Add 'FindCapnProto' CMake module to locate libraries and compile schemas.

CMakeLists.txt

+project("Cap'n Proto" CXX)
+cmake_minimum_required(VERSION 2.8)
+
+set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
+
+add_subdirectory(c++)

c++/CMakeLists.txt

-project("Cap'n Proto" CXX)
-cmake_minimum_required(VERSION 2.8)
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-unused-parameter -std=c++11 -pthread")
 

c++/src/CMakeLists.txt

 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
+find_package(CapnProto)
+set(CAPNP_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR})
+
 # kj ==============================================================
 
 add_library(kj
@@ -164,13 +167,13 @@ add_executable(capnpc_capnp
 target_link_libraries(capnpc_capnp capnp kj)
 set_target_properties(capnpc_capnp PROPERTIES OUTPUT_NAME capnpc-capnp)
 
+# Install ==============================================================
+
 export(TARGETS capnp capnp-tool capnp-rpc capnpc capnpc_cpp capnpc_capnp kj kj-async
   FILE ${CMAKE_CURRENT_BINARY_DIR}/capnp-config.cmake
 )
 export(PACKAGE capnp)
 
-# Install ==============================================================
-
 install(TARGETS capnp capnp-tool capnp-rpc capnpc capnpc_cpp capnpc_capnp kj kj-async
   EXPORT capnp
   RUNTIME DESTINATION bin
@@ -178,8 +181,6 @@ install(TARGETS capnp capnp-tool capnp-rpc capnpc capnpc_cpp capnpc_capnp kj kj-
   ARCHIVE DESTINATION lib
 )
 
-install(EXPORT capnp DESTINATION lib/cmake/capnp)
-
 # Symlink capnpc -> capnp
 install(CODE "execute_process(COMMAND \"${CMAKE_COMMAND}\" -E create_symlink capnp ${CMAKE_INSTALL_PREFIX}/bin/capnpc)")
 
@@ -224,37 +225,14 @@ set(test_capnp_files
   capnp/test-import2.capnp
 )
 
-set(test_capnp_output_dir ${CMAKE_CURRENT_BINARY_DIR}/test_capnp)
-file(MAKE_DIRECTORY ${test_capnp_output_dir})
-
-set(test_capnp_cpp_files)
-set(test_capnp_header_files)
-set(test_capnp_capnp_files)
-
-foreach(_file ${test_capnp_files})
-  list(APPEND test_capnp_cpp_files ${test_capnp_output_dir}/${_file}.c++)
-  list(APPEND test_capnp_header_files ${test_capnp_output_dir}/${_file}.h)
-  get_filename_component(_capnp_abs ${_file} ABSOLUTE)
-  list(APPEND test_capnp_capnp_files ${_capnp_abs})
-  set_source_files_properties(
-    ${test_capnp_output_dir}/${_file}.capnp.c++
-    PROPERTIES GENERATED TRUE)
-endforeach()
-
-add_custom_command(
-  OUTPUT
-    ${test_capnp_cpp_files}
-    ${test_capnp_header_files}
-  COMMAND capnp-tool compile
-    -o $<TARGET_FILE:capnpc_cpp>:${test_capnp_output_dir}
-    --src-prefix=${CMAKE_CURRENT_SOURCE_DIR}
-    -I${CMAKE_CURRENT_SOURCE_DIR}
-    ${test_capnp_capnp_files}
-  DEPENDS capnp-tool capnpc_cpp ${test_capnp_files}
-)
+set(CAPNP_EXECUTABLE $<TARGET_FILE:capnp-tool>)
+set(CAPNPC_CXX_EXECUTABLE $<TARGET_FILE:capnpc_cpp>)
+set(CAPNPC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/test_capnp)
+file(MAKE_DIRECTORY ${CAPNPC_OUTPUT_DIR})
 
+capnp_generate_cpp(test_capnp_cpp_files test_capnp_h_files ${test_capnp_files})
 
-include_directories(${test_capnp_output_dir})
+include_directories(${CAPNPC_OUTPUT_DIR})
 
 add_executable(capnp-tests
   kj/common-test.c++
@@ -304,6 +282,7 @@ add_executable(capnp-tests
   capnp/compiler/lexer-test.c++
   capnp/compiler/md5-test.c++
   ${test_capnp_cpp_files}
+  ${test_capnp_h_files}
 )
 target_link_libraries(capnp-tests
   capnpc

cmake/FindCapnProto.cmake

+#
+# Finds the Cap'n Proto libraries, and compiles schema files.
+#
+# Configuration variables (optional):
+#   CAPNPC_OUTPUT_DIR
+#       Directory to place compiled schema sources (default: the same directory as the schema file).
+#   CAPNPC_IMPORT_DIRS
+#       List of additional include directories for the schema compiler.
+#       (CMAKE_CURRENT_SOURCE_DIR and CAPNP_INCLUDE_DIRS are always included.)
+#   CAPNPC_SRC_PREFIX
+#       Schema file source prefix (default: CMAKE_CURRENT_SOURCE_DIR).
+#   CAPNPC_FLAGS
+#       Additional flags to pass to the schema compiler.
+#
+# Variables that are discovered:
+#   CAPNP_EXECUTABLE
+#       Path to the `capnp` tool (can be set to override).
+#   CAPNPC_CXX_EXECUTABLE
+#       Path to the `capnpc-c++` tool (can be set to override).
+#   CAPNP_INCLUDE_DIRS
+#       Include directories for the library's headers (can be set to override).
+#   CAPNP_LIBRARIES
+#       The necessary library paths to link with.
+#   CAPNP_FOUND
+#       Set if the libraries have been located.
+#
+# Example usage:
+#
+#   find_package(CapnProto REQUIRED)
+#   include_directories(${CAPNP_INCLUDE_DIRS})
+#
+#   capnp_generate_cpp(CAPNP_SRCS CAPNP_HDRS schema.capnp)
+#   add_executable(a a.cc ${CAPNP_SRCS} ${CAPNP_HDRS})
+#   target_link_library(a ${CAPNP_LIBRARIES})
+#
+# For out-of-source builds:
+#
+#   set(CAPNPC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR})
+#   include_directories(${CAPNPC_OUTPUT_DIR})
+#   capnp_generate_cpp(...)
+#
+
+function(CAPNP_GENERATE_CPP SOURCES HEADERS)
+  if(NOT ARGN)
+    message(SEND_ERROR "CAPNP_GENERATE_CPP() called without any source files.")
+  endif()
+  if(NOT CAPNP_EXECUTABLE)
+    message(SEND_ERROR "Could not locate capnp executable (CAPNP_EXECUTABLE).")
+  endif()
+  if(NOT CAPNPC_CXX_EXECUTABLE)
+    message(SEND_ERROR "Could not locate capnpc-c++ executable (CAPNPC_CXX_EXECUTABLE).")
+  endif()
+  if(NOT CAPNP_INCLUDE_DIRS)
+    message(SEND_ERROR "Could not locate capnp header files (CAPNP_INCLUDE_DIRS).")
+  endif()
+
+  # Default compiler includes
+  set(include_path -I ${CMAKE_CURRENT_SOURCE_DIR} -I ${CAPNP_INCLUDE_DIRS})
+
+  if(DEFINED CAPNPC_IMPORT_DIRS)
+    # Append each directory as a series of '-I' flags in ${include_path}
+    foreach(directory ${CAPNPC_IMPORT_DIRS})
+      get_filename_component(absolute_path ${directory} ABSOLUTE)
+      list(APPEND include_path -I ${absolute_path})
+    endforeach()
+  endif()
+
+  if(DEFINED CAPNPC_OUTPUT_DIR)
+    # Prepend a ':' to get the format for the '-o' flag right
+    set(output_dir ":${CAPNPC_OUTPUT_DIR}")
+  else()
+    set(output_dir)
+  endif()
+
+  if(NOT DEFINED CAPNPC_SRC_PREFIX)
+    set(CAPNPC_SRC_PREFIX ${CMAKE_CURRENT_SOURCE_DIR})
+  endif()
+  get_filename_component(CAPNPC_SRC_PREFIX ${CAPNPC_SRC_PREFIX} ABSOLUTE)
+
+  set(${SOURCES})
+  set(${HEADERS})
+  foreach(schema_file ${ARGN})
+    get_filename_component(file_path ${schema_file} ABSOLUTE)
+    get_filename_component(file_dir ${file_path} DIRECTORY)
+
+    # Figure out where the output files will go
+    if (NOT DEFINED CAPNPC_OUTPUT_DIR)
+      set(output_base ${file_path})
+    else()
+      # Output files are placed in CAPNPC_OUTPUT_DIR, at a location as if they were
+      # relative to CAPNPC_SRC_PREFIX.
+      string(LENGTH ${CAPNPC_SRC_PREFIX} prefix_len)
+      string(SUBSTRING ${file_path} 0 ${prefix_len} output_prefix)
+      if(NOT ${CAPNPC_SRC_PREFIX} STREQUAL ${output_prefix})
+        message(SEND_ERROR "Could not determine output path for '${schema_file}' ('${file_path}') with source prefix '${CAPNPC_SRC_PREFIX}' into '${CAPNPC_OUTPUT_DIR}'.")
+      endif()
+
+      string(SUBSTRING ${file_path} ${prefix_len} -1 output_path)
+      set(output_base ${CAPNPC_OUTPUT_DIR}${output_path})
+    endif()
+
+    add_custom_command(
+      OUTPUT "${output_base}.c++" "${output_base}.h"
+      COMMAND ${CAPNP_EXECUTABLE}
+      ARGS compile 
+          -o ${CAPNPC_CXX_EXECUTABLE}${output_dir}
+          --src-prefix ${CAPNPC_SRC_PREFIX}
+          ${include_path}
+          ${CAPNPC_FLAGS}
+          ${file_path}
+      DEPENDS ${schema_file}
+      COMMENT "Compiling Cap'n Proto schema ${schema_file}"
+      VERBATIM
+    )
+    list(APPEND ${SOURCES} "${output_base}.c++")
+    list(APPEND ${HEADERS} "${output_base}.h")
+  endforeach()
+
+  set_source_files_properties(${${SOURCES}} ${${HEADERS}} PROPERTIES GENERATED TRUE)
+  set(${SOURCES} ${${SOURCES}} PARENT_SCOPE)
+  set(${HEADERS} ${${HEADERS}} PARENT_SCOPE)
+endfunction()
+
+find_library(CAPNP_LIB_KJ kj)
+find_library(CAPNP_LIB_KJ-ASYNC kj-async)
+find_library(CAPNP_LIB_CAPNP capnp)
+find_library(CAPNP_LIB_CAPNP-RPC capnp-rpc)
+find_library(CAPNP_LIB_CAPNPC capnpc)
+mark_as_advanced(CAPNP_LIB_KJ CAPNP_LIB_KJ-ASYNC CAPNP_LIB_CAPNP CAPNP_LIB_CAPNP-RPC CAPNP_LIB_CAPNPC)
+set(CAPNP_LIBRARIES
+  ${CAPNP_LIB_KJ}
+  ${CAPNP_LIB_KJ-ASYNC}
+  ${CAPNP_LIB_CAPNP}
+  ${CAPNP_LIB_CAPNP-RPC}
+  ${CAPNP_LIB_CAPNPC}
+)
+
+find_path(CAPNP_INCLUDE_DIRS capnp/generated-header-support.h)
+
+find_program(CAPNP_EXECUTABLE
+  NAMES capnp
+  DOC "Cap'n Proto Command-line Tool"
+)
+
+find_program(CAPNPC_CXX_EXECUTABLE
+  NAMES capnpc-c++
+  DOC "Capn'n Proto C++ Compiler"
+)
+