From 00db8fd8b18c0157bacae17a062f360795b8907c Mon Sep 17 00:00:00 2001
From: Strahinja Val Markovic <val@markovic.io>
Date: Sat, 19 Jan 2013 18:53:30 -0800
Subject: [PATCH] compilation_database.json now fully supported

---
 cpp/ycm/.ycm_clang_options.py          | 32 +++++++++++++++++++-
 python/completers/cpp/clang_helpers.py | 41 ++++++++++++++++++++++++++
 python/completers/cpp/flags.py         |  8 +++++
 3 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 python/completers/cpp/clang_helpers.py

diff --git a/cpp/ycm/.ycm_clang_options.py b/cpp/ycm/.ycm_clang_options.py
index 290e6dca..b72f3058 100644
--- a/cpp/ycm/.ycm_clang_options.py
+++ b/cpp/ycm/.ycm_clang_options.py
@@ -1,5 +1,14 @@
 import os
+import ycm_core
+from clang_helpers import PrepareClangFlags
 
+# Set this to the absolute path to the folder containing the
+# compilation_database.json file to use that instead of 'flags'. See here for
+# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html
+compilation_database_folder = ''
+
+# These are the compilation flags that will be used in case there's no
+# compilation database set.
 flags = [
 '-Wall',
 '-Wextra',
@@ -41,6 +50,12 @@ flags = [
 './tests/gmock/include'
 ]
 
+if compilation_database_folder:
+  database = ycm_core.CompilationDatabase( compilation_database_folder )
+else:
+  database = None
+
+
 def DirectoryOfThisScript():
   return os.path.dirname( os.path.abspath( __file__ ) )
 
@@ -54,7 +69,22 @@ def MakeAbsoluteIfRelativePath( path ):
 
 
 def FlagsForFile( filename ):
+  if database:
+    # Bear in mind that database.FlagsForFile does NOT return a python list, but
+    # a "list-like" StringVec object
+    final_flags = PrepareClangFlags( database.FlagsForFile( filename ) )
+
+    # NOTE: This is just for YouCompleteMe; it's highly likely that your project
+    # does NOT need to remove the stdlib flag. DO NOT USE THIS IN YOUR
+    # ycm_clang_options IF YOU'RE NOT 100% YOU NEED IT.
+    try:
+      final_flags.remove( '-stdlib=libc++' )
+    except ValueError:
+      pass
+  else:
+    final_flags = [ MakeAbsoluteIfRelativePath( x ) for x in flags ]
+
   return {
-    'flags': [ MakeAbsoluteIfRelativePath( x ) for x in flags ],
+    'flags': final_flags,
     'do_cache': True
   }
diff --git a/python/completers/cpp/clang_helpers.py b/python/completers/cpp/clang_helpers.py
new file mode 100644
index 00000000..2b598f0f
--- /dev/null
+++ b/python/completers/cpp/clang_helpers.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2011, 2012  Strahinja Val Markovic  <val@markovic.io>
+#
+# This file is part of YouCompleteMe.
+#
+# YouCompleteMe is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# YouCompleteMe is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.
+
+
+# Given an interable object that produces strings (flags for Clang), removes the
+# '-c' and '-o' options that Clang does not like to see when it's producing
+# completions for a file.
+def PrepareClangFlags( flags ):
+  new_flags = []
+  skip = True
+  for flag in flags:
+    if skip:
+      skip = False
+      continue
+
+    if flag == '-c':
+      skip = True;
+      continue
+
+    if flag == '-o':
+      skip = True;
+      continue
+
+    new_flags.append( flag )
+  return new_flags
diff --git a/python/completers/cpp/flags.py b/python/completers/cpp/flags.py
index 3aa1b4b5..6004e113 100644
--- a/python/completers/cpp/flags.py
+++ b/python/completers/cpp/flags.py
@@ -22,6 +22,7 @@ import os
 import ycm_core
 import random
 import string
+import sys
 
 CLANG_OPTIONS_FILENAME = '.ycm_clang_options.py'
 
@@ -63,7 +64,10 @@ class Flags( object ):
         flags_module = self.flags_module_for_flags_module_file[
           flags_module_file ]
       except KeyError:
+        sys.path.append( _DirectoryOfThisScript() )
         flags_module = imp.load_source( _RandomName(), flags_module_file )
+        del sys.path[ -1 ]
+
         self.flags_module_for_flags_module_file[
           flags_module_file ] = flags_module
 
@@ -125,3 +129,7 @@ def _SpecialClangIncludes():
   libclang_dir = os.path.dirname( ycm_core.__file__ )
   path_to_includes = os.path.join( libclang_dir, 'clang_includes' )
   return [ '-I', path_to_includes ]
+
+
+def _DirectoryOfThisScript():
+  return os.path.dirname( os.path.abspath( __file__ ) )