lex_06.cc

这是一个从音频信号里提取特征参量的程序

// model ( word graph / lattice ) which is represented as a
// DiGraph<LexicalNode>
//
boolean
LexicalTree::buildLexicalTree(DiGraph<LexicalNode>& word_graph_a, 
			      const Vector<DiGraph<LexicalNode> >& pron_vec_a,
			      SingleLinkedList<LexicalTree>& tree_list_a){

  // algorithm for this method:
  // 1 LOOP:
  //        iterate through all the vertexs on this word graph
  //        1.1 build the lexical tree for that node
  //        1.2 insert the lexical tree in a list
  // 2 Exit   
  
  // lexical tree for the start vertex of the DiGraph
  //
  LexicalTree* lex_tree = new LexicalTree();
  GVLexicalNode* root_vert = word_graph_a.getStart();

  if ( NULL == lex_tree->buildLexicalTree(root_vert, pron_vec_a) ){
    delete lex_tree;
  }
  else{
    tree_list_a.insert(lex_tree);
    
    // make the search node point to this lexical tree
    //
    LexicalNode* curr_node = (LexicalNode*)root_vert->getItem();      
    curr_node->setLexicalTree(lex_tree);
  }

  // iterate through all the vertexs on this word graph
  //
  for (boolean more_vertexes = word_graph_a.gotoFirst(); more_vertexes;
       more_vertexes = word_graph_a.gotoNext()) {
    
    // get the successor
    //
    root_vert = word_graph_a.getCurr();
    lex_tree = new LexicalTree();
    
    // we need set the pointer to this lexical tree on root_vert later
    //
    if ( NULL == lex_tree->buildLexicalTree(root_vert, pron_vec_a) ){
      delete lex_tree;
    }
    else{
      tree_list_a.insert(lex_tree);
      
      // make the search node point to this lexical tree
      //
      LexicalNode* curr_node = (LexicalNode*)root_vert->getItem();      
      curr_node->setLexicalTree(lex_tree);
    }
  }

  // exit gracefully
  //
  return true;
}
  
// method: buildLexicalTree
//
// arguments:
//  LexicalNode* root_vert_a: (input) the node from which we expend the
//                           the Lexical tree. Currently, it is defined as:
//                           ==> typedef LexicalNode SearchNode;
//                           ==> GraphVertex<LexicalNode> GVLexicalNode;
//  Vector<DiGraph<LexicalNode>>& pron_vec_a : (input) the pronunciation for
//                           each word in the symbol_list_a; It is a 1:1
//                           mapping. Currently, it is defined as:
//                           ==> typedef DiGraph<LexicalNode> Pronunciation;
//
// return: a boolean indicating status
//
// note: the symbol id on the vertex should be the index of the digraph in
//       the(input) pron_vec_a
//
// this method build the lexical tree for a lexical node in the language
// model ( word graph / lattice ) which is represented as a
// DiGraph<LexicalNode>
//
LexicalTree* LexicalTree::buildLexicalTree(GVLexicalNode*& root_vert_a, 
			      const Vector<DiGraph<LexicalNode> >& pron_vec_a){

  // algorithm for this method:
  // 1 LOOP:
  //        iterate through all the arcs emitted from root_vert_a
  //        1.1 find the subgraph of each successor of root_vert_a 
  //        1.2 insert the pronunciation of the successor
  // 2 Exit   
  
  // test the pointer
  //
  if (root_vert_a == NULL){
    Error::handle(name(), L"buildLexicalTree", Error::NULL_ARG,
			 __FILE__, __LINE__);
    return (LexicalTree*)NULL;
  }

  root_vert_d = root_vert_a;
  
  // no lexical tree for this vertex
  //
  if (root_vert_a->isTerm())
    return (LexicalTree*)NULL;
  
  // iterate through all the arcs emitted from this vertex, we 
  // need to remove arcs already exist
  //
  for (boolean more_arcs = root_vert_a->gotoFirst(); more_arcs;
       more_arcs = root_vert_a->gotoNext()) {
    
    // get the successor
    //
    GVLexicalNode* successor = root_vert_a->getCurr()->getVertex();
    
    // no lexical tree for this vertex
    //
    //if (successor->isTerm())
    //  return (LexicalTree*)NULL;

    float weight = 0;
    
    // get the transition probability
    //
    if ( root_vert_a->getParentGraph()->isWeighted()
	 && (! root_vert_a->getCurr()->getEpsilon()) ){
      weight = root_vert_a->getCurr()->getWeight();
    }
      
    // has a path to term
    //
    if (successor->isTerm()){
      // add an arc directly to the term
      //
      
      continue;
    }

    LexicalNode* curr_node = (LexicalNode*)successor->getItem();
    long symbol_id = curr_node->getSymbolId();

    // error handling
    //
    if ( symbol_id < 0 || symbol_id >= pron_vec_a.length()){
      Long error(symbol_id);
      error.debug(L"invalid symbol id: ");
	Error::handle(name(), L"buildLexicalTree", Error::NULL_ARG,
		      __FILE__, __LINE__);
      return (LexicalTree*)NULL;
    }

    // insert the pronunciation to the lexical tree
    //
    if( !insertPron(successor, pron_vec_a(symbol_id), weight) )
      return (LexicalTree*)NULL;
  }

  // exit gracefully
  //
  return this;
}
  
// method: insertPron
//
// arguments:
//  const GVLexicalNode*& word_vert_a: the pronunciation vertex need to
//                                     be inserted
//                          ==> typedef GraphVertex<LexicalNode> GVLexicalNode;
//  const Pronunciation& pron_a: the pronunciation need to be inserted
//                          ==> typedef DiGraph<LexicalNode> Pronunciation;
//
// return: a boolean indicating status
//
// this method insert a new pronunciation into the lexical tree
//
boolean LexicalTree::insertPron(GVLexicalNode*& word_vert_a,
			    const DiGraph<LexicalNode>& pron_a,
			    const float & weight_a ) {

  // algorithm for this method
  // 1 initialize ( set current lexical tree and prun_a to the start pointer)
  //   curr_lex_vert <- start , curr_pron_vert <- start
  // 2 insertSubgraph( curr_lex_vert, curr_pron_vert, false);
  // 3 exit

  GVLexicalNode* curr_lex_vert = getStart();
  GVLexicalNode* curr_pron_vert = pron_a.getStart();

  // we insert subgraph with checking , that is why we set
  // insert_mode_a = false
  //
  return insertSubgraph( word_vert_a, curr_lex_vert, curr_pron_vert,
			 weight_a, false);
}

// method: insertSubgraph
//
// arguments:
// const GVLexicalNode*& word_vert_a: the subgraph is from the Pronunciation
//                                of this
// const GVLexicalNode*& curr_lex_vert_a: current vertex in the lexical
// const GVLexicalNode*& curr_pron_vert_a: current vertex in the pronunciation
//                                         graph
// boolean insert_mode_a = true: insert the subgraph without checking
//
// note:    ==> typedef DiGraph<LexicalNode> Pronunciation;
//
// return: a boolean indicating status
//
// this method insert a subgraph of a pronunciation into the lexical tree
//             the pronunciation is weighted in this case
//
boolean LexicalTree::insertSubgraph(GVLexicalNode*& word_vert_a,
				    GVLexicalNode*& curr_lex_vert_a,
				    GVLexicalNode*& curr_pron_vert_a,
				    const float & pron_prob_a, 
				    boolean insert_mode_a) {

  // algorithm for this method
  // 1 Error checking
  // 2 IF: insert_mode == true
  //       insert the subgraph of curr_pron_vert to the lexical tree
  //       ( append to curr_lex_vert), no checking for any successors
  //   ELSE: insert_mode == false
  //       check every vertex(succ_pron_vert) following curr_pron_vert.
  //       IF: this successor is a successor(succ_lex_vert) of curr_lex_vert
  //           call recursively:
  //           insertSubgraph(succ_lex_vert, succ_pron_vert, false);
  //       ELSE:
  //           call recursively:
  //           insertSubgraph(succ_lex_vert, succ_pron_vert, true);
  // 3 Exit
  //

  long symbol_id = -1;
  boolean more_arcs = false;
  float pron_prob = pron_prob_a;
  
  // error checking
  //
  if ( curr_lex_vert_a == NULL || curr_pron_vert_a == NULL ){
    return Error::handle(name(), L"insertSubgraph", Error::NULL_ARG,
			 __FILE__, __LINE__);    
  }

  // shouldn't insert a subgraph with only term vertex
  //
  if ( curr_pron_vert_a->isTerm()){
    return Error::handle(name(), L"insertSubgraph", Error::NULL_ARG,
			 __FILE__, __LINE__);    
  }

  // insert anyway
  //
  if ( insert_mode_a ){
    
    // iterate through all the arcs emitted from this vertex
    //
    for (more_arcs = curr_pron_vert_a->gotoFirst(); more_arcs;
	 more_arcs = curr_pron_vert_a->gotoNext()) {
    
      // get the successor
      //
      GVLexicalNode* succ_pron_vert = curr_pron_vert_a->getCurr()->getVertex();

      // accumulate the probability if it is not an epsilon transition
      //
      if ( curr_pron_vert_a->getParentGraph()->isWeighted() ){
	if (! curr_pron_vert_a->getCurr()->getEpsilon()){
	  pron_prob = pron_prob_a + curr_pron_vert_a->getCurr()->getWeight();
	}
      }
      
      LexicalNode* curr_node = (LexicalNode*)NULL;

      // at the end of pronunciation
      // we link it to the up level symbol
      //
      if ( succ_pron_vert->isTerm() ){
	
	// insert the arc to the word with probability
	//
	insertArc(curr_lex_vert_a, word_vert_a, false, pron_prob);

	if (debug_level_d > Integral::BRIEF) {
	  curr_node = (LexicalNode*)word_vert_a->getItem();
	  curr_node->debug(L"link to up level symbol");
	}
	continue;
      }

      // get the lexical
      //
      curr_node = (LexicalNode*)succ_pron_vert->getItem();

      // insert this pronunciation vertex into the lex tree
      //
      GVLexicalNode* succ_lex_vert = insertVertex(curr_node);

      if (debug_level_d > Integral::BRIEF) {
	curr_node->debug(L"add to lexical tree");
      }

      // insert an epsilon arc, the pronunciation probability will
      // only on the arc to the word
      //
      insertArc(curr_lex_vert_a, succ_lex_vert, true);

      // call recursively
      //
      insertSubgraph(word_vert_a, succ_lex_vert, succ_pron_vert,
		     pron_prob, true);
    }
  } // end if insert_mode_a == true
  // don't insert those with the same symbol_id
  //
  else {
    // iterate through all the arcs emitted from this vertex
    //
    for (more_arcs = curr_pron_vert_a->gotoFirst(); more_arcs;
	 more_arcs = curr_pron_vert_a->gotoNext()) {
    
      // get the successor
      //
      GVLexicalNode* succ_pron_vert = curr_pron_vert_a->getCurr()->getVertex();

      // accumulate the probability if it is not an epsilon transition
      //
      if ( curr_pron_vert_a->getParentGraph()->isWeighted() ){
	if (! curr_pron_vert_a->getCurr()->getEpsilon()){
	  pron_prob = pron_prob_a + curr_pron_vert_a->getCurr()->getWeight();
	}
      }
      
      LexicalNode* curr_node = (LexicalNode*)NULL;

      // at the end of pronunciation
      // we link it to the up level symbol
      //
      if ( succ_pron_vert->isTerm() ){

	// insert the arc to the word with probability
	//
	insertArc(curr_lex_vert_a, word_vert_a, false, pron_prob);
	
	if (debug_level_d > Integral::BRIEF) {
	  curr_node = (LexicalNode*)word_vert_a->getItem();
	  curr_node->debug(L"link to up level symbol");
	}
	continue;
      }

      // get the lexical node 
      //
      curr_node = (LexicalNode*)succ_pron_vert->getItem();
      
      // get the symbol id of this node
      //
      symbol_id = curr_node->getSymbolId();
      
      // find the vertex with the same symbol_id in the lexical tree
      //
      GVLexicalNode* succ_lex_vert = findSuccVert(curr_lex_vert_a, symbol_id);

      // we can find a successor with the same id
      // insert the subgraph ( with checking )
      //
      if ( succ_lex_vert != NULL ){
	insertSubgraph(word_vert_a, succ_lex_vert, succ_pron_vert,
		       pron_prob, false);
      }
      // we can't find a successor with the same id
      // insert all subgraph ( without checking )
      //
      else {

	if (debug_level_d > Integral::BRIEF) {
	  curr_node->debug(L"add to lexical tree");
	}

	// insert this pronunciation vertex into the lex tree
	//
	succ_lex_vert= insertVertex(curr_node);
	insertArc(curr_lex_vert_a, succ_lex_vert, true);

	// insert this node and all following nodes
	//
	insertSubgraph(word_vert_a, succ_lex_vert, succ_pron_vert,
		       pron_prob, true);
      }
    } // end of for loop
  } // end if insert_mode_a == false ( insert with checking )
  
  // exit gracefully
  //
  return true;
}

// method: findSuccVert
//
// arguments:
// const GVLexicalNode*& lex_vert_a: the vertex in the lexical
// long symbol_id_a: the symbol id of the lexical vertex we try to find
//
// return: a pointer to the lexical node vertex
//
// this method find the successor with given symbol ID.
// If it is not exsited, return a NULL.
//
LexicalTree::GVLexicalNode*
LexicalTree::findSuccVert(GVLexicalNode*& lex_vert_a,
			  long symbol_id_a ) {

  // algorithm for this method:
  // self-explain
  //

  GVLexicalNode* succ_vert = (GVLexicalNode*)NULL;
  boolean more_arcs = false;

  for ( more_arcs = lex_vert_a->gotoFirst(); more_arcs;
        more_arcs = lex_vert_a->gotoNext() ) {
    
    // get the successor
    //
    succ_vert = lex_vert_a->getCurr()->getVertex();
    LexicalNode* curr_node = (LexicalNode*)succ_vert->getItem();

    // find a lexical node vertex with the same id
    //
    if (symbol_id_a == curr_node->getSymbolId()){
      return succ_vert;
    }
  }

  succ_vert = (GVLexicalNode*)NULL;
  
  // exit gracefully
  //
  return (GVLexicalNode*) succ_vert;
  
}

// method: insertArc
//
// arguments:
//  GVLexicalNode* start_vertex: (input) the start vertex
//  GVLexicalNode* end_vertex: (input) the ending vertex
//  boolean is_epsilon: (input) is the arc an epsilon transition
//  float weight: (input) the weight on the arc (if any)
//  
// return: a boolean value indicating status
//
// this method inserts an arc between two vertices in the graph provided
// that the two vertices are already present in the graph.
// note: the arc inserted will be stored in the SingleLinkedList ( contain
//       all arcs) of the start vertex
//
boolean LexicalTree::insertArc(GVLexicalNode* start_vertex_a,
			       GVLexicalNode* end_vertex_a,
			       boolean is_epsilon_a, float weight_a) {

  
  // make sure neither vertex is NULL
  //
  if ((start_vertex_a == (GVLexicalNode*)NULL) ||
      (end_vertex_a == (GVLexicalNode*)NULL)) {
    return Error::handle(name(), L"insertArc", Error::NULL_ARG,
			 __FILE__, __LINE__);
  }
  
  // add an arc from the start to the end
  //
  boolean return_val = start_vertex_a->insertArc(end_vertex_a, weight_a,
						 is_epsilon_a);
  
  // exit gracefully
  //
  return return_val;
}