Merge pull request #136 from rongjiecomputer/cc_library

[CMake] Implement absl_cc_library as Bazel's cc_library 

1 files changed, 103 insertions, 0 deletions

diff --git a/CMake/AbseilHelpers.cmake b/CMake/AbseilHelpers.cmake
index 0c9341747512..96813b083d01 100644
--- a/CMake/AbseilHelpers.cmake
+++ b/CMake/AbseilHelpers.cmake
@@ -62,7 +62,110 @@ function(absl_library)
   endif()
 endfunction()
 
+#
+# CMake function to imitate Bazel's cc_library rule.
+#
+# Parameters:
+# NAME: name of target (see Note)
+# HDRS: List of public header files for the library
+# SRCS: List of source files for the library
+# DEPS: List of other libraries to be linked in to the binary targets
+# COPTS: List of private compile options
+# DEFINES: List of public defines
+# LINKOPTS: List of link options
+# PUBLIC: Add this so that this library will be exported under absl:: (see Note).
+# TESTONLY: When added, this target will only be built if user passes -DABSL_RUN_TESTS=ON to CMake.
+#
+# Note:
+#
+# By default, absl_cc_library will always create a library named absl_internal_${NAME},
+# which means other targets can only depend this library as absl_internal_${NAME}, not ${NAME}.
+# This is to reduce namespace pollution.
+#
+# absl_cc_library(
+#   NAME
+#     awesome_lib
+#   HDRS
+#     "a.h"
+#   SRCS
+#     "a.cc"
+# )
+# absl_cc_library(
+#   NAME
+#     fantastic_lib
+#   SRCS
+#     "b.cc"
+#   DEPS
+#     absl_internal_awesome_lib # not "awesome_lib"!
+# )
+#
+# If PUBLIC is set, absl_cc_library will instead create a target named
+# absl_${NAME} and an alias absl::${NAME}.
+#
+# absl_cc_library(
+#   NAME
+#     main_lib
+#   ...
+#   PUBLIC
+# )
+#
+# User can then use the library as absl::main_lib (although absl_main_lib is defined too).
+#
+# TODO: Implement "ALWAYSLINK"
 
+function(absl_cc_library)
+  cmake_parse_arguments(ABSL_CC_LIB
+    "DISABLE_INSTALL;PUBLIC;TESTONLY"
+    "NAME"
+    "HDRS;SRCS;COPTS;DEFINES;LINKOPTS;DEPS"
+    ${ARGN}
+  )
+
+  if (NOT ABSL_CC_LIB_TESTONLY OR ABSL_RUN_TESTS)
+    if (ABSL_CC_LIB_PUBLIC)
+      set(_NAME "absl_${ABSL_CC_LIB_NAME}")
+    else()
+      set(_NAME "absl_internal_${ABSL_CC_LIB_NAME}")
+    endif()
+
+    # Check if this is a header-only library
+    if ("${ABSL_CC_LIB_SRCS}" STREQUAL "")
+      set(ABSL_CC_LIB_IS_INTERFACE 1)
+    else()
+      set(ABSL_CC_LIB_IS_INTERFACE 0)
+    endif()
+
+    if(NOT ABSL_CC_LIB_IS_INTERFACE)
+      add_library(${_NAME} STATIC "")
+      target_sources(${_NAME} PRIVATE ${ABSL_CC_LIB_SRCS} ${ABSL_CC_LIB_HDRS})
+      target_include_directories(${_NAME}
+        PUBLIC ${ABSL_COMMON_INCLUDE_DIRS})
+      # TODO(rongjiecomputer): Revisit ABSL_COMPILE_CXXFLAGS when fixing GH#123
+      target_compile_options(${_NAME}
+        PRIVATE ${ABSL_COMPILE_CXXFLAGS} ${ABSL_CC_LIB_COPTS})
+      target_link_libraries(${_NAME}
+        PUBLIC ${ABSL_CC_LIB_DEPS}
+        PRIVATE ${ABSL_CC_LIB_LINKOPTS}
+      )
+      target_compile_definitions(${_NAME} PUBLIC ${ABSL_CC_LIB_DEFINES})
+
+      # Add all Abseil targets to a a folder in the IDE for organization.
+      set_property(TARGET ${_NAME} PROPERTY FOLDER ${ABSL_IDE_FOLDER})
+    else()
+      # Generating header-only library
+      add_library(${_NAME} INTERFACE)
+      target_include_directories(${_NAME} INTERFACE ${ABSL_COMMON_INCLUDE_DIRS})
+      target_link_libraries(${_NAME}
+        INTERFACE ${ABSL_CC_LIB_DEPS} ${ABSL_CC_LIB_LINKOPTS}
+      )
+      target_compile_definitions(${_NAME} INTERFACE ${ABSL_CC_LIB_DEFINES})
+    endif()
+
+    if(ABSL_CC_LIB_PUBLIC)
+      add_library(absl::${ABSL_CC_LIB_NAME} ALIAS ${_NAME})
+    endif()
+  endif()
+endfunction()
 
 #
 # header only virtual target creation