////
+    //  We have to provide specializations for the customization point
+    //  assign_to_attribute_from_value allowing to extract the needed value 
+    //  from the token. 
+    ///////////////////////////////////////////////////////////////////////////
+
+    //  This is called from the parse function of token_def if the token_def
+    //  has been defined to carry a special attribute type
+    template <typename Attribute, typename Iterator, typename AttributeTypes
+      , typename HasState, typename Idtype>
+    struct assign_to_attribute_from_value<Attribute
+      , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+    {
+        static void 
+        call(lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> const& t
+          , Attribute& attr)
+        {
+        //  The goal of this function is to avoid the conversion of the pair of
+        //  iterators (to the matched character sequence) into the token value 
+        //  of the required type being done more than once. For this purpose it 
+        //  checks whether the stored value type is still the default one (pair 
+        //  of iterators) and if yes, replaces the pair of iterators with the 
+        //  converted value to be returned from subsequent calls.
+
+            if (0 == t.value().which()) {
+            //  first access to the token value
+                typedef iterator_range<Iterator> iterpair_type;
+                iterpair_type const& ip = boost::get<iterpair_type>(t.value());
+
+            // Interestingly enough we use the assign_to() framework defined in 
+            // Spirit.Qi allowing to convert the pair of iterators to almost any 
+            // required type (assign_to(), if available, uses the standard Spirit 
+            // parsers to do the conversion).
+                spirit::traits::assign_to(ip.begin(), ip.end(), attr);
+
+            //  If you get an error during the compilation of the following 
+            //  assignment expression, you probably forgot to list one or more 
+            //  types used as token value types (in your token_def<...> 
+            //  definitions) in your definition of the token class. I.e. any token 
+            //  value type used for a token_def<...> definition has to be listed 
+            //  during the declaration of the token type to use. For instance let's 
+            //  assume we have two token_def's:
+            //
+            //      token_def<int> number; number = "...";
+            //      token_def<std::string> identifier; identifier = "...";
+            //
+            //  Then you'll have to use the following token type definition 
+            //  (assuming you are using the token class):
+            //
+            //      typedef mpl::vector<int, std::string> token_values;
+            //      typedef token<base_iter_type, token_values> token_type;
+            //
+            //  where: base_iter_type is the iterator type used to expose the 
+            //         underlying input stream.
+            //
+            //  This token_type has to be used as the second template parameter 
+            //  to the lexer class:
+            //
+            //      typedef lexer<base_iter_type, token_type> lexer_type;
+            //
+            //  again, assuming you're using the lexer<> template for your 
+            //  tokenization.
+
+                typedef lex::lexertl::token<
+                    Iterator, AttributeTypes, HasState, Idtype> token_type;
+                spirit::traits::assign_to(
+                    attr, const_cast<token_type&>(t).value());   // re-assign value
+            }
+            else {
+            // reuse the already assigned value
+                spirit::traits::assign_to(boost::get<Attribute>(t.value()), attr);
+            }
+        }
+    };
+
+    template <typename Attribute, typename Iterator, typename AttributeTypes
+      , typename HasState, typename Idtype>
+    struct assign_to_container_from_value<Attribute
+          , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+      : assign_to_attribute_from_value<Attribute
+          , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+    {};
+
+    template <typename Iterator, typename AttributeTypes
+      , typename HasState, typename Idtype>
+    struct assign_to_container_from_value<utree
+          , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+      : assign_to_attribute_from_value<utree
+          , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+    {};
+
+    template <typename Iterator>
+    struct assign_to_container_from_value<
+        iterator_range<Iterator>, iterator_range<Iterator> >
+    {
+        static void 
+        call(iterator_range<Iterator> const& val, iterator_range<Iterator>& attr)
+        {
+            attr = val;
+        }
+    };
+
+    //  These are called from the parse function of token_def if the token type
+    //  has no special attribute type assigned 
+    template <typename Attribute, typename Iterator, typename HasState
+      , typename Idtype>
+    struct assign_to_attribute_from_value<Attribute
+      , lex::lexertl::token<Iterator, mpl::vector0<>, HasState, Idtype> >
+    {
+        static void 
+        call(lex::lexertl::token<Iterator, mpl::vector0<>, HasState, Idtype> const& t
+          , Attribute& attr)
+        {
+            //  The default type returned by the token_def parser component (if 
+            //  it has no token value type assigned) is the pair of iterators 
+            //  to the matched character sequence.
+            spirit::traits::assign_to(t.value().begin(), t.value().end(), attr);
+        }
+    };
+
+//     template <typename Attribute, typename Iterator, typename HasState
+//       , typename Idtype>
+//     struct assign_to_container_from_value<Attribute
+//           , lex::lexertl::token<Iterator, mpl::vector0<>, HasState, Idtype> >
+//       : assign_to_attribute_from_value<Attribute
+//           , lex::lexertl::token<Iterator, mpl::vector0<>, HasState, Idtype> >
+//     {};
+
+    // same as above but using mpl::vector<> instead of mpl::vector0<>
+    template <typename Attribute, typename Iterator, typename HasState
+      , typename Idtype>
+    struct assign_to_attribute_from_value<Attribute
+      , lex::lexertl::token<Iterator, mpl::vector<>, HasState, Idtype> >
+    {
+        static void 
+        call(lex::lexertl::token<Iterator, mpl::vector<>, HasState, Idtype> const& t
+          , Attribute& attr)
+        {
+            //  The default type returned by the token_def parser component (if 
+            //  it has no token value type assigned) is the pair of iterators 
+            //  to the matched character sequence.
+            spirit::traits::assign_to(t.value().begin(), t.value().end(), attr);
+        }
+    };
+
+//     template <typename Attribute, typename Iterator, typename HasState
+//       , typename Idtype>
+//     struct assign_to_container_from_value<Attribute
+//           , lex::lexertl::token<Iterator, mpl::vector<>, HasState, Idtype> >
+//       : assign_to_attribute_from_value<Attribute
+//           , lex::lexertl::token<Iterator, mpl::vector<>, HasState, Idtype> >
+//     {};
+
+    //  This is called from the parse function of token_def if the token type
+    //  has been explicitly omitted (i.e. no attribute value is used), which
+    //  essentially means that every attribute gets initialized using default 
+    //  constructed values.
+    template <typename Attribute, typename Iterator, typename HasState
+      , typename Idtype>
+    struct assign_to_attribute_from_value<Attribute
+      , lex::lexertl::token<Iterator, lex::omit, HasState, Idtype> >
+    {
+        static void 
+        call(lex::lexertl::token<Iterator, lex::omit, HasState, Idtype> const& t
+          , Attribute& attr)
+        {
+            // do nothing
+        }
+    };
+
+    template <typename Attribute, typename Iterator, typename HasState
+      , typename Idtype>
+    struct assign_to_container_from_value<Attribute
+          , lex::lexertl::token<Iterator, lex::omit, HasState, Idtype> >
+      : assign_to_attribute_from_value<Attribute
+          , lex::lexertl::token<Iterator, lex::omit, HasState, Idtype> >
+    {};
+
+    //  This is called from the parse function of lexer_def_
+    template <typename Iterator, typename AttributeTypes, typename HasState
+      , typename Idtype_, typename Idtype>
+    struct assign_to_attribute_from_value<
+        fusion::vector2<Idtype_, iterator_range<Iterator> >
+      , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+    {
+        static void 
+        call(lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> const& t
+          , fusion::vector2<Idtype_, iterator_range<Iterator> >& attr)
+        {
+            //  The type returned by the lexer_def_ parser components is a 
+            //  fusion::vector containing the token id of the matched token 
+            //  and the pair of iterators to the matched character sequence.
+            typedef iterator_range<Iterator> iterpair_type;
+            typedef fusion::vector2<Idtype_, iterator_range<Iterator> > 
+                attribute_type;
+
+            iterpair_type const& ip = boost::get<iterpair_type>(t.value());
+            attr = attribute_type(t.id(), ip);
+        }
+    };
+
+    template <typename Iterator, typename AttributeTypes, typename HasState
+      , typename Idtype_, typename Idtype>
+    struct assign_to_container_from_value<
+            fusion::vector2<Idtype_, iterator_range<Iterator> >
+          , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+      : assign_to_attribute_from_value<
+            fusion::vector2<Idtype_, iterator_range<Iterator> >
+          , lex::lexertl::token<Iterator, AttributeTypes, HasState, Idtype> >
+    {};
+
+    ///////////////////////////////////////////////////////////////////////////
+    // Overload debug output for a single token, this integrates lexer tokens 
+    // with Qi's simple_trace debug facilities
+    template <typename Iterator, typename Attribute, typename HasState
+      , typename Idtype>
+    struct token_printer_debug<
+        lex::lexertl::token<Iterator, Attribute, HasState, Idtype> >
+    {
+        typedef lex::lexertl::token<Iterator, Attribute, HasState, Idtype> token_type;
+
+        template <typename Out>
+        static void print(Out& out, token_type const& val) 
+        {
+            out << '[';
+            spirit::traits::print_token(out, val.value());
+            out << ']';
+        }
+    };
+}}}
+
+#endif