add reformat-json.py script

R=borenet@google.com

Review URL: https://codereview.chromium.org/19289011

git-svn-id: http://skia.googlecode.com/svn/trunk@10192 2bbb7eff-a529-9590-31e7-b0007b416f81

tools/reformat-json.py

@@ -0,0 +1,55 @@
+#!/usr/bin/python
+
+'''
+Copyright 2013 Google Inc.
+
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+'''
+
+'''
+Rewrites a JSON file to use Python's standard JSON pretty-print format,
+so that subsequent runs of rebaseline.py will generate useful diffs
+(only the actual checksum differences will show up as diffs, not obscured
+by format differences).
+
+Should not modify the JSON contents in any meaningful way.
+'''
+
+# System-level imports
+import argparse
+import os
+import sys
+
+# Imports from within Skia
+#
+# We need to add the 'gm' directory, so that we can import gm_json.py within
+# that directory.  That script allows us to parse the actual-results.json file
+# written out by the GM tool.
+# Make sure that the 'gm' dir is in the PYTHONPATH, but add it at the *end*
+# so any dirs that are already in the PYTHONPATH will be preferred.
+#
+# This assumes that the 'gm' directory has been checked out as a sibling of
+# the 'tools' directory containing this script, which will be the case if
+# 'trunk' was checked out as a single unit.
+GM_DIRECTORY = os.path.realpath(
+    os.path.join(os.path.dirname(os.path.dirname(__file__)), 'gm'))
+if GM_DIRECTORY not in sys.path:
+    sys.path.append(GM_DIRECTORY)
+import gm_json
+
+def Reformat(filename):
+  print 'Reformatting file %s...' % filename
+  gm_json.WriteToFile(gm_json.LoadFromFile(filename), filename)
+
+def _Main():
+  parser = argparse.ArgumentParser(description='Reformat JSON files in-place.')
+  parser.add_argument('filenames', metavar='FILENAME', nargs='+',
+                      help='file to reformat')
+  args = parser.parse_args()
+  for filename in args.filenames:
+    Reformat(filename)
+  sys.exit(0)
+
+if __name__ == '__main__':
+    _Main()