| [ < ] | [ > ] | [ << ] | [Plus haut] | [ >> ] | [Top] | [Table des matières] | [Index] | [ ? ] |
You can customize case conversion by installing a special case table. A case table specifies the mapping between upper case and lower case letters. It affects both the case conversion functions for Lisp objects (see the previous section) and those that apply to text in the buffer (voir la section Case Changes). Each buffer has a case table; there is also a standard case table which is used to initialize the case table of new buffers.
A case table is a char-table (voir la section Char-Tables) whose subtype is
case-table. This char-table maps each character into the
corresponding lower case character. It has three extra slots, which hold
related tables:
The upcase table maps each character into the corresponding upper case character.
The canonicalize table maps all of a set of case-related characters into a particular member of that set.
The equivalences table maps each one of a set of case-related characters into the next character in that set.
In simple cases, all you need to specify is the mapping to lower-case; the three related tables will be calculated automatically from that one.
For some languages, upper and lower case letters are not in one-to-one correspondence. There may be two different lower case letters with the same upper case equivalent. In these cases, you need to specify the maps for both lower case and upper case.
The extra table canonicalize maps each character to a canonical equivalent; any two characters that are related by case-conversion have the same canonical equivalent character. For example, since ‘a’ and ‘A’ are related by case-conversion, they should have the same canonical equivalent character (which should be either ‘a’ for both of them, or ‘A’ for both of them).
The extra table equivalences is a map that cyclically permutes each equivalence class (of characters with the same canonical equivalent). (For ordinary ASCII, this would map ‘a’ into ‘A’ and ‘A’ into ‘a’, and likewise for each set of equivalent characters.)
When you construct a case table, you can provide nil for
canonicalize; then Emacs fills in this slot from the lower case and
upper case mappings. You can also provide nil for
equivalences; then Emacs fills in this slot from canonicalize.
In a case table that is actually in use, those components are
non-nil. Do not try to specify equivalences without also
specifying canonicalize.
Here are the functions for working with case tables:
This predicate returns non-nil if object is a valid case table.
This function makes table the standard case table, so that it will be used in any buffers created subsequently.
This returns the standard case table.
This function returns the current buffer's case table.
This sets the current buffer's case table to table.
The with-case-table macro saves the current case table, makes
table the current case table, evaluates the body forms, and
finally restores the case table. The return value is the value of the last
form in body. The case table is restored even in case of an abnormal
exit via throw or error (voir la section Nonlocal Exits).
Some language environments may modify the case conversions of
ASCII characters; for example, in the Turkish language
environment, the ASCII character ‘I’ is downcased into a
Turkish “dotless i”. This can interfere with code that requires ordinary
ASCII case conversion, such as implementations of ASCII-based
network protocols. In that case, use the with-case-table macro with
the variable ascii-case-table, which stores the unmodified case table
for the ASCII character set.
The case table for the ASCII character set. This should not be modified by any language environment settings.
The following three functions are convenient subroutines for packages that define non-ASCII character sets. They modify the specified case table case-table; they also modify the standard syntax table. @xref{Syntax Tables}. Normally you would use these functions to change the standard case table.
This function specifies a pair of corresponding letters, one upper case and one lower case.
This function makes characters l and r a matching pair of case-invariant delimiters.
This function makes char case-invariant, with syntax syntax.
This command displays a description of the contents of the current buffer's case table.
| [ < ] | [ > ] | [ << ] | [Plus haut] | [ >> ] | [Top] | [Table des matières] | [Index] | [ ? ] |
Ce document a été généré par Eric Reinbold le 13 Octobre 2007 en utilisant texi2html 1.78.