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(elisp)Syntax Table Internals

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Syntax Table Internals
======================

   Lisp programs don't usually work with the elements directly; the
Lisp-level syntax table functions usually work with syntax descriptors
(Note: Syntax Descriptors).  Nonetheless, here we document the
internal format.  This format is used mostly when manipulating syntax
properties.

   Each element of a syntax table is a cons cell of the form
`(SYNTAX-CODE . MATCHING-CHAR)'.  The CAR, SYNTAX-CODE, is an integer
that encodes the syntax class, and any flags.  The CDR, MATCHING-CHAR,
is non-`nil' if a character to match was specified.

   This table gives the value of SYNTAX-CODE which corresponds to each
syntactic type.

     Integer Class          Integer Class          Integer Class
     0    whitespace        5    close parenthesis 10    character quote
     1    punctuation       6    expression prefix 11    comment-start
     2    word              7    string quote      12    comment-end
     3    symbol            8    paired delimiter  13    inherit
     4    open parenthesis  9    escape            14    comment-fence
     15   string-fence                             

   For example, the usual syntax value for `(' is `(4 . 41)'.  (41 is
the character code for `)'.)

   The flags are encoded in higher order bits, starting 16 bits from the
least significant bit.  This table gives the power of two which
corresponds to each syntax flag.

     Prefix Flag            Prefix Flag            Prefix Flag
     `1'    `(lsh 1 16)'    `4'    `(lsh 1 19)'    `b'    `(lsh 1 21)'
     `2'    `(lsh 1 17)'    `p'    `(lsh 1 20)'    `n'    `(lsh 1 22)'
     `3'    `(lsh 1 18)'                           

 - Function: string-to-syntax DESC
     This function returns the internal form `(SYNTAX-CODE .
     MATCHING-CHAR)' corresponding to the syntax descriptor DESC.