Bug 949906 - Add a callback to modify evaluated moz.build sandboxes, fix Sphinx docs; r=glandium

--HG--
extra : rebase_source : 9ef2219145fb754a9cbe9e7e30b6f2841910f13f

python/mozbuild/mozbuild/frontend/reader.py

@@ -592,13 +592,20 @@ class BuildReader(object):
     This is where the build system starts. You give it a tree configuration
     (the output of configuration) and it executes the moz.build files and
     collects the data they define.
+
+    The reader can optionally call a callable after each sandbox is evaluated
+    but before its evaluated content is processed. This gives callers the
+    opportunity to modify sandboxes before side-effects occur from their
+    content. This callback receives the ``Sandbox`` that was evaluated. The
+    return value is ignored.
     """
 
-    def __init__(self, config):
+    def __init__(self, config, sandbox_post_eval_cb=None):
         self.config = config
         self.topsrcdir = config.topsrcdir
         self.topobjdir = config.topobjdir
 
+        self._sandbox_post_eval_cb = sandbox_post_eval_cb
         self._log = logging.getLogger(__name__)
         self._read_files = set()
         self._execution_stack = []
@@ -719,6 +726,10 @@ class BuildReader(object):
         sandbox = MozbuildSandbox(self.config, path, metadata=metadata)
         sandbox.exec_file(path, filesystem_absolute=filesystem_absolute)
         sandbox.execution_time = time.time() - time_start
+
+        if self._sandbox_post_eval_cb:
+            self._sandbox_post_eval_cb(sandbox)
+
         var = metadata.get('var', None)
         forbidden = {
             'TOOL_DIRS': ['DIRS', 'PARALLEL_DIRS', 'TEST_DIRS'],
@@ -770,6 +781,9 @@ class BuildReader(object):
         # so until the library linking operations are moved out of it, at which
         # point PARALLEL_DIRS will be irrelevant anyways.
         for gyp_sandbox in gyp_sandboxes:
+            if self._sandbox_post_eval_cb:
+                self._sandbox_post_eval_cb(gyp_sandbox)
+
             sandbox['DIRS'].append(mozpath.relpath(gyp_sandbox['OBJDIR'], sandbox['OBJDIR']))
 
         yield sandbox

python/mozbuild/mozbuild/test/frontend/test_reader.py

@@ -33,13 +33,13 @@ class TestBuildReader(unittest.TestCase):
 
         return MockConfig(path, **kwargs)
 
-    def reader(self, name, enable_tests=False):
+    def reader(self, name, enable_tests=False, **kwargs):
         extra = {}
         if enable_tests:
             extra['ENABLE_TESTS'] = '1'
         config = self.config(name, extra_substs=extra)
 
-        return BuildReader(config)
+        return BuildReader(config, **kwargs)
 
     def file_path(self, name, *args):
         return mozpath.join(data_path, name, *args)
@@ -266,5 +266,21 @@ class TestBuildReader(unittest.TestCase):
         self.assertEqual([sandbox['XPIDL_MODULE'] for sandbox in sandboxes],
             ['foobar', 'foobar', 'foobar', 'foobar'])
 
+    def test_process_eval_callback(self):
+        def strip_dirs(sandbox):
+            sandbox['DIRS'][:] = []
+            count[0] += 1
+
+        reader = self.reader('traversal-simple',
+            sandbox_post_eval_cb=strip_dirs)
+
+        count = [0]
+
+        sandboxes = list(reader.read_topsrcdir())
+
+        self.assertEqual(len(sandboxes), 1)
+        self.assertEqual(len(count), 1)
+
+
 if __name__ == '__main__':
     main()

tools/docs/mach_commands.py

@@ -38,7 +38,14 @@ class Documentation(MachCommandBase):
         manager = SphinxManager(self.topsrcdir, os.path.join(self.topsrcdir,
             'tools', 'docs'), outdir)
 
-        reader = BuildReader(self.config_environment)
+        # We don't care about GYP projects, so don't process them. This makes
+        # scanning faster and may even prevent an exception.
+        def remove_gyp_dirs(sandbox):
+            sandbox['GYP_DIRS'][:] = []
+
+        reader = BuildReader(self.config_environment,
+            sandbox_post_eval_cb=remove_gyp_dirs)
+
         for sandbox in reader.walk_topsrcdir():
             for dest_dir, source_dir in sandbox['SPHINX_TREES'].items():
                 manager.add_tree(os.path.join(sandbox['RELATIVEDIR'],