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| 1 | +#!/usr/bin/env python3 |
| 2 | +# Copyright (c) 2008-11 Qtrac Ltd. All rights reserved. |
| 3 | +# This program or module is free software: you can redistribute it and/or |
| 4 | +# modify it under the terms of the GNU General Public License as published |
| 5 | +# by the Free Software Foundation, either version 3 of the License, or |
| 6 | +# (at your option) any later version. It is provided for educational |
| 7 | +# purposes and is distributed in the hope that it will be useful, but |
| 8 | +# WITHOUT ANY WARRANTY; without even the implied warranty of |
| 9 | +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 10 | +# General Public License for more details. |
| 11 | + |
| 12 | +""" |
| 13 | +>>> u = Stack() |
| 14 | +>>> u.push(1); u.push(2); u.push(4) |
| 15 | +>>> str(u) |
| 16 | +'[1, 2, 4]' |
| 17 | +>>> u.can_undo |
| 18 | +True |
| 19 | +>>> while u.can_undo: |
| 20 | +... u.undo() |
| 21 | +>>> str(u) |
| 22 | +'[]' |
| 23 | +>>> for x in list(range(-5, 0)) + list(range(5)): |
| 24 | +... u.push(x) |
| 25 | +>>> str(u) |
| 26 | +'[-5, -4, -3, -2, -1, 0, 1, 2, 3, 4]' |
| 27 | +>>> u.top() |
| 28 | +4 |
| 29 | +>>> total = 0 |
| 30 | +>>> for x in range(5): |
| 31 | +... total += u.pop() |
| 32 | +>>> str(u), total |
| 33 | +('[-5, -4, -3, -2, -1]', 10) |
| 34 | +>>> while u.can_undo: |
| 35 | +... u.undo() |
| 36 | +>>> str(u) |
| 37 | +'[]' |
| 38 | +
|
| 39 | +>>> import os |
| 40 | +>>> import tempfile |
| 41 | +>>> filename = os.path.join(tempfile.gettempdir(), "fs.pkl") |
| 42 | +>>> fs = FileStack(filename) |
| 43 | +>>> for x in list(range(-5, 0)) + list(range(5)): |
| 44 | +... fs.push(x) |
| 45 | +>>> str(fs) |
| 46 | +'[-5, -4, -3, -2, -1, 0, 1, 2, 3, 4]' |
| 47 | +>>> fs.top() |
| 48 | +4 |
| 49 | +>>> total = 0 |
| 50 | +>>> for x in range(5): |
| 51 | +... total += fs.pop() |
| 52 | +>>> str(fs), total |
| 53 | +('[-5, -4, -3, -2, -1]', 10) |
| 54 | +>>> fs.push(909) |
| 55 | +>>> str(fs) |
| 56 | +'[-5, -4, -3, -2, -1, 909]' |
| 57 | +>>> os.path.basename(fs.filename) |
| 58 | +'fs.pkl' |
| 59 | +>>> fs.save() |
| 60 | +>>> fs2 = FileStack(filename) |
| 61 | +>>> str(fs2) |
| 62 | +'[]' |
| 63 | +>>> fs2.push(-32) |
| 64 | +>>> fs2.can_undo |
| 65 | +True |
| 66 | +>>> fs2.load() |
| 67 | +>>> fs2.can_undo |
| 68 | +False |
| 69 | +>>> str(fs2) |
| 70 | +'[-5, -4, -3, -2, -1, 909]' |
| 71 | +>>> fs == fs2 |
| 72 | +True |
| 73 | +""" |
| 74 | + |
| 75 | + |
| 76 | +import abc |
| 77 | +import pickle |
| 78 | + |
| 79 | + |
| 80 | +class Undo(metaclass=abc.ABCMeta): |
| 81 | + |
| 82 | + @abc.abstractmethod |
| 83 | + def __init__(self): |
| 84 | + self.__undos = [] |
| 85 | + |
| 86 | + |
| 87 | + @abc.abstractproperty |
| 88 | + def can_undo(self): |
| 89 | + return bool(self.__undos) |
| 90 | + |
| 91 | + |
| 92 | + @abc.abstractmethod |
| 93 | + def undo(self): |
| 94 | + assert self.__undos, "nothing left to undo" |
| 95 | + self.__undos.pop()(self) |
| 96 | + |
| 97 | + |
| 98 | + def add_undo(self, undo): |
| 99 | + self.__undos.append(undo) |
| 100 | + |
| 101 | + |
| 102 | + def clear(self): # In class Undo |
| 103 | + self.__undos = [] |
| 104 | + |
| 105 | + |
| 106 | +class Stack(Undo): |
| 107 | + |
| 108 | + def __init__(self): |
| 109 | + super().__init__() |
| 110 | + self.__stack = [] |
| 111 | + |
| 112 | + |
| 113 | + @property |
| 114 | + def can_undo(self): |
| 115 | + return super().can_undo |
| 116 | + |
| 117 | + |
| 118 | + def undo(self): |
| 119 | + super().undo() |
| 120 | + |
| 121 | + |
| 122 | + def push(self, item): |
| 123 | + self.__stack.append(item) |
| 124 | + self.add_undo(lambda self: self.__stack.pop()) |
| 125 | + |
| 126 | + |
| 127 | + def pop(self): |
| 128 | + item = self.__stack.pop() |
| 129 | + self.add_undo(lambda self: self.__stack.append(item)) |
| 130 | + return item |
| 131 | + |
| 132 | + |
| 133 | + def top(self): |
| 134 | + assert self.__stack, "Stack is empty" |
| 135 | + return self.__stack[-1] |
| 136 | + |
| 137 | + |
| 138 | + def __str__(self): |
| 139 | + return str(self.__stack) |
| 140 | + |
| 141 | + |
| 142 | +class NoFilenameError(Exception): pass |
| 143 | + |
| 144 | + |
| 145 | +class LoadSave: |
| 146 | + |
| 147 | + def __init__(self, filename, *attribute_names): |
| 148 | + self.filename = filename |
| 149 | + self.__attribute_names = [] |
| 150 | + for name in attribute_names: |
| 151 | + if name.startswith("__"): |
| 152 | + name = "_" + self.__class__.__name__ + name |
| 153 | + self.__attribute_names.append(name) |
| 154 | + |
| 155 | + |
| 156 | + def save(self): |
| 157 | + with open(self.filename, "wb") as fh: |
| 158 | + data = [] |
| 159 | + for name in self.__attribute_names: |
| 160 | + data.append(getattr(self, name)) |
| 161 | + pickle.dump(data, fh, pickle.HIGHEST_PROTOCOL) |
| 162 | + |
| 163 | + |
| 164 | + def load(self): |
| 165 | + with open(self.filename, "rb") as fh: |
| 166 | + data = pickle.load(fh) |
| 167 | + for name, value in zip(self.__attribute_names, data): |
| 168 | + setattr(self, name, value) |
| 169 | + |
| 170 | + |
| 171 | +class FileStack(Undo, LoadSave): |
| 172 | + |
| 173 | + def __init__(self, filename): |
| 174 | + Undo.__init__(self) |
| 175 | + LoadSave.__init__(self, filename, "__stack") |
| 176 | + self.__stack = [] |
| 177 | + |
| 178 | + |
| 179 | + def load(self): |
| 180 | + super().load() |
| 181 | + self.clear() |
| 182 | + |
| 183 | + |
| 184 | + @property |
| 185 | + def can_undo(self): |
| 186 | + return super().can_undo |
| 187 | + |
| 188 | + |
| 189 | + def undo(self): |
| 190 | + super().undo() |
| 191 | + |
| 192 | + |
| 193 | + def push(self, item): |
| 194 | + self.__stack.append(item) |
| 195 | + self.add_undo(lambda self: self.__stack.pop()) |
| 196 | + |
| 197 | + |
| 198 | + def pop(self): |
| 199 | + item = self.__stack.pop() |
| 200 | + self.add_undo(lambda self: self.__stack.append(item)) |
| 201 | + return item |
| 202 | + |
| 203 | + |
| 204 | + def top(self): |
| 205 | + assert self.__stack, "Stack is empty" |
| 206 | + return self.__stack[-1] |
| 207 | + |
| 208 | + |
| 209 | + def __eq__(self, other): |
| 210 | + return self.__stack == other.__stack |
| 211 | + |
| 212 | + |
| 213 | + def __str__(self): |
| 214 | + return str(self.__stack) |
| 215 | + |
| 216 | + |
| 217 | +if __name__ == "__main__": |
| 218 | + import doctest |
| 219 | + doctest.testmod() |
| 220 | + |
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