/*
 * Copyright 2015 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.javascript.jscomp.lint;

import com.google.javascript.jscomp.AbstractCompiler;
import com.google.javascript.jscomp.CompilerPass;
import com.google.javascript.jscomp.DiagnosticType;
import com.google.javascript.jscomp.NodeTraversal;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.NodeUtil;
import com.google.javascript.rhino.Node;

/**
 * Check for empty statements (i.e. extraneous semicolons)
 */
public final class CheckEmptyStatements extends AbstractPostOrderCallback implements CompilerPass {
  public static final DiagnosticType USELESS_EMPTY_STATEMENT = DiagnosticType.warning(
      "JSC_USELESS_EMPTY_STATEMENT", "Useless empty statement. Remove semicolon.");

  private final AbstractCompiler compiler;

  public CheckEmptyStatements(AbstractCompiler compiler) {
    this.compiler = compiler;
  }

  @Override
  public void process(Node externs, Node root) {
    NodeTraversal.traverseEs6(compiler, root, this);
  }

  @Override
  public void visit(NodeTraversal t, Node n, Node parent) {
    if (n.isEmpty() && NodeUtil.isStatement(n)) {
      t.report(n, USELESS_EMPTY_STATEMENT);
    }
  }
}

