3 * $Id: darray.h,v 1.2 1999/10/29 22:59:22 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 1.2 1999/10/29 22:59:22 mdw
34 * New array adjustment macros for unsigned arguments.
36 * Revision 1.1 1999/10/22 22:37:26 mdw
37 * New dynamic array implementation replaces `dynarray.h'.
48 /*----- Header files ------------------------------------------------------*/
62 /*----- Various important constants ---------------------------------------*/
64 /* --- @DAEXC_UFLOW@, @DAEXC_OFLOW@ --- *
66 * Underflow and overflow exceptions raised by @DA_SHIFT@, and by @DA_POP@
70 #define DAEXC_UFLOW EXC_ALLOCN(EXC_MLIB, 0)
71 #define DAEXC_OFLOW EXC_ALLOCN(EXC_MLIB, 1)
73 /*----- Data structures ---------------------------------------------------*/
75 /* --- Base structure for dynamic arrays --- *
77 * An actual array has a `vector' @v@ in addition to this data (which is
78 * tucked away in the @b@ member). The vector contains the actual storage
79 * for the array elements.
81 * The vector pointer @v@ potentially points somewhere in the middle of the
82 * allocated storage. The @off@ member explains how far into the storage the
83 * vector points. The allocated storage is sufficient for @sz + off@ items
84 * to be stored. Valid array indices are integers between 0 (inclusive) and
85 * @len@ (exclusive). Thus, from @v@ onwards, there is space for @sz@
86 * elements, and of these, @sz - len@ are currently not considered to be
87 * within the array's bounds.
89 * The @push@ and @unshift@ counts record how many times these operations
90 * have been performed since the last extension of the array. They are used
91 * by the extension algorithm to decide how to position the data offset.
93 * Try to use the access macros rather than the structure members.
96 typedef struct da_base {
97 size_t sz; /* Size of allocated vector */
98 size_t len; /* Length of useful portion */
99 size_t off; /* Offset of @v@ into space */
100 unsigned push, unshift; /* Pushes/unshifts since growth */
103 /* --- @DA_DECL@ --- *
105 * Arguments: @atype@ = type name for the array
106 * @type@ = item type for the array
108 * Use: Declares a structure for decribing a dynamic array.
111 #define DA_DECL(atype, type) \
112 typedef struct atype { da_base b; type *v; } atype
114 /*----- Initialization, creation and destruction --------------------------*/
116 #define DA_INIT { { 0, 0, 0, 0, 0 }, 0 } /* Standard initializer */
118 /* --- @DA_CREATE@ --- *
120 * Arguments: @a@ = pointer to an array block (multiply evaluated)
122 * Use: Initializes an array block.
125 #define DA_CREATE(a) do { \
126 (a)->b.sz = (a)->b.len = 0; \
128 (a)->b.push = (a)->b.unshift = 0; \
132 /* --- @DA_DESTROY@ --- *
134 * Arguments: @a@ = pointer to an array block (multiply evaluated)
136 * Use: Destroys an array. The array is left valid but empty.
139 #define DA_DESTROY(a) do { \
141 free((a)->v - (a)->b.off); \
145 /*----- Storage reservation -----------------------------------------------*/
147 /* --- @DA_ENSURE@ --- *
149 * Arguments: @a@ = pointer to an array block (multiply evaluated)
150 * @n@ = required number of spare items in the array
152 * Use: Ensures that there are at least @n@ spare slots at the end of
156 #define DA_ENSURE(a, n) do { \
158 if (_n > (a)->b.sz - (a)->b.len) \
159 (a)->v = da_ensure(&(a)->b, (a)->v, sizeof((a)->v[0]), _n); \
164 /* --- @DA_SHUNT@ --- *
166 * Arguments: @a@ = pointer to an array block (multiply evaluated)
167 * @n@ = required number of spare items in the array
169 * Use: Ensures that there are at least @n@ spare slots at the start
173 #define DA_SHUNT(a, n) do { \
175 if (_n > (a)->b.off) \
176 (a)->v = da_shunt(&(a)->b, (a)->v, sizeof((a)->v[0]), _n); \
178 (a)->b.unshift += _n; \
181 /* --- @DA_TIDY@ --- *
183 * Arguments: @a@ = pointer to an array block (multiply evaluated)
185 * Use: Reduces the amount of storage required by an array to its
189 #define DA_TIDY(a) ((a)->v = da_tidy(&(a)->b, (a)->v, sizeof((a)->v[0])))
191 /* --- @DA_RESET@ --- *
193 * Arguments: @a@ = pointer to array block
195 * Use: Removes all the items from the named array. This might not
196 * be a good idea. No storage is freed.
199 #define DA_RESET(a) ((a)->b.len = 0)
201 /*----- Access operations -------------------------------------------------*/
205 * Arguments: @a@ = pointer to array block
207 * Use: Expands to a reference to the array proper. Given an array
208 * @a@, item @i@ may be located using the expression @DA(a)[i]@.
211 #define DA(a) ((a)->v + 0)
213 /* --- @DA_LEN@ --- *
215 * Arguments: @a@ = pointer to array block
217 * Use: Expands to the number of elements in the array. Elements are
218 * assigned integer indices in the half-open interval
219 * [0, @DA_LEN(a)@). Don't change the length directly; use
220 * @DA_EXTEND@ instead.
223 #define DA_LEN(a) ((a)->b.len + 0)
225 /* --- @DA_SPARE@ --- *
227 * Arguments: @a@ = pointer to array block (multiply evaluated)
229 * Use: Evaluates to the number of spare array elements above the
233 #define DA_SPARE(a) ((a)->b.sz - (a)->b.len)
235 /* --- @DA_INCLUDE@ --- *
237 * Arguments: @a@ = pointer to array block (multiply evaluated)
238 * @i@ = index into array
240 * Use: Extends the array (if necessary) so that it includes the
244 #define DA_INCLUDE(a, i) do { \
246 size_t _len = DA_LEN(a); \
248 size_t _nn = _i - _len + 1; \
250 DA_UNSAFE_EXTEND(a, _nn); \
254 /* --- @DA_OFFSET@ --- *
256 * Arguments: @a@ = pointer to array block
258 * Use: Evaluates to the number of spare elements before the
259 * beginning of the array. Don't modify the offset directly;
260 * use @DA_SLIDE@ instead.
263 #define DA_OFFSET(a) ((a)->b.off + 0)
265 /* --- @DA_EXTEND@ --- *
267 * Arguments: @a@ = pointer to array block (multiply evaluated)
268 * @n@ = number of slots to add (multiply evaluated)
270 * Use: Extends the end of the array by @n@ elements. The exception
271 * @DAEXC_OFLOW@ is thrown if there is not enough space for the
272 * new elements (i.e., @n > DA_SPARE(a)@) -- call @DA_ENSURE@ to
273 * prevent this from happening. The integer @n@ may be
274 * negative; @DAEXC_UFLOW@ is called if @n < DA_LEN(a)@.
277 #define DA_EXTEND(a, n) do { \
278 if ((n) > 0 && (n) > DA_SPARE(a)) \
279 THROW(DAEXC_OFLOW); \
280 else if ((n) < 0 && -(n) > DA_LEN(a)) \
281 THROW(DAEXC_UFLOW); \
282 DA_UNSAFE_EXTEND(a, n); \
285 /* --- @DA_UNSAFE_EXTEND@ --- *
287 * Arguments: @a@ = pointer to array block (multiply evaluated)
288 * @n@ = number of slots to add (multiply evaluated)
290 * Use: As for @DA_EXTEND@, only it doesn't check for errors.
293 #define DA_UNSAFE_EXTEND(a, n) do { \
297 /* --- @DA_SLIDE@ --- *
299 * Arguments: @a@ = pointer to array block (multiply evaluated)
300 * @n@ = number of positions to slide the array (multiply
304 * Use: Slides the array elements by @n@ positions. A positive @n@
305 * slides upwards, introducing new elements at the bottom; a
306 * negative @n@ slides downwards, removing low-numbered
307 * elements. Formally, what was at index @i - n@ before the
308 * slide is moved to index @i@. It is an error to slide by more
309 * than @DA_OFFSET(a)@ or less than @-DA_LEN(a)@. The exception
310 * @DAEXC_OFLOW@ is raised in the former case, and @DAEXC_UFLOW@
314 #define DA_SLIDE(a, n) do { \
315 if ((n) > 0 && (n) > DA_OFFSET(a)) \
316 THROW(DAEXC_OFLOW); \
317 else if ((n) < 0 && -(n) > DA_LEN(a)) \
318 THROW(DAEXC_UFLOW); \
319 DA_UNSAFE_SLIDE((a), (n)); \
322 /* --- @DA_UNSAFE_SLIDE@ --- *
324 * Arguments: @a@ = pointer to array block (multiply evaluated)
325 * @n@ = number of positions to slide the array (multiply
328 * Use: As for @DA_SLIDE@, only it doesn't check for errors.
331 #define DA_UNSAFE_SLIDE(a, n) do { \
338 /* --- @DA_SHRINK@ --- *
340 * Arguments: @a@ = pointer to array block (multiply evaluated)
341 * @n@ = number of slots to remove (multiply evaluated)
343 * Use: As for @DA_EXTEND@, with the sense of the argument reversed.
346 #define DA_SHRINK(a, n) do { \
347 if ((n) > 0 && (n) > DA_LEN(a)) \
348 THROW(DAEXC_UFLOW); \
349 else if ((n) < 0 && -(n) > DA_SPARE(a)) \
350 THROW(DAEXC_OFLOW); \
351 DA_UNSAFE_SHRINK(a, n); \
354 /* --- @DA_UNSAFE_SHRINK@ --- *
356 * Arguments: @a@ = pointer to array block (multiply evaluated)
357 * @n@ = number of slots to add (multiply evaluated)
359 * Use: As for @DA_SHRINK@, only it doesn't check for errors.
362 #define DA_UNSAFE_SHRINK(a, n) do { \
366 /* --- @DA_UNSLIDE@ --- *
368 * Arguments: @a@ = pointer to array block (multiply evaluated)
369 * @n@ = number of positions to slide the array (multiply
373 * Use: As for @DA_SLIDE@, only in the other direction.
376 #define DA_UNSLIDE(a, n) do { \
377 if ((n) > 0 && (n) > DA_LEN(a)) \
378 THROW(DAEXC_UFLOW); \
379 else if ((n) < 0 && -(n) > DA_OFFSET(a)) \
380 THROW(DAEXC_OFLOW); \
381 DA_UNSAFE_UNSLIDE((a), (n)); \
384 /* --- @DA_UNSAFE_UNSLIDE@ --- *
386 * Arguments: @a@ = pointer to array block (multiply evaluated)
387 * @n@ = number of positions to slide the array (multiply
390 * Use: As for @DA_UNSLIDE@, only it doesn't check for errors.
393 #define DA_UNSAFE_UNSLIDE(a, n) do { \
400 /*----- Stack-like operations ---------------------------------------------*/
402 /* --- @DA_PUSH@ --- *
404 * Arguments: @a@ = pointer to an array block (multiply evaluated)
405 * @x@ = item to append to the end
407 * Use: Appends @x@ as the final element in the array @a@.
410 #define DA_PUSH(a, x) do { \
412 DA(a)[(a)->b.len++] = x; \
415 /* --- @DA_POP@ --- *
417 * Arguments: @a@ = pointer to an array block (multiply evaluated)
419 * Use: Evaluates to the final element in array @a@. The element is
420 * removed. An exception @DAEXC_UFLOW@ is raised if there is
421 * no item available to pop.
425 ((a)->b.len ? ((void)0) : THROW(DAEXC_UFLOW), \
428 /* --- @DA_UNSHIFT@ --- *
430 * Arguments: @a@ = pointer to an array block (multiply evaluated)
431 * @x@ = the new element to insert
433 * Use: Inserts a new element at the beginning of an array. This
434 * might take a while.
437 #define DA_UNSHIFT(a, x) do { \
439 DA_UNSAFE_SLIDE(a, 1); \
443 /* --- @DA_SHIFT@ --- *
445 * Arguments: @a@ = pointer to an array block (multiply evaluated)
447 * Use: Evaluates to the initial element in array @a@. The element
448 * is removed, and all other elements are shifted down one
449 * place. The exception @DAEXC_UFLOW@ is raised if there is no
453 #define DA_SHIFT(a) \
454 ((a)->b.len ? ((void)0) : THROW(DAEXC_UFLOW), \
460 /*----- Functions provided ------------------------------------------------*/
462 /* --- @da_ensure@ --- *
464 * Arguments: @da_base *b@ = pointer to array base structure
465 * @void *v@ = pointer to array vector
466 * @size_t sz@ = size of individual array elements
467 * @size_t n@ = number of items required at the end
469 * Returns: Pointer to newly allocated or adjusted array vector.
471 * Use: Extends a dynamic array to accommodate a number of new items
472 * at its end. This function is a helper for the @DA_ENSURE@
473 * macro, which should be used by preference.
476 extern void *da_ensure(da_base */*b*/, void */*v*/,
477 size_t /*sz*/, size_t /*n*/);
479 /* --- @da_shunt@ --- *
481 * Arguments: @da_base *b@ = pointer to array base structure
482 * @void *v@ = pointer to array vector
483 * @size_t sz@ = size of the array elements
484 * @size_t n@ = number of items required at the start
486 * Returns: Pointer to appropriately bodged vector.
488 * Use: Extends an array to accommodate items inserted at its front.
489 * This function is a helper for the @DA_SHUNT@ macro, which
490 * should be used by preference.
493 extern void *da_shunt(da_base */*b*/, void */*v*/,
494 size_t /*sz*/, size_t /*n*/);
496 /* --- @da_tidy@ --- *
498 * Arguments: @da_base *b@ = pointer to array base structure
499 * @void *v@ = pointer to vector
500 * @size_t sz@ = size of the array elements
502 * Returns: Newly allocated vector.
504 * Use: Minimizes the space occupied by an array. This function is a
505 * helper for the @DA_TIDY@ macro, which should be used by
509 extern void *da_tidy(da_base */*b*/, void */*v*/, size_t /*sz*/);
511 /*----- That's all, folks -------------------------------------------------*/