dlib C++ Library - find_max_parse_cky.h

// Copyright (C) 2012 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_FIND_MAX_PaRSE_CKY_Hh_
#define DLIB_FIND_MAX_PaRSE_CKY_Hh_
#include "find_max_parse_cky_abstract.h"
#include <vector>
#include <string>
#include <sstream>
#include "../serialize.h" 
#include "../array2d.h"
namespace dlib
{
// -----------------------------------------------------------------------------------------
 template <typename T>
 struct constituent 
 {
 unsigned long begin, end, k;
 T left_tag; 
 T right_tag;
 };
 template <typename T>
 void serialize(
 const constituent<T>& item,
 std::ostream& out
 )
 {
 serialize(item.begin, out);
 serialize(item.end, out);
 serialize(item.k, out);
 serialize(item.left_tag, out);
 serialize(item.right_tag, out);
 }
 template <typename T>
 void deserialize(
 constituent<T>& item,
 std::istream& in 
 )
 {
 deserialize(item.begin, in);
 deserialize(item.end, in);
 deserialize(item.k, in);
 deserialize(item.left_tag, in);
 deserialize(item.right_tag, in);
 }
// -----------------------------------------------------------------------------------------
 const unsigned long END_OF_TREE = 0xFFFFFFFF;
// -----------------------------------------------------------------------------------------
 template <typename T>
 struct parse_tree_element
 {
 constituent<T> c;
 T tag; // id for the constituent corresponding to this level of the tree
 unsigned long left;
 unsigned long right; 
 double score; 
 };
 template <typename T>
 void serialize (
 const parse_tree_element<T>& item,
 std::ostream& out
 )
 {
 serialize(item.c, out);
 serialize(item.tag, out);
 serialize(item.left, out);
 serialize(item.right, out);
 serialize(item.score, out);
 }
 template <typename T>
 void deserialize (
 parse_tree_element<T>& item,
 std::istream& in 
 )
 {
 deserialize(item.c, in);
 deserialize(item.tag, in);
 deserialize(item.left, in);
 deserialize(item.right, in);
 deserialize(item.score, in);
 }
// -----------------------------------------------------------------------------------------
 namespace impl
 {
 template <typename T>
 unsigned long fill_parse_tree(
 std::vector<parse_tree_element<T> >& parse_tree, 
 const T& tag,
 const array2d<std::map<T, parse_tree_element<T> > >& back, 
 long r, long c
 )
 /*!
 requires
 - back[r][c].size() == 0 || back[r][c].count(tag) != 0
 !*/
 {
 // base case of the recursion 
 if (back[r][c].size() == 0)
 {
 return END_OF_TREE;
 }
 const unsigned long idx = parse_tree.size();
 const parse_tree_element<T>& item = back[r][c].find(tag)->second;
 parse_tree.push_back(item);
 const long k = item.c.k;
 const unsigned long idx_left = fill_parse_tree(parse_tree, item.c.left_tag, back, r, k-1); 
 const unsigned long idx_right = fill_parse_tree(parse_tree, item.c.right_tag, back, k, c); 
 parse_tree[idx].left = idx_left;
 parse_tree[idx].right = idx_right;
 return idx;
 }
 }
 template <typename T, typename production_rule_function>
 void find_max_parse_cky (
 const std::vector<T>& sequence,
 const production_rule_function& production_rules,
 std::vector<parse_tree_element<T> >& parse_tree
 )
 {
 parse_tree.clear();
 if (sequence.size() == 0)
 return;
 array2d<std::map<T,double> > table(sequence.size(), sequence.size());
 array2d<std::map<T,parse_tree_element<T> > > back(sequence.size(), sequence.size());
 typedef typename std::map<T,double>::iterator itr;
 typedef typename std::map<T,parse_tree_element<T> >::iterator itr_b;
 for (long r = 0; r < table.nr(); ++r)
 table[r][r][sequence[r]] = 0;
 std::vector<std::pair<T,double> > possible_tags;
 for (long r = table.nr()-2; r >= 0; --r)
 {
 for (long c = r+1; c < table.nc(); ++c)
 {
 for (long k = r; k < c; ++k)
 {
 for (itr i = table[k+1][c].begin(); i != table[k+1][c].end(); ++i)
 {
 for (itr j = table[r][k].begin(); j != table[r][k].end(); ++j)
 {
 constituent<T> con;
 con.begin = r;
 con.end = c+1;
 con.k = k+1;
 con.left_tag = j->first;
 con.right_tag = i->first;
 possible_tags.clear();
 production_rules(sequence, con, possible_tags);
 for (unsigned long m = 0; m < possible_tags.size(); ++m)
 {
 const double score = possible_tags[m].second + i->second + j->second;
 itr match = table[r][c].find(possible_tags[m].first);
 if (match == table[r][c].end() || score > match->second)
 {
 table[r][c][possible_tags[m].first] = score;
 parse_tree_element<T> item;
 item.c = con;
 item.score = score;
 item.tag = possible_tags[m].first;
 item.left = END_OF_TREE;
 item.right = END_OF_TREE;
 back[r][c][possible_tags[m].first] = item;
 }
 }
 }
 }
 }
 }
 }
 // now use back pointers to build the parse trees
 const long r = 0;
 const long c = back.nc()-1;
 if (back[r][c].size() != 0)
 {
 // find the max scoring element in back[r][c]
 itr_b max_i = back[r][c].begin();
 itr_b i = max_i;
 ++i;
 for (; i != back[r][c].end(); ++i)
 {
 if (i->second.score > max_i->second.score)
 max_i = i;
 }
 parse_tree.reserve(c);
 impl::fill_parse_tree(parse_tree, max_i->second.tag, back, r, c);
 }
 }
// -----------------------------------------------------------------------------------------
 class parse_tree_to_string_error : public error
 {
 public:
 parse_tree_to_string_error(const std::string& str): error(str) {}
 };
 namespace impl
 {
 template <bool enabled, typename T>
 typename enable_if_c<enabled>::type conditional_print(
 const T& item,
 std::ostream& out
 ) { out << item << " "; }
 template <bool enabled, typename T>
 typename disable_if_c<enabled>::type conditional_print(
 const T& ,
 std::ostream& 
 ) { }
 template <bool print_tag, bool skip_tag, typename T, typename U >
 void print_parse_tree_helper (
 const std::vector<parse_tree_element<T> >& tree,
 const std::vector<U>& words,
 unsigned long i,
 const T& tag_to_skip,
 std::ostream& out
 )
 {
 if (!skip_tag || tree[i].tag != tag_to_skip)
 out << "[";
 bool left_recurse = false;
 // Only print if we are supposed to. Doing it this funny way avoids compiler
 // errors in parse_tree_to_string() for the case where tag isn't
 // printable.
 if (!skip_tag || tree[i].tag != tag_to_skip)
 conditional_print<print_tag>(tree[i].tag, out);
 if (tree[i].left < tree.size())
 {
 left_recurse = true;
 print_parse_tree_helper<print_tag,skip_tag>(tree, words, tree[i].left, tag_to_skip, out);
 }
 else
 {
 if ((tree[i].c.begin) < words.size())
 {
 out << words[tree[i].c.begin] << " ";
 }
 else
 {
 std::ostringstream sout;
 sout << "Parse tree refers to element " << tree[i].c.begin 
 << " of sequence which is only of size " << words.size() << ".";
 throw parse_tree_to_string_error(sout.str());
 }
 }
 if (left_recurse == true)
 out << " ";
 if (tree[i].right < tree.size())
 {
 print_parse_tree_helper<print_tag,skip_tag>(tree, words, tree[i].right, tag_to_skip, out);
 }
 else
 {
 if (tree[i].c.k < words.size())
 {
 out << words[tree[i].c.k];
 }
 else
 {
 std::ostringstream sout;
 sout << "Parse tree refers to element " << tree[i].c.k 
 << " of sequence which is only of size " << words.size() << ".";
 throw parse_tree_to_string_error(sout.str());
 }
 }
 if (!skip_tag || tree[i].tag != tag_to_skip)
 out << "]";
 }
 }
// -----------------------------------------------------------------------------------------
 template <typename T, typename U>
 std::string parse_tree_to_string (
 const std::vector<parse_tree_element<T> >& tree,
 const std::vector<U>& words,
 const unsigned long root_idx = 0
 )
 {
 if (root_idx >= tree.size())
 return "";
 std::ostringstream sout;
 impl::print_parse_tree_helper<false,false>(tree, words, root_idx, tree[root_idx].tag, sout);
 return sout.str();
 }
// -----------------------------------------------------------------------------------------
 template <typename T, typename U>
 std::string parse_tree_to_string_tagged (
 const std::vector<parse_tree_element<T> >& tree,
 const std::vector<U>& words,
 const unsigned long root_idx = 0
 )
 {
 if (root_idx >= tree.size())
 return "";
 std::ostringstream sout;
 impl::print_parse_tree_helper<true,false>(tree, words, root_idx, tree[root_idx].tag, sout);
 return sout.str();
 }
// -----------------------------------------------------------------------------------------
 template <typename T, typename U>
 std::string parse_trees_to_string (
 const std::vector<parse_tree_element<T> >& tree,
 const std::vector<U>& words,
 const T& tag_to_skip
 )
 {
 if (tree.size() == 0)
 return "";
 std::ostringstream sout;
 impl::print_parse_tree_helper<false,true>(tree, words, 0, tag_to_skip, sout);
 return sout.str();
 }
// -----------------------------------------------------------------------------------------
 template <typename T, typename U>
 std::string parse_trees_to_string_tagged (
 const std::vector<parse_tree_element<T> >& tree,
 const std::vector<U>& words,
 const T& tag_to_skip
 )
 {
 if (tree.size() == 0)
 return "";
 std::ostringstream sout;
 impl::print_parse_tree_helper<true,true>(tree, words, 0, tag_to_skip, sout);
 return sout.str();
 }
// -----------------------------------------------------------------------------------------
 namespace impl
 {
 template <typename T>
 void helper_find_trees_without_tag (
 const std::vector<parse_tree_element<T> >& tree,
 const T& tag,
 std::vector<unsigned long>& tree_roots,
 unsigned long idx
 )
 {
 if (idx < tree.size())
 {
 if (tree[idx].tag != tag)
 {
 tree_roots.push_back(idx);
 }
 else
 {
 helper_find_trees_without_tag(tree, tag, tree_roots, tree[idx].left);
 helper_find_trees_without_tag(tree, tag, tree_roots, tree[idx].right);
 }
 }
 }
 }
 template <typename T>
 void find_trees_not_rooted_with_tag (
 const std::vector<parse_tree_element<T> >& tree,
 const T& tag,
 std::vector<unsigned long>& tree_roots 
 )
 {
 tree_roots.clear();
 impl::helper_find_trees_without_tag(tree, tag, tree_roots, 0);
 }
// -----------------------------------------------------------------------------------------
}
#endif // DLIB_FIND_MAX_PaRSE_CKY_Hh_