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+/**
+ * @file lltreeiterators.h
+ * @author Nat Goodspeed
+ * @date 2008-08-19
+ * @brief This file defines iterators useful for traversing arbitrary node
+ * classes, potentially polymorphic, linked into strict tree
+ * structures.
+ *
+ * Dereferencing any one of these iterators actually yields a @em
+ * pointer to the node in question. For example, given an
+ * LLLinkedIter<MyNode> <tt>li</tt>, <tt>*li</tt> gets you a pointer
+ * to MyNode, and <tt>**li</tt> gets you the MyNode instance itself.
+ * More commonly, instead of writing <tt>li->member</tt>, you write
+ * <tt>(*li)->member</tt> -- as you would if you were traversing an
+ * STL container of MyNode pointers.
+ *
+ * It would certainly be possible to build these iterators so that
+ * <tt>*iterator</tt> would return a reference to the node itself
+ * rather than a pointer to the node, and for many purposes it would
+ * even be more convenient. However, that would be insufficiently
+ * flexible. If you want to use an iterator range to (e.g.) initialize
+ * a std::vector collecting results -- you rarely want to actually @em
+ * copy the nodes in question. You're much more likely to want to copy
+ * <i>pointers to</i> the traversed nodes. Hence these iterators
+ * produce pointers.
+ *
+ * Though you specify the actual NODE class as the template parameter,
+ * these iterators internally use LLPtrTo<> to discover whether to
+ * store and return an LLPointer<NODE> or a simple NODE*.
+ *
+ * By strict tree structures, we mean that each child must have
+ * exactly one parent. This forbids a child claiming any ancestor as a
+ * child of its own. Child nodes with multiple parents will be visited
+ * once for each parent. Cycles in the graph will result in either an
+ * infinite loop or an out-of-memory crash. You Have Been Warned.
+ *
+ * $LicenseInfo:firstyear=2008&license=viewergpl$
+ *
+ * Copyright (c) 2008-2009, Linden Research, Inc.
+ *
+ * Second Life Viewer Source Code
+ * The source code in this file ("Source Code") is provided by Linden Lab
+ * to you under the terms of the GNU General Public License, version 2.0
+ * ("GPL"), unless you have obtained a separate licensing agreement
+ * ("Other License"), formally executed by you and Linden Lab. Terms of
+ * the GPL can be found in doc/GPL-license.txt in this distribution, or
+ * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
+ *
+ * There are special exceptions to the terms and conditions of the GPL as
+ * it is applied to this Source Code. View the full text of the exception
+ * in the file doc/FLOSS-exception.txt in this software distribution, or
+ * online at
+ * http://secondlifegrid.net/programs/open_source/licensing/flossexception
+ *
+ * By copying, modifying or distributing this software, you acknowledge
+ * that you have read and understood your obligations described above,
+ * and agree to abide by those obligations.
+ *
+ * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
+ * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
+ * COMPLETENESS OR PERFORMANCE.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_LLTREEITERATORS_H)
+#define LL_LLTREEITERATORS_H
+
+#include "llptrto.h"
+#include <vector>
+#include <deque>
+#include <boost/iterator/iterator_facade.hpp>
+#include <boost/function.hpp>
+#include <boost/static_assert.hpp>
+
+namespace LLTreeIter
+{
+ /// Discriminator between LLTreeUpIter and LLTreeDownIter
+ enum RootIter { UP, DOWN };
+ /// Discriminator between LLTreeDFSIter, LLTreeDFSPostIter and LLTreeBFSIter
+ enum WalkIter { DFS_PRE, DFS_POST, BFS };
+}
+
+/**
+ * LLBaseIter defines some machinery common to all these iterators. We use
+ * boost::iterator_facade to define the iterator boilerplate: the conventional
+ * operators and methods necessary to implement a standards-conforming
+ * iterator. That allows us to specify the actual iterator semantics in terms
+ * of equal(), dereference() and increment() methods.
+ */
+template <class SELFTYPE, class NODE>
+class LLBaseIter: public boost::iterator_facade<SELFTYPE,
+ // use pointer type as the
+ // reference type
+ typename LLPtrTo<NODE>::type,
+ boost::forward_traversal_tag>
+{
+protected:
+ /// LLPtrTo<NODE>::type is either NODE* or LLPointer<NODE>, as appropriate
+ typedef typename LLPtrTo<NODE>::type ptr_type;
+ /// function that advances from this node to next accepts a node pointer
+ /// and returns another
+ typedef boost::function<ptr_type(const ptr_type&)> func_type;
+ typedef SELFTYPE self_type;
+};
+
+/// Functor returning NULL, suitable for an end-iterator's 'next' functor
+template <class NODE>
+typename LLPtrTo<NODE>::type LLNullNextFunctor(const typename LLPtrTo<NODE>::type&)
+{
+ return typename LLPtrTo<NODE>::type();
+}
+
+/**
+ * LLLinkedIter is an iterator over an intrusive singly-linked list. The
+ * beginning of the list is represented by LLLinkedIter(list head); the end is
+ * represented by LLLinkedIter().
+ *
+ * The begin LLLinkedIter must be instantiated with a functor to extract the
+ * 'next' pointer from the current node. Supposing that the link pointer is @c
+ * public, something like:
+ *
+ * @code
+ * NODE* mNext;
+ * @endcode
+ *
+ * you can use (e.g.) <tt>boost::bind(&NODE::mNext, _1)</tt> for the purpose.
+ * Alternatively, you can bind whatever accessor method is normally used to
+ * advance to the next node, e.g. for:
+ *
+ * @code
+ * NODE* next() const;
+ * @endcode
+ *
+ * you can use <tt>boost::bind(&NODE::next, _1)</tt>.
+ */
+template <class NODE>
+class LLLinkedIter: public LLBaseIter<LLLinkedIter<NODE>, NODE>
+{
+ typedef LLBaseIter<LLLinkedIter<NODE>, NODE> super;
+protected:
+ /// some methods need to return a reference to self
+ typedef typename super::self_type self_type;
+ typedef typename super::ptr_type ptr_type;
+ typedef typename super::func_type func_type;
+public:
+ /// Instantiate an LLLinkedIter to start a range, or to end a range before
+ /// a particular list entry. Pass a functor to extract the 'next' pointer
+ /// from the current node.
+ LLLinkedIter(const ptr_type& entry, const func_type& nextfunc):
+ mCurrent(entry),
+ mNextFunc(nextfunc)
+ {}
+ /// Instantiate an LLLinkedIter to end a range at the end of the list
+ LLLinkedIter():
+ mCurrent(),
+ mNextFunc(LLNullNextFunctor<NODE>)
+ {}
+
+private:
+ /// leverage boost::iterator_facade
+ friend class boost::iterator_core_access;
+
+ /// advance
+ void increment()
+ {
+ mCurrent = mNextFunc(mCurrent);
+ }
+ /// equality
+ bool equal(const self_type& that) const { return this->mCurrent == that.mCurrent; }
+ /// dereference
+ ptr_type& dereference() const { return const_cast<ptr_type&>(mCurrent); }
+
+ ptr_type mCurrent;
+ func_type mNextFunc;
+};
+
+/**
+ * LLTreeUpIter walks from the node in hand to the root of the tree. The term
+ * "up" is applied to a tree visualized with the root at the top.
+ *
+ * LLTreeUpIter is an alias for LLLinkedIter, since any linked tree that you
+ * can navigate that way at all contains parent pointers.
+ */
+template <class NODE>
+class LLTreeUpIter: public LLLinkedIter<NODE>
+{
+ typedef LLLinkedIter<NODE> super;
+public:
+ /// Instantiate an LLTreeUpIter to start from a particular tree node, or
+ /// to end a parent traversal before reaching a particular ancestor. Pass
+ /// a functor to extract the 'parent' pointer from the current node.
+ LLTreeUpIter(const typename super::ptr_type& node,
+ const typename super::func_type& parentfunc):
+ super(node, parentfunc)
+ {}
+ /// Instantiate an LLTreeUpIter to end a range at the root of the tree
+ LLTreeUpIter():
+ super()
+ {}
+};
+
+/**
+ * LLTreeDownIter walks from the root of the tree to the node in hand. The
+ * term "down" is applied to a tree visualized with the root at the top.
+ *
+ * Though you instantiate the begin() LLTreeDownIter with a pointer to some
+ * node at an arbitrary location in the tree, the root will be the first node
+ * you dereference and the passed node will be the last node you dereference.
+ *
+ * On construction, LLTreeDownIter walks from the current node to the root,
+ * capturing the path. Then in use, it replays that walk in reverse. As with
+ * all traversals of interesting data structures, it is actively dangerous to
+ * modify the tree during an LLTreeDownIter walk.
+ */
+template <class NODE>
+class LLTreeDownIter: public LLBaseIter<LLTreeDownIter<NODE>, NODE>
+{
+ typedef LLBaseIter<LLTreeDownIter<NODE>, NODE> super;
+ typedef typename super::self_type self_type;
+protected:
+ typedef typename super::ptr_type ptr_type;
+ typedef typename super::func_type func_type;
+private:
+ typedef std::vector<ptr_type> list_type;
+public:
+ /// Instantiate an LLTreeDownIter to end at a particular tree node. Pass a
+ /// functor to extract the 'parent' pointer from the current node.
+ LLTreeDownIter(const ptr_type& node,
+ const func_type& parentfunc)
+ {
+ for (ptr_type n = node; n; n = parentfunc(n))
+ mParents.push_back(n);
+ }
+ /// Instantiate an LLTreeDownIter representing "here", the end of the loop
+ LLTreeDownIter() {}
+
+private:
+ /// leverage boost::iterator_facade
+ friend class boost::iterator_core_access;
+
+ /// advance
+ void increment()
+ {
+ mParents.pop_back();
+ }
+ /// equality
+ bool equal(const self_type& that) const { return this->mParents == that.mParents; }
+ /// implement dereference/indirection operators
+ ptr_type& dereference() const { return const_cast<ptr_type&>(mParents.back()); }
+
+ list_type mParents;
+};
+
+/**
+ * When you want to select between LLTreeUpIter and LLTreeDownIter with a
+ * compile-time discriminator, use LLTreeRootIter with an LLTreeIter::RootIter
+ * template arg.
+ */
+template <LLTreeIter::RootIter DISCRIM, class NODE>
+class LLTreeRootIter
+{
+ enum { use_a_valid_LLTreeIter_RootIter_value = false };
+public:
+ /// Bogus constructors for default (unrecognized discriminator) case
+ template <typename TYPE1, typename TYPE2>
+ LLTreeRootIter(TYPE1, TYPE2)
+ {
+ BOOST_STATIC_ASSERT(use_a_valid_LLTreeIter_RootIter_value);
+ }
+ LLTreeRootIter()
+ {
+ BOOST_STATIC_ASSERT(use_a_valid_LLTreeIter_RootIter_value);
+ }
+};
+
+/// Specialize for LLTreeIter::UP
+template <class NODE>
+class LLTreeRootIter<LLTreeIter::UP, NODE>: public LLTreeUpIter<NODE>
+{
+ typedef LLTreeUpIter<NODE> super;
+public:
+ /// forward begin ctor
+ LLTreeRootIter(const typename super::ptr_type& node,
+ const typename super::func_type& parentfunc):
+ super(node, parentfunc)
+ {}
+ /// forward end ctor
+ LLTreeRootIter():
+ super()
+ {}
+};
+
+/// Specialize for LLTreeIter::DOWN
+template <class NODE>
+class LLTreeRootIter<LLTreeIter::DOWN, NODE>: public LLTreeDownIter<NODE>
+{
+ typedef LLTreeDownIter<NODE> super;
+public:
+ /// forward begin ctor
+ LLTreeRootIter(const typename super::ptr_type& node,
+ const typename super::func_type& parentfunc):
+ super(node, parentfunc)
+ {}
+ /// forward end ctor
+ LLTreeRootIter():
+ super()
+ {}
+};
+
+/**
+ * Instantiated with a tree node, typically the root, LLTreeDFSIter "flattens"
+ * a depth-first tree walk through that node and all its descendants.
+ *
+ * The begin() LLTreeDFSIter must be instantiated with functors to obtain from
+ * a given node begin() and end() iterators for that node's children. For this
+ * reason, you must specify the type of the node's child iterator as an
+ * additional template parameter.
+ *
+ * Specifically, the begin functor must return an iterator whose dereferenced
+ * value is a @em pointer to a child tree node. For instance, if each node
+ * tracks its children in an STL container of node* pointers, you can simply
+ * return that container's begin() iterator.
+ *
+ * Alternatively, if a node tracks its children with a classic linked list,
+ * write a functor returning LLLinkedIter<NODE>.
+ *
+ * The end() LLTreeDFSIter must, of course, match the begin() iterator's
+ * template parameters, but is constructed without runtime parameters.
+ */
+template <class NODE, typename CHILDITER>
+class LLTreeDFSIter: public LLBaseIter<LLTreeDFSIter<NODE, CHILDITER>, NODE>
+{
+ typedef LLBaseIter<LLTreeDFSIter<NODE, CHILDITER>, NODE> super;
+ typedef typename super::self_type self_type;
+protected:
+ typedef typename super::ptr_type ptr_type;
+ // The func_type is different for this: from a NODE pointer, we must
+ // obtain a CHILDITER.
+ typedef boost::function<CHILDITER(const ptr_type&)> func_type;
+private:
+ typedef std::vector<ptr_type> list_type;
+public:
+ /// Instantiate an LLTreeDFSIter to start a depth-first walk. Pass
+ /// functors to extract the 'child begin' and 'child end' iterators from
+ /// each node.
+ LLTreeDFSIter(const ptr_type& node, const func_type& beginfunc, const func_type& endfunc):
+ mBeginFunc(beginfunc),
+ mEndFunc(endfunc),
+ mSkipChildren(false)
+ {
+ // Only push back this node if it's non-NULL!
+ if (node)
+ mPending.push_back(node);
+ }
+ /// Instantiate an LLTreeDFSIter to mark the end of the walk
+ LLTreeDFSIter() {}
+
+ /// flags iterator logic to skip traversing children of current node on next increment
+ void skipChildren(bool skip = true) { mSkipChildren = skip; }
+
+private:
+ /// leverage boost::iterator_facade
+ friend class boost::iterator_core_access;
+
+ /// advance
+ /// This implementation is due to http://en.wikipedia.org/wiki/Depth-first_search
+ void increment()
+ {
+ // Capture the node we were just looking at
+ ptr_type current = mPending.back();
+ // Remove it from mPending so we don't process it again later
+ mPending.pop_back();
+ if (!mSkipChildren)
+ {
+ // Add all its children to mPending
+ addChildren(current);
+ }
+ // reset flag after each step
+ mSkipChildren = false;
+ }
+ /// equality
+ bool equal(const self_type& that) const { return this->mPending == that.mPending; }
+ /// implement dereference/indirection operators
+ ptr_type& dereference() const { return const_cast<ptr_type&>(mPending.back()); }
+
+ /// Add the direct children of the specified node to mPending
+ void addChildren(const ptr_type& node)
+ {
+ // If we just use push_back() for each child in turn, we'll end up
+ // processing children in reverse order. We don't want to assume
+ // CHILDITER is reversible: some of the linked trees we'll be
+ // processing manage their children using singly-linked lists. So
+ // figure out how many children there are, grow mPending by that size
+ // and reverse-copy the children into the new space.
+ CHILDITER chi = mBeginFunc(node), chend = mEndFunc(node);
+ // grow mPending by the number of children
+ mPending.resize(mPending.size() + std::distance(chi, chend));
+ // reverse-copy the children into the newly-expanded space
+ std::copy(chi, chend, mPending.rbegin());
+ }
+
+ /// list of the nodes yet to be processed
+ list_type mPending;
+ /// functor to extract begin() child iterator
+ func_type mBeginFunc;
+ /// functor to extract end() child iterator
+ func_type mEndFunc;
+ /// flag which controls traversal of children (skip children of current node if true)
+ bool mSkipChildren;
+};
+
+/**
+ * Instantiated with a tree node, typically the root, LLTreeDFSPostIter
+ * "flattens" a depth-first tree walk through that node and all its
+ * descendants. Whereas LLTreeDFSIter visits each node before visiting any of
+ * its children, LLTreeDFSPostIter visits all of a node's children before
+ * visiting the node itself.
+ *
+ * The begin() LLTreeDFSPostIter must be instantiated with functors to obtain
+ * from a given node begin() and end() iterators for that node's children. For
+ * this reason, you must specify the type of the node's child iterator as an
+ * additional template parameter.
+ *
+ * Specifically, the begin functor must return an iterator whose dereferenced
+ * value is a @em pointer to a child tree node. For instance, if each node
+ * tracks its children in an STL container of node* pointers, you can simply
+ * return that container's begin() iterator.
+ *
+ * Alternatively, if a node tracks its children with a classic linked list,
+ * write a functor returning LLLinkedIter<NODE>.
+ *
+ * The end() LLTreeDFSPostIter must, of course, match the begin() iterator's
+ * template parameters, but is constructed without runtime parameters.
+ */
+template <class NODE, typename CHILDITER>
+class LLTreeDFSPostIter: public LLBaseIter<LLTreeDFSPostIter<NODE, CHILDITER>, NODE>
+{
+ typedef LLBaseIter<LLTreeDFSPostIter<NODE, CHILDITER>, NODE> super;
+ typedef typename super::self_type self_type;
+protected:
+ typedef typename super::ptr_type ptr_type;
+ // The func_type is different for this: from a NODE pointer, we must
+ // obtain a CHILDITER.
+ typedef boost::function<CHILDITER(const ptr_type&)> func_type;
+private:
+ // Upon reaching a given node in our pending list, we need to know whether
+ // we've already pushed that node's children, so we must associate a bool
+ // with each node pointer.
+ typedef std::vector< std::pair<ptr_type, bool> > list_type;
+public:
+ /// Instantiate an LLTreeDFSPostIter to start a depth-first walk. Pass
+ /// functors to extract the 'child begin' and 'child end' iterators from
+ /// each node.
+ LLTreeDFSPostIter(const ptr_type& node, const func_type& beginfunc, const func_type& endfunc):
+ mBeginFunc(beginfunc),
+ mEndFunc(endfunc)
+ {
+ if (! node)
+ return;
+ mPending.push_back(typename list_type::value_type(node, false));
+ makeCurrent();
+ }
+ /// Instantiate an LLTreeDFSPostIter to mark the end of the walk
+ LLTreeDFSPostIter() {}
+
+private:
+ /// leverage boost::iterator_facade
+ friend class boost::iterator_core_access;
+
+ /// advance
+ /// This implementation is due to http://en.wikipedia.org/wiki/Depth-first_search
+ void increment()
+ {
+ // Pop the previous current node
+ mPending.pop_back();
+ makeCurrent();
+ }
+ /// equality
+ bool equal(const self_type& that) const { return this->mPending == that.mPending; }
+ /// implement dereference/indirection operators
+ ptr_type& dereference() const { return const_cast<ptr_type&>(mPending.back().first); }
+
+ /// Call this each time we change mPending.back() -- that is, every time
+ /// we're about to change the value returned by dereference(). If we
+ /// haven't yet pushed the new node's children, do so now.
+ void makeCurrent()
+ {
+ // Once we've popped the last node, this becomes a no-op.
+ if (mPending.empty())
+ return;
+ // Here mPending.back() holds the node pointer we're proposing to
+ // dereference next. Have we pushed that node's children yet?
+ if (mPending.back().second)
+ return; // if so, it's okay to visit this node now
+ // We haven't yet pushed this node's children. Do so now. Remember
+ // that we did -- while the node in question is still back().
+ mPending.back().second = true;
+ addChildren(mPending.back().first);
+ // Now, because we've just changed mPending.back(), make that new node
+ // current.
+ makeCurrent();
+ }
+
+ /// Add the direct children of the specified node to mPending
+ void addChildren(const ptr_type& node)
+ {
+ // If we just use push_back() for each child in turn, we'll end up
+ // processing children in reverse order. We don't want to assume
+ // CHILDITER is reversible: some of the linked trees we'll be
+ // processing manage their children using singly-linked lists. So
+ // figure out how many children there are, grow mPending by that size
+ // and reverse-copy the children into the new space.
+ CHILDITER chi = mBeginFunc(node), chend = mEndFunc(node);
+ // grow mPending by the number of children
+ mPending.resize(mPending.size() + std::distance(chi, chend));
+ // Reverse-copy the children into the newly-expanded space. We can't
+ // just use std::copy() because the source is a ptr_type, whereas the
+ // dest is a pair of (ptr_type, bool).
+ for (typename list_type::reverse_iterator pi = mPending.rbegin(); chi != chend; ++chi, ++pi)
+ {
+ pi->first = *chi; // copy the child pointer
+ pi->second = false; // we haven't yet pushed this child's chldren
+ }
+ }
+
+ /// list of the nodes yet to be processed
+ list_type mPending;
+ /// functor to extract begin() child iterator
+ func_type mBeginFunc;
+ /// functor to extract end() child iterator
+ func_type mEndFunc;
+};
+
+/**
+ * Instantiated with a tree node, typically the root, LLTreeBFSIter "flattens"
+ * a breadth-first tree walk through that node and all its descendants.
+ *
+ * The begin() LLTreeBFSIter must be instantiated with functors to obtain from
+ * a given node the begin() and end() iterators of that node's children. For
+ * this reason, you must specify the type of the node's child iterator as an
+ * additional template parameter.
+ *
+ * Specifically, the begin functor must return an iterator whose dereferenced
+ * value is a @em pointer to a child tree node. For instance, if each node
+ * tracks its children in an STL container of node* pointers, you can simply
+ * return that container's begin() iterator.
+ *
+ * Alternatively, if a node tracks its children with a classic linked list,
+ * write a functor returning LLLinkedIter<NODE>.
+ *
+ * The end() LLTreeBFSIter must, of course, match the begin() iterator's
+ * template parameters, but is constructed without runtime parameters.
+ */
+template <class NODE, typename CHILDITER>
+class LLTreeBFSIter: public LLBaseIter<LLTreeBFSIter<NODE, CHILDITER>, NODE>
+{
+ typedef LLBaseIter<LLTreeBFSIter<NODE, CHILDITER>, NODE> super;
+ typedef typename super::self_type self_type;
+protected:
+ typedef typename super::ptr_type ptr_type;
+ // The func_type is different for this: from a NODE pointer, we must
+ // obtain a CHILDITER.
+ typedef boost::function<CHILDITER(const ptr_type&)> func_type;
+private:
+ // We need a FIFO queue rather than a LIFO stack. Use a deque rather than
+ // a vector, since vector can't implement pop_front() efficiently.
+ typedef std::deque<ptr_type> list_type;
+public:
+ /// Instantiate an LLTreeBFSIter to start a depth-first walk. Pass
+ /// functors to extract the 'child begin' and 'child end' iterators from
+ /// each node.
+ LLTreeBFSIter(const ptr_type& node, const func_type& beginfunc, const func_type& endfunc):
+ mBeginFunc(beginfunc),
+ mEndFunc(endfunc)
+ {
+ if (node)
+ mPending.push_back(node);
+ }
+ /// Instantiate an LLTreeBFSIter to mark the end of the walk
+ LLTreeBFSIter() {}
+
+private:
+ /// leverage boost::iterator_facade
+ friend class boost::iterator_core_access;
+
+ /// advance
+ /// This implementation is due to http://en.wikipedia.org/wiki/Breadth-first_search
+ void increment()
+ {
+ // Capture the node we were just looking at
+ ptr_type current = mPending.front();
+ // Remove it from mPending so we don't process it again later
+ mPending.pop_front();
+ // Add all its children to mPending
+ CHILDITER chend = mEndFunc(current);
+ for (CHILDITER chi = mBeginFunc(current); chi != chend; ++chi)
+ mPending.push_back(*chi);
+ }
+ /// equality
+ bool equal(const self_type& that) const { return this->mPending == that.mPending; }
+ /// implement dereference/indirection operators
+ ptr_type& dereference() const { return const_cast<ptr_type&>(mPending.front()); }
+
+ /// list of the nodes yet to be processed
+ list_type mPending;
+ /// functor to extract begin() child iterator
+ func_type mBeginFunc;
+ /// functor to extract end() child iterator
+ func_type mEndFunc;
+};
+
+/**
+ * When you want to select between LLTreeDFSIter, LLTreeDFSPostIter and
+ * LLTreeBFSIter with a compile-time discriminator, use LLTreeWalkIter with an
+ * LLTreeIter::WalkIter template arg.
+ */
+template <LLTreeIter::WalkIter DISCRIM, class NODE, typename CHILDITER>
+class LLTreeWalkIter
+{
+ enum { use_a_valid_LLTreeIter_WalkIter_value = false };
+public:
+ /// Bogus constructors for default (unrecognized discriminator) case
+ template <typename TYPE1, typename TYPE2>
+ LLTreeWalkIter(TYPE1, TYPE2)
+ {
+ BOOST_STATIC_ASSERT(use_a_valid_LLTreeIter_WalkIter_value);
+ }
+ LLTreeWalkIter()
+ {
+ BOOST_STATIC_ASSERT(use_a_valid_LLTreeIter_WalkIter_value);
+ }
+};
+
+/// Specialize for LLTreeIter::DFS_PRE
+template <class NODE, typename CHILDITER>
+class LLTreeWalkIter<LLTreeIter::DFS_PRE, NODE, CHILDITER>:
+ public LLTreeDFSIter<NODE, CHILDITER>
+{
+ typedef LLTreeDFSIter<NODE, CHILDITER> super;
+public:
+ /// forward begin ctor
+ LLTreeWalkIter(const typename super::ptr_type& node,
+ const typename super::func_type& beginfunc,
+ const typename super::func_type& endfunc):
+ super(node, beginfunc, endfunc)
+ {}
+ /// forward end ctor
+ LLTreeWalkIter():
+ super()
+ {}
+};
+
+/// Specialize for LLTreeIter::DFS_POST
+template <class NODE, typename CHILDITER>
+class LLTreeWalkIter<LLTreeIter::DFS_POST, NODE, CHILDITER>:
+ public LLTreeDFSPostIter<NODE, CHILDITER>
+{
+ typedef LLTreeDFSPostIter<NODE, CHILDITER> super;
+public:
+ /// forward begin ctor
+ LLTreeWalkIter(const typename super::ptr_type& node,
+ const typename super::func_type& beginfunc,
+ const typename super::func_type& endfunc):
+ super(node, beginfunc, endfunc)
+ {}
+ /// forward end ctor
+ LLTreeWalkIter():
+ super()
+ {}
+};
+
+/// Specialize for LLTreeIter::BFS
+template <class NODE, typename CHILDITER>
+class LLTreeWalkIter<LLTreeIter::BFS, NODE, CHILDITER>:
+ public LLTreeBFSIter<NODE, CHILDITER>
+{
+ typedef LLTreeBFSIter<NODE, CHILDITER> super;
+public:
+ /// forward begin ctor
+ LLTreeWalkIter(const typename super::ptr_type& node,
+ const typename super::func_type& beginfunc,
+ const typename super::func_type& endfunc):
+ super(node, beginfunc, endfunc)
+ {}
+ /// forward end ctor
+ LLTreeWalkIter():
+ super()
+ {}
+};
+
+#endif /* ! defined(LL_LLTREEITERATORS_H) */