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144 lines
4.2 KiB
ReStructuredText
144 lines
4.2 KiB
ReStructuredText
:mod:`stringprep` --- Internet String Preparation
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=================================================
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.. module:: stringprep
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:synopsis: String preparation, as per RFC 3453
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.. moduleauthor:: Martin v. Löwis <martin@v.loewis.de>
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.. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>
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**Source code:** :source:`Lib/stringprep.py`
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--------------
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When identifying things (such as host names) in the internet, it is often
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necessary to compare such identifications for "equality". Exactly how this
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comparison is executed may depend on the application domain, e.g. whether it
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should be case-insensitive or not. It may be also necessary to restrict the
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possible identifications, to allow only identifications consisting of
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"printable" characters.
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:rfc:`3454` defines a procedure for "preparing" Unicode strings in internet
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protocols. Before passing strings onto the wire, they are processed with the
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preparation procedure, after which they have a certain normalized form. The RFC
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defines a set of tables, which can be combined into profiles. Each profile must
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define which tables it uses, and what other optional parts of the ``stringprep``
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procedure are part of the profile. One example of a ``stringprep`` profile is
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``nameprep``, which is used for internationalized domain names.
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The module :mod:`stringprep` only exposes the tables from :rfc:`3454`. As these
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tables would be very large to represent them as dictionaries or lists, the
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module uses the Unicode character database internally. The module source code
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itself was generated using the ``mkstringprep.py`` utility.
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As a result, these tables are exposed as functions, not as data structures.
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There are two kinds of tables in the RFC: sets and mappings. For a set,
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:mod:`stringprep` provides the "characteristic function", i.e. a function that
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returns true if the parameter is part of the set. For mappings, it provides the
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mapping function: given the key, it returns the associated value. Below is a
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list of all functions available in the module.
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.. function:: in_table_a1(code)
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Determine whether *code* is in tableA.1 (Unassigned code points in Unicode 3.2).
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.. function:: in_table_b1(code)
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Determine whether *code* is in tableB.1 (Commonly mapped to nothing).
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.. function:: map_table_b2(code)
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Return the mapped value for *code* according to tableB.2 (Mapping for
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case-folding used with NFKC).
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.. function:: map_table_b3(code)
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Return the mapped value for *code* according to tableB.3 (Mapping for
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case-folding used with no normalization).
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.. function:: in_table_c11(code)
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Determine whether *code* is in tableC.1.1 (ASCII space characters).
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.. function:: in_table_c12(code)
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Determine whether *code* is in tableC.1.2 (Non-ASCII space characters).
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.. function:: in_table_c11_c12(code)
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Determine whether *code* is in tableC.1 (Space characters, union of C.1.1 and
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C.1.2).
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.. function:: in_table_c21(code)
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Determine whether *code* is in tableC.2.1 (ASCII control characters).
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.. function:: in_table_c22(code)
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Determine whether *code* is in tableC.2.2 (Non-ASCII control characters).
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.. function:: in_table_c21_c22(code)
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Determine whether *code* is in tableC.2 (Control characters, union of C.2.1 and
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C.2.2).
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.. function:: in_table_c3(code)
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Determine whether *code* is in tableC.3 (Private use).
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.. function:: in_table_c4(code)
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Determine whether *code* is in tableC.4 (Non-character code points).
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.. function:: in_table_c5(code)
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Determine whether *code* is in tableC.5 (Surrogate codes).
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.. function:: in_table_c6(code)
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Determine whether *code* is in tableC.6 (Inappropriate for plain text).
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.. function:: in_table_c7(code)
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Determine whether *code* is in tableC.7 (Inappropriate for canonical
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representation).
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.. function:: in_table_c8(code)
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Determine whether *code* is in tableC.8 (Change display properties or are
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deprecated).
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.. function:: in_table_c9(code)
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Determine whether *code* is in tableC.9 (Tagging characters).
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.. function:: in_table_d1(code)
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Determine whether *code* is in tableD.1 (Characters with bidirectional property
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"R" or "AL").
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.. function:: in_table_d2(code)
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Determine whether *code* is in tableD.2 (Characters with bidirectional property
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"L").
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