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| 54 | <H1><A NAME="SECTION0061100000000000000000"> |
| 55 | 4.11 <tt class="module">stringprep</tt> -- |
| 56 | Internet String Preparation</A> |
| 57 | </H1> |
| 58 | |
| 59 | <P> |
| 60 | <A NAME="module-stringprep"></A> |
| 61 | |
| 62 | <P> |
| 63 | When identifying things (such as host names) in the internet, it is |
| 64 | often necessary to compare such identifications for |
| 65 | ``equality''. Exactly how this comparison is executed may depend on |
| 66 | the application domain, e.g. whether it should be case-insensitive or |
| 67 | not. It may be also necessary to restrict the possible |
| 68 | identifications, to allow only identifications consisting of |
| 69 | ``printable'' characters. |
| 70 | |
| 71 | <P> |
| 72 | <a class="rfc" id='rfcref-87139' xml:id='rfcref-87139' |
| 73 | href="http://www.faqs.org/rfcs/rfc3454.html">RFC 3454</a> defines a procedure for ``preparing'' Unicode strings in |
| 74 | internet protocols. Before passing strings onto the wire, they are |
| 75 | processed with the preparation procedure, after which they have a |
| 76 | certain normalized form. The RFC defines a set of tables, which can be |
| 77 | combined into profiles. Each profile must define which tables it uses, |
| 78 | and what other optional parts of the <code>stringprep</code> procedure are |
| 79 | part of the profile. One example of a <code>stringprep</code> profile is |
| 80 | <code>nameprep</code>, which is used for internationalized domain names. |
| 81 | |
| 82 | <P> |
| 83 | The module <tt class="module">stringprep</tt> only exposes the tables from RFC |
| 84 | 3454. As these tables would be very large to represent them as |
| 85 | dictionaries or lists, the module uses the Unicode character database |
| 86 | internally. The module source code itself was generated using the |
| 87 | <code>mkstringprep.py</code> utility. |
| 88 | |
| 89 | <P> |
| 90 | As a result, these tables are exposed as functions, not as data |
| 91 | structures. There are two kinds of tables in the RFC: sets and |
| 92 | mappings. For a set, <tt class="module">stringprep</tt> provides the ``characteristic |
| 93 | function'', i.e. a function that returns true if the parameter is part |
| 94 | of the set. For mappings, it provides the mapping function: given the |
| 95 | key, it returns the associated value. Below is a list of all functions |
| 96 | available in the module. |
| 97 | |
| 98 | <P> |
| 99 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 100 | <td><nobr><b><tt id='l2h-1039' xml:id='l2h-1039' class="function">in_table_a1</tt></b>(</nobr></td> |
| 101 | <td><var>code</var>)</td></tr></table></dt> |
| 102 | <dd> |
| 103 | Determine whether <var>code</var> is in tableA.1 (Unassigned code points |
| 104 | in Unicode 3.2). |
| 105 | </dl> |
| 106 | |
| 107 | <P> |
| 108 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 109 | <td><nobr><b><tt id='l2h-1040' xml:id='l2h-1040' class="function">in_table_b1</tt></b>(</nobr></td> |
| 110 | <td><var>code</var>)</td></tr></table></dt> |
| 111 | <dd> |
| 112 | Determine whether <var>code</var> is in tableB.1 (Commonly mapped to |
| 113 | nothing). |
| 114 | </dl> |
| 115 | |
| 116 | <P> |
| 117 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 118 | <td><nobr><b><tt id='l2h-1041' xml:id='l2h-1041' class="function">map_table_b2</tt></b>(</nobr></td> |
| 119 | <td><var>code</var>)</td></tr></table></dt> |
| 120 | <dd> |
| 121 | Return the mapped value for <var>code</var> according to tableB.2 |
| 122 | (Mapping for case-folding used with NFKC). |
| 123 | </dl> |
| 124 | |
| 125 | <P> |
| 126 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 127 | <td><nobr><b><tt id='l2h-1042' xml:id='l2h-1042' class="function">map_table_b3</tt></b>(</nobr></td> |
| 128 | <td><var>code</var>)</td></tr></table></dt> |
| 129 | <dd> |
| 130 | Return the mapped value for <var>code</var> according to tableB.3 |
| 131 | (Mapping for case-folding used with no normalization). |
| 132 | </dl> |
| 133 | |
| 134 | <P> |
| 135 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 136 | <td><nobr><b><tt id='l2h-1043' xml:id='l2h-1043' class="function">in_table_c11</tt></b>(</nobr></td> |
| 137 | <td><var>code</var>)</td></tr></table></dt> |
| 138 | <dd> |
| 139 | Determine whether <var>code</var> is in tableC.1.1 |
| 140 | (ASCII space characters). |
| 141 | </dl> |
| 142 | |
| 143 | <P> |
| 144 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 145 | <td><nobr><b><tt id='l2h-1044' xml:id='l2h-1044' class="function">in_table_c12</tt></b>(</nobr></td> |
| 146 | <td><var>code</var>)</td></tr></table></dt> |
| 147 | <dd> |
| 148 | Determine whether <var>code</var> is in tableC.1.2 |
| 149 | (Non-ASCII space characters). |
| 150 | </dl> |
| 151 | |
| 152 | <P> |
| 153 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 154 | <td><nobr><b><tt id='l2h-1045' xml:id='l2h-1045' class="function">in_table_c11_c12</tt></b>(</nobr></td> |
| 155 | <td><var>code</var>)</td></tr></table></dt> |
| 156 | <dd> |
| 157 | Determine whether <var>code</var> is in tableC.1 |
| 158 | (Space characters, union of C.1.1 and C.1.2). |
| 159 | </dl> |
| 160 | |
| 161 | <P> |
| 162 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 163 | <td><nobr><b><tt id='l2h-1046' xml:id='l2h-1046' class="function">in_table_c21</tt></b>(</nobr></td> |
| 164 | <td><var>code</var>)</td></tr></table></dt> |
| 165 | <dd> |
| 166 | Determine whether <var>code</var> is in tableC.2.1 |
| 167 | (ASCII control characters). |
| 168 | </dl> |
| 169 | |
| 170 | <P> |
| 171 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 172 | <td><nobr><b><tt id='l2h-1047' xml:id='l2h-1047' class="function">in_table_c22</tt></b>(</nobr></td> |
| 173 | <td><var>code</var>)</td></tr></table></dt> |
| 174 | <dd> |
| 175 | Determine whether <var>code</var> is in tableC.2.2 |
| 176 | (Non-ASCII control characters). |
| 177 | </dl> |
| 178 | |
| 179 | <P> |
| 180 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 181 | <td><nobr><b><tt id='l2h-1048' xml:id='l2h-1048' class="function">in_table_c21_c22</tt></b>(</nobr></td> |
| 182 | <td><var>code</var>)</td></tr></table></dt> |
| 183 | <dd> |
| 184 | Determine whether <var>code</var> is in tableC.2 |
| 185 | (Control characters, union of C.2.1 and C.2.2). |
| 186 | </dl> |
| 187 | |
| 188 | <P> |
| 189 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 190 | <td><nobr><b><tt id='l2h-1049' xml:id='l2h-1049' class="function">in_table_c3</tt></b>(</nobr></td> |
| 191 | <td><var>code</var>)</td></tr></table></dt> |
| 192 | <dd> |
| 193 | Determine whether <var>code</var> is in tableC.3 |
| 194 | (Private use). |
| 195 | </dl> |
| 196 | |
| 197 | <P> |
| 198 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 199 | <td><nobr><b><tt id='l2h-1050' xml:id='l2h-1050' class="function">in_table_c4</tt></b>(</nobr></td> |
| 200 | <td><var>code</var>)</td></tr></table></dt> |
| 201 | <dd> |
| 202 | Determine whether <var>code</var> is in tableC.4 |
| 203 | (Non-character code points). |
| 204 | </dl> |
| 205 | |
| 206 | <P> |
| 207 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 208 | <td><nobr><b><tt id='l2h-1051' xml:id='l2h-1051' class="function">in_table_c5</tt></b>(</nobr></td> |
| 209 | <td><var>code</var>)</td></tr></table></dt> |
| 210 | <dd> |
| 211 | Determine whether <var>code</var> is in tableC.5 |
| 212 | (Surrogate codes). |
| 213 | </dl> |
| 214 | |
| 215 | <P> |
| 216 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 217 | <td><nobr><b><tt id='l2h-1052' xml:id='l2h-1052' class="function">in_table_c6</tt></b>(</nobr></td> |
| 218 | <td><var>code</var>)</td></tr></table></dt> |
| 219 | <dd> |
| 220 | Determine whether <var>code</var> is in tableC.6 |
| 221 | (Inappropriate for plain text). |
| 222 | </dl> |
| 223 | |
| 224 | <P> |
| 225 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 226 | <td><nobr><b><tt id='l2h-1053' xml:id='l2h-1053' class="function">in_table_c7</tt></b>(</nobr></td> |
| 227 | <td><var>code</var>)</td></tr></table></dt> |
| 228 | <dd> |
| 229 | Determine whether <var>code</var> is in tableC.7 |
| 230 | (Inappropriate for canonical representation). |
| 231 | </dl> |
| 232 | |
| 233 | <P> |
| 234 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 235 | <td><nobr><b><tt id='l2h-1054' xml:id='l2h-1054' class="function">in_table_c8</tt></b>(</nobr></td> |
| 236 | <td><var>code</var>)</td></tr></table></dt> |
| 237 | <dd> |
| 238 | Determine whether <var>code</var> is in tableC.8 |
| 239 | (Change display properties or are deprecated). |
| 240 | </dl> |
| 241 | |
| 242 | <P> |
| 243 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 244 | <td><nobr><b><tt id='l2h-1055' xml:id='l2h-1055' class="function">in_table_c9</tt></b>(</nobr></td> |
| 245 | <td><var>code</var>)</td></tr></table></dt> |
| 246 | <dd> |
| 247 | Determine whether <var>code</var> is in tableC.9 |
| 248 | (Tagging characters). |
| 249 | </dl> |
| 250 | |
| 251 | <P> |
| 252 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 253 | <td><nobr><b><tt id='l2h-1056' xml:id='l2h-1056' class="function">in_table_d1</tt></b>(</nobr></td> |
| 254 | <td><var>code</var>)</td></tr></table></dt> |
| 255 | <dd> |
| 256 | Determine whether <var>code</var> is in tableD.1 |
| 257 | (Characters with bidirectional property ``R'' or ``AL''). |
| 258 | </dl> |
| 259 | |
| 260 | <P> |
| 261 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 262 | <td><nobr><b><tt id='l2h-1057' xml:id='l2h-1057' class="function">in_table_d2</tt></b>(</nobr></td> |
| 263 | <td><var>code</var>)</td></tr></table></dt> |
| 264 | <dd> |
| 265 | Determine whether <var>code</var> is in tableD.2 |
| 266 | (Characters with bidirectional property ``L''). |
| 267 | </dl> |
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