Review

11

com/google/javascript/jscomp/MustBeReachingVariableDef.java

apply(MustBeReachingVariableDef$MustDef, MustBeReachingVariableDef$MustDef)

    @Override
    public MustDef apply(MustDef a, MustDef b) {
      MustDef result = new MustDef();
      Map<Var, Definition> resultMap = result.reachingDef;

      // Take the join of all variables that are not TOP in this.
      for (Var var : a.reachingDef.keySet()) {

        Definition aDef = a.reachingDef.get(var);

        if (aDef == null) {
          // "a" is BOTTOM implies that the variable has more than one possible
          // definition. We set the join of this to be BOTTOM regardless of what
          // "b" might be.
          resultMap.put(var, null);
          continue;
        }

        Node aNode = aDef.node;

        if (b.reachingDef.containsKey(var)) {
          Definition bDef = b.reachingDef.get(var);

          if (aDef.equals(bDef)) {
            resultMap.put(var, aDef);
          } else {
            resultMap.put(var, null);
          }
        } else {
          resultMap.put(var, aDef);
        }
      }

      // Take the join of all variables that are not TOP in other but it is TOP
      // in this.
      for (Var var : b.reachingDef.keySet()) {
        if (!a.reachingDef.containsKey(var)) {
          resultMap.put(var, b.reachingDef.get(var));
        }
      }
      return result;
    }
  }