Strip comments and whitespace from javascript resources

third_party/closure_compiler/js_minify.py

+#!/usr/bin/python
+# Copyright 2016 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.
+
+import sys
+import tempfile
+from compile2 import Checker
+
+
+closure_args = [

[Dan Beam, 2016/07/25 17:29:16]

can we just compose these rather than duplicate them from
closure_args.{gypi.gni}?

[aberent, 2016/07/27 09:46:35]

Now using closure_args.gni.

+  "compilation_level=WHITESPACE_ONLY",
+
+  "extra_annotation_name=attribute",
+  "extra_annotation_name=demo",
+  "extra_annotation_name=element",
+  "extra_annotation_name=group",
+  "extra_annotation_name=hero",
+  "extra_annotation_name=homepage",
+  "extra_annotation_name=status",
+  "extra_annotation_name=submodule",
+  "language_in=ECMASCRIPT6_STRICT",
+  "language_out=ECMASCRIPT5_STRICT",
+
+  "polymer_pass",
+
+  "source_map_format=V3",
+]
+
+
+def Minify(source):
+  with tempfile.NamedTemporaryFile(suffix='.js') as t1, tempfile.NamedTemporaryFile(suffix='.js', delete=False) as t2:

[Dan Beam, 2016/07/25 17:29:16]

80 col wrap

[Dan Beam, 2016/07/25 17:29:16]

nit: use double quotes (") instead of single quotes (') as that's what this file
generally does

[Dirk Pranke, 2016/07/25 21:12:36]

I would actually change everything else to be single quotes since that's the
normal style.

[aberent, 2016/07/27 09:46:35]

Done. All single quotes.

[aberent, 2016/07/27 09:46:36]

Done.

+    t1.write(source)
+    t1.seek(0)
+    checker = Checker()
+    checker.check([t1.name], out_file=t2.name, closure_args=closure_args)
+    t2.seek(0)
+    result = t2.read()
+    return result
+

[Dan Beam, 2016/07/25 17:29:16]

this should be 2 blank lines between top-level globals

[aberent, 2016/07/27 09:46:36]

Done.

+if __name__ == "__main__":
+  orig_stdout = sys.stdout

[Dan Beam, 2016/07/25 17:29:16]

you probably want to wrap this in a try/finally, i.e.

orig_stdout = sys.stdout
try:
  sys.stdout = sys.stderr
  result = Minify(...)
finally:
  sys.stdout = orig_stdout

[aberent, 2016/07/27 09:46:35]

Done.

+  sys.stdout = sys.stderr

[Dan Beam, 2016/07/25 17:29:16]

why is this stderr/stdout redirection required?

[aberent, 2016/07/27 09:46:35]

In traditional Unix pipeline style (and as I define in grit) this minifier takes
its input on standard input, and produces its output (the minified JS file) on
standard output. For this to work I have to ensure that standard output receives
nothing other than the minified output, so have to redirect the compiler's
standard output elsewhere.

+  result = Minify(sys.stdin.read())
+  sys.stdout = orig_stdout
+  print result
+