Make the last change hook also generate C header files.

build/util/lastchange.py

Index: build/util/lastchange.py
diff --git a/build/util/lastchange.py b/build/util/lastchange.py
index 3c1ce28e28ae33965546328a4c338af64a4792c4..e32c4825c4e12c1a0387ed4468bb71c337c2ecce 100755
--- a/build/util/lastchange.py
+++ b/build/util/lastchange.py
@@ -168,6 +168,42 @@ def FetchVersionInfo(default_lastchange, directory=None,
       version_info = VersionInfo(None, None)
   return version_info
 
+def GetHeaderGuard(path):
+  """
+  Returns the header #define guard for the given file path.
+  This treats everything after the last instance of "src/" as being a
+  relevant part of the guard. If there is no "src/", then the entire path
+  is used.
+  """
+  src_index = path.rfind("src/")
+  if src_index != -1:
+    guard = path[src_index + 4:]
+  else:
+    guard = path
+  guard = guard.upper()
+  return guard.replace("/", "_").replace(".", "_") + "_"

[viettrungluu, 2013/10/24 21:06:40]

Note: This may generate invalid macro names (e.g., with invalid characters or
leading digits). <shrug>

+
+def GetHeaderContents(path, define, version):
+  """
+  Returns what the contents of the header file should be that indicate the given
+  revision. Note that the #define is specified as a string, even though it's
+  currently always a SVN revision number, in case we need to move to git hashes.
+  """
+  header_guard = GetHeaderGuard(path)
+
+  header_contents = """/* Generated by lastchange.py, do not edit.*/
+
+#ifndef %(header_guard)s
+#define %(header_guard)s
+
+#define %(define)s "%(version)s"
+
+#endif  // %(header_guard)s
+"""
+  header_contents = header_contents % { "header_guard": header_guard,

[viettrungluu, 2013/10/24 21:06:40]

It's fairly conventional in Python to use single quotes for strings with
semantic meaning (like these) and double quotes for strings that are only
intended for human consumption. This file vaguely follows that so probably you
should too here.

+                                        "define": define,
+                                        "version": version }
+  return header_contents
 
 def WriteIfChanged(file_name, contents):
   """
@@ -191,16 +227,26 @@ def main(argv=None):
 
   parser = optparse.OptionParser(usage="lastchange.py [options]")
   parser.add_option("-d", "--default-lastchange", metavar="FILE",
-                    help="default last change input FILE")
+                    help="Default last change input FILE.")
+  parser.add_option("", "--define",
+                    help="Name of C #define when using --header. Defaults to " +
+                    "LASTCHANGE.",
+                    default="LASTCHANGE")
   parser.add_option("-o", "--output", metavar="FILE",
-                    help="write last change to FILE")
+                    help="Write last change to FILE. " +
+                    "Can be combined with --header to write both files.")
+  parser.add_option("", "--header", metavar="FILE",
+                    help="Write last change to FILE as a C/C++ header. " +
+                    "Can be combined with --output to write both files.")
   parser.add_option("--revision-only", action='store_true',
-                    help="just print the SVN revision number")
+                    help="Just print the SVN revision number. Overrides any " +
+                    "file-output-related options.")
   parser.add_option("-s", "--source-dir", metavar="DIR",
-                    help="use repository in the given directory")
+                    help="Use repository in the given directory.")
   opts, args = parser.parse_args(argv[1:])
 
   out_file = opts.output
+  header = opts.header
 
   while len(args) and out_file is None:
     if out_file is None:
@@ -224,10 +270,15 @@ def main(argv=None):
     print version_info.revision
   else:
     contents = "LASTCHANGE=%s\n" % version_info.revision
-    if out_file:
-      WriteIfChanged(out_file, contents)
-    else:
+    if not out_file and not opts.header:
       sys.stdout.write(contents)
+    else:
+      if out_file:
+        WriteIfChanged(out_file, contents)
+      if header:
+        WriteIfChanged(header,
+                       GetHeaderContents(header, opts.define,
+                                         version_info.revision))
 
   return 0