Create js_library and js_binary templates for closure compiling.

third_party/closure_compiler/js_binary.py

Index: third_party/closure_compiler/js_binary.py
diff --git a/third_party/closure_compiler/js_binary.py b/third_party/closure_compiler/js_binary.py
new file mode 100644
index 0000000000000000000000000000000000000000..af835feeafa2c3ace318b1e954f6132db56e8de2
--- /dev/null
+++ b/third_party/closure_compiler/js_binary.py
@@ -0,0 +1,116 @@
+# Copyright 2017 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.
+"""Used by a js_binary action to compile javascript files.
+
+This script takes in a list of sources and dependencies and compiles them all
+together into a single compiled .js file.  The dependencies are ordered in a
+post-order, left-to-right traversal order.  If multiple instances of the same
+source file are read, only the first is kept. The script can also take in
+optional --flags argument which will add custom flags to the compiler.  Any
+extern files can also be passed in using the --extern flag.
+"""
+
+from argparse import ArgumentParser
+import os
+import subprocess
+import sys
+
+EXIT_FAILURE = 1
+
+def IsExecutable(path):
+  return os.path.isfile(path) and os.access(path, os.X_OK)
+
+
+def FindCommand(command):
+  filepath, _ = os.path.split(command)
+  if filepath and IsExecutable(command):
+    return command
+
+  if sys.platform == 'win32':
+    # On Windows, if the command does not have an extension, cmd.exe will
+    # try all extensions from PATHEXT when resolving the full path.
+    command, ext = os.path.splitext(command)
+    exts = [ext] if ext else os.environ['PATHEXT'].split(os.path.pathsep)
+  else:
+    exts = ['']
+
+  for path in os.environ['PATH'].split(os.path.pathsep):
+    for ext in exts:
+      path = os.path.join(path, command) + ext
+      if IsExecutable(path):
+        return path
+
+  return None
+
+
+def RunCompiler(args):
+  java_path = FindCommand('java')
+  if not java_path:
+    sys.stderr.write('java: command not found\n')
+    sys.exit(EXIT_FAILURE)
+  return subprocess.check_call([java_path, '-jar'] + args)
+
+
+def ParseDepList(dep):
+  """Parses a depenency list, returns |sources, deps|."""
+  assert os.path.isfile(dep), dep[:-11] + ' is not a js_library target'

[mbjorge, 2017/04/19 01:15:42]

I think dpream@ was getting at -11 looks random for a person reading it.
Something like os.path.splitext(dep)[0] (or possibly dep[:-len('.js_library')])
would be more obvious at a glance

[damargulis, 2017/04/19 01:36:19]

Done.

+  with open(dep, 'r') as dep_list:
+    lines = dep_list.read().splitlines()
+  assert 'deps:' in lines, dep + ' is not formated correctly'

[mbjorge, 2017/04/19 01:15:42]

nit: formatted

add something a bit more specific about what isn't correct +': missing "deps:"
line'

[damargulis, 2017/04/19 01:36:19]

Done.

+  split = lines.index('deps:')
+  return lines[1:split], lines[split+1:]
+
+
+def CrawlDepsTree(deps, sources):
+  """Parses the dependency tree creating a post-order listing of sources."""
+  for dep in deps:
+    new_sources, new_deps = ParseDepList(dep)
+
+    sources = CrawlDepsTree(new_deps, sources)
+    sources = sources + [source for source in new_sources
+                         if source not in sources]
+  return sources
+
+
+def main():
+  parser = ArgumentParser()
+  parser.add_argument('-c', '--compiler', required=True,
+                      help='Path to compiler')
+  parser.add_argument('-s', '--sources', nargs='*', default=[],
+                      help='List of js source files')
+  parser.add_argument('-o', '--output', required=True,
+                      help='Compile to output')
+  parser.add_argument('-d', '--deps', nargs='*', default = [],
+                      help='List of js_libarary dependencies')
+  parser.add_argument('-b', '--bootstrap',
+                      help='A file to include before all others')
+  parser.add_argument('-cf', '--config', nargs='*', default = [],
+                      help='A list of files to include after bootstrap and' \
+                      'before all others')
+  parser.add_argument('-f', '--flags', nargs='*', default = [],
+                      help='A list of custom flags to pass to the compiler. ' \
+                      'Do not include leading dashes')
+  parser.add_argument('-e', '--externs', nargs='*', default = [],
+                      help='A list of extern files to pass to the compiler')
+
+  args = parser.parse_args()
+  sources = CrawlDepsTree(args.deps, []) + args.sources
+
+  flags = ['--' + flag for flag in args.flags]

[mbjorge, 2017/04/19 01:15:42]

nit: match the style below '--%s' % flag

[damargulis, 2017/04/19 01:36:19]

Done.

+  compiler_args = [args.compiler] + flags
+  compiler_args += ['--externs=%s' % e for e in args.externs]
+  compiler_args += [
+      '--js_output_file',
+      args.output,
+      '--js',
+  ]
+  if args.bootstrap:
+    compiler_args += [args.bootstrap]
+  compiler_args += args.config
+  compiler_args += sources
+  RunCompiler(compiler_args)
+
+
+if __name__ == '__main__':
+  main()