Created by: luotao1

由于合并中英文目录到doc/后，会有index_en.rst和index_cn.rst。而sphinx编译时，必须有名字为index.rst或index.md的文件。因此在sphinx编译前复制index_en/cn.rst为index.rst，编译后删除复制出的index.rst，能生成两颗目录树。

将doc_cn目录合并到doc后，只需修改doc/CMakeLists.txt如下，就能在一个doc目录下，生成两颗目录树。：

set(BINARY_BUILD_DIR_EN "${CMAKE_CURRENT_BINARY_DIR}/en/_build")
set(SPHINX_CACHE_DIR_EN "${CMAKE_CURRENT_BINARY_DIR}/en/_doctrees")
set(SPHINX_HTML_DIR_EN "${CMAKE_CURRENT_BINARY_DIR}/en/html")
set(INDEX_NAME_EN "index_en.rst")

configure_file(
    "${CMAKE_CURRENT_SOURCE_DIR}/conf.py.in"
    "${BINARY_BUILD_DIR_EN}/conf.py"
    @ONLY)

sphinx_add_target(paddle_docs
                  html
                  ${BINARY_BUILD_DIR_EN}
                  ${SPHINX_CACHE_DIR_EN}
                  ${CMAKE_CURRENT_SOURCE_DIR}
                  ${SPHINX_HTML_DIR_EN}
                  ${INDEX_NAME_EN})

add_dependencies(paddle_docs
  gen_proto_py)
-----------------------------------------------------
set(BINARY_BUILD_DIR_CN "${CMAKE_CURRENT_BINARY_DIR}/cn/_build")
set(SPHINX_CACHE_DIR_CN "${CMAKE_CURRENT_BINARY_DIR}/cn/_doctrees")
set(SPHINX_HTML_DIR_CN "${CMAKE_CURRENT_BINARY_DIR}/cn/html")
set(INDEX_NAME_CN "index_cn.rst")

configure_file(
    "${CMAKE_CURRENT_SOURCE_DIR}/conf.py.in"
    "${BINARY_BUILD_DIR_CN}/conf.py"
    @ONLY)

sphinx_add_target(paddle_docs_cn
                  html
                  ${BINARY_BUILD_DIR_CN}
                  ${SPHINX_CACHE_DIR_CN}
                  ${CMAKE_CURRENT_SOURCE_DIR}
                  ${SPHINX_HTML_DIR_CN}
                  ${INDEX_NAME_CN})

add_dependencies(paddle_docs_cn
  gen_proto_py)