emacs/src/syntax.h

/* Declarations having to do with GNU Emacs syntax tables.

Copyright (C) 1985, 1993-1994, 1997-1998, 2001-2024 Free Software
Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

#ifndef EMACS_SYNTAX_H
#define EMACS_SYNTAX_H

#include "buffer.h"
#include "lisp.h"

INLINE_HEADER_BEGIN

extern void update_syntax_table (ptrdiff_t, EMACS_INT, bool, Lisp_Object);
extern void update_syntax_table_forward (ptrdiff_t, bool, Lisp_Object);

/* The standard syntax table is stored where it will automatically
   be used in all new buffers.  */
#define Vstandard_syntax_table BVAR (&buffer_defaults, syntax_table)

/* A syntax table is a chartable whose elements are cons cells
   (CODE+FLAGS . MATCHING-CHAR).  MATCHING-CHAR can be nil if the char
   is not a kind of parenthesis.

   The low 8 bits of CODE+FLAGS is a code, as follows:  */

enum syntaxcode
  {
    Swhitespace, /* for a whitespace character */
    Spunct,	 /* for random punctuation characters */
    Sword,	 /* for a word constituent */
    Ssymbol,	 /* symbol constituent but not word constituent */
    Sopen,	 /* for a beginning delimiter */
    Sclose,      /* for an ending delimiter */
    Squote,	 /* for a prefix character like Lisp ' */
    Sstring,	 /* for a string-grouping character like Lisp " */
    Smath,	 /* for delimiters like $ in Tex.  */
    Sescape,	 /* for a character that begins a C-style escape */
    Scharquote,  /* for a character that quotes the following character */
    Scomment,    /* for a comment-starting character */
    Sendcomment, /* for a comment-ending character */
    Sinherit,    /* use the standard syntax table for this character */
    Scomment_fence, /* Starts/ends comment which is delimited on the
		       other side by any char with the same syntaxcode.  */
    Sstring_fence,  /* Starts/ends string which is delimited on the
		       other side by any char with the same syntaxcode.  */
    Smax	 /* Upper bound on codes that are meaningful.  */
  };


struct gl_state_s
{
  Lisp_Object object;			/* The object we are scanning.  */
  ptrdiff_t start;			/* Where to stop.  */
  ptrdiff_t stop;			/* Where to stop.  */
  bool use_global;			/* Whether to use global_code
					   or c_s_t.  */
  Lisp_Object global_code;		/* Syntax code of current char.  */
  Lisp_Object current_syntax_table;	/* Syntax table for current pos.  */
  Lisp_Object old_prop;			/* Syntax-table prop at prev pos.  */
  ptrdiff_t b_property;			/* First index where c_s_t is valid.  */
  ptrdiff_t e_property;			/* First index where c_s_t is
					   not valid.  */
  bool e_property_truncated;		/* true if e_property if was truncated
					   by parse_sexp_propertize_done.  */
  INTERVAL forward_i;			/* Where to start lookup on forward.  */
  INTERVAL backward_i;			/* or backward movement.  The
					   data in c_s_t is valid
					   between these intervals,
					   and possibly at the
					   intervals too, depending
					   on:  */
};

extern struct gl_state_s gl_state;

/* Fetch the information from the entry for character C
   in the current buffer's syntax table,
   or (if VIA_PROPERTY) from globally kept data (gl_state).
   Does inheritance.  */

INLINE Lisp_Object
syntax_property_entry (int c, bool via_property)
{
  if (via_property)
    return (gl_state.use_global
	    ? gl_state.global_code
	    : CHAR_TABLE_REF (gl_state.current_syntax_table, c));
  return CHAR_TABLE_REF (BVAR (current_buffer, syntax_table), c);
}
INLINE Lisp_Object
SYNTAX_ENTRY (int c)
{
  return syntax_property_entry (c, false);
}

/* Extract the information from the entry for character C
   in the current syntax table.  */

INLINE int
syntax_property_with_flags (int c, bool via_property)
{
  Lisp_Object ent = syntax_property_entry (c, via_property);
  return CONSP (ent) ? XFIXNUM (XCAR (ent)) : Swhitespace;
}
INLINE int
SYNTAX_WITH_FLAGS (int c)
{
  return syntax_property_with_flags (c, false);
}

INLINE enum syntaxcode
syntax_property (int c, bool via_property)
{
  return syntax_property_with_flags (c, via_property) & 0xff;
}
INLINE enum syntaxcode
SYNTAX (int c)
{
  return syntax_property (c, false);
}


/* Whether the syntax of the character C has the prefix flag set.  */
extern bool syntax_prefix_flag_p (int c);

/* This array, indexed by a character less than 256, contains the
   syntax code which that character signifies (as an unsigned char).
   For example, syntax_spec_code['w'] == Sword.  */

extern unsigned char const syntax_spec_code[0400];

/* Convert the regexp's BYTEOFFSET into a character position,
   for the object recorded in gl_state with RE_SETUP_SYNTAX_TABLE_FOR_OBJECT.

   The value is meant for use in code that does nothing when
   parse_sexp_lookup_properties is false, so return 0 in that case,
   for speed.  */

INLINE ptrdiff_t
RE_SYNTAX_TABLE_BYTE_TO_CHAR (ptrdiff_t byteoffset)
{
  return (! parse_sexp_lookup_properties
	  ? 0
	  : STRINGP (gl_state.object)
	  ? string_byte_to_char (gl_state.object, byteoffset)
	  : BUFFERP (gl_state.object)
	  ? ((buf_bytepos_to_charpos
	      (XBUFFER (gl_state.object),
	       (byteoffset + BUF_BEGV_BYTE (XBUFFER (gl_state.object))))))
	  : NILP (gl_state.object)
	  ? BYTE_TO_CHAR (byteoffset + BEGV_BYTE)
	  : byteoffset);
}

/* Make syntax table state (gl_state) good for CHARPOS, assuming it is
   currently good for a position before CHARPOS.  */

INLINE void
UPDATE_SYNTAX_TABLE_FORWARD (ptrdiff_t charpos)
{ /* Performs just-in-time syntax-propertization.  */
  if (parse_sexp_lookup_properties && charpos >= gl_state.e_property)
    update_syntax_table_forward (charpos, false, gl_state.object);
}

/* Make syntax table state (gl_state) good for CHARPOS, assuming it is
   currently good for a position after CHARPOS.  */

INLINE void
UPDATE_SYNTAX_TABLE_BACKWARD (ptrdiff_t charpos)
{
  if (parse_sexp_lookup_properties && charpos < gl_state.b_property)
    update_syntax_table (charpos, -1, false, gl_state.object);
}

/* Make syntax table good for CHARPOS.  */

INLINE void
UPDATE_SYNTAX_TABLE (ptrdiff_t charpos)
{
  UPDATE_SYNTAX_TABLE_BACKWARD (charpos);
  UPDATE_SYNTAX_TABLE_FORWARD (charpos);
}

/* Set up the buffer-global syntax table.  */

INLINE void
SETUP_BUFFER_SYNTAX_TABLE (void)
{
  gl_state.use_global = false;
  gl_state.e_property_truncated = false;
  gl_state.current_syntax_table = BVAR (current_buffer, syntax_table);
}

extern ptrdiff_t scan_words (ptrdiff_t, EMACS_INT);
extern void RE_SETUP_SYNTAX_TABLE_FOR_OBJECT (Lisp_Object, ptrdiff_t);

INLINE_HEADER_END

#endif /* EMACS_SYNTAX_H */