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 int and 'other' if appropriate." 78 79 if isinstance(other, basestring): 80 return op(self.__data__, other.__data__) 81 else: 82 return NotImplemented 83 84 def __iadd__(self, other): 85 86 "Return a string combining this string with 'other'." 87 88 return self._binary_op(str_add, other) 89 90 __add__ = __radd__ = __iadd__ 91 92 def __mul__(self, other): pass 93 def __rmul__(self, other): pass 94 def __mod__(self, other): pass 95 def __rmod__(self, other): pass 96 97 def __lt__(self, other): 98 99 "Return whether this string is less than 'other'." 100 101 return self._binary_op(str_lt, other) 102 103 def __gt__(self, other): 104 105 "Return whether this string is greater than 'other'." 106 107 return self._binary_op(str_gt, other) 108 109 def __le__(self, other): 110 111 "Return whether this string is less than or equal to 'other'." 112 113 return _negate(self.__gt__(other)) 114 115 def __ge__(self, other): 116 117 "Return whether this string is greater than or equal to 'other'." 118 119 return _negate(self.__lt__(other)) 120 121 def __eq__(self, other): 122 123 "Return whether this string is equal to 'other'." 124 125 return self._binary_op(str_eq, other) 126 127 def __ne__(self, other): 128 129 "Return whether this string is not equal to 'other'." 130 131 return _negate(self.__eq__(other)) 132 133 def __len__(self): 134 135 "Return the length of this string." 136 137 return str_len(self.__data__) 138 139 def __str__(self): 140 141 "Return a string representation." 142 143 return self 144 145 def __repr__(self): 146 147 "Return a program representation." 148 149 # NOTE: To be implemented with proper quoting. 150 b = buffer(['"', self, '"']) 151 return str(b) 152 153 def __bool__(self): 154 return str_nonempty(self.__data__) 155 156 def endswith(self, s): pass 157 def find(self, sub, start=None, end=None): pass 158 def index(self, sub, start=None, end=None): pass 159 160 def join(self, l): 161 162 "Join the elements in 'l' with this string." 163 164 # Empty strings just cause the list elements to be concatenated. 165 166 if not self.__bool__(): 167 return str(buffer(l)) 168 169 # Non-empty strings join the elements together in a buffer. 170 171 b = buffer() 172 first = True 173 174 for s in l: 175 if first: 176 first = False 177 else: 178 b.append(self) 179 b.append(s) 180 181 return str(b) 182 183 def lower(self): pass 184 def lstrip(self, chars=None): pass 185 def replace(self, old, new, count=None): pass 186 def rfind(self, sub, start=None, end=None): pass 187 def rsplit(self, sep=None, maxsplit=None): pass 188 def rstrip(self, chars=None): pass 189 def split(self, sep=None, maxsplit=None): pass 190 def splitlines(self, keepends=False): pass 191 def startswith(self, s): pass 192 def strip(self, chars=None): pass 193 def upper(self): pass 194 195 # Special implementation methods. 196 197 def __get_single_item__(self, index): 198 199 "Return the item at the normalised (positive) 'index'." 200 201 self._check_index(index) 202 return str_substr(self.__data__, index, index + 1, 1) 203 204 def __get_multiple_items__(self, start, end, step): 205 206 """ 207 Return items from 'start' until (but excluding) 'end', at 'step' 208 intervals. 209 """ 210 211 self._check_index(start) 212 self._check_end_index(end) 213 check_int(step) 214 215 if step == 0: 216 raise ValueError(step) 217 218 if start == end: 219 return "" 220 221 return str_substr(self.__data__, start, end, step) 222 223 class string(basestring): 224 225 "A plain string of bytes." 226 227 pass 228 229 def str(obj): 230 231 "Return the string representation of 'obj'." 232 233 # Class attributes of instances provide __str__. 234 235 return obj.__str__() 236 237 # vim: tabstop=4 expandtab shiftwidth=4