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Stanford CoreNLP provides a set of natural language analysis tools which can take raw English language text input and give the base forms of words, their parts of speech, whether they are names of companies, people, etc., normalize dates, times, and numeric quantities, mark up the structure of sentences in terms of phrases and word dependencies, and indicate which noun phrases refer to the same entities. It provides the foundational building blocks for higher level text understanding applications.

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package edu.stanford.nlp.parser.lexparser;

import java.io.*;
import java.util.*;

import edu.stanford.nlp.parser.common.ParserConstraint;
import edu.stanford.nlp.util.Generics;

public class Lattice implements Serializable, Iterable {

	private static final long serialVersionUID = 5135076134500512556L;
  
  private final List constraints;
	
	private final List edges;
	private final Set nodes;
	private final Map> edgeStartsAt;
	private int maxNode = -1;
	
	public Lattice() {
		edges = new ArrayList<>();
		nodes = Generics.newHashSet();
		constraints = new ArrayList<>();
		edgeStartsAt = Generics.newHashMap();
	}

	//TODO Do node normalization here
	public void addEdge(LatticeEdge e) { 
		nodes.add(e.start);
		nodes.add(e.end);
		edges.add(e); 
		if(e.end > maxNode)
		  maxNode = e.end;
		
		if(edgeStartsAt.get(e.start) == null) {
		  List edges = new ArrayList<>();
		  edges.add(e);
		  edgeStartsAt.put(e.start, edges);
		} else {
		  edgeStartsAt.get(e.start).add(e);
		}
	}
	
	public void addConstraint(ParserConstraint c) { constraints.add(c); }
	
	public int getNumNodes() { return nodes.size(); }

	public List getConstraints() {
	  return Collections.unmodifiableList(constraints);
	}
	
	public int getNumEdges() { return edges.size(); }
	
	public List getEdgesOverSpan(int start, int end) {
	 
	  List allEdges = edgeStartsAt.get(start);
	  List spanningEdges = new ArrayList<>();
	  if(allEdges != null)
	    for(LatticeEdge e : allEdges)
	      if(e.end == end)
	        spanningEdges.add(e);
	  
	  return spanningEdges;
	}
	
	
	@Override
	public String toString() {
	  StringBuilder sb = new StringBuilder();
	  sb.append(String.format("[ Lattice: %d edges  %d nodes ]\n",edges.size(), nodes.size()));
	  for(LatticeEdge e : edges)
	    sb.append("  " + e.toString() + "\n");
		return sb.toString();
	}

	public void setEdge(int id, LatticeEdge e) { edges.set(id, e); }
	
	public Iterator iterator() { return edges.iterator(); }

  public void addBoundary() {
    //Log prob of 0.0 since we have to take this transition
    LatticeEdge boundary = new LatticeEdge(Lexicon.BOUNDARY, 0.0, maxNode, maxNode + 1);
    addEdge(boundary);
  }

}