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

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import fig.basic.LispTree;
import fig.basic.LogInfo;
import fig.basic.Pair;

/**
 * Represent a binary using a list of pairs.
 *
 * @author ppasupat
 */
public class PairListValue extends Value {
  public final List<Pair<Value, Value>> pairs;

  public PairListValue(LispTree tree) {
    pairs = new ArrayList<>();
    for (int i = 1; i < tree.children.size(); i++)
      pairs.add(new Pair<>(
          Values.fromLispTree(tree.child(i).child(0)),
          Values.fromLispTree(tree.child(i).child(1))));
  }

  public PairListValue(List<Pair<Value, Value>> pairs) { this.pairs = pairs; }

  protected static final LispTree NULL_LEAF = LispTree.proto.newLeaf(null);

  public LispTree toLispTree() {
    LispTree tree = LispTree.proto.newList();
    tree.addChild("pairs");
    for (Pair<Value, Value> pair : pairs) {
      Value first = pair.getFirst(), second = pair.getSecond();
      tree.addChild(LispTree.proto.newList(
          first == null ? NULL_LEAF : first.toLispTree(), second == null ? NULL_LEAF : second.toLispTree()));
    }
    return tree;
  }

  public void log() {
    for (Pair<Value, Value> pair : pairs)
      LogInfo.logs("%s | %s", pair.getFirst(), pair.getSecond());
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    PairListValue that = (PairListValue) o;
    return pairs.equals(that.pairs);
  }

  @Override public int hashCode() { return pairs.hashCode(); }

  // Sorted on string representation
  public PairListValue getSorted() {
    List<Pair<Value, Value>> sorted = new ArrayList<>(pairs);
    Collections.sort(sorted,
        (Pair<Value, Value> p1, Pair<Value, Value> p2) -> getQuickStringOfPair(p1).compareTo(getQuickStringOfPair(p2)));
    return new PairListValue(sorted);
  }
  private static String getQuickStringOfPair(Pair<Value, Value> pair) {
    Value v1 = pair.getFirst(), v2 = pair.getSecond();
    return (v1 == null ? "null" : v1.sortString()) + " " + (v2 == null ? "null" : v2.sortString());
  }
}
