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Georg Brandl116aa622007-08-15 14:28:22 +00001:mod:`stringprep` --- Internet String Preparation
2=================================================
3
4.. module:: stringprep
5 :synopsis: String preparation, as per RFC 3453
Terry Jan Reedyfa089b92016-06-11 15:02:54 -04006
Georg Brandl116aa622007-08-15 14:28:22 +00007.. moduleauthor:: Martin v. Löwis <martin@v.loewis.de>
8.. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>
9
Terry Jan Reedyfa089b92016-06-11 15:02:54 -040010**Source code:** :source:`Lib/stringprep.py`
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Georg Brandl116aa622007-08-15 14:28:22 +000013
Georg Brandl116aa622007-08-15 14:28:22 +000014When identifying things (such as host names) in the internet, it is often
15necessary to compare such identifications for "equality". Exactly how this
16comparison is executed may depend on the application domain, e.g. whether it
17should be case-insensitive or not. It may be also necessary to restrict the
18possible identifications, to allow only identifications consisting of
19"printable" characters.
20
21:rfc:`3454` defines a procedure for "preparing" Unicode strings in internet
22protocols. Before passing strings onto the wire, they are processed with the
23preparation procedure, after which they have a certain normalized form. The RFC
24defines a set of tables, which can be combined into profiles. Each profile must
25define which tables it uses, and what other optional parts of the ``stringprep``
26procedure are part of the profile. One example of a ``stringprep`` profile is
27``nameprep``, which is used for internationalized domain names.
28
Serhiy Storchaka0a36ac12018-05-31 07:39:00 +030029The module :mod:`stringprep` only exposes the tables from :rfc:`3454`. As these
Georg Brandl116aa622007-08-15 14:28:22 +000030tables would be very large to represent them as dictionaries or lists, the
31module uses the Unicode character database internally. The module source code
32itself was generated using the ``mkstringprep.py`` utility.
33
34As a result, these tables are exposed as functions, not as data structures.
35There are two kinds of tables in the RFC: sets and mappings. For a set,
36:mod:`stringprep` provides the "characteristic function", i.e. a function that
37returns true if the parameter is part of the set. For mappings, it provides the
38mapping function: given the key, it returns the associated value. Below is a
39list of all functions available in the module.
40
41
42.. function:: in_table_a1(code)
43
44 Determine whether *code* is in tableA.1 (Unassigned code points in Unicode 3.2).
45
46
47.. function:: in_table_b1(code)
48
49 Determine whether *code* is in tableB.1 (Commonly mapped to nothing).
50
51
52.. function:: map_table_b2(code)
53
54 Return the mapped value for *code* according to tableB.2 (Mapping for
55 case-folding used with NFKC).
56
57
58.. function:: map_table_b3(code)
59
60 Return the mapped value for *code* according to tableB.3 (Mapping for
61 case-folding used with no normalization).
62
63
64.. function:: in_table_c11(code)
65
66 Determine whether *code* is in tableC.1.1 (ASCII space characters).
67
68
69.. function:: in_table_c12(code)
70
71 Determine whether *code* is in tableC.1.2 (Non-ASCII space characters).
72
73
74.. function:: in_table_c11_c12(code)
75
76 Determine whether *code* is in tableC.1 (Space characters, union of C.1.1 and
77 C.1.2).
78
79
80.. function:: in_table_c21(code)
81
82 Determine whether *code* is in tableC.2.1 (ASCII control characters).
83
84
85.. function:: in_table_c22(code)
86
87 Determine whether *code* is in tableC.2.2 (Non-ASCII control characters).
88
89
90.. function:: in_table_c21_c22(code)
91
92 Determine whether *code* is in tableC.2 (Control characters, union of C.2.1 and
93 C.2.2).
94
95
96.. function:: in_table_c3(code)
97
98 Determine whether *code* is in tableC.3 (Private use).
99
100
101.. function:: in_table_c4(code)
102
103 Determine whether *code* is in tableC.4 (Non-character code points).
104
105
106.. function:: in_table_c5(code)
107
108 Determine whether *code* is in tableC.5 (Surrogate codes).
109
110
111.. function:: in_table_c6(code)
112
113 Determine whether *code* is in tableC.6 (Inappropriate for plain text).
114
115
116.. function:: in_table_c7(code)
117
118 Determine whether *code* is in tableC.7 (Inappropriate for canonical
119 representation).
120
121
122.. function:: in_table_c8(code)
123
124 Determine whether *code* is in tableC.8 (Change display properties or are
125 deprecated).
126
127
128.. function:: in_table_c9(code)
129
130 Determine whether *code* is in tableC.9 (Tagging characters).
131
132
133.. function:: in_table_d1(code)
134
135 Determine whether *code* is in tableD.1 (Characters with bidirectional property
136 "R" or "AL").
137
138
139.. function:: in_table_d2(code)
140
141 Determine whether *code* is in tableD.2 (Characters with bidirectional property
142 "L").
143