tools: Add a script to generate arch-specific ctags

tools/dev/gen-tags.py

Index: tools/dev/gen-tags.py
diff --git a/tools/dev/gen-tags.py b/tools/dev/gen-tags.py
new file mode 100755
index 0000000000000000000000000000000000000000..3d0aa8ba889c65587f0204b0569e426eb21c1a1e
--- /dev/null
+++ b/tools/dev/gen-tags.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+# Copyright 2017 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.
+"""\
+Convenience script for generating arch-specific ctags file.
+This script MUST be executed at the top directory.
+
+Usage:
+    $ tools/dev/gen-tags.py [<arch>...]
+
+The example usage is as follows:
+    $ tools/dev/gen-tags.py x64
+
+If no <arch> is given, it generates tags file for all arches:
+    $ tools/dev/gen-tags.py
+"""
+import os
+import subprocess
+import sys
+from itertools import chain
+
+# All arches that this script understands.
+ARCHES = ["ia32", "x64", "arm", "arm64", "mips", "mips64", "ppc", "s390", "x87"]
+
+def PrintHelpAndExit():
+  print(__doc__)
+  sys.exit(0)
+
+def _Call(cmd, silent=False):
+  if not silent: print("# %s" % cmd)
+  return subprocess.call(cmd, shell=True)
+
+class ArgumentParser(object):
+  def __init__(self):

[Jakob Kummerow, 2017/03/22 12:11:09]

You don't need this constructor.

[honggyu.kim, 2017/03/22 15:19:15]

Done.

+    self.global_targets = set()
+    self.configs = {}
+
+  def ParseArg(self, argstring):
+    if argstring in ("-h", "--help", "help"):
+      PrintHelpAndExit()
+    return argstring
+
+  def ParseArguments(self, argv):
+    if not "tools/dev" in argv[0]:
+      PrintHelpAndExit()
+    argv = argv[1:]
+
+    # If no argument is given, then generate ctags for all arches.
+    if len(argv) == 0:
+      return ARCHES
+
+    user_arches = []
+    for argstring in argv:
+      user_arches.append(self.ParseArg(argstring))

[Jakob Kummerow, 2017/03/22 12:11:09]

If you inline ParseArg here, you don't need the class ArgumentParser at all.
Just make "ParseArguments(argv)" a top-level function. It would also be nice to
guard against typos here:

for argstring in argv:
  if argstring in ("-h", "--help", "help":
    PrintHelpAndExit()
  if argstring not in ARCHES:
    print("Invalid argument: %s" % argstring)
    sys.exit(1)
  user_arches.append(argstring)

[honggyu.kim, 2017/03/22 15:19:15]

Done.

+
+    return user_arches
+
+def Main(argv):
+  user_arches = []
+
+  parser = ArgumentParser()
+  user_arches = parser.ParseArguments(argv)
+
+  exclude_arches = list(ARCHES)
+  for user_arch in user_arches:
+    exclude_arches.remove(user_arch)
+
+  paths = ["include", "src", "test"]
+  exts = [".h", ".cc", ".c"]
+
+  gtags_filename = "gtags.files"
+  gtags = open(gtags_filename, "w")

[Jakob Kummerow, 2017/03/22 12:11:10]

instead of a manual open/close pair, please use a with-block, which is simpler
and more robust:

with open(gtags_filename, "w") as gtags:
  # ...
  gtags.write(...)

[honggyu.kim, 2017/03/22 15:19:15]

Done.

+
+  # Generate a list of files to be analyzed
+  for root, dirs, files in chain.from_iterable(os.walk(path) for path in paths):
+    for file in files:
+      if file.endswith(tuple(exts)):
+        fullpath = os.path.join(root, file)
+        exclude_flag = False

[Jakob Kummerow, 2017/03/22 12:11:09]

A more Pythonic way would be to pull out the inner loop into a function (can be
global, since this script is so small) and use "return" instead of
"break"+exclude_flag:

def Exclude(fullpath, exclude_arches):
  for arch in exclude_arches:
    if ("/%s/" % arch) in fullpath: return True
  return False

And then you can write the main part (with an explicit for-loop instead of
itertools.chain for increased simplicity) as:

with open(gtags_filename, "w") as gtags:
  for path in paths:
    for root, dirs, files in os.walk(path):
      for file in files:
        if not file.endswith(tuple(exts)): continue
        fullpath = os.path.join(root, file)
        if exclude(fullpath, exclude_arches): continue
        gtags.write(fullpath + os.linesep)

[honggyu.kim, 2017/03/22 15:19:15]

Done.

+        for arch in exclude_arches:
+          arch = "/%s/" % arch
+          if arch in fullpath:
+            exclude_flag = True
+            break
+        if not exclude_flag:
+          gtags.write(os.path.join(root, file) + os.linesep)
+
+  gtags.close()
+
+  command = "ctags --fields=+l -L " + gtags_filename

[Jakob Kummerow, 2017/03/22 12:11:09]

nit: just inline this into _Call() below, it's cleaner.

[honggyu.kim, 2017/03/22 15:19:15]

Done.

+  _Call(command)
+
+if __name__ == "__main__":
+  sys.exit(Main(sys.argv))