137 lines
4.5 KiB
TeX
137 lines
4.5 KiB
TeX
\section{\module{stringprep} ---
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Internet String Preparation}
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\declaremodule{standard}{stringprep}
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\modulesynopsis{String preparation, as per RFC 3453}
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\moduleauthor{Martin v. L\"owis}{martin@v.loewis.de}
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\sectionauthor{Martin v. L\"owis}{martin@v.loewis.de}
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\versionadded{2.3}
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When identifying things (such as host names) in the internet, it is
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often necessary to compare such identifications for
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``equality''. Exactly how this comparison is executed may depend on
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the application domain, e.g. whether it should be case-insensitive or
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not. It may be also necessary to restrict the possible
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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
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internet protocols. Before passing strings onto the wire, they are
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processed with the preparation procedure, after which they have a
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certain normalized form. The RFC defines a set of tables, which can be
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combined into profiles. Each profile must define which tables it uses,
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and what other optional parts of the \code{stringprep} procedure are
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part of the profile. One example of a \code{stringprep} profile is
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\code{nameprep}, which is used for internationalized domain names.
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The module \module{stringprep} only exposes the tables from RFC
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3454. As these tables would be very large to represent them as
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dictionaries or lists, the module uses the Unicode character database
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internally. The module source code itself was generated using the
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\code{mkstringprep.py} utility.
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As a result, these tables are exposed as functions, not as data
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structures. There are two kinds of tables in the RFC: sets and
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mappings. For a set, \module{stringprep} provides the ``characteristic
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function'', i.e. a function that returns true if the parameter is part
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of the set. For mappings, it provides the mapping function: given the
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key, it returns the associated value. Below is a list of all functions
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available in the module.
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\begin{funcdesc}{in_table_a1}{code}
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Determine whether \var{code} is in table{A.1} (Unassigned code points
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in Unicode 3.2).
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\end{funcdesc}
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\begin{funcdesc}{in_table_b1}{code}
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Determine whether \var{code} is in table{B.1} (Commonly mapped to
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nothing).
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\end{funcdesc}
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\begin{funcdesc}{map_table_b2}{code}
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Return the mapped value for \var{code} according to table{B.2}
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(Mapping for case-folding used with NFKC).
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\end{funcdesc}
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\begin{funcdesc}{map_table_b3}{code}
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Return the mapped value for \var{code} according to table{B.3}
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(Mapping for case-folding used with no normalization).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c11}{code}
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Determine whether \var{code} is in table{C.1.1}
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(ASCII space characters).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c12}{code}
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Determine whether \var{code} is in table{C.1.2}
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(Non-ASCII space characters).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c11_c12}{code}
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Determine whether \var{code} is in table{C.1}
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(Space characters, union of C.1.1 and C.1.2).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c21}{code}
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Determine whether \var{code} is in table{C.2.1}
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(ASCII control characters).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c22}{code}
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Determine whether \var{code} is in table{C.2.2}
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(Non-ASCII control characters).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c21_c22}{code}
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Determine whether \var{code} is in table{C.2}
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(Control characters, union of C.2.1 and C.2.2).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c3}{code}
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Determine whether \var{code} is in table{C.3}
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(Private use).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c4}{code}
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Determine whether \var{code} is in table{C.4}
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(Non-character code points).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c5}{code}
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Determine whether \var{code} is in table{C.5}
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(Surrogate codes).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c6}{code}
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Determine whether \var{code} is in table{C.6}
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(Inappropriate for plain text).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c7}{code}
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Determine whether \var{code} is in table{C.7}
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(Inappropriate for canonical representation).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c8}{code}
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Determine whether \var{code} is in table{C.8}
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(Change display properties or are deprecated).
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\end{funcdesc}
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\begin{funcdesc}{in_table_c9}{code}
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Determine whether \var{code} is in table{C.9}
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(Tagging characters).
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\end{funcdesc}
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\begin{funcdesc}{in_table_d1}{code}
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Determine whether \var{code} is in table{D.1}
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(Characters with bidirectional property ``R'' or ``AL'').
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\end{funcdesc}
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\begin{funcdesc}{in_table_d2}{code}
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Determine whether \var{code} is in table{D.2}
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(Characters with bidirectional property ``L'').
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\end{funcdesc}
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