src/libpspp/array.h

   1 /*
   2 PSPP - a program for statistical analysis.
   3 Copyright (C) 2017 Free Software Foundation, Inc.
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, either version 3 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #ifndef ALGORITHM_H
  20 #define ALGORITHM_H 1
  21
  22 #include <stddef.h>
  23 #include <stdbool.h>
  24
  25 /* Compares A and B, given auxiliary data AUX, and returns a
  26    strcmp()-type result. */
  27
  28 typedef int algo_compare_func (const void *a, const void *b, const void *aux);
  29
  30 /* Tests a predicate on DATA, given auxiliary data AUX */
  31 typedef bool algo_predicate_func (const void *data, const void *aux);
  32
  33 /* Returns a random number in the range 0 through MAX exclusive,
  34    given auxiliary data AUX. */
  35 typedef unsigned algo_random_func (unsigned max, const void *aux);
  36
  37 /* A generally suitable random function. */
  38 algo_random_func algo_default_random;
  39
  40 /* Finds an element in ARRAY, which contains COUNT elements of
  41    SIZE bytes each, using COMPARE for comparisons.  Returns the
  42    first element in ARRAY that matches TARGET, or a null pointer
  43    on failure.  AUX is passed to each comparison as auxiliary
  44    data. */
  45 void *find (const void *array, size_t count, size_t size,
  46             const void *target,
  47             algo_compare_func *compare, const void *aux);
  48
  49 /* Counts and return the number of elements in ARRAY, which
  50    contains COUNT elements of SIZE bytes each, which are equal to
  51    ELEMENT as compared with COMPARE.  AUX is passed as auxiliary
  52    data to COMPARE. */
  53 size_t count_equal (const void *array, size_t count, size_t size,
  54                     const void *element,
  55                     algo_compare_func *compare, const void *aux);
  56
  57 /* Counts and return the number of elements in ARRAY, which
  58    contains COUNT elements of SIZE bytes each, for which
  59    PREDICATE returns true.  AUX is passed as auxiliary data to
  60    PREDICATE. */
  61 size_t count_if (const void *array, size_t count, size_t size,
  62                  algo_predicate_func *predicate, const void *aux);
  63
  64 /* Sorts ARRAY, which contains COUNT elements of SIZE bytes each,
  65    using COMPARE for comparisons.  AUX is passed to each
  66    comparison as auxiliary data. */
  67 void sort (void *array, size_t count, size_t size,
  68            algo_compare_func *compare, const void *aux);
  69
  70 /* Tests whether ARRAY, which contains COUNT elements of SIZE
  71    bytes each, is sorted in order according to COMPARE.  AUX is
  72    passed to COMPARE as auxiliary data. */
  73 bool is_sorted (const void *array, size_t count, size_t size,
  74                algo_compare_func *compare, const void *aux);
  75
  76 /* Makes the elements in ARRAY unique, by moving up duplicates,
  77    and returns the new number of elements in the array.  Sorted
  78    arrays only.  Arguments same as for sort() above. */
  79 size_t unique (void *array, size_t count, size_t size,
  80                algo_compare_func *compare, const void *aux);
  81
  82 /* Helper function that calls sort(), then unique(). */
  83 size_t sort_unique (void *array, size_t count, size_t size,
  84                     algo_compare_func *compare, const void *aux);
  85
  86 /* Reorders ARRAY, which contains COUNT elements of SIZE bytes
  87    each, so that the elements for which PREDICATE returns true
  88    precede those for which PREDICATE returns false.  AUX is passed
  89    as auxiliary data to PREDICATE.  Returns the number of
  90    elements for which PREDICATE returns true.  Not stable. */
  91 size_t partition (void *array, size_t count, size_t size,
  92                   algo_predicate_func *predicate, const void *aux);
  93
  94 /* Checks whether ARRAY, which contains COUNT elements of SIZE
  95    bytes each, is partitioned such that PREDICATE returns true
  96    for the first TRUE_CNT elements and zero for the remaining
  97    elements.  AUX is passed as auxiliary data to PREDICATE. */
  98 bool is_partitioned (const void *array, size_t count, size_t size,
  99                     size_t n_trues,
 100                     algo_predicate_func *predicate, const void *aux);
 101
 102 /* Randomly reorders ARRAY, which contains COUNT elements of SIZE
 103    bytes each.  Uses RANDOM as a source of random data, passing
 104    AUX as the auxiliary data.  RANDOM may be null to use a
 105    default random source. */
 106 void random_shuffle (void *array, size_t count, size_t size,
 107                      algo_random_func *random, const void *aux);
 108
 109 /* Copies the COUNT elements of SIZE bytes each from ARRAY to
 110    RESULT, except that elements for which PREDICATE is false are
 111    not copied.  Returns the number of elements copied.  AUX is
 112    passed to PREDICATE as auxiliary data.  */
 113 size_t copy_if (const void *array, size_t count, size_t size,
 114                 void *result,
 115                 algo_predicate_func *predicate, const void *aux);
 116
 117 /* Removes N elements starting at IDX from ARRAY, which consists
 118    of COUNT elements of SIZE bytes each, by shifting the elements
 119    following them, if any, into its position. */
 120 void remove_range (void *array, size_t count, size_t size,
 121                    size_t idx, size_t n);
 122
 123 /* Removes element IDX from ARRAY, which consists of COUNT
 124    elements of SIZE bytes each, by shifting the elements
 125    following it, if any, into its position. */
 126 void remove_element (void *array, size_t count, size_t size,
 127                      size_t idx);
 128
 129 /* Makes room for N elements starting at IDX in ARRAY, which
 130    initially consists of COUNT elements of SIZE bytes each, by
 131    shifting elements IDX...COUNT (exclusive) to the right by N
 132    positions. */
 133 void insert_range (void *array, size_t count, size_t size,
 134                    size_t idx, size_t n);
 135
 136 /* Makes room for a new element at IDX in ARRAY, which initially
 137    consists of COUNT elements of SIZE bytes each, by shifting
 138    elements IDX...COUNT (exclusive) to the right by one
 139    position. */
 140 void insert_element (void *array, size_t count, size_t size,
 141                      size_t idx);
 142
 143 /* Moves an element in ARRAY, which consists of COUNT elements of
 144    SIZE bytes each, from OLD_IDX to NEW_IDX, shifting around
 145    other elements as needed.  Runs in O(abs(OLD_IDX - NEW_IDX))
 146    time. */
 147 void move_element (void *array, size_t count, size_t size,
 148                    size_t old_idx, size_t new_idx);
 149
 150 /* Moves N elements in ARRAY starting at OLD_IDX, which consists
 151    of COUNT elements of SIZE bytes each, so that they now start
 152    at NEW_IDX, shifting around other elements as needed. */
 153 void move_range (void *array, size_t count, size_t size,
 154                  size_t old_idx, size_t new_idx, size_t n);
 155
 156 /* Removes elements equal to ELEMENT from ARRAY, which consists
 157    of COUNT elements of SIZE bytes each.  Returns the number of
 158    remaining elements.  AUX is passed to COMPARE as auxiliary
 159    data. */
 160 size_t remove_equal (void *array, size_t count, size_t size,
 161                      void *element,
 162                      algo_compare_func *compare, const void *aux);
 163
 164 /* Copies the COUNT elements of SIZE bytes each from ARRAY to
 165    RESULT, except that elements for which PREDICATE is true are
 166    not copied.  Returns the number of elements copied.  AUX is
 167    passed to PREDICATE as auxiliary data.  */
 168 size_t remove_copy_if (const void *array, size_t count, size_t size,
 169                        void *result,
 170                        algo_predicate_func *predicate, const void *aux);
 171
 172 /* Searches ARRAY, which contains COUNT elements of SIZE bytes
 173    each, for VALUE, using a binary search.  ARRAY must ordered
 174    according to COMPARE.  AUX is passed to COMPARE as auxiliary
 175    data. */
 176 void *binary_search (const void *array, size_t count, size_t size,
 177                      void *value,
 178                      algo_compare_func *compare, const void *aux);
 179
 180 /* Lexicographically compares ARRAY1, which contains COUNT1
 181    elements of SIZE bytes each, to ARRAY2, which contains COUNT2
 182    elements of SIZE bytes, according to COMPARE.  Returns a
 183    strcmp()-type result.  AUX is passed to COMPARE as auxiliary
 184    data. */
 185 int lexicographical_compare_3way (const void *array1, size_t count1,
 186                                   const void *array2, size_t count2,
 187                                   size_t size,
 188                                   algo_compare_func *compare, const void *aux);
 189
 190 /* Computes the generalized set difference, ARRAY1 minus ARRAY2,
 191    into RESULT, and returns the number of elements written to
 192    RESULT.  If a value appears M times in ARRAY1 and N times in
 193    ARRAY2, then it will appear max(M - N, 0) in RESULT.  ARRAY1
 194    and ARRAY2 must be sorted, and RESULT is sorted and stable.
 195    ARRAY1 consists of COUNT1 elements, ARRAY2 of COUNT2 elements,
 196    each SIZE bytes.  AUX is passed to COMPARE as auxiliary
 197    data. */
 198 size_t set_difference (const void *array1, size_t count1,
 199                        const void *array2, size_t count2,
 200                        size_t size,
 201                        void *result,
 202                        algo_compare_func *compare, const void *aux);
 203
 204 /* Finds the first pair of adjacent equal elements in ARRAY,
 205    which has COUNT elements of SIZE bytes.  Returns the first
 206    element in ARRAY such that COMPARE returns true when it and
 207    its successor element are compared.  AUX is passed to COMPARE
 208    as auxiliary data. */
 209 void *adjacent_find_equal (const void *array, size_t count, size_t size,
 210                            algo_compare_func *compare, const void *aux);
 211
 212 /* ARRAY contains COUNT elements of SIZE bytes each.  Initially
 213    the first COUNT - 1 elements of these form a heap, followed by
 214    a single element not part of the heap.  This function adds the
 215    final element, forming a heap of COUNT elements in ARRAY.
 216    Uses COMPARE to compare elements, passing AUX as auxiliary
 217    data. */
 218 void push_heap (void *array, size_t count, size_t size,
 219                 algo_compare_func *compare, const void *aux);
 220
 221 /* ARRAY contains COUNT elements of SIZE bytes each.  Initially
 222    all COUNT elements form a heap.  This function moves the
 223    largest element in the heap to the final position in ARRAY and
 224    reforms a heap of the remaining COUNT - 1 elements at the
 225    beginning of ARRAY.  Uses COMPARE to compare elements, passing
 226    AUX as auxiliary data. */
 227 void pop_heap (void *array, size_t count, size_t size,
 228                algo_compare_func *compare, const void *aux);
 229
 230 /* Turns ARRAY, which contains COUNT elements of SIZE bytes, into
 231    a heap.  Uses COMPARE to compare elements, passing AUX as
 232    auxiliary data. */
 233 void make_heap (void *array, size_t count, size_t size,
 234                 algo_compare_func *compare, const void *aux);
 235
 236 /* ARRAY contains COUNT elements of SIZE bytes each.  Initially
 237    all COUNT elements form a heap.  This function turns the heap
 238    into a fully sorted array.  Uses COMPARE to compare elements,
 239    passing AUX as auxiliary data. */
 240 void sort_heap (void *array, size_t count, size_t size,
 241                 algo_compare_func *compare, const void *aux);
 242
 243 /* ARRAY contains COUNT elements of SIZE bytes each.  This
 244    function tests whether ARRAY is a heap and returns true if so,
 245    false otherwise.  Uses COMPARE to compare elements, passing
 246    AUX as auxiliary data. */
 247 bool is_heap (const void *array, size_t count, size_t size,
 248              algo_compare_func *compare, const void *aux);
 249
 250 /* Reverses the order of ARRAY, which contains COUNT elements of SIZE bytes
 251    each. */
 252 void reverse_array (void *array, size_t count, size_t size);
 253
 254 #endif /* algorithm.h */