Add command_trace.py from firebase-ios-sdk

Author: andrewheard

scripts/lib/command_trace.py

@@ -0,0 +1,79 @@
+# Copyright 2019 Google
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from lib import terminal
+
+_commands = logging.getLogger('commands')
+
+
+def log(command_args):
+  """Logs that a command has run.
+
+  Args:
+    command_args: A list of the command and its arguments.
+  """
+  if _commands.isEnabledFor(logging.DEBUG):
+    columns = terminal.columns()
+
+    text = ' '.join(command_args)
+
+    # When just passing --trace, shorten output to the width of the current
+    # window. When running extra verbose don't shorten.
+    if not logging.root.isEnabledFor(logging.INFO):
+      if len(text) >= columns:
+        text = text[0:columns - 5] + ' ...'
+
+    _commands.debug('%s', text)
+
+
+def add_arguments(parser):
+  """Adds standard arguments to the given ArgumentParser."""
+  parser.add_argument('--trace', action='store_true',
+                      help='show commands')
+  parser.add_argument('--verbose', '-v', action='count', default=0,
+                      help='run verbosely')
+
+
+def enable_tracing():
+  """Enables tracing of command execution."""
+  _commands.setLevel(logging.DEBUG)
+
+
+def setup(args):
+  """Prepares for tracing/verbosity based on the given parsed arguments."""
+  level = logging.WARN
+
+  if args.trace:
+    enable_tracing()
+
+  if args.verbose >= 2:
+    level = logging.DEBUG
+  elif args.verbose >= 1:
+    level = logging.INFO
+
+  logging.basicConfig(format='%(message)s', level=level)
+
+
+def parse_args(parser):
+  """Shortcut that adds arguments, parses, and runs setup.
+
+  Returns:
+    The args result from parser.parse_args().
+  """
+  add_arguments(parser)
+  args = parser.parse_args()
+  setup(args)
+  return args