[Fuchsia] Build only the parts of the SDK that are needed

tools/copy_tree.py

+#!/usr/bin/env python
+# Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+import argparse
+import os
+import re
+import shutil
+import sys
+
+def ParseArgs(args):
+  args = args[1:]
+  parser = argparse.ArgumentParser(
+      description='A script to copy a file tree somewhere')
+
+  parser.add_argument('--exclude_patterns', '-e',
+      type=str,
+      help='Patterns to exclude [passed to shutil.copytree]')
+  parser.add_argument('--from', '-f',
+      dest="copy_from",
+      type=str,
+      required=True,
+      help='Source tree root')
+  parser.add_argument('--to', '-t',
+      type=str,
+      required=True,
+      help='Destination')
+
+  return parser.parse_args(args)
+
+
+def ValidateArgs(args):
+  if not os.path.isdir(args.copy_from):
+    print "--from argument must refer to a directory"
+    return False
+  return True
+
+
+def Main(argv):
+  args = ParseArgs(argv)
+  if not ValidateArgs(args):
+    return -1
+  if os.path.exists(args.to):
+    shutil.rmtree(args.to)
+  if args.exclude_patterns == None:
+    shutil.copytree(args.copy_from, args.to)
+  else:
+    patterns = args.exclude_patterns.split(',')
+    shutil.copytree(args.copy_from, args.to,
+                    ignore=shutil.ignore_patterns(tuple(patterns)))
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(Main(sys.argv))