Add a preliminary Python API for retrieving Google API keys.

google_apis/google_api_keys.py

Index: google_apis/google_api_keys.py
diff --git a/google_apis/google_api_keys.py b/google_apis/google_api_keys.py
new file mode 100755
index 0000000000000000000000000000000000000000..ecff70c2dfd25f544fe2cc08dc55b38875969626
--- /dev/null
+++ b/google_apis/google_api_keys.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 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.
+
+"""Python API for retrieving API keys.
+
+Note that this cannot have the exact same semantics (at the moment) as
+the C++ API in google_api_keys.h, since it does not have access to gyp
+variables or preprocessor defines.
+
+TODO(joi): Give this have the same semantics as the C++ API.
+"""
+
+import os
+import re
+import sys
+
+
+def _GetTokenFromOfficialFile(token_name):
+  """Parses the token from the official file if it exists, else returns None."""
+  official_path = os.path.join(sys.path[0],
+                               'internal/google_chrome_api_keys.h')
+  if not os.path.isfile(official_path):
+    return None
+
+  line_regexp = '^#define\s*%s\s*"([^"]+)"\s*$' % token_name
+  line_pattern = re.compile(line_regexp)
+  def ParseLine(current_line):
+    result = line_pattern.match(current_line)
+    if result:
+      return result.group(1)
+    else:
+      return None
+
+  with open(official_path) as f:
+    current_line = ''
+    for line in f:
+      line = line.strip()

[Jamie, 2012/09/17 22:28:55]

I'm not sure what the call to strip accomplishes here. At least, it will cause
the next line to trigger incorrectly on a line ending in "\ ".

[Jói, 2012/09/17 22:46:38]

strip() only strips whitespace, so this is indeed to fix lines ending with e.g.
"\ ".  The duplicate doesn't matter but is an error as you pointed out.

[Jamie, 2012/09/17 22:58:05]

My point was that lines ending with "\ " are not considered continuation lines
by the preprocessor (I don't think...) but this script would treat them as such.
Perhaps we don't care; I just wanted to make sure you were aware of it.

[Jói, 2012/09/17 23:12:47]

Oh, I see, and I think you're right.  The strip was also to remove the \n at the
end of the line.  I switched to removing two characters instead of one.

+      if line.strip().endswith('\\'):

[Jamie, 2012/09/17 22:28:55]

Duplicate call to split.

[Jói, 2012/09/17 22:46:38]

Done.

+        current_line += line[:-1]

[Jamie, 2012/09/17 22:28:56]

If you're going to handle multi-line defines, I tihnk you need to remove quotes
to handle preprocessor string concatenation.

[Jói, 2012/09/17 22:46:38]

Oh, right, that's true, although in practice this is not a problem .  Added a
TODO for now, since the official keys header currently does not use string
concatenation; is this OK with you?

[Jamie, 2012/09/17 22:58:05]

The problem is that the error will be very hard to detect, since this code will
return the first part of the key and the error won't occur until run-time. Could
you add something to cause a build failure in this case? For example, I think
could you check for multiple quoted strings in ParseLine and throw an exception?

[Jói, 2012/09/17 23:12:47]

Done, although in a slightly different fashion than you suggested.

+      elif current_line:
+        # Last line in multi-line #define, time to parse it.
+        current_line += line
+        token = ParseLine(current_line)
+        current_line = ''
+      else:

[Jamie, 2012/09/17 22:28:56]

Not sure you need this final "else" since current_line is initialized to ''.

[Jói, 2012/09/17 22:46:38]

I do, since it's in a loop; I don't want current_line set to '' if the top
condition (endswith \) is hit.

[Jamie, 2012/09/17 22:58:05]

I actually meant the entire else clause can go. If current_line is empty then
it's identical to the previous one. I should more accurately have said that
lines 43-47 inclusive can be deleted.

[Jói, 2012/09/17 23:12:47]

Ah, yes, thanks for that.

+        current_line = line
+        token = ParseLine(current_line)
+        current_line = ''
+      if token:
+        return token
+    return None
+
+
+def _GetToken(token_name):
+  """Returns the API token with the given name, or dummytoken by default."""
+  token = _GetTokenFromOfficialFile(token_name)
+  if token:
+    return token
+  elif token_name in os.environ:

[Jamie, 2012/09/17 22:28:56]

I think this test would be better if it came before the official file test so
that devs with src-internal checkouts who want to build with an unofficial key
for some reason can do so.

[Jói, 2012/09/17 22:46:38]

Changed.  I was trying to stay as close to the semantics of the C++ API as
possible, but for now this makes more sense.

Once we can get the gyp variables in Python as well (my plan is to output the
relevant ones to some file when chromium_gyp runs), then we can use the same
approach as C++ devs would use, which is to set a gyp variable to not use the
src-internal stuff even when it's there.

+    return os.environ[token_name]
+  else:
+    return 'dummytoken'
+
+
+def GetAPIKey():
+  """Returns the simple API key."""
+  return _GetToken('GOOGLE_API_KEY')
+
+
+def GetClientID(client_name):
+  """Returns the OAuth 2.0 client ID for the client of the given name."""
+  return _GetToken('GOOGLE_CLIENT_ID_%s' % client_name)
+
+
+def GetClientSecret(client_name):
+  """Returns the OAuth 2.0 client secret for the client of the given name."""
+  return _GetToken('GOOGLE_CLIENT_SECRET_%s' % client_name)
+
+
+if __name__ == "__main__":

[Jamie, 2012/09/17 22:28:56]

Is this test code, or should it stay?

[Jói, 2012/09/17 22:46:38]

It is test code, but it is a useful self test and there is nothing else obvious
that the file should do when run as main, so I think it should just stay.

[Jamie, 2012/09/17 22:58:05]

Fair enough. It will probably end up out-of-date if we add other client ids and
secrets, but I guess the point is that we don't want to do that.

+  print 'GOOGLE_API_KEY=%s' % GetAPIKey()
+  print 'GOOGLE_CLIENT_ID_MAIN=%s' % GetClientID('MAIN')
+  print 'GOOGLE_CLIENT_SECRET_MAIN=%s' % GetClientSecret('MAIN')
+  print 'GOOGLE_CLIENT_ID_CLOUD_PRINT=%s' % GetClientID('CLOUD_PRINT')
+  print 'GOOGLE_CLIENT_SECRET_CLOUD_PRINT=%s' % GetClientSecret('CLOUD_PRINT')
+  print 'GOOGLE_CLIENT_ID_REMOTING=%s' % GetClientID('REMOTING')
+  print 'GOOGLE_CLIENT_SECRET_REMOTING=%s' % GetClientSecret('REMOTING')