common.hpp

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        container_t new_children;
        std::size_t length = 0;
        std::size_t tree_size = m.trees.size();

        // the infix_node_d[] make no sense for nodes with no subnodes
        BOOST_SPIRIT_ASSERT(tree_size >= 1);

        bool keep = true;
#if !defined(BOOST_SPIRIT_USE_LIST_FOR_TREES)
        new_children.reserve((tree_size+1)/2);
#endif
        iter_t i_end = m.trees.end();
        for (iter_t i = m.trees.begin(); i != i_end; ++i)
        {
            if (keep) {
                // adjust the length
                length += std::distance((*i).value.begin(), (*i).value.end());

                // move the child node
                new_children.push_back(value_t());
                swap(new_children.back(), *i);
                keep = false;
            }
            else {
                // ignore this child node
                keep = true;
            }
        }

        m = MatchT(length, new_children);
    }
};

const node_parser_gen<infix_node_op> infix_node_d =
    node_parser_gen<infix_node_op>();

struct discard_first_node_op
{
    template <typename MatchT>
    void operator()(MatchT& m) const
    {
        typedef typename MatchT::container_t container_t;
        typedef typename MatchT::container_t::iterator iter_t;
        typedef typename MatchT::container_t::value_type value_t;

        using std::swap;
        using boost::swap;
        using BOOST_SPIRIT_CLASSIC_NS::swap;

        // copying the tree nodes is expensive, since it may copy a whole
        // tree.  swapping them is cheap, so swap the nodes we want into
        // a new container of children, instead of saying
        // m.trees.erase(m.trees.begin()) because, on a container_t that will 
        // cause all the nodes afterwards to be copied into the previous 
        // position.
        container_t new_children;
        std::size_t length = 0;
        std::size_t tree_size = m.trees.size();

        // the discard_first_node_d[] make no sense for nodes with no subnodes
        BOOST_SPIRIT_ASSERT(tree_size >= 1);

        if (tree_size > 1) {
#if !defined(BOOST_SPIRIT_USE_LIST_FOR_TREES)
            new_children.reserve(tree_size - 1);
#endif
            iter_t i = m.trees.begin(), i_end = m.trees.end();
            for (++i; i != i_end; ++i)
            {
                // adjust the length
                length += std::distance((*i).value.begin(), (*i).value.end());

                // move the child node
                new_children.push_back(value_t());
                swap(new_children.back(), *i);
            }
        }
        else {
        // if there was a tree and now there isn't any, insert an empty node
            iter_t i = m.trees.begin(); 

        // This isn't entirely correct, since the empty node will reference
        // the end of the discarded node, but I currently don't see any way to 
        // get at the begin of the node following this subnode.
        // This should be safe anyway because the it shouldn't get dereferenced
        // under any circumstances.
            typedef typename value_t::parse_node_t::iterator_t iterator_type;
            iterator_type it = (*i).value.end();
            
            new_children.push_back(
                value_t(typename value_t::parse_node_t(it, it)));
        }
        
        m = MatchT(length, new_children);
    }
};

const node_parser_gen<discard_first_node_op> discard_first_node_d =
    node_parser_gen<discard_first_node_op>();

struct discard_last_node_op
{
    template <typename MatchT>
    void operator()(MatchT& m) const
    {
        typedef typename MatchT::container_t container_t;
        typedef typename MatchT::container_t::iterator iter_t;
        typedef typename MatchT::container_t::value_type value_t;

        using std::swap;
        using boost::swap;
        using BOOST_SPIRIT_CLASSIC_NS::swap;

        // copying the tree nodes is expensive, since it may copy a whole
        // tree.  swapping them is cheap, so swap the nodes we want into
        // a new container of children, instead of saying
        // m.trees.erase(m.trees.begin()) because, on a container_t that will 
        // cause all the nodes afterwards to be copied into the previous 
        // position.
        container_t new_children;
        std::size_t length = 0;
        std::size_t tree_size = m.trees.size();

        // the discard_last_node_d[] make no sense for nodes with no subnodes
        BOOST_SPIRIT_ASSERT(tree_size >= 1);

        if (tree_size > 1) {
            m.trees.pop_back();
#if !defined(BOOST_SPIRIT_USE_LIST_FOR_TREES)
            new_children.reserve(tree_size - 1);
#endif            
            iter_t i_end = m.trees.end();
            for (iter_t i = m.trees.begin(); i != i_end; ++i)
            {
                // adjust the length
                length += std::distance((*i).value.begin(), (*i).value.end());

                // move the child node
                new_children.push_back(value_t());
                swap(new_children.back(), *i);
            }
        }
        else {
        // if there was a tree and now there isn't any, insert an empty node
            iter_t i = m.trees.begin(); 

            typedef typename value_t::parse_node_t::iterator_t iterator_type;
            iterator_type it = (*i).value.begin();
            
            new_children.push_back(
                value_t(typename value_t::parse_node_t(it, it)));
        }
        
        m = MatchT(length, new_children);
    }
};

const node_parser_gen<discard_last_node_op> discard_last_node_d =
    node_parser_gen<discard_last_node_op>();

struct inner_node_op
{
    template <typename MatchT>
    void operator()(MatchT& m) const
    {
        typedef typename MatchT::container_t container_t;
        typedef typename MatchT::container_t::iterator iter_t;
        typedef typename MatchT::container_t::value_type value_t;

        using std::swap;
        using boost::swap;
        using BOOST_SPIRIT_CLASSIC_NS::swap;

        // copying the tree nodes is expensive, since it may copy a whole
        // tree.  swapping them is cheap, so swap the nodes we want into
        // a new container of children, instead of saying
        // m.trees.erase(m.trees.begin()) because, on a container_t that will 
        // cause all the nodes afterwards to be copied into the previous 
        // position.
        container_t new_children;
        std::size_t length = 0;
        std::size_t tree_size = m.trees.size();
        
        // the inner_node_d[] make no sense for nodes with less then 2 subnodes
        BOOST_SPIRIT_ASSERT(tree_size >= 2);

        if (tree_size > 2) {
            m.trees.pop_back(); // erase the last element
#if !defined(BOOST_SPIRIT_USE_LIST_FOR_TREES)
            new_children.reserve(tree_size - 1);
#endif
            iter_t i = m.trees.begin(); // skip over the first element
            iter_t i_end = m.trees.end();
            for (++i; i != i_end; ++i)
            {
                // adjust the length
                length += std::distance((*i).value.begin(), (*i).value.end());
                
                // move the child node
                new_children.push_back(value_t());
                swap(new_children.back(), *i);
            }
        }
        else {
        // if there was a tree and now there isn't any, insert an empty node
            iter_t i = m.trees.begin(); // skip over the first element

            typedef typename value_t::parse_node_t::iterator_t iterator_type;
            iterator_type it = (*++i).value.begin();
            
            new_children.push_back(
                value_t(typename value_t::parse_node_t(it, it)));
        }
        
        m = MatchT(length, new_children);
    }
};

const node_parser_gen<inner_node_op> inner_node_d =
    node_parser_gen<inner_node_op>();


//////////////////////////////////
// action_directive_parser and action_directive_parser_gen
// are meant to be used as a template to create directives that
// generate action classes.  For example access_match and
// access_node.  The ActionParserT template parameter must be
// a class that has an innter class called action that is templated
// on the parser type and the action type.
template <typename ActionParserT>
struct action_directive_parser_gen;

template <typename T, typename ActionParserT>
struct action_directive_parser
:   public unary<T, parser<action_directive_parser<T, ActionParserT> > >
{
    typedef action_directive_parser<T, ActionParserT> self_t;
    typedef action_directive_parser_gen<ActionParserT> parser_generator_t;
    typedef unary_parser_category parser_category_t;

    action_directive_parser(T const& a)
        : unary<T, parser<action_directive_parser<T, ActionParserT> > >(a) {}

    template <typename ScannerT>
    struct result
    {
        typedef typename parser_result<T, ScannerT>::type type;
    };

    template <typename ScannerT>
    typename parser_result<self_t, ScannerT>::type
    parse(ScannerT const& scanner) const
    {
        return this->subject().parse(scanner);
    }

    template <typename ActionT>
    typename ActionParserT::template action<action_directive_parser<T, ActionParserT>, ActionT>
    operator[](ActionT const& actor) const
    {
        typedef typename
            ActionParserT::template action<action_directive_parser, ActionT>
            action_t;
        return action_t(*this, actor);
    }
};

//////////////////////////////////
template <typename ActionParserT>
struct action_directive_parser_gen
{
    template <typename T>
    struct result {

        typedef action_directive_parser<T, ActionParserT> type;
    };

    template <typename T>
    static action_directive_parser<T, ActionParserT>
    generate(parser<T> const& s)
    {
        return action_directive_parser<T, ActionParserT>(s.derived());
    }

    template <typename T>
    action_directive_parser<T, ActionParserT>
    operator[](parser<T> const& s) const
    {
        return action_directive_parser<T, ActionParserT>(s.derived());
    }
};

//////////////////////////////////
// Calls the attached action passing it the match from the parser
// and the first and last iterators.
// The inner template class is used to simulate template-template parameters
// (declared in common_fwd.hpp).
template <typename ParserT, typename ActionT>
struct access_match_action::action
:   public unary<ParserT, parser<access_match_action::action<ParserT, ActionT> > >
{
    typedef action_parser_category parser_category;
    typedef action<ParserT, ActionT> self_t;
    
    template <typename ScannerT>
    struct result
    {
        typedef typename parser_result<ParserT, ScannerT>::type type;
    };

    action( ParserT const& subject,
            ActionT const& actor_);

    template <typename ScannerT>
    typename parser_result<self_t, ScannerT>::type
    parse(ScannerT const& scanner) const;

    ActionT const &predicate() const;

    private:
    ActionT actor;
};

//////////////////////////////////
template <typename ParserT, typename ActionT>
access_match_action::action<ParserT, ActionT>::action(
    ParserT const& subject,
    ActionT const& actor_)
: unary<ParserT, parser<access_match_action::action<ParserT, ActionT> > >(subject)
, actor(actor_)
{}

//////////////////////////////////
template <typename ParserT, typename ActionT>
template <typename ScannerT>
typename parser_result<access_match_action::action<ParserT, ActionT>, ScannerT>::type
access_match_action::action<ParserT, ActionT>::
parse(ScannerT const& scan) const
{
    typedef typename ScannerT::iterator_t iterator_t;
    typedef typename parser_result<self_t, ScannerT>::type result_t;
    if (!scan.at_end())
    {
        iterator_t save = scan.first;
        result_t hit = this->subject().parse(scan);
        actor(hit, save, scan.first);
        return hit;
    }
    return scan.no_match();
}

//////////////////////////////////
template <typename ParserT, typename ActionT>
ActionT const &access_match_action::action<ParserT, ActionT>::predicate() const
{
    return actor;
}

//////////////////////////////////
const action_directive_parser_gen<access_match_action> access_match_d
    = action_directive_parser_gen<access_match_action>();



//////////////////////////////////
// Calls the attached action passing it the node from the parser
// and the first and last iterators
// The inner template class is used to simulate template-template parameters
// (declared in common_fwd.hpp).
template <typename ParserT, typename ActionT>
struct access_node_action::action
:   public unary<ParserT, parser<access_node_action::action<ParserT, ActionT> > >
{
    typedef action_parser_category parser_category;
    typedef action<ParserT, ActionT> self_t;
    
    template <typename ScannerT>
    struct result
    {
        typedef typename parser_result<ParserT, ScannerT>::type type;
    };

    action( ParserT const& subject,
            ActionT const& actor_);

    template <typename ScannerT>
    typename parser_result<self_t, ScannerT>::type
    parse(ScannerT const& scanner) const;

    ActionT const &predicate() const;

    private:
    ActionT actor;
};

//////////////////////////////////
template <typename ParserT, typename ActionT>
access_node_action::action<ParserT, ActionT>::action(
    ParserT const& subject,
    ActionT const& actor_)
: unary<ParserT, parser<access_node_action::action<ParserT, ActionT> > >(subject)
, actor(actor_)
{}

//////////////////////////////////
template <typename ParserT, typename ActionT>
template <typename ScannerT>
typename parser_result<access_node_action::action<ParserT, ActionT>, ScannerT>::type
access_node_action::action<ParserT, ActionT>::
parse(ScannerT const& scan) const
{
    typedef typename ScannerT::iterator_t iterator_t;
    typedef typename parser_result<self_t, ScannerT>::type result_t;
    if (!scan.at_end())
    {
        iterator_t save = scan.first;
        result_t hit = this->subject().parse(scan);
        if (hit && hit.trees.size() > 0)
            actor(*hit.trees.begin(), save, scan.first);
        return hit;
    }
    return scan.no_match();
}

//////////////////////////////////
template <typename ParserT, typename ActionT>
ActionT const &access_node_action::action<ParserT, ActionT>::predicate() const
{
    return actor;
}

//////////////////////////////////
const action_directive_parser_gen<access_node_action> access_node_d
    = action_directive_parser_gen<access_node_action>();



//////////////////////////////////

///////////////////////////////////////////////////////////////////////////////
//
//  tree_parse_info
//
//      Results returned by the tree parse functions:
//
//      stop:   points to the final parse position (i.e parsing
//              processed the input up to this point).
//
//      match:  true if parsing is successful. This may be full:
//              the parser consumed all the input, or partial:
//              the parser consumed only a portion of the input.
//
//      full:   true when we have a full match (i.e the parser
//              consumed all the input.
//
//      length: The number of characters consumed by the parser.
//              This is valid only if we have a successful match
//              (either partial or full). A negative value means
//              that the match is unsucessful.
//
//     trees:   Contains the root node(s) of the tree.
//
///////////////////////////////////////////////////////////////////////////////
template <
    typename IteratorT,
    typename NodeFactoryT,
    typename T
>
struct tree_parse_info 
{
    IteratorT   stop;
    bool        match;
    bool        full;
    std::size_t length;
    typename tree_match<IteratorT, NodeFactoryT, T>::container_t trees;

    tree_parse_info()
        : stop()
        , match(false)
        , full(false)
        , length(0)
        , trees()
    {}

    template <typename IteratorT2>
    tree_parse_info(tree_parse_info<IteratorT2> const& pi)
        : stop(pi.stop)
        , match(pi.match)
        , full(pi.full)
        , length(pi.length)
        , trees()
    {
        using std::swap;
        using boost::swap;
        using BOOST_SPIRIT_CLASSIC_NS::swap;

        // use auto_ptr like ownership for the trees data member
        swap(trees, pi.trees);
    }

    tree_parse_info(
        IteratorT   stop_,
        bool        match_,
        bool        full_,
        std::size_t length_,
        typename tree_match<IteratorT, NodeFactoryT, T>::container_t trees_)
    :   stop(stop_)
        , match(match_)
        , full(full_)
        , length(length_)
        , trees()
    {
        using std::swap;
        using boost::swap;
        using BOOST_SPIRIT_CLASSIC_NS::swap;

        // use auto_ptr like ownership for the trees data member
        swap(trees, trees_);
    }
};

BOOST_SPIRIT_CLASSIC_NAMESPACE_END

}} // namespace BOOST_SPIRIT_CLASSIC_NS

#endif