VariableStrings.java

package edu.stanford.nlp.trees.tregex;

import edu.stanford.nlp.stats.IntCounter;

import java.util.Map;
import java.util.HashMap;

/** A class that takes care of the stuff necessary for variable strings.
 *
 *  @author Roger Levy (rog@nlp.stanford.edu)
 */
class VariableStrings {

  private Map<String, String> varsToStrings;
  private IntCounter<String> numVarsSet;

  public VariableStrings() {
    varsToStrings = new HashMap<String,String>();
    numVarsSet = new IntCounter<String>();
  }

  public boolean isSet(String o) {
    return numVarsSet.getCount(o) == 1;
  }

  public void setVar(String var, String string) {
    String oldString = varsToStrings.put(var,string);
    if(oldString != null && ! oldString.equals(string))
      throw new RuntimeException("Error -- can't setVar to a different string -- old: " + oldString + " new: " + string);
    numVarsSet.incrementCount(var);
  }

  public void unsetVar(String var) {
    if(numVarsSet.getCount(var) > 0)
      numVarsSet.decrementCount(var);
    if(numVarsSet.getCount(var)==0)
      varsToStrings.put(var,null);
  }

  public String getString(String var) {
    return varsToStrings.get(var);
  }

}