Find a2x through CMake

Fixes #63

CMake/FindA2X.cmake

@@ -0,0 +1,75 @@
+#
+# (c)2015 KiCad Developers
+# (c)2015 Brian Sidebotham <brian.sidebotham@gmail.com>
+#
+# CMake module to find a2x (part of the asciidoc toolchain).
+#
+# Variables generated:
+#
+# A2X_FOUND     true when A2X_COMMAND is valid
+# A2X_COMMAND   The command to run a2x (may be a list including an interpreter)
+# A2X_VERSION   The a2x version that has been found
+#
+
+# Have a go at finding a a2x executable
+find_program( A2X_PROGRAM a2x )
+
+# Found something, attempt to try and use it...
+if( A2X_PROGRAM )
+    execute_process(
+        COMMAND ${A2X_PROGRAM} --version
+        OUTPUT_VARIABLE _OUT
+        ERROR_VARIABLE _ERR
+        RESULT_VARIABLE _RES
+        OUTPUT_STRIP_TRAILING_WHITESPACE )
+
+    # If it worked, set the A2X_COMMAND
+    if( _RES MATCHES 0 )
+        set( A2X_COMMAND "${A2X_PROGRAM}" )
+    endif()
+endif()
+
+# If nothing could be found, test to see if we can just find the script file,
+# that we'll then run with the python interpreter
+if( NOT A2X_COMMAND )
+    find_file( A2X_SCRIPT a2x.py )
+
+    if( A2X_SCRIPT )
+        # Find the python interpreter quietly
+        if( NOT PYTHONINTERP_FOUND )
+            find_package( PYTHONINTERP QUIET )
+        endif()
+
+        if( NOT PYTHONINTERP_FOUND )
+            # Python's not available so can't find a2x...
+            set( A2X_COMMAND "" )
+        else()
+            # Build the python based command
+            set( A2X_COMMAND "${PYTHON_EXECUTABLE}" "${A2X_SCRIPT}" )
+
+            execute_process(
+                COMMAND ${A2X_COMMAND} --version
+                OUTPUT_VARIABLE _OUT
+                ERROR_VARIABLE _ERR
+                RESULT_VARIABLE _RES
+                OUTPUT_STRIP_TRAILING_WHITESPACE )
+
+            # If it still can't be run, then give up
+            if( NOT _RES MATCHES 0 )
+                set( A2X_COMMAND "" )
+            endif()
+        endif()
+    endif()
+endif()
+
+# If we've found a command that works, check the version
+if( A2X_COMMAND )
+    string(REGEX REPLACE ".*a2x[^0-9.]*\([0-9.]+\).*" "\\1" A2X_VERSION "${_OUT}")
+endif()
+
+# Generate the *_FOUND as necessary, etc.
+include( FindPackageHandleStandardArgs )
+find_package_handle_standard_args(
+    A2X
+    REQUIRED_VARS A2X_COMMAND
+    VERSION_VAR A2X_VERSION )

CMakeLists.txt

@@ -8,6 +8,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${PROJECT_SOURCE_DIR}/CMake)
 
 find_package(XKBCommon REQUIRED)
 find_package(WLC REQUIRED)
+find_package(A2X REQUIRED)
 
 if (UNIX)
    find_library(DL_LIBRARY dl)
@@ -45,13 +46,13 @@ INSTALL(
 )
 
 ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/sway.1
-  COMMAND a2x --no-xmllint --doctype manpage --format manpage
+  COMMAND ${A2X_COMMAND} --no-xmllint --doctype manpage --format manpage
     -D ${CMAKE_RUNTIME_OUTPUT_DIRECTORY} ${CMAKE_CURRENT_SOURCE_DIR}/sway.1.txt 
   DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/sway.1.txt
 )
 
 ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/sway.5
-  COMMAND a2x --no-xmllint --doctype manpage --format manpage
+  COMMAND ${A2X_COMMAND} --no-xmllint --doctype manpage --format manpage
     -D ${CMAKE_RUNTIME_OUTPUT_DIRECTORY} ${CMAKE_CURRENT_SOURCE_DIR}/sway.5.txt 
   DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/sway.5.txt
 )