1 #!/usr/bin/env python 2 3 """ 4 String objects. 5 6 Copyright (C) 2015, 2016 Paul Boddie <paul@boddie.org.uk> 7 8 This program is free software; you can redistribute it and/or modify it under 9 the terms of the GNU General Public License as published by the Free Software 10 Foundation; either version 3 of the License, or (at your option) any later 11 version. 12 13 This program is distributed in the hope that it will be useful, but WITHOUT 14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 15 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 16 details. 17 18 You should have received a copy of the GNU General Public License along with 19 this program. If not, see <http://www.gnu.org/licenses/>. 20 """ 21 22 from __builtins__.int import maxint 23 from __builtins__.operator import _negate 24 from __builtins__.sequence import itemaccess 25 from __builtins__.types import check_int 26 from native import str_add, str_lt, str_gt, str_eq, str_len, str_nonempty, \ 27 str_substr 28 29 class basestring(itemaccess): 30 31 "The base class for all strings." 32 33 _p = maxint / 32 34 _a = 31 35 36 def __init__(self, other=None): 37 38 "Initialise the string, perhaps from 'other'." 39 40 # Note the __data__ member. Since strings are either initialised from 41 # literals or converted using routines defined for other types, no form 42 # of actual initialisation is performed here. 43 44 # NOTE: Cannot perform "other and other.__data__ or None" since the 45 # NOTE: __data__ attribute is not a normal attribute. 46 47 if other: 48 self.__data__ = other.__data__ 49 else: 50 self.__data__ = None 51 52 # Note the __key__ member. This is also initialised statically. Where 53 # a string is the same as an attribute name, the __key__ member contains 54 # attribute position and code details. 55 56 if other: 57 self.__key__ = other.__key__ 58 else: 59 self.__key__ = None 60 61 def __hash__(self): 62 63 "Return a value for hashing purposes." 64 65 result = 0 66 l = self.__len__() 67 i = 0 68 69 while i < l: 70 result = (result * self._a + ord(self.__get_single_item__(i))) % self._p 71 i += 1 72 73 return result 74 75 def _binary_op(self, op, other): 76 77 "Perform 'op' on this object and 'other' if appropriate." 78 79 # Refuse to operate on specialisations of this class. 80 81 if self.__class__ is not other.__class__: 82 return NotImplemented 83 84 # Otherwise, perform the operation on the operands' data. 85 86 else: 87 return op(self.__data__, other.__data__) 88 89 def _binary_op_rev(self, op, other): 90 91 "Perform 'op' on 'other' and this object if appropriate." 92 93 # Refuse to operate on specialisations of this class. 94 95 if self.__class__ is not other.__class__: 96 return NotImplemented 97 98 # Otherwise, perform the operation on the operands' data. 99 100 else: 101 return op(other.__data__, self.__data__) 102 103 def __iadd__(self, other): 104 105 "Return a string combining this string with 'other'." 106 107 return self._binary_op(str_add, other) 108 109 __add__ = __iadd__ 110 111 def __radd__(self, other): 112 113 "Return a string combining this string with 'other'." 114 115 return self._binary_op_rev(str_add, other) 116 117 def __mul__(self, other): pass 118 def __rmul__(self, other): pass 119 def __mod__(self, other): pass 120 def __rmod__(self, other): pass 121 122 def __lt__(self, other): 123 124 "Return whether this string is less than 'other'." 125 126 return self._binary_op(str_lt, other) 127 128 def __gt__(self, other): 129 130 "Return whether this string is greater than 'other'." 131 132 return self._binary_op(str_gt, other) 133 134 def __le__(self, other): 135 136 "Return whether this string is less than or equal to 'other'." 137 138 return _negate(self.__gt__(other)) 139 140 def __ge__(self, other): 141 142 "Return whether this string is greater than or equal to 'other'." 143 144 return _negate(self.__lt__(other)) 145 146 def __eq__(self, other): 147 148 "Return whether this string is equal to 'other'." 149 150 return self._binary_op(str_eq, other) 151 152 def __ne__(self, other): 153 154 "Return whether this string is not equal to 'other'." 155 156 return _negate(self.__eq__(other)) 157 158 def bytelength(self): 159 160 "Return the number of bytes in this string." 161 162 return str_len(self.__data__) 163 164 __len__ = bytelength 165 166 def __str__(self): 167 168 "Return a string representation." 169 170 return self 171 172 def __repr__(self): 173 174 "Return a program representation." 175 176 # NOTE: To be implemented with proper quoting. 177 b = buffer(['"', self, '"']) 178 return str(b) 179 180 def __bool__(self): 181 return str_nonempty(self.__data__) 182 183 def endswith(self, s): pass 184 def find(self, sub, start=None, end=None): pass 185 def index(self, sub, start=None, end=None): pass 186 187 def join(self, l): 188 189 "Join the elements in 'l' with this string." 190 191 # Empty strings just cause the list elements to be concatenated. 192 193 if not self.__bool__(): 194 return str(buffer(l)) 195 196 # Non-empty strings join the elements together in a buffer. 197 198 b = buffer() 199 first = True 200 201 for s in l: 202 if first: 203 first = False 204 else: 205 b.append(self) 206 b.append(s) 207 208 return str(b) 209 210 def lower(self): pass 211 def lstrip(self, chars=None): pass 212 def replace(self, old, new, count=None): pass 213 def rfind(self, sub, start=None, end=None): pass 214 def rsplit(self, sep=None, maxsplit=None): pass 215 def rstrip(self, chars=None): pass 216 def split(self, sep=None, maxsplit=None): pass 217 def splitlines(self, keepends=False): pass 218 def startswith(self, s): pass 219 def strip(self, chars=None): pass 220 def upper(self): pass 221 222 # Special implementation methods. 223 224 def __get_single_item__(self, index): 225 226 "Return the item at the normalised (positive) 'index'." 227 228 self._check_index(index) 229 return str_substr(self.__data__, index, index + 1, 1) 230 231 def __get_multiple_items__(self, start, end, step): 232 233 """ 234 Return items from 'start' until (but excluding) 'end', at 'step' 235 intervals. 236 """ 237 238 self._check_index(start) 239 self._check_end_index(end) 240 check_int(step) 241 242 if step == 0: 243 raise ValueError(step) 244 245 if start == end: 246 return "" 247 248 return str_substr(self.__data__, start, end, step) 249 250 class string(basestring): 251 252 "A plain string of bytes." 253 254 pass 255 256 def str(obj): 257 258 "Return the string representation of 'obj'." 259 260 # Class attributes of instances provide __str__. 261 262 return obj.__str__() 263 264 # vim: tabstop=4 expandtab shiftwidth=4