Refactor calculation of variables, common to many generators.

pylib/gyp/msvs_emulation.py

Index: pylib/gyp/msvs_emulation.py
===================================================================
--- pylib/gyp/msvs_emulation.py	(revision 1746)
+++ pylib/gyp/msvs_emulation.py	(working copy)
@@ -848,3 +848,22 @@
       # path for a slightly less crazy looking output.
       cleaned_up = [os.path.normpath(x) for x in missing]
       raise Exception('Missing input files:\n%s' % '\n'.join(cleaned_up))
+
+# Sets some values in default_variables, which are required for many
+# generators, run on Windows.
+def CalculateCommonVariables(default_variables, params):
+  generator_flags = params.get('generator_flags', {})
+
+  # Set a variable so conditions can be based on msvs_version.
+  msvs_version = gyp.msvs_emulation.GetVSVersion(generator_flags)
+  default_variables['MSVS_VERSION'] = msvs_version.ShortName()
+
+  # To determine processor word size on Windows, in addition to checking
+  # PROCESSOR_ARCHITECTURE (which reflects the word size of the current
+  # process), it is also necessary to check PROCESSOR_ARCHITEW6432 (which
+  # contains the actual word size of the system when running thru WOW64).
+  if ('64' in os.environ.get('PROCESSOR_ARCHITECTURE', '') or
+      '64' in os.environ.get('PROCESSOR_ARCHITEW6432', '')):
+    default_variables['MSVS_OS_BITS'] = 64
+  else:
+    default_variables['MSVS_OS_BITS'] = 32