refactor: redesign cmake build system

BREAKING CHANGE: major redesign of the cmake build system, many macros and
functions have been changed and the build system overall has been
simplified.
Refer to the documentation for more information.

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "third_party/gsl"]
 	path = third_party/gsl
 	url = https://github.com/microsoft/GSL.git
+[submodule "cmake/common"]
+	path = cmake/common
+	url = https://github.com/abdes/cmake

.vscode/settings.json

@@ -292,5 +292,4 @@
   "cmakeFormat.args": [
     "--config-file=${workspaceFolder}/.cmake-format.yaml"
   ],
-  "python.pythonPath": "${workspaceFolder}\\.sphinx\\python"
 }

cmake/AsapTargets.cmake

@@ -0,0 +1,128 @@
+# ~~~
+#        Copyright The Authors 2018.
+#    Distributed under the 3-Clause BSD License.
+#    (See accompanying file LICENSE or copy at
+#   https://opensource.org/licenses/BSD-3-Clause)
+# ~~~
+
+include(CMakePackageConfigHelpers)
+include(common/SwiftTargets)
+include(CompileDefinitions)
+
+# --------------------------------------------------------------------------------------------------
+# Meta information about the this module
+# --------------------------------------------------------------------------------------------------
+
+macro(asap_declare_module)
+  set(options)
+  set(oneValueArgs
+      MODULE_NAME
+      DESCRIPTION
+      GITHUB_REPO
+      AUTHOR_MAINTAINER
+      VERSION_MAJOR
+      VERSION_MINOR
+      VERSION_PATCH)
+  set(multiValueArgs)
+
+  cmake_parse_arguments(x "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+  if(NOT DEFINED x_MODULE_NAME)
+    message(FATAL_ERROR "Module name is required.")
+    return()
+  endif()
+  if(NOT
+     (DEFINED x_VERSION_MAJOR
+      AND DEFINED x_VERSION_MINOR
+      AND DEFINED x_VERSION_PATCH))
+    message(
+      FATAL_ERROR "PLease specify all of VERSION_MAJOR VERSION_MINOR VERSION_PATCH for the module.")
+    return()
+  endif()
+
+  # cmake-format: off
+  set(META_MODULE_NAME                "${x_MODULE_NAME}")
+  set(META_MODULE_DESCRIPTION         "${x_DESCRIPTION}")
+  set(META_MODULE_GITHUB_REPO         "${x_GITHUB_REPO}")
+  set(META_MODULE_AUTHOR_MAINTAINER   "${x_AUTHOR_MAINTAINER}")
+  set(META_MODULE_VERSION_MAJOR       "${x_VERSION_MAJOR}")
+  set(META_MODULE_VERSION_MINOR       "${x_VERSION_MINOR}")
+  set(META_MODULE_VERSION_PATCH       "${x_VERSION_PATCH}")
+  set(META_MODULE_VERSION             "${META_MODULE_VERSION_MAJOR}.${META_MODULE_VERSION_MINOR}.${META_MODULE_VERSION_PATCH}")
+  set(META_MODULE_NAME_VERSION        "${META_MODULE_PROJECT_NAME} v${META_MODULE_VERSION}")
+  # cmake-format: on
+  message("=> [module: ${META_PROJECT_NAME}/${META_MODULE_NAME} ${META_MODULE_VERSION}]")
+
+endmacro()
+
+# --------------------------------------------------------------------------------------------------
+# CMake package config
+# --------------------------------------------------------------------------------------------------
+
+macro(_module_cmake_config_files)
+  set(TARGETS_EXPORT_NAME "${MODULE_TARGET_NAME}Targets")
+
+  # generate the config file that includes the exports
+  configure_package_config_file(
+    ${CMAKE_CURRENT_SOURCE_DIR}/config.cmake.in
+    "${CMAKE_CURRENT_BINARY_DIR}/${MODULE_TARGET_NAME}Config.cmake"
+    INSTALL_DESTINATION "${ASAP_INSTALL_CMAKE}/${META_MODULE_NAME}"
+    PATH_VARS META_MODULE_VERSION MODULE_TARGET_NAME)
+
+  # generate the version file for the config file
+  write_basic_package_version_file(
+    "${CMAKE_CURRENT_BINARY_DIR}/${MODULE_TARGET_NAME}ConfigVersion.cmake"
+    VERSION "${META_MODULE_VERSION}"
+    COMPATIBILITY AnyNewerVersion)
+endmacro()
+
+# --------------------------------------------------------------------------------------------------
+# Pkg-config file.
+# --------------------------------------------------------------------------------------------------
+
+macro(_module_pkgconfig_files)
+  set(MODULE_PKGCONFIG_FILE ${MODULE_TARGET_NAME}.pc)
+  get_target_property(TARGET_DEBUG_POSTFIX ${MODULE_TARGET_NAME} DEBUG_POSTFIX)
+  set(MODULE_LINK_LIBS "-l${MODULE_TARGET_NAME}${TARGET_DEBUG_POSTFIX}")
+  configure_file(config.pc.in ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_PKGCONFIG_FILE} @ONLY)
+  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${MODULE_PKGCONFIG_FILE}
+          DESTINATION ${ASAP_INSTALL_PKGCONFIG})
+endmacro()
+
+macro(asap_add_library target)
+  swift_add_library("${target}" ${ARGN})
+
+  # We can refer to this target either with its standalone target name or with a project scoped name
+  # (<project>::<module>) which we will alias to the target name.
+  add_library("${META_PROJECT_NAME}::${META_MODULE_NAME}" ALIAS ${MODULE_TARGET_NAME})
+  asap_set_compile_definitions(${target})
+
+  set_target_properties(
+    ${MODULE_TARGET_NAME}
+    PROPERTIES FOLDER "Libraries"
+               VERSION ${META_MODULE_VERSION}
+               SOVERSION ${META_MODULE_VERSION_MAJOR}
+               DEBUG_POSTFIX "d")
+
+  # Generate export headers for the library
+  asap_generate_export_headers(${MODULE_TARGET_NAME} ${META_MODULE_NAME})
+
+  _module_cmake_config_files()
+  _module_pkgconfig_files()
+endmacro()
+
+macro(asap_add_executable target)
+  swift_add_executable("${target}" ${ARGN})
+endmacro()
+
+macro(asap_add_tool target)
+  swift_add_tool("${target}" ${ARGN})
+endmacro()
+
+macro(asap_add_tool_library target)
+  swift_add_tool_library("${target}" ${ARGN})
+endmacro()
+
+macro(asap_add_test_library target)
+  swift_add_test_library("${target}" ${ARGN})
+endmacro()