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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs. This binary checks for style issues such as incorrect or missing JSDoc usage, and missing goog.require() statements. It does not do more advanced checks such as typechecking.

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/*
 * Copyright 2008 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;

import com.google.javascript.jscomp.NodeTraversal.Callback;
import com.google.javascript.rhino.Node;

/**
 * A simple pass to ensure that all AST nodes have line numbers,
 * an that the line numbers are monotonically increasing.
 *
 * @author [email protected] (Nick Santos)
 */
class LineNumberCheck implements Callback, CompilerPass {

  static final DiagnosticType MISSING_LINE_INFO = DiagnosticType.error(
      "JSC_MISSING_LINE_INFO",
      "No source location information associated with {0}."
          + "\nMost likely a Node has been created without setting the source file"
          + " and line/column location.  Usually this is done using"
          + " Node.useSourceInfoIfMissingFrom and supplying a Node from the source AST.");

  private static final DiagnosticType MISSING_LENGTH =
      DiagnosticType.error(
          "JSC_MISSING_LENGTH",
          "Negative length associated with {0}.\n"
              + "Most likely a Node's source information was set incorrectly at parse time.");

  private final AbstractCompiler compiler;
  private boolean requiresLineNumbers = false;

  LineNumberCheck(AbstractCompiler compiler) {
    this.compiler = compiler;
  }

  public void setCheckSubTree(Node root) {
    requiresLineNumbers = true;

    NodeTraversal.traverse(compiler, root, this);
  }

  @Override
  public void process(Node externs, Node root) {
    requiresLineNumbers = false;

    NodeTraversal.traverse(compiler, root, this);
  }

  @Override
  public boolean shouldTraverse(NodeTraversal unused, Node n, Node parent) {
    // Each JavaScript file is rooted in a script node, so we'll only
    // have line number information inside the script node.
    if (n.isScript()) {
      requiresLineNumbers = true;
    }
    return true;
  }

  @Override
  public void visit(NodeTraversal unused, Node n, Node parent) {
    if (n.isScript()) {
      requiresLineNumbers = false;
    } else if (requiresLineNumbers) {
      if (n.getLineno() == -1) {
        // The tree version of the node is really the best diagnostic
        // info we have to offer here.
        compiler.report(JSError.make(n, MISSING_LINE_INFO, n.toStringTree()));
      } else if (n.getLength() < 0) {
        compiler.report(JSError.make(n, MISSING_LENGTH, n.toStringTree()));
      }
    }
  }
}