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gtsam/gtsam/base/treeTraversal-inst.h

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/* ----------------------------------------------------------------------------
* GTSAM Copyright 2010, Georgia Tech Research Corporation,
* Atlanta, Georgia 30332-0415
* All Rights Reserved
* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
* See LICENSE for the license information
* -------------------------------------------------------------------------- */
/**
* @file treeTraversal-inst.h
* @author Richard Roberts
* @date April 9, 2013
*/
#pragma once
#include <gtsam/base/treeTraversal/parallelTraversalTasks.h>
#include <gtsam/base/treeTraversal/statistics.h>
#include <gtsam/base/FastList.h>
#include <gtsam/base/FastVector.h>
#include <gtsam/inference/Key.h>
#include <gtsam/config.h> // for GTSAM_USE_TBB
#include <stack>
#include <vector>
#include <string>
#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>
#include <boost/foreach.hpp>
#include <boost/bind.hpp>
namespace gtsam {
/** Internal functions used for traversing trees */
namespace treeTraversal {
/* ************************************************************************* */
namespace {
// Internal node used in DFS preorder stack
template<typename NODE, typename DATA>
struct TraversalNode {
bool expanded;
const boost::shared_ptr<NODE>& treeNode;
DATA& parentData;
typename FastList<DATA>::iterator dataPointer;
TraversalNode(const boost::shared_ptr<NODE>& _treeNode, DATA& _parentData) :
expanded(false), treeNode(_treeNode), parentData(_parentData) {}
};
// Do nothing - default argument for post-visitor for tree traversal
struct no_op {
template<typename NODE, typename DATA>
void operator()(const boost::shared_ptr<NODE>& node, const DATA& data) {}
};
}
/** Traverse a forest depth-first with pre-order and post-order visits.
* @param forest The forest of trees to traverse. The method \c forest.roots() should exist
* and return a collection of (shared) pointers to \c FOREST::Node.
* @param visitorPre \c visitorPre(node, parentData) will be called at every node, before
* visiting its children, and will be passed, by reference, the \c DATA object returned
* by the visit to its parent. Likewise, \c visitorPre should return the \c DATA object
* to pass to the children. The returned \c DATA object will be copy-constructed only
* upon returning to store internally, thus may be modified by visiting the children.
* Regarding efficiency, this copy-on-return is usually optimized out by the compiler.
* @param visitorPost \c visitorPost(node, data) will be called at every node, after visiting
* its children, and will be passed, by reference, the \c DATA object returned by the
* call to \c visitorPre (the \c DATA object may be modified by visiting the children).
* @param rootData The data to pass by reference to \c visitorPre when it is called on each
* root node. */
template<class FOREST, typename DATA, typename VISITOR_PRE, typename VISITOR_POST>
void DepthFirstForest(FOREST& forest, DATA& rootData, VISITOR_PRE& visitorPre, VISITOR_POST& visitorPost)
{
// Typedefs
typedef typename FOREST::Node Node;
typedef boost::shared_ptr<Node> sharedNode;
// Depth first traversal stack
typedef TraversalNode<typename FOREST::Node, DATA> TraversalNode;
typedef FastList<TraversalNode> Stack;
Stack stack;
FastList<DATA> dataList; // List to store node data as it is returned from the pre-order visitor
// Add roots to stack (insert such that they are visited and processed in order
{
typename Stack::iterator insertLocation = stack.begin();
BOOST_FOREACH(const sharedNode& root, forest.roots())
stack.insert(insertLocation, TraversalNode(root, rootData));
}
// Traverse
while(!stack.empty())
{
// Get next node
TraversalNode& node = stack.front();
if(node.expanded) {
// If already expanded, then the data stored in the node is no longer needed, so visit
// then delete it.
(void) visitorPost(node.treeNode, *node.dataPointer);
dataList.erase(node.dataPointer);
stack.pop_front();
} else {
// If not already visited, visit the node and add its children (use reverse iterators so
// children are processed in the order they appear)
node.dataPointer = dataList.insert(dataList.end(), visitorPre(node.treeNode, node.parentData));
typename Stack::iterator insertLocation = stack.begin();
BOOST_FOREACH(const sharedNode& child, node.treeNode->children)
stack.insert(insertLocation, TraversalNode(child, *node.dataPointer));
node.expanded = true;
}
}
assert(dataList.empty());
}
/** Traverse a forest depth-first, with a pre-order visit but no post-order visit.
* @param forest The forest of trees to traverse. The method \c forest.roots() should exist
* and return a collection of (shared) pointers to \c FOREST::Node.
* @param visitorPre \c visitorPre(node, parentData) will be called at every node, before
* visiting its children, and will be passed, by reference, the \c DATA object returned
* by the visit to its parent. Likewise, \c visitorPre should return the \c DATA object
* to pass to the children. The returned \c DATA object will be copy-constructed only
* upon returning to store internally, thus may be modified by visiting the children.
* Regarding efficiency, this copy-on-return is usually optimized out by the compiler.
* @param rootData The data to pass by reference to \c visitorPre when it is called on each
* root node. */
template<class FOREST, typename DATA, typename VISITOR_PRE>
void DepthFirstForest(FOREST& forest, DATA& rootData, VISITOR_PRE& visitorPre)
{
no_op visitorPost;
DepthFirstForest(forest, rootData, visitorPre, visitorPost);
}
/** Traverse a forest depth-first with pre-order and post-order visits.
* @param forest The forest of trees to traverse. The method \c forest.roots() should exist
* and return a collection of (shared) pointers to \c FOREST::Node.
* @param visitorPre \c visitorPre(node, parentData) will be called at every node, before
* visiting its children, and will be passed, by reference, the \c DATA object returned
* by the visit to its parent. Likewise, \c visitorPre should return the \c DATA object
* to pass to the children. The returned \c DATA object will be copy-constructed only
* upon returning to store internally, thus may be modified by visiting the children.
* Regarding efficiency, this copy-on-return is usually optimized out by the compiler.
* @param visitorPost \c visitorPost(node, data) will be called at every node, after visiting
* its children, and will be passed, by reference, the \c DATA object returned by the
* call to \c visitorPre (the \c DATA object may be modified by visiting the children).
* @param rootData The data to pass by reference to \c visitorPre when it is called on each
* root node. */
template<class FOREST, typename DATA, typename VISITOR_PRE, typename VISITOR_POST>
void DepthFirstForestParallel(FOREST& forest, DATA& rootData, VISITOR_PRE& visitorPre, VISITOR_POST& visitorPost,
int problemSizeThreshold = 10)
{
#ifdef GTSAM_USE_TBB
// Typedefs
typedef typename FOREST::Node Node;
typedef boost::shared_ptr<Node> sharedNode;
tbb::task::spawn_root_and_wait(internal::CreateRootTask<Node>(
forest.roots(), rootData, visitorPre, visitorPost, problemSizeThreshold));
#else
DepthFirstForest(forest, rootData, visitorPre, visitorPost);
#endif
}
/* ************************************************************************* */
/** Traversal function for CloneForest */
namespace {
template<typename NODE>
boost::shared_ptr<NODE>
CloneForestVisitorPre(const boost::shared_ptr<NODE>& node, const boost::shared_ptr<NODE>& parentPointer)
{
// Clone the current node and add it to its cloned parent
boost::shared_ptr<NODE> clone = boost::make_shared<NODE>(*node);
clone->children.clear();
parentPointer->children.push_back(clone);
return clone;
}
}
/** Clone a tree, copy-constructing new nodes (calling boost::make_shared) and setting up child
* pointers for a clone of the original tree.
* @param forest The forest of trees to clone. The method \c forest.roots() should exist and
* return a collection of shared pointers to \c FOREST::Node.
* @return The new collection of roots. */
template<class FOREST>
FastVector<boost::shared_ptr<typename FOREST::Node> > CloneForest(const FOREST& forest)
{
typedef typename FOREST::Node Node;
boost::shared_ptr<Node> rootContainer = boost::make_shared<Node>();
DepthFirstForest(forest, rootContainer, CloneForestVisitorPre<Node>);
return FastVector<boost::shared_ptr<Node> >(rootContainer->children.begin(), rootContainer->children.end());
}
/* ************************************************************************* */
/** Traversal function for PrintForest */
namespace {
struct PrintForestVisitorPre
{
const KeyFormatter& formatter;
PrintForestVisitorPre(const KeyFormatter& formatter) : formatter(formatter) {}
template<typename NODE> std::string operator()(const boost::shared_ptr<NODE>& node, const std::string& parentString)
{
// Print the current node
node->print(parentString + "-", formatter);
// Increment the indentation
return parentString + "| ";
}
};
}
/** Print a tree, prefixing each line with \c str, and formatting keys using \c keyFormatter.
* To print each node, this function calls the \c print function of the tree nodes. */
template<class FOREST>
void PrintForest(const FOREST& forest, std::string str, const KeyFormatter& keyFormatter) {
PrintForestVisitorPre visitor(keyFormatter);
DepthFirstForest(forest, str, visitor);
}
}
}
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