Review

19

com/google/javascript/jscomp/PureFunctionIdentifier.java

visit(NodeTraversal, Node, Node)

class PureFunctionIdentifier.FunctionAnalyzer {
    @Override
    public void visit(NodeTraversal traversal, Node node, Node parent) {

      if (inExterns) {
        return;
      }

      if (!NodeUtil.nodeTypeMayHaveSideEffects(node)
          && node.getType() != Token.RETURN) {
        return;
      }

      if (NodeUtil.isCall(node) || NodeUtil.isNew(node)) {
        allFunctionCalls.add(node);
      }

      Node enclosingFunction = traversal.getEnclosingFunction();
      if (enclosingFunction != null) {
        FunctionInformation sideEffectInfo =
            functionSideEffectMap.get(enclosingFunction);
        Preconditions.checkNotNull(sideEffectInfo);

        if (NodeUtil.isAssignmentOp(node)) {
          visitAssignmentOrUnaryOperator(
              sideEffectInfo, traversal.getScope(),
              node, node.getFirstChild(), node.getLastChild());
        } else {
          switch(node.getType()) {
            case Token.CALL:
            case Token.NEW:
              visitCall(sideEffectInfo, node);
              break;
            case Token.DELPROP:
            case Token.DEC:
            case Token.INC:
              visitAssignmentOrUnaryOperator(
                  sideEffectInfo, traversal.getScope(),
                  node, node.getFirstChild(), null);
              break;
            case Token.NAME:
              // Variable definition are not side effects.
              // Just check that the name appears in the context of a
              // variable declaration.
              Preconditions.checkArgument(
                  NodeUtil.isVarDeclaration(node));
              Node value = node.getFirstChild();
              // Assignment to local, if the value isn't a safe local value,
              // new object creation or literal or known primitive result
              // value, add it to the local blacklist.
              if (value != null && !NodeUtil.evaluatesToLocalValue(value)) {
                Scope scope = traversal.getScope();
                Var var = scope.getVar(node.getString());
                sideEffectInfo.blacklistLocal(var);
              }
              break;
            case Token.THROW:
              visitThrow(sideEffectInfo);
              break;
            case Token.RETURN:
              if (node.hasChildren()
                  && !NodeUtil.evaluatesToLocalValue(node.getFirstChild())) {
                sideEffectInfo.setTaintsReturn();
              }
              break;
            default:
              throw new IllegalArgumentException(
                  "Unhandled side effect node type " +
                  Token.name(node.getType()));
          }
        }
      }
    }

}