3 * $Id: darray.h,v 1.4 1999/12/10 23:42:04 mdw Exp $
5 * Dynamically growing dense arrays
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.4 1999/12/10 23:42:04 mdw
34 * Change header file guard names.
36 * Revision 1.3 1999/11/05 14:32:43 mdw
37 * Minor change in argument naming.
39 * Revision 1.2 1999/10/29 22:59:22 mdw
40 * New array adjustment macros for unsigned arguments.
42 * Revision 1.1 1999/10/22 22:37:26 mdw
43 * New dynamic array implementation replaces `dynarray.h'.
54 /*----- Header files ------------------------------------------------------*/
68 /*----- Various important constants ---------------------------------------*/
70 /* --- @DAEXC_UFLOW@, @DAEXC_OFLOW@ --- *
72 * Underflow and overflow exceptions raised by @DA_SHIFT@, and by @DA_POP@
76 #define DAEXC_UFLOW EXC_ALLOCN(EXC_MLIB, 0)
77 #define DAEXC_OFLOW EXC_ALLOCN(EXC_MLIB, 1)
79 /*----- Data structures ---------------------------------------------------*/
81 /* --- Base structure for dynamic arrays --- *
83 * An actual array has a `vector' @v@ in addition to this data (which is
84 * tucked away in the @b@ member). The vector contains the actual storage
85 * for the array elements.
87 * The vector pointer @v@ potentially points somewhere in the middle of the
88 * allocated storage. The @off@ member explains how far into the storage the
89 * vector points. The allocated storage is sufficient for @sz + off@ items
90 * to be stored. Valid array indices are integers between 0 (inclusive) and
91 * @len@ (exclusive). Thus, from @v@ onwards, there is space for @sz@
92 * elements, and of these, @sz - len@ are currently not considered to be
93 * within the array's bounds.
95 * The @push@ and @unshift@ counts record how many times these operations
96 * have been performed since the last extension of the array. They are used
97 * by the extension algorithm to decide how to position the data offset.
99 * Try to use the access macros rather than the structure members.
102 typedef struct da_base {
103 size_t sz; /* Size of allocated vector */
104 size_t len; /* Length of useful portion */
105 size_t off; /* Offset of @v@ into space */
106 unsigned push, unshift; /* Pushes/unshifts since growth */
109 /* --- @DA_DECL@ --- *
111 * Arguments: @atype@ = type name for the array
112 * @type@ = item type for the array
114 * Use: Declares a structure for decribing a dynamic array.
117 #define DA_DECL(type_v, type) \
118 typedef struct type_v { da_base b; type *v; } type_v
120 /*----- Initialization, creation and destruction --------------------------*/
122 #define DA_INIT { { 0, 0, 0, 0, 0 }, 0 } /* Standard initializer */
124 /* --- @DA_CREATE@ --- *
126 * Arguments: @a@ = pointer to an array block (multiply evaluated)
128 * Use: Initializes an array block.
131 #define DA_CREATE(a) do { \
132 (a)->b.sz = (a)->b.len = 0; \
134 (a)->b.push = (a)->b.unshift = 0; \
138 /* --- @DA_DESTROY@ --- *
140 * Arguments: @a@ = pointer to an array block (multiply evaluated)
142 * Use: Destroys an array. The array is left valid but empty.
145 #define DA_DESTROY(a) do { \
147 free((a)->v - (a)->b.off); \
151 /*----- Storage reservation -----------------------------------------------*/
153 /* --- @DA_ENSURE@ --- *
155 * Arguments: @a@ = pointer to an array block (multiply evaluated)
156 * @n@ = required number of spare items in the array
158 * Use: Ensures that there are at least @n@ spare slots at the end of
162 #define DA_ENSURE(a, n) do { \
164 if (_n > (a)->b.sz - (a)->b.len) \
165 (a)->v = da_ensure(&(a)->b, (a)->v, sizeof((a)->v[0]), _n); \
170 /* --- @DA_SHUNT@ --- *
172 * Arguments: @a@ = pointer to an array block (multiply evaluated)
173 * @n@ = required number of spare items in the array
175 * Use: Ensures that there are at least @n@ spare slots at the start
179 #define DA_SHUNT(a, n) do { \
181 if (_n > (a)->b.off) \
182 (a)->v = da_shunt(&(a)->b, (a)->v, sizeof((a)->v[0]), _n); \
184 (a)->b.unshift += _n; \
187 /* --- @DA_TIDY@ --- *
189 * Arguments: @a@ = pointer to an array block (multiply evaluated)
191 * Use: Reduces the amount of storage required by an array to its
195 #define DA_TIDY(a) ((a)->v = da_tidy(&(a)->b, (a)->v, sizeof((a)->v[0])))
197 /* --- @DA_RESET@ --- *
199 * Arguments: @a@ = pointer to array block
201 * Use: Removes all the items from the named array. This might not
202 * be a good idea. No storage is freed.
205 #define DA_RESET(a) ((a)->b.len = 0)
207 /*----- Access operations -------------------------------------------------*/
211 * Arguments: @a@ = pointer to array block
213 * Use: Expands to a reference to the array proper. Given an array
214 * @a@, item @i@ may be located using the expression @DA(a)[i]@.
217 #define DA(a) ((a)->v + 0)
219 /* --- @DA_LEN@ --- *
221 * Arguments: @a@ = pointer to array block
223 * Use: Expands to the number of elements in the array. Elements are
224 * assigned integer indices in the half-open interval
225 * [0, @DA_LEN(a)@). Don't change the length directly; use
226 * @DA_EXTEND@ instead.
229 #define DA_LEN(a) ((a)->b.len + 0)
231 /* --- @DA_SPARE@ --- *
233 * Arguments: @a@ = pointer to array block (multiply evaluated)
235 * Use: Evaluates to the number of spare array elements above the
239 #define DA_SPARE(a) ((a)->b.sz - (a)->b.len)
241 /* --- @DA_INCLUDE@ --- *
243 * Arguments: @a@ = pointer to array block (multiply evaluated)
244 * @i@ = index into array
246 * Use: Extends the array (if necessary) so that it includes the
250 #define DA_INCLUDE(a, i) do { \
252 size_t _len = DA_LEN(a); \
254 size_t _nn = _i - _len + 1; \
256 DA_UNSAFE_EXTEND(a, _nn); \
260 /* --- @DA_OFFSET@ --- *
262 * Arguments: @a@ = pointer to array block
264 * Use: Evaluates to the number of spare elements before the
265 * beginning of the array. Don't modify the offset directly;
266 * use @DA_SLIDE@ instead.
269 #define DA_OFFSET(a) ((a)->b.off + 0)
271 /* --- @DA_EXTEND@ --- *
273 * Arguments: @a@ = pointer to array block (multiply evaluated)
274 * @n@ = number of slots to add (multiply evaluated)
276 * Use: Extends the end of the array by @n@ elements. The exception
277 * @DAEXC_OFLOW@ is thrown if there is not enough space for the
278 * new elements (i.e., @n > DA_SPARE(a)@) -- call @DA_ENSURE@ to
279 * prevent this from happening. The integer @n@ may be
280 * negative; @DAEXC_UFLOW@ is called if @n < DA_LEN(a)@.
283 #define DA_EXTEND(a, n) do { \
284 if ((n) > 0 && (n) > DA_SPARE(a)) \
285 THROW(DAEXC_OFLOW); \
286 else if ((n) < 0 && -(n) > DA_LEN(a)) \
287 THROW(DAEXC_UFLOW); \
288 DA_UNSAFE_EXTEND(a, n); \
291 /* --- @DA_UNSAFE_EXTEND@ --- *
293 * Arguments: @a@ = pointer to array block (multiply evaluated)
294 * @n@ = number of slots to add (multiply evaluated)
296 * Use: As for @DA_EXTEND@, only it doesn't check for errors.
299 #define DA_UNSAFE_EXTEND(a, n) do { \
303 /* --- @DA_SLIDE@ --- *
305 * Arguments: @a@ = pointer to array block (multiply evaluated)
306 * @n@ = number of positions to slide the array (multiply
310 * Use: Slides the array elements by @n@ positions. A positive @n@
311 * slides upwards, introducing new elements at the bottom; a
312 * negative @n@ slides downwards, removing low-numbered
313 * elements. Formally, what was at index @i - n@ before the
314 * slide is moved to index @i@. It is an error to slide by more
315 * than @DA_OFFSET(a)@ or less than @-DA_LEN(a)@. The exception
316 * @DAEXC_OFLOW@ is raised in the former case, and @DAEXC_UFLOW@
320 #define DA_SLIDE(a, n) do { \
321 if ((n) > 0 && (n) > DA_OFFSET(a)) \
322 THROW(DAEXC_OFLOW); \
323 else if ((n) < 0 && -(n) > DA_LEN(a)) \
324 THROW(DAEXC_UFLOW); \
325 DA_UNSAFE_SLIDE((a), (n)); \
328 /* --- @DA_UNSAFE_SLIDE@ --- *
330 * Arguments: @a@ = pointer to array block (multiply evaluated)
331 * @n@ = number of positions to slide the array (multiply
334 * Use: As for @DA_SLIDE@, only it doesn't check for errors.
337 #define DA_UNSAFE_SLIDE(a, n) do { \
344 /* --- @DA_SHRINK@ --- *
346 * Arguments: @a@ = pointer to array block (multiply evaluated)
347 * @n@ = number of slots to remove (multiply evaluated)
349 * Use: As for @DA_EXTEND@, with the sense of the argument reversed.
352 #define DA_SHRINK(a, n) do { \
353 if ((n) > 0 && (n) > DA_LEN(a)) \
354 THROW(DAEXC_UFLOW); \
355 else if ((n) < 0 && -(n) > DA_SPARE(a)) \
356 THROW(DAEXC_OFLOW); \
357 DA_UNSAFE_SHRINK(a, n); \
360 /* --- @DA_UNSAFE_SHRINK@ --- *
362 * Arguments: @a@ = pointer to array block (multiply evaluated)
363 * @n@ = number of slots to add (multiply evaluated)
365 * Use: As for @DA_SHRINK@, only it doesn't check for errors.
368 #define DA_UNSAFE_SHRINK(a, n) do { \
372 /* --- @DA_UNSLIDE@ --- *
374 * Arguments: @a@ = pointer to array block (multiply evaluated)
375 * @n@ = number of positions to slide the array (multiply
379 * Use: As for @DA_SLIDE@, only in the other direction.
382 #define DA_UNSLIDE(a, n) do { \
383 if ((n) > 0 && (n) > DA_LEN(a)) \
384 THROW(DAEXC_UFLOW); \
385 else if ((n) < 0 && -(n) > DA_OFFSET(a)) \
386 THROW(DAEXC_OFLOW); \
387 DA_UNSAFE_UNSLIDE((a), (n)); \
390 /* --- @DA_UNSAFE_UNSLIDE@ --- *
392 * Arguments: @a@ = pointer to array block (multiply evaluated)
393 * @n@ = number of positions to slide the array (multiply
396 * Use: As for @DA_UNSLIDE@, only it doesn't check for errors.
399 #define DA_UNSAFE_UNSLIDE(a, n) do { \
406 /*----- Stack-like operations ---------------------------------------------*/
408 /* --- @DA_PUSH@ --- *
410 * Arguments: @a@ = pointer to an array block (multiply evaluated)
411 * @x@ = item to append to the end
413 * Use: Appends @x@ as the final element in the array @a@.
416 #define DA_PUSH(a, x) do { \
418 DA(a)[(a)->b.len++] = x; \
421 /* --- @DA_POP@ --- *
423 * Arguments: @a@ = pointer to an array block (multiply evaluated)
425 * Use: Evaluates to the final element in array @a@. The element is
426 * removed. An exception @DAEXC_UFLOW@ is raised if there is
427 * no item available to pop.
431 ((a)->b.len ? ((void)0) : THROW(DAEXC_UFLOW), \
434 /* --- @DA_UNSHIFT@ --- *
436 * Arguments: @a@ = pointer to an array block (multiply evaluated)
437 * @x@ = the new element to insert
439 * Use: Inserts a new element at the beginning of an array. This
440 * might take a while.
443 #define DA_UNSHIFT(a, x) do { \
445 DA_UNSAFE_SLIDE(a, 1); \
449 /* --- @DA_SHIFT@ --- *
451 * Arguments: @a@ = pointer to an array block (multiply evaluated)
453 * Use: Evaluates to the initial element in array @a@. The element
454 * is removed, and all other elements are shifted down one
455 * place. The exception @DAEXC_UFLOW@ is raised if there is no
459 #define DA_SHIFT(a) \
460 ((a)->b.len ? ((void)0) : THROW(DAEXC_UFLOW), \
466 /*----- Functions provided ------------------------------------------------*/
468 /* --- @da_ensure@ --- *
470 * Arguments: @da_base *b@ = pointer to array base structure
471 * @void *v@ = pointer to array vector
472 * @size_t sz@ = size of individual array elements
473 * @size_t n@ = number of items required at the end
475 * Returns: Pointer to newly allocated or adjusted array vector.
477 * Use: Extends a dynamic array to accommodate a number of new items
478 * at its end. This function is a helper for the @DA_ENSURE@
479 * macro, which should be used by preference.
482 extern void *da_ensure(da_base */*b*/, void */*v*/,
483 size_t /*sz*/, size_t /*n*/);
485 /* --- @da_shunt@ --- *
487 * Arguments: @da_base *b@ = pointer to array base structure
488 * @void *v@ = pointer to array vector
489 * @size_t sz@ = size of the array elements
490 * @size_t n@ = number of items required at the start
492 * Returns: Pointer to appropriately bodged vector.
494 * Use: Extends an array to accommodate items inserted at its front.
495 * This function is a helper for the @DA_SHUNT@ macro, which
496 * should be used by preference.
499 extern void *da_shunt(da_base */*b*/, void */*v*/,
500 size_t /*sz*/, size_t /*n*/);
502 /* --- @da_tidy@ --- *
504 * Arguments: @da_base *b@ = pointer to array base structure
505 * @void *v@ = pointer to vector
506 * @size_t sz@ = size of the array elements
508 * Returns: Newly allocated vector.
510 * Use: Minimizes the space occupied by an array. This function is a
511 * helper for the @DA_TIDY@ macro, which should be used by
515 extern void *da_tidy(da_base */*b*/, void */*v*/, size_t /*sz*/);
517 /*----- That's all, folks -------------------------------------------------*/