1#!/usr/bin/env python
2#
3# Copyright 2011, Google Inc.
4# All rights reserved.
5#
6# Redistribution and use in source and binary forms, with or without
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10#     * Redistributions of source code must retain the above copyright
11# notice, this list of conditions and the following disclaimer.
12#     * Redistributions in binary form must reproduce the above
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19#
20# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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30# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31
32
33"""Memorizing file.
34
35A memorizing file wraps a file and memorizes lines read by readline.
36"""
37
38
39import sys
40
41
42class MemorizingFile(object):
43    """MemorizingFile wraps a file and memorizes lines read by readline.
44
45    Note that data read by other methods are not memorized. This behavior
46    is good enough for memorizing lines SimpleHTTPServer reads before
47    the control reaches WebSocketRequestHandler.
48    """
49
50    def __init__(self, file_, max_memorized_lines=sys.maxint):
51        """Construct an instance.
52
53        Args:
54            file_: the file object to wrap.
55            max_memorized_lines: the maximum number of lines to memorize.
56                Only the first max_memorized_lines are memorized.
57                Default: sys.maxint.
58        """
59
60        self._file = file_
61        self._memorized_lines = []
62        self._max_memorized_lines = max_memorized_lines
63        self._buffered = False
64        self._buffered_line = None
65
66    def __getattribute__(self, name):
67        if name in ('_file', '_memorized_lines', '_max_memorized_lines',
68                    '_buffered', '_buffered_line', 'readline',
69                    'get_memorized_lines'):
70            return object.__getattribute__(self, name)
71        return self._file.__getattribute__(name)
72
73    def readline(self, size=-1):
74        """Override file.readline and memorize the line read.
75
76        Note that even if size is specified and smaller than actual size,
77        the whole line will be read out from underlying file object by
78        subsequent readline calls.
79        """
80
81        if self._buffered:
82            line = self._buffered_line
83            self._buffered = False
84        else:
85            line = self._file.readline()
86            if line and len(self._memorized_lines) < self._max_memorized_lines:
87                self._memorized_lines.append(line)
88        if size >= 0 and size < len(line):
89            self._buffered = True
90            self._buffered_line = line[size:]
91            return line[:size]
92        return line
93
94    def get_memorized_lines(self):
95        """Get lines memorized so far."""
96        return self._memorized_lines
97
98
99# vi:sts=4 sw=4 et
100