New script to build the mojom parser.

mojom/mojom_parser/tools/build_mojom_parser.py

Index: mojom/mojom_parser/tools/build_mojom_parser.py
diff --git a/mojom/mojom_parser/tools/build_mojom_parser.py b/mojom/mojom_parser/tools/build_mojom_parser.py
new file mode 100755
index 0000000000000000000000000000000000000000..bfc75f3b0abd69bda9d95ebf59a53a4f46c930aa
--- /dev/null
+++ b/mojom/mojom_parser/tools/build_mojom_parser.py
@@ -0,0 +1,105 @@
+#!/usr/bin/env python
+# Copyright 2015 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.
+
+# This script will build the mojom parser for both mac and linux.
+
+import argparse
+import subprocess
+import sys
+import os
+
+
+def get_parser_builder(src_root=None, go_tool=None, go_root=None):
+  """Builds a parser building function.
+
+  Args:
+    src_root: Path to the root of the source tree.

[rudominer, 2015/12/16 22:47:40]

if None then...

[azani, 2015/12/16 23:11:03]

Done.

+    go_tool: Path to the go tool.

[rudominer, 2015/12/16 22:47:40]

if None then...

[azani, 2015/12/16 23:11:03]

Done.

+    go_root: Path to the root of the go installation.

[rudominer, 2015/12/16 22:47:41]

if None then...

[azani, 2015/12/16 23:11:03]

Done.

+
+  Returns:
+    A function which accepts a compilation target and builds the parser for it.
+  """
+  if src_root:
+    src_root = os.path.abspath(src_root)
+  else:
+    src_root = os.path.abspath(__file__)
+    while os.path.basename(src_root) != 'src':
+      assert src_root != '' and src_root != '/'
+      src_root = os.path.dirname(src_root)

[rudominer, 2015/12/16 22:47:41]

It seems more fragile to me to have the hidden dependency that this script can
never be moved into a folder named 'src' than it does to have the explicit
dependency that this script can never be moved at all. I would just assume this
script is in a specific location.

[azani, 2015/12/16 23:11:03]

Done.

+
+  assert os.path.exists(src_root)
+
+  if go_tool:
+    go_tool = os.path.abspath(go_tool)
+  else:
+    go_tool = os.path.join(src_root,
+        'third_party', 'go', 'tool', 'linux_amd64', 'bin', 'go')
+  assert os.path.exists(go_tool)
+
+  if go_root:
+    go_root = os.path.abspath(go_root)
+  else:
+    go_root = os.path.dirname(os.path.dirname(go_tool))
+  assert os.path.exists(go_root)
+
+  def _build_parser(target_os, target_arch):
+    """Builds the mojom parser for target_os and target_arch.
+
+    Args:
+      target_os: Any value valid for GOOS.
+      target_arch: Any value valid for GOARCH.
+
+    Returns:
+      The go tool's return value.
+    """
+    output = 'mojom_parser_%s_%s' % (target_os, target_arch)

[rudominer, 2015/12/16 22:47:40]

How about: the output directory is an argument to this script. It defaults to
cwd. When invoked from ninja we will use some directory in out/Debug or
out/Release etc.

[azani, 2015/12/16 23:11:03]

Done.

+
+    environ = {
+        'GOROOT': go_root,
+        'GOPATH': os.path.dirname(src_root),
+        'GOOS': target_os,
+        'GOARCH': target_arch,
+        }
+
+    save_cwd = os.getcwd()
+    os.chdir(os.path.join(src_root, 'mojom', 'mojom_parser'))
+    result = subprocess.call([go_tool, 'build', '-o', output] , env=environ)

[rudominer, 2015/12/16 22:47:41]

I was under the impression that we had an older version of the go tool currently
in our repo that did not support -o. If so we will have to upgrade.

[azani, 2015/12/16 23:11:03]

It works and if you call help build on it, it documents -o.

+
+    os.chdir(save_cwd)
+
+    return result
+
+  return _build_parser
+
+
+def main():
+  parser = argparse.ArgumentParser(description="Build the mojom parser.")
+  parser.add_argument('--src-root', dest='src_root', action='store',
+                      help='Path to the source tree.')

[rudominer, 2015/12/16 22:47:41]

add to 'optional' help string.
(Do you envision anyone ever using this?)

[azani, 2015/12/16 23:11:03]

I mostly put it there for completeness' sake.

+  parser.add_argument('--go-tool', dest='go_tool', action='store',
+                      help='Path to the go tool.')
+  parser.add_argument('--go-root', dest='go_root', action='store',
+                      help='Path to the root of the go installation.')
+  args = parser.parse_args()

[rudominer, 2015/12/16 22:47:41]

out_dir seems like a natural optional argument.

[azani, 2015/12/16 23:11:03]

Done.

+  build_parser = get_parser_builder(
+      src_root=args.src_root,
+      go_tool=args.go_tool,
+      go_root=args.go_root)
+
+  targets = [
+      ('darwin', 'amd64'),
+      ('linux', 'amd64'),
+      ]
+  for target_os, target_arch in targets:
+    result = build_parser(target_os, target_arch)
+    if result != 0:
+      return result
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())