text: # Copyright (c) 2012 The Chromium Authors. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  """Presubmit script for Chromium JS resources.
  
  See chrome/browser/PRESUBMIT.py
  """
  
  import regex_check
  
  
  class JSChecker(object):
    def __init__(self, input_api, output_api, file_filter=None):
      self.input_api = input_api
      self.output_api = output_api
      self.file_filter = file_filter
  
    def RegexCheck(self, line_number, line, regex, message):
      return regex_check.RegexCheck(
          self.input_api.re, line_number, line, regex, message)
  
    def BindThisCheck(self, i, line):
      return self.RegexCheck(i, line, r"(\.bind\(this)[^)]*\)",
          "Prefer arrow (=>) functions over bind(this)");
  
    def ChromeSendCheck(self, i, line):
      """Checks for a particular misuse of "chrome.send"."""
      return self.RegexCheck(i, line, r"chrome\.send\('[^']+'\s*(, \[\])\)",
          "Passing an empty array to chrome.send is unnecessary")
  
    def CommentIfAndIncludeCheck(self, line_number, line):
      return self.RegexCheck(line_number, line, r"(?<!\/\/ )(<if|<include) ",
          "<if> or <include> should be in a single line comment with a space " +
          "after the slashes. Examples:\n" +
          '    // <include src="...">\n' +
          '    // <if expr="chromeos">\n' +
          "    // </if>\n")
  
    def EndJsDocCommentCheck(self, i, line):
      msg = "End JSDoc comments with */ instead of **/"
      def _check(regex):
        return self.RegexCheck(i, line, regex, msg)
      return _check(r"^\s*(\*\*/)\s*$") or _check(r"/\*\* @[a-zA-Z]+.* (\*\*/)")
  
    def ExtraDotInGenericCheck(self, i, line):
      return self.RegexCheck(i, line, r"((?:Array|Object|Promise)\.<)",
          "Don't use a dot after generics (Object.<T> should be Object<T>).")
  
    def InheritDocCheck(self, i, line):
      """Checks for use of "@inheritDoc" instead of "@override"."""
      return self.RegexCheck(i, line, r"\* (@inheritDoc)",
          "@inheritDoc is deprecated, use @override instead")
  
    def PolymerLocalIdCheck(self, i, line):
      """Checks for use of element.$.localId."""
      return self.RegexCheck(i, line, r"(?<!this)(\.\$)[\[\.](?![a-zA-Z]+\()",
          "Please only use this.$.localId, not element.$.localId")
  
    def RunEsLintChecks(self, affected_js_files, format="stylish"):
      """Runs lint checks using ESLint. The ESLint rules being applied are defined
         in the .eslintrc.js configuration file.
      """
      os_path = self.input_api.os_path
  
      # Extract paths to be passed to ESLint.
      affected_js_files_paths = []
      for f in affected_js_files:
        affected_js_files_paths.append(f.AbsoluteLocalPath())
  
      from os import isatty as os_isatty
      args = ["--color"] if os_isatty(self.input_api.sys.stdout.fileno()) else []
      args += ["--format", format, "--ignore-pattern '!.eslintrc.js'"]
      args += affected_js_files_paths
  
      import eslint
      output = eslint.Run(os_path=os_path, args=args)
  
      return [self.output_api.PresubmitError(output)] if output else []
  
    def VariableNameCheck(self, i, line):
      """See the style guide. http://goo.gl/eQiXVW"""
      return self.RegexCheck(i, line,
          r"(?:var|let|const) (?!g_\w+)(_?[a-z][a-zA-Z]*[_$][\w_$]*)(?<! \$)",
          "Please use variable namesLikeThis <https://goo.gl/eQiXVW>")
  
    def _GetErrorHighlight(self, start, length):
      """Takes a start position and a length, and produces a row of "^"s to
         highlight the corresponding part of a string.
      """
      return start * " " + length * "^"
  
    def RunChecks(self):
      """Check for violations of the Chromium JavaScript style guide. See
         https://chromium.googlesource.com/chromium/src/+/master/styleguide/web/web.md#JavaScript
      """
      results = []
  
      affected_files = self.input_api.AffectedFiles(file_filter=self.file_filter,
                                                    include_deletes=False)
      affected_js_files = filter(lambda f: f.LocalPath().endswith(".js"),
                                 affected_files)
  
      if affected_js_files:
        results += self.RunEsLintChecks(affected_js_files)
  
      for f in affected_js_files:
        error_lines = []
  
        for i, line in enumerate(f.NewContents(), start=1):
          error_lines += filter(None, [
              self.ChromeSendCheck(i, line),
              self.CommentIfAndIncludeCheck(i, line),
              self.EndJsDocCommentCheck(i, line),
              self.ExtraDotInGenericCheck(i, line),
              self.InheritDocCheck(i, line),
              self.PolymerLocalIdCheck(i, line),
              self.VariableNameCheck(i, line),
          ])
  
        if error_lines:
          error_lines = [
              "Found JavaScript style violations in %s:" %
              f.LocalPath()] + error_lines
          results.append(self.output_api.PresubmitError("\n".join(error_lines)))
  
      if results:
        results.append(self.output_api.PresubmitNotifyResult(
            "See the JavaScript style guide at "
            "https://chromium.googlesource.com/chromium/src/+/master/styleguide/web/web.md#JavaScript"))
  
      return results
  