Bug 1287924 - Add a template for conditionally including moz.configure files. r=glandium

MozReview-Commit-ID: FyT7jLmTxvP

build/moz.configure/toolchain.configure

@@ -65,12 +65,10 @@ def extra_toolchain_flags(_):
 # ==============================================================
 
 @depends('--disable-compile-environment', build_project, gonkdir, '--help')
-def android_ndk_include(compile_env, build_project, gonkdir, _):
-    if compile_env and (gonkdir or build_project in ('mobile/android', 'js')):
-        return 'android-ndk.configure'
-
-include(android_ndk_include)
+def compiling_android(compile_env, build_project, gonkdir, _):
+    return compile_env and (gonkdir or build_project in ('mobile/android', 'js'))
 
+include_when('android-ndk.configure', when=compiling_android)
 
 # MacOS deployment target version
 # ==============================================================

build/moz.configure/util.configure

@@ -214,3 +214,13 @@ def depends_when(*args, **kwargs):
                 return fn(*args)
         return wrapper
     return decorator
+
+# Includes a file when the given condition evaluates to a truthy value.
+@template
+def include_when(filename, when):
+    # Assume, for now, our condition already depends on --help.
+    @depends(when, '--help')
+    def conditional_include(value, _):
+        if value:
+            return filename
+    include(conditional_include)

moz.configure

@@ -93,26 +93,12 @@ js_option('--enable-debug',
 add_old_configure_assignment('MOZ_DEBUG',
                              depends('--enable-debug')(lambda v: bool(v)))
 
-@depends('--disable-compile-environment', '--help')
-def toolchain_include(compile_env, help):
-    if compile_env:
-        return 'build/moz.configure/toolchain.configure'
-
-include(toolchain_include)
-
-@depends('--disable-compile-environment', '--help')
-def memory_include(compile_env, help):
-    if compile_env:
-        return 'build/moz.configure/memory.configure'
-
-include(memory_include)
-
-@depends('--disable-compile-environment', '--help')
-def headers_check_include(compile_env, help):
-    if compile_env:
-        return 'build/moz.configure/headers.configure'
-
-include(headers_check_include)
+include_when('build/moz.configure/toolchain.configure',
+             when='--enable-compile-environment')
+include_when('build/moz.configure/memory.configure',
+             when='--enable-compile-environment')
+include_when('build/moz.configure/headers.configure',
+             when='--enable-compile-environment')
 
 @depends('--help')
 @imports(_from='mozbuild.backend', _import='backends')