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      1 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 # Autocompletion config for YouCompleteMe in Chromium.
      6 #
      7 # USAGE:
      8 #
      9 #   1. Install YCM [https://github.com/Valloric/YouCompleteMe]
     10 #          (Googlers should check out [go/ycm])
     11 #
     12 #   2. Point to this config file in your .vimrc:
     13 #          let g:ycm_global_ycm_extra_conf =
     14 #              '<chrome_depot>/src/tools/vim/chromium.ycm_extra_conf.py'
     15 #
     16 #   3. Profit
     17 #
     18 #
     19 # Usage notes:
     20 #
     21 #   * You must use ninja & clang to build Chromium.
     22 #
     23 #   * You must have run gyp_chromium and built Chromium recently.
     24 #
     25 #
     26 # Hacking notes:
     27 #
     28 #   * The purpose of this script is to construct an accurate enough command line
     29 #     for YCM to pass to clang so it can build and extract the symbols.
     30 #
     31 #   * Right now, we only pull the -I and -D flags. That seems to be sufficient
     32 #     for everything I've used it for.
     33 #
     34 #   * That whole ninja & clang thing? We could support other configs if someone
     35 #     were willing to write the correct commands and a parser.
     36 #
     37 #   * This has only been tested on gPrecise.
     38 
     39 
     40 import os
     41 import subprocess
     42 
     43 
     44 # Flags from YCM's default config.
     45 flags = [
     46 '-DUSE_CLANG_COMPLETER',
     47 '-std=c++11',
     48 '-x',
     49 'c++',
     50 ]
     51 
     52 
     53 def PathExists(*args):
     54   return os.path.exists(os.path.join(*args))
     55 
     56 
     57 def FindChromeSrcFromFilename(filename):
     58   """Searches for the root of the Chromium checkout.
     59 
     60   Simply checks parent directories until it finds .gclient and src/.
     61 
     62   Args:
     63     filename: (String) Path to source file being edited.
     64 
     65   Returns:
     66     (String) Path of 'src/', or None if unable to find.
     67   """
     68   curdir = os.path.normpath(os.path.dirname(filename))
     69   while not (PathExists(curdir, 'src') and PathExists(curdir, 'src', 'DEPS')
     70              and (PathExists(curdir, '.gclient')
     71                   or PathExists(curdir, 'src', '.git'))):
     72     nextdir = os.path.normpath(os.path.join(curdir, '..'))
     73     if nextdir == curdir:
     74       return None
     75     curdir = nextdir
     76   return os.path.join(curdir, 'src')
     77 
     78 
     79 # Largely copied from ninja-build.vim (guess_configuration)
     80 def GetNinjaOutputDirectory(chrome_root):
     81   """Returns either <chrome_root>/out/Release or <chrome_root>/out/Debug.
     82 
     83   The configuration chosen is the one most recently generated/built."""
     84   root = os.path.join(chrome_root, 'out')
     85   debug_path = os.path.join(root, 'Debug')
     86   release_path = os.path.join(root, 'Release')
     87 
     88   def is_release_15s_newer(test_path):
     89     try:
     90       debug_mtime = os.path.getmtime(os.path.join(debug_path, test_path))
     91     except os.error:
     92       debug_mtime = 0
     93     try:
     94       rel_mtime = os.path.getmtime(os.path.join(release_path, test_path))
     95     except os.error:
     96       rel_mtime = 0
     97     return rel_mtime - debug_mtime >= 15
     98 
     99   if is_release_15s_newer('build.ninja') or is_release_15s_newer('protoc'):
    100     return release_path
    101   return debug_path
    102 
    103 
    104 def GetClangCommandFromNinjaForFilename(chrome_root, filename):
    105   """Returns the command line to build |filename|.
    106 
    107   Asks ninja how it would build the source file. If the specified file is a
    108   header, tries to find its companion source file first.
    109 
    110   Args:
    111     chrome_root: (String) Path to src/.
    112     filename: (String) Path to source file being edited.
    113 
    114   Returns:
    115     (List of Strings) Command line arguments for clang.
    116   """
    117   if not chrome_root:
    118     return []
    119 
    120   # Generally, everyone benefits from including Chromium's src/, because all of
    121   # Chromium's includes are relative to that.
    122   chrome_flags = ['-I' + os.path.join(chrome_root)]
    123 
    124   # Header files can't be built. Instead, try to match a header file to its
    125   # corresponding source file.
    126   if filename.endswith('.h'):
    127     alternates = ['.cc', '.cpp']
    128     for alt_extension in alternates:
    129       alt_name = filename[:-2] + alt_extension
    130       if os.path.exists(alt_name):
    131         filename = alt_name
    132         break
    133     else:
    134       # If this is a standalone .h file with no source, the best we can do is
    135       # try to use the default flags.
    136       return chrome_flags
    137 
    138   # Ninja needs the path to the source file from the output build directory.
    139   # Cut off the common part and /.
    140   subdir_filename = filename[len(chrome_root)+1:]
    141   rel_filename = os.path.join('..', '..', subdir_filename)
    142 
    143   out_dir = GetNinjaOutputDirectory(chrome_root)
    144 
    145   # Ask ninja how it would build our source file.
    146   p = subprocess.Popen(['ninja', '-v', '-C', out_dir, '-t',
    147                         'commands', rel_filename + '^'],
    148                        stdout=subprocess.PIPE)
    149   stdout, stderr = p.communicate()
    150   if p.returncode:
    151     return chrome_flags
    152 
    153   # Ninja might execute several commands to build something. We want the last
    154   # clang command.
    155   clang_line = None
    156   for line in reversed(stdout.split('\n')):
    157     if 'clang' in line:
    158       clang_line = line
    159       break
    160   else:
    161     return chrome_flags
    162 
    163   # Parse out the -I and -D flags. These seem to be the only ones that are
    164   # important for YCM's purposes.
    165   for flag in clang_line.split(' '):
    166     if flag.startswith('-I'):
    167       # Relative paths need to be resolved, because they're relative to the
    168       # output dir, not the source.
    169       if flag[2] == '/':
    170         chrome_flags.append(flag)
    171       else:
    172         abs_path = os.path.normpath(os.path.join(out_dir, flag[2:]))
    173         chrome_flags.append('-I' + abs_path)
    174     elif flag.startswith('-') and flag[1] in 'DWFfmO':
    175       if flag == '-Wno-deprecated-register' or flag == '-Wno-header-guard':
    176         # These flags causes libclang (3.3) to crash. Remove it until things
    177         # are fixed.
    178         continue
    179       chrome_flags.append(flag)
    180 
    181   return chrome_flags
    182 
    183 
    184 def FlagsForFile(filename):
    185   """This is the main entry point for YCM. Its interface is fixed.
    186 
    187   Args:
    188     filename: (String) Path to source file being edited.
    189 
    190   Returns:
    191     (Dictionary)
    192       'flags': (List of Strings) Command line flags.
    193       'do_cache': (Boolean) True if the result should be cached.
    194   """
    195   chrome_root = FindChromeSrcFromFilename(filename)
    196   chrome_flags = GetClangCommandFromNinjaForFilename(chrome_root,
    197                                                      filename)
    198   final_flags = flags + chrome_flags
    199 
    200   return {
    201     'flags': final_flags,
    202     'do_cache': True
    203   }
    204