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      1 # Copyright 2015 the V8 project 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 V8.
      6 #
      7 # USAGE:
      8 #
      9 #   1. Install YCM [https://github.com/Valloric/YouCompleteMe]
     10 #          (Googlers should check out [go/ycm])
     11 #
     12 #   2. Profit
     13 #
     14 #
     15 # Usage notes:
     16 #
     17 #   * You must use ninja & clang to build V8.
     18 #
     19 #   * You must have run gyp_v8 and built V8 recently.
     20 #
     21 #
     22 # Hacking notes:
     23 #
     24 #   * The purpose of this script is to construct an accurate enough command line
     25 #     for YCM to pass to clang so it can build and extract the symbols.
     26 #
     27 #   * Right now, we only pull the -I and -D flags. That seems to be sufficient
     28 #     for everything I've used it for.
     29 #
     30 #   * That whole ninja & clang thing? We could support other configs if someone
     31 #     were willing to write the correct commands and a parser.
     32 #
     33 #   * This has only been tested on gTrusty.
     34 
     35 
     36 import os
     37 import os.path
     38 import subprocess
     39 import sys
     40 
     41 
     42 # Flags from YCM's default config.
     43 flags = [
     44 '-DUSE_CLANG_COMPLETER',
     45 '-std=gnu++11',
     46 '-x',
     47 'c++',
     48 ]
     49 
     50 
     51 def PathExists(*args):
     52   return os.path.exists(os.path.join(*args))
     53 
     54 
     55 def FindV8SrcFromFilename(filename):
     56   """Searches for the root of the V8 checkout.
     57 
     58   Simply checks parent directories until it finds .gclient and v8/.
     59 
     60   Args:
     61     filename: (String) Path to source file being edited.
     62 
     63   Returns:
     64     (String) Path of 'v8/', or None if unable to find.
     65   """
     66   curdir = os.path.normpath(os.path.dirname(filename))
     67   while not (PathExists(curdir, 'v8') and PathExists(curdir, 'v8', 'DEPS')
     68              and (PathExists(curdir, '.gclient')
     69                   or PathExists(curdir, 'v8', '.git'))):
     70     nextdir = os.path.normpath(os.path.join(curdir, '..'))
     71     if nextdir == curdir:
     72       return None
     73     curdir = nextdir
     74   return os.path.join(curdir, 'v8')
     75 
     76 
     77 def GetClangCommandFromNinjaForFilename(v8_root, filename):
     78   """Returns the command line to build |filename|.
     79 
     80   Asks ninja how it would build the source file. If the specified file is a
     81   header, tries to find its companion source file first.
     82 
     83   Args:
     84     v8_root: (String) Path to v8/.
     85     filename: (String) Path to source file being edited.
     86 
     87   Returns:
     88     (List of Strings) Command line arguments for clang.
     89   """
     90   if not v8_root:
     91     return []
     92 
     93   # Generally, everyone benefits from including V8's root, because all of
     94   # V8's includes are relative to that.
     95   v8_flags = ['-I' + os.path.join(v8_root)]
     96 
     97   # Version of Clang used to compile V8 can be newer then version of
     98   # libclang that YCM uses for completion. So it's possible that YCM's libclang
     99   # doesn't know about some used warning options, which causes compilation
    100   # warnings (and errors, because of '-Werror');
    101   v8_flags.append('-Wno-unknown-warning-option')
    102 
    103   # Header files can't be built. Instead, try to match a header file to its
    104   # corresponding source file.
    105   if filename.endswith('.h'):
    106     alternates = ['.cc', '.cpp']
    107     for alt_extension in alternates:
    108       alt_name = filename[:-2] + alt_extension
    109       if os.path.exists(alt_name):
    110         filename = alt_name
    111         break
    112     else:
    113       if filename.endswith('-inl.h'):
    114         for alt_extension in alternates:
    115           alt_name = filename[:-6] + alt_extension
    116           if os.path.exists(alt_name):
    117             filename = alt_name
    118             break;
    119         else:
    120           # If this is a standalone -inl.h file with no source, the best we can
    121           # do is try to use the default flags.
    122           return v8_flags
    123       else:
    124         # If this is a standalone .h file with no source, the best we can do is
    125         # try to use the default flags.
    126         return v8_flags
    127 
    128   sys.path.append(os.path.join(v8_root, 'tools', 'ninja'))
    129   from ninja_output import GetNinjaOutputDirectory
    130   out_dir = os.path.realpath(GetNinjaOutputDirectory(v8_root))
    131 
    132   # Ninja needs the path to the source file relative to the output build
    133   # directory.
    134   rel_filename = os.path.relpath(os.path.realpath(filename), out_dir)
    135 
    136   # Ask ninja how it would build our source file.
    137   p = subprocess.Popen(['ninja', '-v', '-C', out_dir, '-t',
    138                         'commands', rel_filename + '^'],
    139                        stdout=subprocess.PIPE)
    140   stdout, stderr = p.communicate()
    141   if p.returncode:
    142     return v8_flags
    143 
    144   # Ninja might execute several commands to build something. We want the last
    145   # clang command.
    146   clang_line = None
    147   for line in reversed(stdout.split('\n')):
    148     if 'clang' in line:
    149       clang_line = line
    150       break
    151   else:
    152     return v8_flags
    153 
    154   # Parse flags that are important for YCM's purposes.
    155   for flag in clang_line.split(' '):
    156     if flag.startswith('-I'):
    157       # Relative paths need to be resolved, because they're relative to the
    158       # output dir, not the source.
    159       if flag[2] == '/':
    160         v8_flags.append(flag)
    161       else:
    162         abs_path = os.path.normpath(os.path.join(out_dir, flag[2:]))
    163         v8_flags.append('-I' + abs_path)
    164     elif flag.startswith('-std'):
    165       v8_flags.append(flag)
    166     elif flag.startswith('-') and flag[1] in 'DWFfmO':
    167       if flag == '-Wno-deprecated-register' or flag == '-Wno-header-guard':
    168         # These flags causes libclang (3.3) to crash. Remove it until things
    169         # are fixed.
    170         continue
    171       v8_flags.append(flag)
    172 
    173   return v8_flags
    174 
    175 
    176 def FlagsForFile(filename):
    177   """This is the main entry point for YCM. Its interface is fixed.
    178 
    179   Args:
    180     filename: (String) Path to source file being edited.
    181 
    182   Returns:
    183     (Dictionary)
    184       'flags': (List of Strings) Command line flags.
    185       'do_cache': (Boolean) True if the result should be cached.
    186   """
    187   v8_root = FindV8SrcFromFilename(filename)
    188   v8_flags = GetClangCommandFromNinjaForFilename(v8_root, filename)
    189   final_flags = flags + v8_flags
    190   return {
    191     'flags': final_flags,
    192     'do_cache': True
    193   }
    194