cmake: Add C++ documentation

CMakeLists.txt

@@ -257,6 +257,8 @@ message(STATUS "XPRESS support: ${USE_XPRESS}")
 
 # Language specific options
 if(BUILD_CXX)
+  CMAKE_DEPENDENT_OPTION(BUILD_CXX_DOC "Build the C++ doc" OFF "NOT BUILD_DOC" ON)
+  message(STATUS "C++: Build doc: ${BUILD_CXX_DOC}")
 endif()
 
 if(BUILD_DOTNET)

cmake/README.md

@@ -222,6 +222,7 @@ cmake -S. -Bbuild -LH
 | `USE_XPRESS` | OFF | Enable XPRESS support |
 | | | |
 | `BUILD_DOC`   | OFF\* | Build all documentations |
+| `BUILD_CXX_DOC` | OFF\* | Build C++ documentation<br>**Forced** to ON if `BUILD_DOC=ON` |
 | `INSTALL_DOC` | OFF\* | Install all documentations<br>**Forced** to OFF if `BUILD_CXX=OFF` or `BUILD_DOC=OFF` |
 | | | |
 | `BUILD_SAMPLES`  | ON\* | Build all samples<br>Default to ON if `BUILD_DEPS=ON` |

cmake/cpp.cmake

@@ -287,6 +287,35 @@ add_subdirectory(ortools/linear_solver/proto_solver)
 target_sources(${PROJECT_NAME} PRIVATE $<TARGET_OBJECTS:${PROJECT_NAME}_linear_solver_proto_solver>)
 add_dependencies(${PROJECT_NAME} ${PROJECT_NAME}_linear_solver_proto_solver)
 
+###############
+## Doc rules ##
+###############
+if(BUILD_CXX_DOC)
+  # add a target to generate API documentation with Doxygen
+  find_package(Doxygen REQUIRED)
+  if(DOXYGEN_FOUND)
+    configure_file(${PROJECT_SOURCE_DIR}/ortools/cpp/Doxyfile.in ${PROJECT_BINARY_DIR}/cpp/Doxyfile @ONLY)
+    file(DOWNLOAD
+      https://raw.githubusercontent.com/jothepro/doxygen-awesome-css/v2.1.0/doxygen-awesome.css
+      ${PROJECT_BINARY_DIR}/cpp/doxygen-awesome.css
+      SHOW_PROGRESS
+    )
+    add_custom_target(${PROJECT_NAME}_cxx_doc ALL
+      #COMMAND ${CMAKE_COMMAND} -E rm -rf ${PROJECT_BINARY_DIR}/docs/cpp
+      COMMAND ${CMAKE_COMMAND} -E make_directory ${PROJECT_BINARY_DIR}/docs/cpp
+      COMMAND ${DOXYGEN_EXECUTABLE} ${PROJECT_BINARY_DIR}/cpp/Doxyfile
+      DEPENDS
+        ${PROJECT_BINARY_DIR}/cpp/Doxyfile
+        ${PROJECT_BINARY_DIR}/cpp/doxygen-awesome.css
+        ${PROJECT_SOURCE_DIR}/ortools/cpp/stylesheet.css
+      WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+      COMMENT "Generating C++ API documentation with Doxygen"
+      VERBATIM)
+  else()
+    message(WARNING "cmd `doxygen` not found, C++ doc generation is disable!")
+  endif()
+endif()
+
 ###################
 ## Install rules ##
 ###################

ortools/cpp/main.cpp.dox

@@ -0,0 +1,29 @@
+/*! @file
+* @author Laurent Perron <lperron@google.com>
+* @author Corentin "Mizux" Le Molgat <corentinl@google.com>
+*/
+
+/*! @mainpage OR-Tools
+This is the reference documentation for Google OR-Tools.
+
+This repository contains several component:
+
+@li @ref ortools/algorithms "Algorithms"
+@li @ref ortools/graph "Graph"
+@li @ref ortools/linear_solver "Linear Solver"
+@li @ref ortools/math_opt "Math Opt" (Bazel only)
+@li @ref ortools/glop "GLOP"
+@li @ref ortools/sat "SAT"
+@li @ref ortools/pdlp "PDLP"
+@li @ref ortools/constraint_solver "Constraint Solver"
+@li @ref ortools/routing "Routing"
+@li @ref ortools/packing "Packing"
+@li @ref ortools/scheduling "Scheduling"
+
+Misc:
+
+@li @ref ortools/init "init"
+@li @ref ortools/base "base"
+@li @ref ortools/util "util"
+
+*/

ortools/cpp/stylesheet.css

@@ -0,0 +1,16 @@
+/* The standard CSS for doxygen 1.9.6*/
+
+html {
+/* page base colors */
+/*--page-background-color: white;*/
+/*--page-foreground-color: black;*/
+
+/* header */
+--header-background: #4285f4;
+--header-foreground: white;
+
+/* footer */
+--footer-background: #4285f4;
+--footer-foreground: white;
+}
+