/* Declarations having to do with XEmacs syntax tables.
   Copyright (C) 1985, 1992, 1993 Free Software Foundation, Inc.
   Copyright (C) 2002, 2003 Ben Wing.

This file is part of XEmacs.

XEmacs 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.

XEmacs 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 XEmacs.  If not, see <http://www.gnu.org/licenses/>. */

/* Synched up with: FSF 19.28. */

#ifndef INCLUDED_syntax_h_
#define INCLUDED_syntax_h_

#include "chartab.h"

/* A syntax table is a type of char table.

The values in a syntax table are either integers or conses of
integers and chars.  The lowest 7 bits of the integer are the syntax
class.  If this is Sinherit, then the actual syntax value needs to
be retrieved from the standard syntax table.

It turns out to be worth optimizing lookups of character syntax in two
ways.  First, although the logic involved in finding the actual integer
isn't complex, the syntax value is accessed in functions such as
scan_lists() many times for each character scanned.  A "mirror syntax
table" that contains the actual integers speeds this up.

Second, due to the syntax-table text property, the table for looking up
syntax may change from character to character.  Since looking up properties
is expensive, a "syntax cache" which contains the current syntax table and
the region where it is valid can speed up linear scans dramatically.

The low 7 bits of the integer is a code, as follows. The 8th bit is
used as the prefix bit flag (see below).
*/

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

enum syntaxcode charset_syntax (struct buffer *buf, Lisp_Object charset,
				int *multi_p_out);

void update_syntax_table (Lisp_Object table);

DECLARE_INLINE_HEADER (
void
update_mirror_syntax_if_dirty (Lisp_Object table)
)
{
  if (XCHAR_TABLE (table)->dirty)
    update_syntax_table (table);
}

/* Return the syntax code for a particular character and mirror table. */

DECLARE_INLINE_HEADER (
int
SYNTAX_CODE (Lisp_Object table, Ichar c)
)
{
  type_checking_assert (XCHAR_TABLE (table)->mirror_table_p);
  update_mirror_syntax_if_dirty (table);
  return XFIXNUM (get_char_table_mirrors_ok (c, table));
}

#ifdef NOT_WORTH_THE_EFFORT

/* Same but skip the dirty check. */

DECLARE_INLINE_HEADER (
int
SYNTAX_CODE_1 (Lisp_Object table, Ichar c)
)
{
  type_checking_assert (XCHAR_TABLE (table)->mirror_table_p);
  return (enum syntaxcode) XFIXNUM (get_char_table_mirrors_ok (c, table));
}

#endif /* NOT_WORTH_THE_EFFORT */

#define SYNTAX_FROM_CODE(code) ((enum syntaxcode) ((code) & 0177))

#define SYNTAX(table, c) SYNTAX_FROM_CODE (SYNTAX_CODE (table, c))

DECLARE_INLINE_HEADER (
int
WORD_SYNTAX_P (Lisp_Object table, Ichar c)
)
{
  return SYNTAX (table, c) == Sword;
}

/* OK, here's a graphic diagram of the format of the syntax values.
   Here, the value has already been extracted from the Lisp integer,
   so there are no tag bits to worry about.

   Bit number:

 [ 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 ]
 [ 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 ]

   | <-----------> <-------------> <-------------> ^ <----------->
   |     unused    |comment bits |     unused      |  syntax code
   v               | | | | | | | |                 |
   unusable        | | | | | | | |                 |
   due to          | | | | | | | |                 |
   type tag        | | | | | | | |                 `--> prefix flag
   in Lisp         | | | | | | | |
   integer         | | | | | | | `--> comment end style B, second char
                   | | | | | | `----> comment end style A, second char
                   | | | | | `------> comment end style B, first char
                   | | | | `--------> comment end style A, first char
                   | | | `----------> comment start style B, second char
                   | | `------------> comment start style A, second char
                   | `--------------> comment start style B, first char
                   `----------------> comment start style A, first char

  In a 64-bit integer, there would be 32 more unused bits between
  the unusable bit and the comment bits.

  In older versions of XEmacs, bits 8-14 contained the matching
  character for parentheses.  Such a scheme will not work for Mule,
  because the matching parenthesis could be any character and
  requires 21 bits, which we don't have on a 32-bit platform.

  What we do is use another char table for the matching parenthesis
  and store a pointer to it in the first char table. (This frees
  code from having to worry about passing two tables around.)
*/


/* The prefix flag bit for backward-prefix-chars is in bit 7. */

#define SYNTAX_PREFIX(table, c) \
  ((SYNTAX_CODE (table, c) >> 7) & 1)

/* Bits 23-16 are used to implement up to two comment styles
   in a single buffer. They have the following meanings:
  bit
  23   first of a one or two character comment-start sequence of style a.
  22   first of a one or two character comment-start sequence of style b.
  21   second of a two-character comment-start sequence of style a.
  20   second of a two-character comment-start sequence of style b.
  19   first of a one or two character comment-end sequence of style a.
  18   first of a one or two character comment-end sequence of style b.
  17   second of a two-character comment-end sequence of style a.
  16   second of a two-character comment-end sequence of style b.
 */

#define SYNTAX_COMMENT_BITS(table, c) \
  ((SYNTAX_CODE (table, c) >> 16) &0xff)

#define SYNTAX_FIRST_OF_START_A  0x80
#define SYNTAX_FIRST_OF_START_B  0x40
#define SYNTAX_SECOND_OF_START_A 0x20
#define SYNTAX_SECOND_OF_START_B 0x10
#define SYNTAX_FIRST_OF_END_A    0x08
#define SYNTAX_FIRST_OF_END_B    0x04
#define SYNTAX_SECOND_OF_END_A   0x02
#define SYNTAX_SECOND_OF_END_B   0x01

#define SYNTAX_COMMENT_STYLE_A   0xaa
#define SYNTAX_COMMENT_STYLE_B   0x55
#define SYNTAX_FIRST_CHAR_START  0xc0
#define SYNTAX_FIRST_CHAR_END    0x0c
#define SYNTAX_FIRST_CHAR        0xcc
#define SYNTAX_SECOND_CHAR_START 0x30
#define SYNTAX_SECOND_CHAR_END   0x03
#define SYNTAX_SECOND_CHAR       0x33

/* Array of syntax codes, indexed by characters which designate them.
   Designators must be ASCII characters (ie, in the range 0x00-0x7F).
   Bounds checking is the responsibility of calling code. */
extern const unsigned char syntax_spec_code[0200];

/* Array of designators indexed by syntax code.
   Indicies should be of type enum syntaxcode. */
extern const unsigned char syntax_code_spec[];

Lisp_Object scan_lists (struct buffer *buf, Charbpos from, int count,
			int depth, int sexpflag, int no_error);
int char_quoted (struct buffer *buf, Charbpos pos);

/* TABLE is a syntax table, not the mirror table. */
Lisp_Object syntax_match (Lisp_Object table, Ichar ch);

extern int no_quit_in_re_search;


/****************************** syntax caches ********************************/

extern int lookup_syntax_properties;

/* The `syntax-table' property overrides the syntax table or directly
   specifies the syntax.  Since looking up properties is expensive, we cache
   the information about the syntax-table property.  When moving linearly
   through text (e.g. in the regex routines or the scanning routines in
   syntax.c), recalculation is needed only when the syntax-table property
   changes (i.e. not every position).
   When we do need to recalculate, we can update the info from the previous
   info faster than if we did the whole calculation from scratch.
   #### sjt sez: I'm not sure I believe that last claim.  That seems to
   require that we use directional information, etc, but that is ignored in
   the current implementation. */

enum syntax_source { syntax_source_property_code = 0,
		     syntax_source_property_table = 1,
		     syntax_source_buffer_table = 2 };
#define SOURCE_IS_TABLE(source) (source)

struct syntax_cache
{
#ifdef NEW_GC
  NORMAL_LISP_OBJECT_HEADER header;
#endif /* NEW_GC */
  enum syntax_source source;	/* Source of syntax information: the buffer's
				   syntax table, a syntax table specified by
				   a syntax-table property, or a syntax code
				   specified by a syntax-table property. */
  Lisp_Object object;		/* The buffer or string the current syntax
				   cache applies to, or Qnil for a string of
				   text not coming from a buffer or string. */
  struct buffer *buffer;	/* The buffer that supplies the syntax tables,
				   or NULL for the standard syntax table.  If
				   OBJECT is a buffer, this will always be
				   the same buffer. */
  int syntax_code;		/* Syntax code of current char. */
  Lisp_Object syntax_table;	/* Syntax table for current pos. */
  Lisp_Object mirror_table;	/* Mirror table for this table. */
  Lisp_Object start, end;	/* Markers to keep track of the known region
				   in a buffer.
				   Both are Qnil if object is a string.
				   Normally these correspond to prev_change
				   and next_change, respectively, except when
				   insertions and deletions occur.  Then
				   prev_change and next change will be
				   refreshed from these markers.  See
				   signal_syntax_cache_extent_adjust().
				   We'd like to use an extent, but it seems
				   that having an extent over the entire
				   buffer causes serious slowdowns in extent
				   operations!  Yuck!
				   #### May not be true any more. */
  Charxpos next_change;		/* Position of the next extent change. */
  Charxpos prev_change;		/* Position of the previous extent change. */
};

#ifdef NEW_GC
typedef struct syntax_cache Lisp_Syntax_Cache;

DECLARE_LISP_OBJECT (syntax_cache, Lisp_Syntax_Cache);

#define XSYNTAX_CACHE(x) \
  XRECORD (x, syntax_cache, Lisp_Syntax_Cache)
#define wrap_syntax_cache(p) wrap_record (p, syntax_cache)
#define SYNTAX_CACHE_P(x) RECORDP (x, syntax_cache)
#define CHECK_SYNTAX_CACHE(x) CHECK_RECORD (x, syntax_cache)
#define CONCHECK_SYNTAX_CACHE(x) CONCHECK_RECORD (x, syntax_cache)
#endif /* NEW_GC */

extern const struct sized_memory_description syntax_cache_description;

/* Note that the external interface to the syntax cache uses charpos's, but
   internally we use bytepos's, for speed. */
void update_syntax_cache (struct syntax_cache *cache, Charxpos pos, int count);
struct syntax_cache *setup_syntax_cache (struct syntax_cache *cache,
					 Lisp_Object object,
					 struct buffer *buffer,
					 Charxpos from, int count);
struct syntax_cache *setup_buffer_syntax_cache (struct buffer *buffer,
						Charxpos from, int count);

/* Make syntax cache state good for CHARPOS, assuming it is
   currently good for a position before CHARPOS.  */
DECLARE_INLINE_HEADER (
void
UPDATE_SYNTAX_CACHE_FORWARD (struct syntax_cache *cache, Charxpos pos)
)
{
  /* #### Formerly this function, and the next one, had

     if (pos < cache->prev_change || pos >= cache->next_change)

     just like for plain UPDATE_SYNTAX_CACHE.  However, sometimes the
     value of POS may be invalid (particularly, it may be 0 for a buffer).
     FSF has the check at only one end, so let's try the same. */
  if (pos >= cache->next_change)
    update_syntax_cache (cache, pos, 1);
}

/* Make syntax cache state good for CHARPOS, assuming it is
   currently good for a position after CHARPOS.  */
DECLARE_INLINE_HEADER (
void
UPDATE_SYNTAX_CACHE_BACKWARD (struct syntax_cache *cache, Charxpos pos)
)
{
  if (pos < cache->prev_change)
    update_syntax_cache (cache, pos, -1);
}

/* Make syntax cache state good for CHARPOS */
DECLARE_INLINE_HEADER (
void
UPDATE_SYNTAX_CACHE (struct syntax_cache *cache, Charxpos pos)
)
{
  if (pos < cache->prev_change || pos >= cache->next_change)
    update_syntax_cache (cache, pos, 0);
}

#define SYNTAX_FROM_CACHE(cache, c)			\
   SYNTAX_FROM_CODE (SYNTAX_CODE_FROM_CACHE (cache, c))

#define SYNTAX_CODE_FROM_CACHE(cache, c)	\
  (SOURCE_IS_TABLE ((cache)->source)		\
   ? SYNTAX_CODE ((cache)->mirror_table, c)	\
   : (cache)->syntax_code)

#ifdef NOT_WORTH_THE_EFFORT
/* If we really cared about the theoretical performance hit of the dirty
   check in SYNTAX_CODE, we could use SYNTAX_CODE_1 and endeavor to always
   keep the mirror table clean, e.g. by checking for dirtiness at the time
   we set up the syntax cache.  There are lots of potential problems, of
   course -- incomplete understanding of the possible pathways into the
   code, with some that are bypassing the setups, Lisp code being executed
   in the meantime that could change things (e.g. QUIT is called in many
   functions and could execute arbitrary Lisp very easily), etc.  The QUIT
   problem is the biggest one, probably, and one of the main reasons it's
   probably just not worth it. */
#define SYNTAX_CODE_FROM_CACHE(cache, c)	\
  (SOURCE_IS_TABLE ((cache)->source)		\
   ? SYNTAX_CODE_1 ((cache)->mirror_table, c)	\
   : (cache)->syntax_code)
#endif


/***************************** syntax code macros ****************************/

#define SYNTAX_CODE_PREFIX(c) \
  ((c >> 7) & 1)

#define SYNTAX_CODE_COMMENT_BITS(c) \
  ((c >> 16) &0xff)

#define SYNTAX_CODES_START_P(a, b)                                    \
  (((SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_FIRST_CHAR_START) >> 2)    \
   & (SYNTAX_CODE_COMMENT_BITS (b) & SYNTAX_SECOND_CHAR_START))

#define SYNTAX_CODES_END_P(a, b)                                    \
  (((SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_FIRST_CHAR_END) >> 2)    \
   & (SYNTAX_CODE_COMMENT_BITS (b) & SYNTAX_SECOND_CHAR_END))

#define SYNTAX_CODES_COMMENT_MASK_START(a, b)			\
  (SYNTAX_CODES_MATCH_START_P (a, b, SYNTAX_COMMENT_STYLE_A) 	\
   ? SYNTAX_COMMENT_STYLE_A					\
   : (SYNTAX_CODES_MATCH_START_P (a, b, SYNTAX_COMMENT_STYLE_B)	\
      ? SYNTAX_COMMENT_STYLE_B					\
      : 0))
#define SYNTAX_CODES_COMMENT_MASK_END(a, b)			\
  (SYNTAX_CODES_MATCH_END_P (a, b, SYNTAX_COMMENT_STYLE_A) 	\
   ? SYNTAX_COMMENT_STYLE_A					\
   : (SYNTAX_CODES_MATCH_END_P (a, b, SYNTAX_COMMENT_STYLE_B)	\
      ? SYNTAX_COMMENT_STYLE_B					\
      : 0))

#define SYNTAX_CODE_START_FIRST_P(a) \
  (SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_FIRST_CHAR_START)

#define SYNTAX_CODE_START_SECOND_P(a) \
  (SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_SECOND_CHAR_START)

#define SYNTAX_CODE_END_FIRST_P(a) \
  (SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_FIRST_CHAR_END)

#define SYNTAX_CODE_END_SECOND_P(a) \
  (SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_SECOND_CHAR_END)


#define SYNTAX_CODES_MATCH_START_P(a, b, mask)				\
  ((SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_FIRST_CHAR_START & (mask))	\
   && (SYNTAX_CODE_COMMENT_BITS (b)					\
       & SYNTAX_SECOND_CHAR_START & (mask)))

#define SYNTAX_CODES_MATCH_END_P(a, b, mask)				\
  ((SYNTAX_CODE_COMMENT_BITS (a) & SYNTAX_FIRST_CHAR_END & (mask))	\
   && (SYNTAX_CODE_COMMENT_BITS (b) & SYNTAX_SECOND_CHAR_END & (mask)))

#define SYNTAX_CODE_MATCHES_1CHAR_P(a, mask)	\
  ((SYNTAX_CODE_COMMENT_BITS (a) & (mask)))

#define SYNTAX_CODE_COMMENT_1CHAR_MASK(a)			\
  ((SYNTAX_CODE_MATCHES_1CHAR_P (a, SYNTAX_COMMENT_STYLE_A)	\
    ? SYNTAX_COMMENT_STYLE_A					\
    : (SYNTAX_CODE_MATCHES_1CHAR_P (a, SYNTAX_COMMENT_STYLE_B)	\
       ? SYNTAX_COMMENT_STYLE_B					\
       : 0)))


#endif /* INCLUDED_syntax_h_ */
