HOL-master/examples/lassie/sempre/src/edu/stanford/nlp/sempre/DerivOpCountFeatureComputer.java
package edu.stanford.nlp.sempre;

import java.util.*;

import com.google.common.collect.Sets;

import fig.basic.*;

/**
 * Extracts indicator features that count how many times semantic functions and
 * LHSs have been used in the derivation For now we count how many times MergeFn
 * and JoinFn, also how many time unary, binary and entity lexical entries have
 * been used. The feature is a pair with the operation and the count
 *
 * @author jonathanberant
 */
public class DerivOpCountFeatureComputer implements FeatureComputer {
  public static class Options {
    @Option(gloss = "Count only basic categories and SemanticFns")
    public boolean countBasicOnly = true;
  }
  public static Options opts = new Options();

  public static final String entityCat = "$Entity";
  public static final String unaryCat = "$Unary";
  public static final String binaryCat = "$Binary";
  public static final String joinFn = "JoinFn";
  public static final String mergeFn = "MergeFn";
  public static final String bridgeFn = "BridgeFn";
  public static Set<String> featureNames = Sets.newHashSet(entityCat, unaryCat, binaryCat, joinFn, mergeFn, bridgeFn);

  @Override
  public void extractLocal(Example ex, Derivation deriv) {
    if (!FeatureExtractor.containsDomain("opCount")) return;
    if (!deriv.isRoot(ex.numTokens())) return;

    // extract the operation count
    Map<String, Integer> opCounter = new HashMap<>();
    extractOperationsRecurse(deriv, opCounter);
    addFeatures(deriv, opCounter);
  }

  private void extractOperationsRecurse(Derivation deriv, Map<String, Integer> opCounter) {
    // Basic case: no rule
    if (deriv.children.isEmpty()) return;
    // increment counts for current rule
    MapUtils.incr(opCounter, deriv.rule.lhs);
    MapUtils.incr(opCounter, deriv.rule.sem.getClass().getSimpleName());
    // recursive call
    for (Derivation child : deriv.children)
      extractOperationsRecurse(child, opCounter);
  }

  private void addFeatures(Derivation deriv, Map<String, Integer> opCounter) {
    for (String feature : (opts.countBasicOnly ? featureNames : opCounter.keySet()))
      deriv.addFeature("opCount", "count(" + feature + ")=" + MapUtils.get(opCounter, feature, 0));
  }
}
