Add script to generate the v8 version.

BUG=chromium:446166
LOG=n
TBR=jkummerow@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/835903003

Cr-Commit-Position: refs/heads/master@{#25964}

tools/push-to-trunk/generate_version.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python
+# Copyright 2014 the V8 project authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+Script to set v8's version file to the version given by the latest tag.
+"""
+
+
+import os
+import re
+import subprocess
+import sys
+
+
+CWD = os.path.abspath(
+    os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
+VERSION_CC = os.path.join(CWD, "src", "version.cc")
+
+def main():
+  tag = subprocess.check_output(
+      "git describe --tags",
+      shell=True,
+      cwd=CWD,
+  ).strip()
+  assert tag
+
+  # Check for commits not exactly matching a tag. Those are candidate builds
+  # for the next version. The output has the form
+  # <tag name>-<n commits>-<hash>.
+  if "-" in tag:
+    version = tag.split("-")[0]
+    candidate = "1"
+  else:
+    version = tag
+    candidate = "0"
+  version_levels = version.split(".")
+
+  # Set default patch level if none is given.
+  if len(version_levels) == 3:
+    version_levels.append("0")
+  assert len(version_levels) == 4
+
+  major, minor, build, patch = version_levels
+
+  # Increment build level for candidate builds.
+  if candidate == "1":
+    build = str(int(build) + 1)
+    patch = "0"
+
+  # Modify version.cc with the new values.
+  with open(VERSION_CC, "r") as f:
+    text = f.read()
+  output = []
+  for line in text.split("\n"):
+    for definition, substitute in (
+        ("MAJOR_VERSION", major),
+        ("MINOR_VERSION", minor),
+        ("BUILD_NUMBER", build),
+        ("PATCH_LEVEL", patch),
+        ("IS_CANDIDATE_VERSION", candidate)):
+      if line.startswith("#define %s" % definition):
+        line =  re.sub("\d+$", substitute, line)
+    output.append(line)
+  with open(VERSION_CC, "w") as f:
+    f.write("\n".join(output))
+
+  # Log what was done.
+  candidate_txt = " (candidate)" if candidate == "1" else ""
+  patch_txt = ".%s" % patch if patch != "0" else ""
+  version_txt = ("%s.%s.%s%s%s" %
+                 (major, minor, build, patch_txt, candidate_txt))
+  print "Modified version.cc. Set V8 version to %s" %  version_txt
+  return 0
+
+if __name__ == "__main__":
+  sys.exit(main())