[bpt/emacs.git] / src / buffer.h

/* Header file for the buffer manipulation primitives.
   Copyright (C) 1985, 1986, 1990 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 1, 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; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


#ifdef lint
#include "undo.h"
#endif /* lint */


#define SET_PT(position) (current_buffer->text.pt = (position))

/* Character position of beginning of buffer.  */ 
#define BEG (1)

/* Character position of beginning of accessible range of buffer.  */ 
#define BEGV (current_buffer->text.begv)

/* Character position of point in buffer.  The "+ 0" makes this
   not an l-value, so you can't assign to it.  Use SET_PT instead.  */ 
#define PT (current_buffer->text.pt + 0)

/* Character position of gap in buffer.  */ 
#define GPT (current_buffer->text.gpt)

/* Character position of end of accessible range of buffer.  */ 
#define ZV (current_buffer->text.zv)

/* Character position of end of buffer.  */ 
#define Z (current_buffer->text.z)

/* Modification count.  */
#define MODIFF (current_buffer->text.modiff)

/* Address of beginning of buffer.  */ 
#define BEG_ADDR (current_buffer->text.beg)

/* Address of beginning of accessible range of buffer.  */ 
#define BEGV_ADDR (&FETCH_CHAR (current_buffer->text.begv))

/* Address of point in buffer.  */ 
#define PT_ADDR (&FETCH_CHAR (current_buffer->text.pt))

/* Address of beginning of gap in buffer.  */ 
#define GPT_ADDR (current_buffer->text.beg + current_buffer->text.gpt - 1)

/* Address of end of gap in buffer.  */
#define GAP_END_ADDR (current_buffer->text.beg + current_buffer->text.gpt + current_buffer->text.gap_size - 1)

/* Address of end of accessible range of buffer.  */ 
#define ZV_ADDR (&FETCH_CHAR (current_buffer->text.zv))

/* Size of gap.  */
#define GAP_SIZE (current_buffer->text.gap_size)

/* Now similar macros for a specified buffer.
   Note that many of these evaluate the buffer argument more than once.  */

/* Character position of beginning of buffer.  */ 
#define BUF_BEG(buf) (1)

/* Character position of beginning of accessible range of buffer.  */ 
#define BUF_BEGV(buf) ((buf)->text.begv)

/* Character position of point in buffer.  */ 
#define BUF_PT(buf) ((buf)->text.pt)

/* Character position of gap in buffer.  */ 
#define BUF_GPT(buf) ((buf)->text.gpt)

/* Character position of end of accessible range of buffer.  */ 
#define BUF_ZV(buf) ((buf)->text.zv)

/* Character position of end of buffer.  */ 
#define BUF_Z(buf) ((buf)->text.z)

/* Modification count.  */
#define BUF_MODIFF(buf) ((buf)->text.modiff)

/* Address of beginning of buffer.  */
#define BUF_BEG_ADDR(buf) ((buf)->text.beg)

/* Macro for setting the value of BUF_ZV (BUF) to VALUE,
   by varying the end of the accessible region.  */
#define SET_BUF_ZV(buf, value) ((buf)->text.zv = (value))
#define SET_BUF_PT(buf, value) ((buf)->text.pt = (value))

/* Size of gap.  */
#define BUF_GAP_SIZE(buf) ((buf)->text.gap_size)

/* Return the address of character at position POS in buffer BUF. 
   Note that both arguments can be computed more than once.  */
#define BUF_CHAR_ADDRESS(buf, pos) \
((buf)->text.beg + (pos) - 1		\
 + ((pos) >= (buf)->text.gpt ? (buf)->text.gap_size : 0))

/* Convert the address of a char in the buffer into a character position.  */
#define PTR_CHAR_POS(ptr) \
((ptr) - (current_buffer)->text.beg					\
 - (ptr - (current_buffer)->text.beg < (unsigned) GPT ? 0 : GAP_SIZE)	\
 + 1)
\f
struct buffer_text
  {
    unsigned char *beg;		/* Actual address of buffer contents. */    
    int begv;			/* Index of beginning of accessible range. */
    int pt;			/* Position of point in buffer. */
    int gpt;			/* Index of gap in buffer. */
    int zv;			/* Index of end of accessible range. */
    int z;			/* Index of end of buffer. */
    int gap_size;		/* Size of buffer's gap */
    int modiff;			/* This counts buffer-modification events
				   for this buffer.  It is incremented for
				   each such event, and never otherwise
				   changed.  */

  };

struct buffer
  {
    /* Everything before the `name' slot must be of a non-Lisp_Object type,
       and every slot after `name' must be a Lisp_Object.

       Check out mark_buffer (alloc.c) to see why.
     */

    /* This structure holds the coordinates of the buffer contents.  */
    struct buffer_text text;
    /* Next buffer, in chain of all buffers including killed buffers.
       This chain is used only for garbage collection, in order to
       collect killed buffers properly.  */
    struct buffer *next;
    /* Flags saying which DEFVAR_PER_BUFFER variables
       are local to this buffer.  */
    int local_var_flags;
    /* Value of text.modified as of when visited file was read or written. */
    int save_modified;
    /* Set to the modtime of the visited file when read or written.
       -1 means visited file was nonexistent.
       0 means visited file modtime unknown; in no case complain
       about any mismatch on next save attempt.  */
    int modtime;
    /* the value of text.modiff at the last auto-save. */
    int auto_save_modified;
    /* Position in buffer at which display started
       the last time this buffer was displayed */
    int last_window_start;

    /* This is a special exception -- as this slot should not be
       marked by gc_sweep, and as it is not lisp-accessible as
       a local variable -- so we regard it as not really being of type
       Lisp_Object */
    /* the markers that refer to this buffer.
       This is actually a single marker ---
       successive elements in its marker `chain'
       are the other markers referring to this
       buffer */
    Lisp_Object markers;


    /* Everything from here down must be a Lisp_Object */


    /* the name of this buffer */
    Lisp_Object name;
    /* Nuked: buffer number, assigned when buffer made Lisp_Object number;*/
    /* the name of the file associated with this buffer */
    Lisp_Object filename;
    /* Dir for expanding relative pathnames */
    Lisp_Object directory;
    /* true iff this buffer has been been backed
       up (if you write to its associated file
       and it hasn't been backed up, then a
       backup will be made) */
    /* This isn't really used by the C code, so could be deleted.  */
    Lisp_Object backed_up;
    /* Length of file when last read or saved. */
    Lisp_Object save_length;
    /* file name used for auto-saving this buffer */
    Lisp_Object auto_save_file_name;
    /* Non-nil if buffer read-only */
    Lisp_Object read_only;
    /* "The mark"; no longer allowed to be nil */
    Lisp_Object mark;

    /* Alist of elements (SYMBOL . VALUE-IN-THIS-BUFFER)
       for all per-buffer variables of this buffer.  */
    Lisp_Object local_var_alist;


    /* Symbol naming major mode (eg lisp-mode) */
    Lisp_Object major_mode;
    /* Pretty name of major mode (eg "Lisp") */
    Lisp_Object mode_name;
    /* Format string for mode line */
    Lisp_Object mode_line_format;

    /* Keys that are bound local to this buffer */
    Lisp_Object keymap;
    /* This buffer's local abbrev table */
    Lisp_Object abbrev_table;
    /* This buffer's syntax table. */
    Lisp_Object syntax_table;

    /* Values of several buffer-local variables */
    /* tab-width is buffer-local so that redisplay can find it
       in buffers that are not current */
    Lisp_Object case_fold_search;
    Lisp_Object tab_width;
    Lisp_Object fill_column;
    Lisp_Object left_margin;
    /* Function to call when insert space past fill column */
    Lisp_Object auto_fill_function;

    /* String of length 256 mapping each char to its lower-case version.  */
    Lisp_Object downcase_table;
    /* String of length 256 mapping each char to its upper-case version.  */
    Lisp_Object upcase_table;

    /* Non-nil means do not display continuation lines */
    Lisp_Object truncate_lines;
    /* Non-nil means display ctl chars with uparrow */
    Lisp_Object ctl_arrow;
    /* Non-nil means do selective display;
       See doc string in syms_of_buffer (buffer.c) for details.  */
    Lisp_Object selective_display;
#ifndef old
    /* Non-nil means show ... at end of line followed by invisible lines.  */
    Lisp_Object selective_display_ellipses;
#endif
    /* Alist of (FUNCTION . STRING) for each minor mode enabled in buffer. */
    Lisp_Object minor_modes;
    /* t if "self-insertion" should overwrite */
    Lisp_Object overwrite_mode;
    /* non-nil means abbrev mode is on.  Expand abbrevs automatically. */
    Lisp_Object abbrev_mode;
    /* Display table to use for text in this buffer. */
    Lisp_Object display_table;
    /* Translate table for case-folding search.  */
    Lisp_Object case_canon_table;
    /* Inverse translate (equivalence class) table for case-folding search.  */
    Lisp_Object case_eqv_table;
    /* Changes in the buffer are recorded here for undo.
       t means don't record anything.  */
    Lisp_Object undo_list;

    /* List of fields in this buffer.  */
    Lisp_Object fieldlist;
};

extern struct buffer *current_buffer;

/* This structure holds the default values of the buffer-local variables
   defined with DefBufferLispVar, that have special slots in each buffer.
   The default value occupies the same slot in this structure
   as an individual buffer's value occupies in that buffer.
   Setting the default value also goes through the alist of buffers
   and stores into each buffer that does not say it has a local value.  */

extern struct buffer buffer_defaults;

/* This structure marks which slots in a buffer have corresponding
   default values in buffer_defaults.
   Each such slot has a nonzero value in this structure.
   The value has only one nonzero bit.

   When a buffer has its own local value for a slot,
   the bit for that slot (found in the same slot in this structure)
   is turned on in the buffer's local_var_flags slot.

   If a slot in this structure is zero, then even though there may
   be a DefBufferLispVar for the slot, there is no default valuefeor it;
   and the corresponding slot in buffer_defaults is not used.  */

extern struct buffer buffer_local_flags;

/* For each buffer slot, this points to the Lisp symbol name
   for that slot in the current buffer.  It is 0 for slots
   that don't have such names.  */

extern struct buffer buffer_local_symbols;

/* Point in the current buffer. */

#define point (current_buffer->text.pt + 0)

/* Return character at position n.  No range checking */
#define FETCH_CHAR(n) *(((n)>= GPT ? GAP_SIZE : 0) + (n) + BEG_ADDR - 1)

/* BUFFER_CEILING_OF (resp. BUFFER_FLOOR_OF), when applied to n, return
   the max (resp. min) p such that

   &FETCH_CHAR (p) - &FETCH_CHAR (n) == p - n       */

#define BUFFER_CEILING_OF(n) (((n) < GPT && GPT < ZV ? GPT : ZV) - 1)
#define BUFFER_FLOOR_OF(n) (BEGV <= GPT && GPT <= (n) ? GPT : BEGV)

extern void reset_buffer ();

/* Functions to call before and after each text change. */
extern Lisp_Object Vbefore_change_function;
extern Lisp_Object Vafter_change_function;
extern Lisp_Object Vfirst_change_function;

/* Fields.

A field is like a marker but it defines a region rather than a
point.  Like a marker, a field is asocated with a buffer.
The field mechanism uses the marker mechanism in the
sense that its start and end points are maintained as markers
updated in the usual way as the buffer changes.

A field can be protected or unprotected.  If it is protected,
no modifications can be made that affect the field in its buffer,
when protected field checking is enabled.

Each field also contains an alist, in which you can store
whatever you like.  */

/* Slots in a field:  */

#define FIELD_BUFFER(f) (XVECTOR(f)->contents[1])
#define FIELD_START_MARKER(f) (XVECTOR(f)->contents[2])
#define FIELD_END_MARKER(f) (XVECTOR(f)->contents[3])
#define FIELD_PROTECTED_FLAG(f) (XVECTOR(f)->contents[4])
#define FIELD_ALIST(f) (XVECTOR(f)->contents[5])

/* Allocation of buffer data. */
#ifdef REL_ALLOC
#define BUFFER_ALLOC(data,size) ((unsigned char *) r_alloc (&data, (size)))
#define BUFFER_REALLOC(data,size) ((unsigned char *) r_re_alloc (&data, (size)))
#define BUFFER_FREE(data) (r_alloc_free (&data))
#define R_ALLOC_DECLARE(var,data) (r_alloc_declare (&var, (data)))
#else
#define BUFFER_ALLOC(data,size) (data = (unsigned char *) malloc ((size)))
#define BUFFER_REALLOC(data,size) ((unsigned char *) realloc ((data), (size)))
#define BUFFER_FREE(data) (free ((data)))
#define R_ALLOC_DECLARE(var,data)
#endif

/* A search buffer, with a fastmap allocated and ready to go.  */
extern struct re_pattern_buffer searchbuf;
Commit	Line	Data
b3ec245a JB	1	/* Header file for the buffer manipulation primitives.
	2	Copyright (C) 1985, 1986, 1990 Free Software Foundation, Inc.
	3
	4	This file is part of GNU Emacs.
	5
	6	GNU Emacs is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 1, or (at your option)
	9	any later version.
	10
	11	GNU Emacs is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with GNU Emacs; see the file COPYING. If not, write to
	18	the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
	19
	20
	21	#ifdef lint
	22	#include "undo.h"
	23	#endif /* lint */
	24
	25
	26	#define SET_PT(position) (current_buffer->text.pt = (position))
	27
	28	/* Character position of beginning of buffer. */
	29	#define BEG (1)
	30
	31	/* Character position of beginning of accessible range of buffer. */
	32	#define BEGV (current_buffer->text.begv)
	33
	34	/* Character position of point in buffer. The "+ 0" makes this
	35	not an l-value, so you can't assign to it. Use SET_PT instead. */
	36	#define PT (current_buffer->text.pt + 0)
	37
	38	/* Character position of gap in buffer. */
	39	#define GPT (current_buffer->text.gpt)
	40
	41	/* Character position of end of accessible range of buffer. */
	42	#define ZV (current_buffer->text.zv)
	43
	44	/* Character position of end of buffer. */
	45	#define Z (current_buffer->text.z)
	46
	47	/* Modification count. */
	48	#define MODIFF (current_buffer->text.modiff)
	49
	50	/* Address of beginning of buffer. */
	51	#define BEG_ADDR (current_buffer->text.beg)
	52
	53	/* Address of beginning of accessible range of buffer. */
	54	#define BEGV_ADDR (&FETCH_CHAR (current_buffer->text.begv))
	55
	56	/* Address of point in buffer. */
	57	#define PT_ADDR (&FETCH_CHAR (current_buffer->text.pt))
	58
	59	/* Address of beginning of gap in buffer. */
	60	#define GPT_ADDR (current_buffer->text.beg + current_buffer->text.gpt - 1)
	61
	62	/* Address of end of gap in buffer. */
	63	#define GAP_END_ADDR (current_buffer->text.beg + current_buffer->text.gpt + current_buffer->text.gap_size - 1)
	64
65	/* Address of end of accessible range of buffer. */
66	#define ZV_ADDR (&FETCH_CHAR (current_buffer->text.zv))
67
68	/* Size of gap. */
69	#define GAP_SIZE (current_buffer->text.gap_size)
70
71	/* Now similar macros for a specified buffer.
72	Note that many of these evaluate the buffer argument more than once. */
73
74	/* Character position of beginning of buffer. */
75	#define BUF_BEG(buf) (1)
76
77	/* Character position of beginning of accessible range of buffer. */
78	#define BUF_BEGV(buf) ((buf)->text.begv)
79
80	/* Character position of point in buffer. */
81	#define BUF_PT(buf) ((buf)->text.pt)
82
83	/* Character position of gap in buffer. */
84	#define BUF_GPT(buf) ((buf)->text.gpt)
85
86	/* Character position of end of accessible range of buffer. */
87	#define BUF_ZV(buf) ((buf)->text.zv)
88
89	/* Character position of end of buffer. */
90	#define BUF_Z(buf) ((buf)->text.z)
91
92	/* Modification count. */
93	#define BUF_MODIFF(buf) ((buf)->text.modiff)
94
95	/* Address of beginning of buffer. */
96	#define BUF_BEG_ADDR(buf) ((buf)->text.beg)
97
98	/* Macro for setting the value of BUF_ZV (BUF) to VALUE,
99	by varying the end of the accessible region. */
100	#define SET_BUF_ZV(buf, value) ((buf)->text.zv = (value))
101	#define SET_BUF_PT(buf, value) ((buf)->text.pt = (value))
102
103	/* Size of gap. */
104	#define BUF_GAP_SIZE(buf) ((buf)->text.gap_size)
105
106	/* Return the address of character at position POS in buffer BUF.
107	Note that both arguments can be computed more than once. */
108	#define BUF_CHAR_ADDRESS(buf, pos) \
109	((buf)->text.beg + (pos) - 1 \
110	+ ((pos) >= (buf)->text.gpt ? (buf)->text.gap_size : 0))
111
112	/* Convert the address of a char in the buffer into a character position. */
113	#define PTR_CHAR_POS(ptr) \
114	((ptr) - (current_buffer)->text.beg \
115	- (ptr - (current_buffer)->text.beg < (unsigned) GPT ? 0 : GAP_SIZE) \
116	+ 1)
117	\f
118	struct buffer_text
119	{
120	unsigned char beg; / Actual address of buffer contents. */
121	int begv; /* Index of beginning of accessible range. */
122	int pt; /* Position of point in buffer. */
123	int gpt; /* Index of gap in buffer. */
124	int zv; /* Index of end of accessible range. */
125	int z; /* Index of end of buffer. */
126	int gap_size; /* Size of buffer's gap */
127	int modiff; /* This counts buffer-modification events
128	for this buffer. It is incremented for
129	each such event, and never otherwise
130	changed. */
131
132	};
133
134	struct buffer
135	{
136	/* Everything before the `name' slot must be of a non-Lisp_Object type,
137	and every slot after `name' must be a Lisp_Object.
138
139	Check out mark_buffer (alloc.c) to see why.
140	*/
141
142	/* This structure holds the coordinates of the buffer contents. */
143	struct buffer_text text;
144	/* Next buffer, in chain of all buffers including killed buffers.
145	This chain is used only for garbage collection, in order to
146	collect killed buffers properly. */
147	struct buffer *next;
148	/* Flags saying which DEFVAR_PER_BUFFER variables
149	are local to this buffer. */
150	int local_var_flags;
151	/* Value of text.modified as of when visited file was read or written. */
152	int save_modified;
153	/* Set to the modtime of the visited file when read or written.
154	-1 means visited file was nonexistent.
155	0 means visited file modtime unknown; in no case complain
156	about any mismatch on next save attempt. */
157	int modtime;
158	/* the value of text.modiff at the last auto-save. */
159	int auto_save_modified;
160	/* Position in buffer at which display started
161	the last time this buffer was displayed */
162	int last_window_start;
163
164	/* This is a special exception -- as this slot should not be
165	marked by gc_sweep, and as it is not lisp-accessible as
166	a local variable -- so we regard it as not really being of type
167	Lisp_Object */
168	/* the markers that refer to this buffer.
169	This is actually a single marker ---
170	successive elements in its marker `chain'
171	are the other markers referring to this
172	buffer */
173	Lisp_Object markers;
174
175
176	/* Everything from here down must be a Lisp_Object */
177
178
179	/* the name of this buffer */
180	Lisp_Object name;
181	/* Nuked: buffer number, assigned when buffer made Lisp_Object number;*/
182	/* the name of the file associated with this buffer */
183	Lisp_Object filename;
184	/* Dir for expanding relative pathnames */
185	Lisp_Object directory;
186	/* true iff this buffer has been been backed
187	up (if you write to its associated file
188	and it hasn't been backed up, then a
189	backup will be made) */
190	/* This isn't really used by the C code, so could be deleted. */
191	Lisp_Object backed_up;
192	/* Length of file when last read or saved. */
193	Lisp_Object save_length;
194	/* file name used for auto-saving this buffer */
195	Lisp_Object auto_save_file_name;
196	/* Non-nil if buffer read-only */
197	Lisp_Object read_only;
198	/* "The mark"; no longer allowed to be nil */
199	Lisp_Object mark;
200
201	/* Alist of elements (SYMBOL . VALUE-IN-THIS-BUFFER)
202	for all per-buffer variables of this buffer. */
203	Lisp_Object local_var_alist;
204
205
206	/* Symbol naming major mode (eg lisp-mode) */
207	Lisp_Object major_mode;
208	/* Pretty name of major mode (eg "Lisp") */
209	Lisp_Object mode_name;
210	/* Format string for mode line */
211	Lisp_Object mode_line_format;
212
213	/* Keys that are bound local to this buffer */
214	Lisp_Object keymap;
215	/* This buffer's local abbrev table */
216	Lisp_Object abbrev_table;
217	/* This buffer's syntax table. */
218	Lisp_Object syntax_table;
219
220	/* Values of several buffer-local variables */
221	/* tab-width is buffer-local so that redisplay can find it
222	in buffers that are not current */
223	Lisp_Object case_fold_search;
224	Lisp_Object tab_width;
225	Lisp_Object fill_column;
226	Lisp_Object left_margin;
227	/* Function to call when insert space past fill column */
228	Lisp_Object auto_fill_function;
229
230	/* String of length 256 mapping each char to its lower-case version. */
231	Lisp_Object downcase_table;
232	/* String of length 256 mapping each char to its upper-case version. */
233	Lisp_Object upcase_table;
234
235	/* Non-nil means do not display continuation lines */
236	Lisp_Object truncate_lines;
237	/* Non-nil means display ctl chars with uparrow */
238	Lisp_Object ctl_arrow;
239	/* Non-nil means do selective display;
240	See doc string in syms_of_buffer (buffer.c) for details. */
241	Lisp_Object selective_display;
242	#ifndef old
243	/* Non-nil means show ... at end of line followed by invisible lines. */
244	Lisp_Object selective_display_ellipses;
245	#endif
246	/* Alist of (FUNCTION . STRING) for each minor mode enabled in buffer. */
247	Lisp_Object minor_modes;
248	/* t if "self-insertion" should overwrite */
249	Lisp_Object overwrite_mode;
250	/* non-nil means abbrev mode is on. Expand abbrevs automatically. */
251	Lisp_Object abbrev_mode;
252	/* Display table to use for text in this buffer. */
253	Lisp_Object display_table;
254	/* Translate table for case-folding search. */
255	Lisp_Object case_canon_table;
256	/* Inverse translate (equivalence class) table for case-folding search. */
257	Lisp_Object case_eqv_table;
258	/* Changes in the buffer are recorded here for undo.
259	t means don't record anything. */
260	Lisp_Object undo_list;
261
262	/* List of fields in this buffer. */
263	Lisp_Object fieldlist;
264	};
265
266	extern struct buffer *current_buffer;
267
268	/* This structure holds the default values of the buffer-local variables
269	defined with DefBufferLispVar, that have special slots in each buffer.
270	The default value occupies the same slot in this structure
271	as an individual buffer's value occupies in that buffer.
272	Setting the default value also goes through the alist of buffers
273	and stores into each buffer that does not say it has a local value. */
274
275	extern struct buffer buffer_defaults;
276
277	/* This structure marks which slots in a buffer have corresponding
278	default values in buffer_defaults.
279	Each such slot has a nonzero value in this structure.
280	The value has only one nonzero bit.
281
282	When a buffer has its own local value for a slot,
283	the bit for that slot (found in the same slot in this structure)
284	is turned on in the buffer's local_var_flags slot.
285
286	If a slot in this structure is zero, then even though there may
287	be a DefBufferLispVar for the slot, there is no default valuefeor it;
288	and the corresponding slot in buffer_defaults is not used. */
289
290	extern struct buffer buffer_local_flags;
291
292	/* For each buffer slot, this points to the Lisp symbol name
293	for that slot in the current buffer. It is 0 for slots
294	that don't have such names. */
295
296	extern struct buffer buffer_local_symbols;
297
298	/* Point in the current buffer. */
299
300	#define point (current_buffer->text.pt + 0)
301
302	/* Return character at position n. No range checking */
303	#define FETCH_CHAR(n) *(((n)>= GPT ? GAP_SIZE : 0) + (n) + BEG_ADDR - 1)
304
305	/* BUFFER_CEILING_OF (resp. BUFFER_FLOOR_OF), when applied to n, return
306	the max (resp. min) p such that
307
308	&FETCH_CHAR (p) - &FETCH_CHAR (n) == p - n */
309
310	#define BUFFER_CEILING_OF(n) (((n) < GPT && GPT < ZV ? GPT : ZV) - 1)
311	#define BUFFER_FLOOR_OF(n) (BEGV <= GPT && GPT <= (n) ? GPT : BEGV)
312
313	extern void reset_buffer ();
314
315	/* Functions to call before and after each text change. */
316	extern Lisp_Object Vbefore_change_function;
317	extern Lisp_Object Vafter_change_function;
318	extern Lisp_Object Vfirst_change_function;
319
320	/* Fields.
321
322	A field is like a marker but it defines a region rather than a
323	point. Like a marker, a field is asocated with a buffer.
324	The field mechanism uses the marker mechanism in the
325	sense that its start and end points are maintained as markers
326	updated in the usual way as the buffer changes.
327
328	A field can be protected or unprotected. If it is protected,
329	no modifications can be made that affect the field in its buffer,
330	when protected field checking is enabled.
331
332	Each field also contains an alist, in which you can store
333	whatever you like. */
334
335	/* Slots in a field: */
336
337	#define FIELD_BUFFER(f) (XVECTOR(f)->contents[1])
338	#define FIELD_START_MARKER(f) (XVECTOR(f)->contents[2])
339	#define FIELD_END_MARKER(f) (XVECTOR(f)->contents[3])
340	#define FIELD_PROTECTED_FLAG(f) (XVECTOR(f)->contents[4])
341	#define FIELD_ALIST(f) (XVECTOR(f)->contents[5])
342
343	/* Allocation of buffer data. */
344	#ifdef REL_ALLOC
345	#define BUFFER_ALLOC(data,size) ((unsigned char *) r_alloc (&data, (size)))
346	#define BUFFER_REALLOC(data,size) ((unsigned char *) r_re_alloc (&data, (size)))
347	#define BUFFER_FREE(data) (r_alloc_free (&data))
348	#define R_ALLOC_DECLARE(var,data) (r_alloc_declare (&var, (data)))
349	#else
350	#define BUFFER_ALLOC(data,size) (data = (unsigned char *) malloc ((size)))
351	#define BUFFER_REALLOC(data,size) ((unsigned char *) realloc ((data), (size)))
352	#define BUFFER_FREE(data) (free ((data)))
353	#define R_ALLOC_DECLARE(var,data)
354	#endif
355
356	/* A search buffer, with a fastmap allocated and ready to go. */
357	extern struct re_pattern_buffer searchbuf;