Add a script that allows developers to run checkstyle.

Allow developers to run Java style check in two ways.

Specific file:
checkstyle.py -f path/to/file/View.java

Lines modified in the latest commit:
checkstyle.py

Review moved from https://googleplex-android-review.googlesource.com/#/c/818813/
due to move from packages/experimental to development/tools

Bug: 25852971
Change-Id: Ibcf9d80644f2938828b21e8f50ab0d6f39c286b0
(cherry picked from commit 96f27d0960)

tools/checkstyle/checkstyle.py

@@ -0,0 +1,148 @@
+#!/usr/bin/python
+
+#
+# Copyright 2015, The Android Open Source Project
+#
+# 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.
+#
+
+"""Script that is used by developers to run style checks on Java files."""
+
+import argparse
+import errno
+import os
+import subprocess
+import sys
+import xml.dom.minidom
+import gitlint.git as git
+
+
+MAIN_DIRECTORY = os.path.normpath(os.path.dirname(__file__))
+CHECKSTYLE_JAR = os.path.join(MAIN_DIRECTORY, 'checkstyle.jar')
+CHECKSTYLE_STYLE = os.path.join(MAIN_DIRECTORY, 'android-style.xml')
+FORCED_RULES = ['com.puppycrawl.tools.checkstyle.checks.imports.ImportOrderCheck',
+                'com.puppycrawl.tools.checkstyle.checks.imports.UnusedImportsCheck']
+
+def RunCheckstyle(java_files):
+  if not os.path.exists(CHECKSTYLE_STYLE):
+    print 'Java checkstyle configuration file is missing'
+    sys.exit(1)
+
+  if java_files:
+    # Files to check were specified via command line.
+    print 'Running Checkstyle on inputted files'
+    sha = ''
+    last_commit_modified_files = {}
+    java_files = map(os.path.abspath, java_files)
+  else:
+    # Files where not specified exclicitly. Let's use last commit files.
+    sha, last_commit_modified_files = _GetModifiedFiles()
+    print 'Running Checkstyle on %s commit' % sha
+    java_files = last_commit_modified_files.keys()
+
+    if not java_files:
+      print 'No files to check'
+      return
+
+  stdout = _ExecuteCheckstyle(java_files)
+  (errors, warnings) = _ParseAndFilterOutput(stdout,
+                                             sha,
+                                             last_commit_modified_files)
+
+  if errors:
+    print 'ERRORS:'
+    print '\n'.join(errors)
+  if warnings:
+    print 'WARNINGS:'
+    print '\n'.join(warnings)
+  if errors or warnings:
+    sys.exit(1)
+
+  print 'SUCCESS! NO ISSUES FOUND'
+  sys.exit(0)
+
+
+def _ExecuteCheckstyle(java_files):
+  # Run checkstyle
+  checkstyle_env = os.environ.copy()
+  checkstyle_env['JAVA_CMD'] = 'java'
+  try:
+    check = subprocess.Popen(['java', '-cp',
+                              CHECKSTYLE_JAR,
+                              'com.puppycrawl.tools.checkstyle.Main', '-c',
+                              CHECKSTYLE_STYLE, '-f', 'xml'] + java_files,
+                             stdout=subprocess.PIPE, env=checkstyle_env)
+    stdout, _ = check.communicate()
+  except OSError as e:
+    if e.errno == errno.ENOENT:
+      print 'Error running Checkstyle!'
+      sys.exit(1)
+
+  # Work-around for Checkstyle printing error count to stdio.
+  if 'Checkstyle ends with' in stdout.splitlines()[-1]:
+    stdout = '\n'.join(stdout.splitlines()[:-1])
+  return stdout
+
+def _ParseAndFilterOutput(stdout, sha, last_commit_modified_files):
+  result_errors = []
+  result_warnings = []
+  root = xml.dom.minidom.parseString(stdout)
+  for file_element in root.getElementsByTagName('file'):
+    file_name = file_element.attributes['name'].value
+    if last_commit_modified_files:
+      modified_lines = git.modified_lines(file_name,
+                                          last_commit_modified_files[file_name],
+                                          sha)
+    file_name = os.path.relpath(file_name)
+    errors = file_element.getElementsByTagName('error')
+    for error in errors:
+      line = error.attributes['line'].value
+      if last_commit_modified_files and int(line) not in modified_lines:
+        if error.attributes['source'].value not in FORCED_RULES:
+          continue
+
+      column = ''
+      if error.hasAttribute('column'):
+        column = '%s:' % (error.attributes['column'].value)
+      message = error.attributes['message'].value
+      result = '  %s:%s:%s %s' % (file_name, line, column, message)
+
+      severity = error.attributes['severity'].value
+      if severity == 'error':
+        result_errors.append(result)
+      elif severity == 'warning':
+        result_warnings.append(result)
+  return (result_errors, result_warnings)
+
+
+def _GetModifiedFiles():
+  root = git.repository_root()
+  sha = git.last_commit()
+  working_files = git.modified_files(root)
+  if working_files:
+    print 'You need to commit all the files before running Checkstyle'
+    sys.exit(1)
+  modified_files = git.modified_files(root, True, sha)
+  modified_files = {os.path.abspath(f): modified_files[f] for f
+                    in modified_files if f.endswith('.java')}
+  return (sha, modified_files)
+
+
+def main(args=None):
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--file', '-f', nargs='+')
+  args = parser.parse_args()
+  RunCheckstyle(args.file)
+
+if __name__ == '__main__':
+  main()