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1#!/usr/bin/python
2# Copyright (C) 2010 Google Inc. All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
6# met:
7#
8#     * Redistributions of source code must retain the above copyright
9# notice, this list of conditions and the following disclaimer.
10#     * Redistributions in binary form must reproduce the above
11# copyright notice, this list of conditions and the following disclaimer
12# in the documentation and/or other materials provided with the
13# distribution.
14#     * Neither the name of Google Inc. nor the names of its
15# contributors may be used to endorse or promote products derived from
16# this software without specific prior written permission.
17#
18# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30"""Package that private an array-based implementation of a stream."""
31
32
33class ArrayStream(object):
34    """Simple class that implmements a stream interface on top of an array.
35
36    This is used primarily by unit test classes to mock output streams. It
37    performs a similar function to StringIO, but (a) it is write-only, and
38    (b) it can be used to retrieve each individual write(); StringIO
39    concatenates all of the writes together.
40    """
41
42    def __init__(self):
43        self._contents = []
44
45    def write(self, msg):
46        """Implement stream.write() by appending to the stream's contents."""
47        self._contents.append(msg)
48
49    def get(self):
50        """Return the contents of a stream (as an array)."""
51        return self._contents
52
53    def reset(self):
54        """Empty the stream."""
55        self._contents = []
56
57    def empty(self):
58        """Return whether the stream is empty."""
59        return (len(self._contents) == 0)
60
61    def flush(self):
62        """Flush the stream (a no-op implemented for compatibility)."""
63        pass
64
65    def __repr__(self):
66        return '<ArrayStream: ' + str(self._contents) + '>'
67