Add Doxygen support to CMake build.

Unfortunately the ``Doxyfile`` needs to be configured (Doxyfile.in ->
Doxyfile) for out of source builds which means the Makefile also had to
be taught to do this.

An option ``WITH_DOCS`` has been added so that setting up the build
system to be able to build documentation can be disabled. Note the
``doc`` target is not run by default because it is a phony target and
if it was added to all it would run everytime.


Former-commit-id: 27b90ca

.gitignore

@@ -155,6 +155,7 @@ src/test_*.s
 *.guru
 *.dSYM
 .*.swp
+Doxyfile
 
 # jrk editor settings
 .tm_properties

CMakeLists.txt

@@ -60,3 +60,19 @@ if (!WIN32)
   add_subdirectory(apps)
   add_subdirectory(tutorial)
 endif()
+
+option(WITH_DOCS "Enable building of documentation" ON)
+if (WITH_DOCS)
+find_package(Doxygen)
+  if (NOT DOXYGEN_FOUND)
+    message(FATAL_ERROR "Could not find Doxygen. Either install it or set WITH_DOCS to OFF")
+  endif()
+
+  configure_file(${CMAKE_SOURCE_DIR}/Doxyfile.in ${CMAKE_BINARY_DIR}/Doxyfile @ONLY)
+  # Note documentation is not built by default, the user needs to build the "doc" target
+  add_custom_target(doc
+    COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_BINARY_DIR}/Doxyfile
+    WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+    COMMENT "Building Doxygen documentation"
+  )
+endif()

Doxyfile → Doxyfile.in

@@ -38,7 +38,7 @@ PROJECT_NUMBER         =
 # If a relative path is entered, it will be relative to the location
 # where doxygen was started. If left blank the current directory will be used.
 
-OUTPUT_DIRECTORY       = doc
+OUTPUT_DIRECTORY       = @CMAKE_BINARY_DIR@/doc
 
 # If the CREATE_SUBDIRS tag is set to YES, then doxygen will create
 # 4096 sub-directories (in 2 levels) under the output directory of each output
@@ -574,7 +574,7 @@ WARN_LOGFILE           =
 # directories like "/usr/src/myproject". Separate the files or directories
 # with spaces.
 
-INPUT                  = src test
+INPUT                  = "@CMAKE_SOURCE_DIR@/src" "@CMAKE_SOURCE_DIR@/test"
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding, which is
@@ -631,7 +631,7 @@ EXCLUDE_SYMBOLS        =
 # directories that contain example code fragments that are included (see
 # the \include command).
 
-EXAMPLE_PATH           = tutorial
+EXAMPLE_PATH           = @CMAKE_SOURCE_DIR@
 
 # If the value of the EXAMPLE_PATH tag contains directories, you can use the
 # EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp

Makefile

@@ -969,9 +969,15 @@ endif
 
 .PHONY: doc
 docs: doc
-doc: src
+doc: src Doxyfile
 	doxygen
 
+Doxyfile: Doxyfile.in
+	@echo "Generating $@"
+	@sed -e "s#@CMAKE_BINARY_DIR@#$(shell pwd)#g" \
+	     -e "s#@CMAKE_SOURCE_DIR@#$(shell pwd)#g" \
+	    $< > $@
+
 $(DISTRIB_DIR)/halide.tgz: $(BIN_DIR)/libHalide.a $(BIN_DIR)/libHalide.so include/Halide.h include/HalideRuntime.h
 	mkdir -p $(DISTRIB_DIR)/include $(DISTRIB_DIR)/bin $(DISTRIB_DIR)/tutorial $(DISTRIB_DIR)/tutorial/images $(DISTRIB_DIR)/tools
 	cp $(BIN_DIR)/libHalide.a $(BIN_DIR)/libHalide.so $(DISTRIB_DIR)/bin