Review

19

com/google/javascript/jscomp/CoalesceVariableNames.java

visit(NodeTraversal, Node, Node)

class CoalesceVariableNames {
  @Override
  public void visit(NodeTraversal t, Node n, Node parent) {
    if (colorings.isEmpty() || !NodeUtil.isName(n) ||
        NodeUtil.isFunction(parent)) {
      // Don't rename named functions.
      return;
    }
    Var var = t.getScope().getVar(n.getString());
    GraphNode<Var, ?> vNode = colorings.peek().getGraph().getNode(var);
    if (vNode == null) {
      // This is not a local.
      return;
    }
    Var coalescedVar = colorings.peek().getPartitionSuperNode(var);

    if (!usePseudoNames) {
      if (vNode.getValue().equals(coalescedVar)) {
        // The coalesced name is itself, nothing to do.
        return;
      }

      // Rename.
      n.setString(coalescedVar.name);
      compiler.reportCodeChange();

      if (NodeUtil.isVar(parent)) {
        removeVarDeclaration(n);
      }
    } else {
      // This code block is slow but since usePseudoName is for debugging,
      // we should not sacrifice performance for non-debugging compilation to
      // make this fast.
      String pseudoName = null;
      Set<String> allMergedNames = Sets.newTreeSet();
      for (Iterator<Var> i = t.getScope().getVars(); i.hasNext();) {
        Var iVar = i.next();

        // Look for all the variables that can be merged (in the graph by now)
        // and it is merged with the current coalscedVar.
        if (colorings.peek().getGraph().getNode(iVar) != null &&
            coalescedVar.equals(colorings.peek().getPartitionSuperNode(iVar))) {
          allMergedNames.add(iVar.name);
        }
      }

      // Keep its original name.
      if (allMergedNames.size() == 1) {
        return;
      }

      pseudoName = Joiner.on("_").join(allMergedNames);

      while (t.getScope().isDeclared(pseudoName, true)) {
        pseudoName += "$";
      }

      n.setString(pseudoName);
      compiler.reportCodeChange();

      if (!vNode.getValue().equals(coalescedVar) && NodeUtil.isVar(parent)) {
        removeVarDeclaration(n);
      }
    }
  }
}