A script generate cscope index and .ycm_extra_conf.py, find parse all Android.mk files under current directory to get all include paths.-- 根据当前目录下所有的Android.mk文件，来生成cscope索引和.ycm_extra_conf.py文件。

cscope-ycm-android.sh

#!/bin/bash - 
#===============================================================================
#
#          FILE: cscope-android.sh
# 
#         USAGE: 
#               . build/envsetup.sh
#               lunch
#               cd /path/to/workdir
#               # first setup, find c include path by mmm command:
#               source ~/bin/cscope-ycm-android.sh 1 # must run by source!
#               # second setup, generate cscope index and .ycm_extra_conf.py
#               ~/bin/cscope-ycm-android.sh 2
# 
#   DESCRIPTION: A script generate cscope index and .ycm_extra_conf.py, find 
#                parse all Android.mk files under current directory to get all 
#                include paths.
#                根据当前目录下所有的Android.mk文件，来生成cscope索引和
#                .ycm_extra_conf.py文件。
# 
#       OPTIONS: ---
#  REQUIREMENTS: 
#               cp cscope-ycm-android.sh ~/bin/
#               chmod +x ~/bin/cscope-ycm-android.sh
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: linkscue(scue)
#  ORGANIZATION: 
#       CREATED: 2015年09月10日 15:39
#      REVISION:  ---
#===============================================================================


#-------------------------------------------------------------------------------
# 背景故事:
#   现在正式做Android的底层开发，第一个任务就是视频流的硬解码工作；
#   但是在过程中发现，VIM编辑Android这些底层的源码，跳转得不是很灵活，尝试过
#   1）使用Eclipse和Android Studio，把整个Android工程导入进行代码浏览    -- 太大
#   2）使用Source Insight进入源码索引，这个方法按理说是最好的     -- 需要Windows
#   3）使用OpenGrok进入源码浏览，这个也是非常好的    -- 但它基于搜索的不是很精确
#
# 所以最后还是选择了VIM + cscope来操作   -- 因为我现在只在一个不起眼的目录下工作
# 我只要把这个目录下，所依赖的头文件都整理出来，交给cscope来建立一个完善的索引
# 或者，让 youcomleteme 正确的找到头文件，ycm最强大的功能莫过于可以帮助检查错误
# 
# 于是乎，最后写了一这个这样子的简单脚本，实现我以上的需求
#
#-------------------------------------------------------------------------------

MYSRCTOP=/source/VDI4.5-Android-OS4C

# 用于存储C/C++头文件索引路径
include_path_file=LOCAL_C_INCLUDES.txt

#-------------------------------------------------------------------------------
# 运行方法:
#   . build/envsetup.sh
#   lunch
#   cd /path/to/workdir
#   source ~/bin/cscope-ycm-android.sh 1 
# 因为调用mmm命令解析 LOCAL_C_INCLUDE 变量，所以必须使用 source 来执行
#
# 输出结果:
#   文件: LOCAL_C_INCLUDES.txt
# 包含从Android.mk中解决出来的 LOCAL_C_INCLUDE 变量，保存形式 $MYSRCTOP/具体路径
#
# 之所以定义一个 $MYSRCTOP，是因为某些童鞋，Android编译环境可能是Docker容器里边的
# 路径，与外边的Ubuntu真实路径有所不一致，若你没有这个问题，大可以设定MYSRCTOP为$T
#-------------------------------------------------------------------------------
find_c_include(){
(
    # 错误检查
    if [[ ! -f Android.mk ]]; then
        echo "Error: can't find an Android.mk file in currect path"
        return 1
    fi

    # 备份旧的Android.mk文件
    find . -name Android.mk -exec cp -f {} {}_ \;

    # 直接修改Android.mk文件，添加输出信息
    find . -name Android.mk -exec \
        sed -i '/include \$(BUILD_/ i\$(info LOCAL_C_INCLUDES=$(LOCAL_PATH))' {} \;

    # 逐个Android.mk文件进行分析
    echo -e "\nFind all Android.mk under currect directory ..\n"
    while read line; do
        include_path=$(echo $line | awk -F'=' '{print $2}')
        for path in $include_path ; do
            echo -e "$MYSRCTOP/$path" | tee -a $include_path_file
        done
    done < <(mmm . -n | grep '^LOCAL_C_INCLUDES')

    # 恢复原始的Android.mk文件
    echo -e "\nRestore the origin Android.mk files .."
    find . -name Android.mk_ | while read mkfile; do
        mv -f $mkfile ${mkfile%_}
    done
)
}


#-------------------------------------------------------------------------------
# 运行方法:
#   cd /path/to/workdir
#   ~/bin/cscope-ycm-android.sh 2
# 输出结果:
#   cscope.files        -- cscope 索引时自动读取这个文件
#   cscope.out          -- cscope 索引输出文件，我们主要目的是要这个文件
#   .ycm_extra_conf.py  -- YouCompleteMe 额外配置文件，有了它可以检查Android编程
#                          错误，以及实际跳转（cscope也可以跳转，两者不冲突）
#-------------------------------------------------------------------------------
generate_cscope_ycmconf(){
(
    # 获取 cscope 搜索路径
    cscsope_paths="."
    while read line; do
        cscsope_paths="$cscsope_paths $line"
    done < <(cat $include_path_file)

    # 保存至 cscope.files
    find $cscsope_paths \
        -iname '*.java'    -print -o \
        -iname '*.aidl'    -print -o \
        -iname '*.hpp'     -print -o \
        -iname '*.cpp'     -print -o \
        -iname '*.xml'     -print -o \
        -iname '*.mk'      -print -o \
        -iname '*.[chxsS]' -print > cscope.files
    # 生成索引
    cscope -Rbqk && echo -e "\nGenerate cscope index done!"

    # Youcompleteme
    ycm_extra_conf_temp=/tmp/.ycm_extra_conf.py_android.tmp
    for path in $cscsope_paths ; do
        echo -e "'-isystem',\n'$path',"
    done > $ycm_extra_conf_temp

    test -s $ycm_extra_conf_temp    && \
        test -f .ycm_extra_conf.py  && \
        mv .ycm_extra_conf.py .ycm_extra_conf.py.bak

cat <<-EOF > .ycm_extra_conf.py
#!/usr/bin/env python
#
# Copyright (C) 2014  Google Inc.
#
# 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/>.

import os
import ycm_core

# These are the compilation flags that will be used in case there's no
# compilation database set (by default, one is not set).
# CHANGE THIS LIST OF FLAGS. YES, THIS IS THE DROID YOU HAVE BEEN LOOKING FOR.
flags = [
'-Wall',
'-Wextra',
'-Werror',
'-fexceptions',
'-DNDEBUG',
# THIS IS IMPORTANT! Without a "-std=<something>" flag, clang won't know which
# language to use when compiling headers. So it will guess. Badly. So C++
# headers will be compiled as C headers. You don't want that so ALWAYS specify
# a "-std=<something>".
# For a C project, you would set this to something like 'c99' instead of
# 'c++11'.
'-std=c++11',
# ...and the same thing goes for the magic -x option which specifies the
# language that the files to be compiled are written in. This is mostly
# relevant for c++ headers.
# For a C project, you would set this to 'c' instead of 'c++'.
'-x',
'c++',
$(cat $ycm_extra_conf_temp)
''
]


# Set this to the absolute path to the folder (NOT the file!) containing the
# compile_commands.json file to use that instead of 'flags'. See here for
# more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html
#
# Most projects will NOT need to set this to anything; you can just change the
# 'flags' list of compilation flags.
compilation_database_folder = ''

if os.path.exists( compilation_database_folder ):
  database = ycm_core.CompilationDatabase( compilation_database_folder )
else:
  database = None

SOURCE_EXTENSIONS = [ '.cpp', '.cxx', '.cc', '.c', '.m', '.mm' ]

def DirectoryOfThisScript():
  return os.path.dirname( os.path.abspath( __file__ ) )


def MakeRelativePathsInFlagsAbsolute( flags, working_directory ):
  if not working_directory:
    return list( flags )
  new_flags = []
  make_next_absolute = False
  path_flags = [ '-isystem', '-I', '-iquote', '--sysroot=' ]
  for flag in flags:
    new_flag = flag

    if make_next_absolute:
      make_next_absolute = False
      if not flag.startswith( '/' ):
        new_flag = os.path.join( working_directory, flag )

    for path_flag in path_flags:
      if flag == path_flag:
        make_next_absolute = True
        break

      if flag.startswith( path_flag ):
        path = flag[ len( path_flag ): ]
        new_flag = path_flag + os.path.join( working_directory, path )
        break

    if new_flag:
      new_flags.append( new_flag )
  return new_flags


def IsHeaderFile( filename ):
  extension = os.path.splitext( filename )[ 1 ]
  return extension in [ '.h', '.hxx', '.hpp', '.hh' ]


def GetCompilationInfoForFile( filename ):
  # The compilation_commands.json file generated by CMake does not have entries
  # for header files. So we do our best by asking the db for flags for a
  # corresponding source file, if any. If one exists, the flags for that file
  # should be good enough.
  if IsHeaderFile( filename ):
    basename = os.path.splitext( filename )[ 0 ]
    for extension in SOURCE_EXTENSIONS:
      replacement_file = basename + extension
      if os.path.exists( replacement_file ):
        compilation_info = database.GetCompilationInfoForFile(
          replacement_file )
        if compilation_info.compiler_flags_:
          return compilation_info
    return None
  return database.GetCompilationInfoForFile( filename )


# This is the entry point; this function is called by ycmd to produce flags for
# a file.
def FlagsForFile( filename, **kwargs ):
  if database:
    # Bear in mind that compilation_info.compiler_flags_ does NOT return a
    # python list, but a "list-like" StringVec object
    compilation_info = GetCompilationInfoForFile( filename )
    if not compilation_info:
      return None

    final_flags = MakeRelativePathsInFlagsAbsolute(
      compilation_info.compiler_flags_,
      compilation_info.compiler_working_dir_ )
  else:
    relative_to = DirectoryOfThisScript()
    final_flags = MakeRelativePathsInFlagsAbsolute( flags, relative_to )

  return {
    'flags': final_flags,
    'do_cache': True
  }
EOF
echo -e "\nGenerate .ycm_extra_conf.py done!"

)
}

case $1 in
    1|f|find )
        find_c_include
        ;;
    2|g|gen )
        generate_cscope_ycmconf
        ;;
esac