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set_chtab(+Char, +Class)

Sets the lexical class of character Char to class Class, this provides an interface to ECLiPSe 's lexical analyser.

+Char: Integer in range 0 to 255.
+Class: Atom indicating the character class.

Description

Changes the lexical class of a given character. This is especially useful for implementing compatibility packages. The possible character classes which a character may have been given are shown below.

Note It is not recommended to change the class of the special characters, since in some cases it might make it impossible to correctly parse Prolog terms.

The following table lists the character classes and the default corresponding characters:

 Class          Default member characters
---------------------------------------------------------
 upper_case     all upper case letters
 underline      _
 lower_case     all lower case letters
 digit          digits
 blank_space    space, tab, carriage return (CR) etc
 end_of_line    newline (NL)
 atom_quote     '
 string_quote   "
 list_quote
 radix
 ascii
 solo           ( ) ] }
 special        ! , ; [ { |
 line_comment   %
 escape         \
 first_comment  /
 second_comment *
 symbol         # + - . : < = > ? @ ^ ` ~ & $
 unused         ASCII codes 8, 17, 21, 24

Fail Conditions

None.

Resatisfiable

No.

Exceptions

(4) instantiation fault: Char and/or Class are not instantiated.
(5) type error: Char is not an integer in the range 0 to 255.
(6) out of range: Class is not a valid lexical class.

Examples