Make json5_generator.Writer always take a list of files.

third_party/WebKit/Source/build/scripts/json5_generator.py

 # Copyright (c) 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generic generator for configuration files in JSON5 format.
 
 The configuration file is expected to contain either a data array or a data map,
 an optional parameters validation map, and an optional metdata map. Examples:
 {
   data: [
@@ skipping 81 matching lines @@
 class Json5File(object):
     def __init__(self, file_paths, doc, default_metadata=None, default_parameters=None):
         self.file_paths = file_paths
         self.name_dictionaries = []
         self.metadata = copy.deepcopy(default_metadata if default_metadata else {})
         self.parameters = copy.deepcopy(default_parameters if default_parameters else {})
         self._defaults = {}
         self._process(doc)
 
     @classmethod
-    def load_from_files(cls, file_paths, default_metadata, default_parameters=None):
+    def load_from_files(cls, file_paths, default_metadata=None, default_parameters=None):
+        if isinstance(file_paths, basestring):
+            file_paths = [file_paths]
+
         merged_doc = dict()
         for path in file_paths:
             assert path.endswith(".json5")
             with open(os.path.abspath(path)) as json5_file:
                 doc = _json5_load(json5_file.read())
                 if not merged_doc:
                     merged_doc = doc
                 else:
                     _merge_doc(merged_doc, doc)
         return Json5File(file_paths, merged_doc, default_metadata, default_parameters)
@@ skipping 76 matching lines @@
 
 class Writer(object):
     # Subclasses should override.
     class_name = None
     default_metadata = None
     default_parameters = None
 
     def __init__(self, json5_files):
         self._outputs = {}  # file_name -> generator
         self.gperf_path = None
-        if isinstance(json5_files, basestring):
-            json5_files = [json5_files]

[alancutter (OOO until 2018), 2017/04/13 03:23:52]

This code (that existed) smells bad. Are we certain that this needs to be a
branch point and the condition is not the same at every call site? Can you give
examples where it differs?

I'm not comfortable having it moved to a place with a name like
load_from_files() without properly understanding its reason for existing.

[shend, 2017/04/13 03:57:43]

Done.

         if json5_files:
             self.json5_file = Json5File.load_from_files(json5_files,
                                                         self.default_metadata,
                                                         self.default_parameters)
 
     def _write_file_if_changed(self, output_dir, contents, file_name):
         path = os.path.join(output_dir, file_name)
 
         # The build system should ensure our output directory exists, but just
         # in case.
@@ skipping 30 matching lines @@
         parser.add_argument("--developer_dir", help="Path to Xcode.")
         parser.add_argument("--output_dir", default=os.getcwd())
         args = parser.parse_args()
 
         if args.developer_dir:
             os.environ["DEVELOPER_DIR"] = args.developer_dir
 
         writer = self._writer_class(args.files)
         writer.set_gperf_path(args.gperf)
         writer.write_files(args.output_dir)