src/data/transformations.c

   1 /* PSPP - a program for statistical analysis.
   2    Copyright (C) 1997-9, 2000, 2006, 2009, 2011, 2013 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
  16
  17 #include <config.h>
  18
  19 #include "data/transformations.h"
  20
  21 #include <assert.h>
  22 #include <stdlib.h>
  23
  24 #include "libpspp/str.h"
  25
  26 #include "gl/xalloc.h"
  27
  28 /* A single transformation. */
  29 struct transformation
  30   {
  31     /* Offset to add to EXECUTE's return value, if it returns a
  32        transformation index.  Normally 0 but set to the starting
  33        index of a spliced chain after splicing. */
  34     int idx_ofs;
  35     trns_finalize_func *finalize;       /* Finalize proc. */
  36     trns_proc_func *execute;            /* Executes the transformation. */
  37     trns_free_func *free;               /* Garbage collector proc. */
  38     void *aux;                          /* Auxiliary data. */
  39   };
  40
  41 /* A chain of transformations. */
  42 struct trns_chain
  43   {
  44     struct transformation *trns;        /* Array of transformations. */
  45     size_t trns_cnt;                    /* Number of transformations. */
  46     size_t trns_cap;                    /* Allocated capacity. */
  47     bool finalized;                     /* Finalize functions called? */
  48   };
  49
  50 /* Allocates and returns a new transformation chain. */
  51 struct trns_chain *
  52 trns_chain_create (void)
  53 {
  54   struct trns_chain *chain = xmalloc (sizeof *chain);
  55   chain->trns = NULL;
  56   chain->trns_cnt = 0;
  57   chain->trns_cap = 0;
  58   chain->finalized = false;
  59   return chain;
  60 }
  61
  62 /* Finalizes all the un-finalized transformations in CHAIN.
  63    Any given transformation is only finalized once. */
  64 void
  65 trns_chain_finalize (struct trns_chain *chain)
  66 {
  67   while (!chain->finalized)
  68     {
  69       size_t i;
  70
  71       chain->finalized = true;
  72       for (i = 0; i < chain->trns_cnt; i++)
  73         {
  74           struct transformation *trns = &chain->trns[i];
  75           trns_finalize_func *finalize = trns->finalize;
  76
  77           trns->finalize = NULL;
  78           if (finalize != NULL)
  79             finalize (trns->aux);
  80         }
  81     }
  82 }
  83
  84 /* Destroys CHAIN, finalizing it in the process if it has not
  85    already been finalized. */
  86 bool
  87 trns_chain_destroy (struct trns_chain *chain)
  88 {
  89   bool ok = true;
  90
  91   if (chain != NULL)
  92     {
  93       size_t i;
  94
  95       /* Needed to ensure that the control stack gets cleared. */
  96       trns_chain_finalize (chain);
  97
  98       for (i = 0; i < chain->trns_cnt; i++)
  99         {
 100           struct transformation *trns = &chain->trns[i];
 101           if (trns->free != NULL)
 102             ok = trns->free (trns->aux) && ok;
 103         }
 104       free (chain->trns);
 105       free (chain);
 106     }
 107
 108   return ok;
 109 }
 110
 111 /* Returns true if CHAIN contains any transformations,
 112    false otherwise. */
 113 bool
 114 trns_chain_is_empty (const struct trns_chain *chain)
 115 {
 116   return chain->trns_cnt == 0;
 117 }
 118
 119 /* Adds a transformation to CHAIN with finalize function
 120    FINALIZE, execute function EXECUTE, free function FREE, and
 121    auxiliary data AUX. */
 122 void
 123 trns_chain_append (struct trns_chain *chain, trns_finalize_func *finalize,
 124                    trns_proc_func *execute, trns_free_func *free,
 125                    void *aux)
 126 {
 127   struct transformation *trns;
 128
 129   chain->finalized = false;
 130
 131   if (chain->trns_cnt == chain->trns_cap)
 132     chain->trns = x2nrealloc (chain->trns, &chain->trns_cap,
 133                               sizeof *chain->trns);
 134
 135   trns = &chain->trns[chain->trns_cnt++];
 136   trns->idx_ofs = 0;
 137   trns->finalize = finalize;
 138   trns->execute = execute;
 139   trns->free = free;
 140   trns->aux = aux;
 141 }
 142
 143 /* Appends the transformations in SRC to those in DST,
 144    and destroys SRC.
 145    Both DST and SRC must already be finalized. */
 146 void
 147 trns_chain_splice (struct trns_chain *dst, struct trns_chain *src)
 148 {
 149   size_t i;
 150
 151   assert (dst->finalized);
 152   assert (src->finalized);
 153
 154   if (dst->trns_cnt + src->trns_cnt > dst->trns_cap)
 155     {
 156       dst->trns_cap = dst->trns_cnt + src->trns_cnt;
 157       dst->trns = xnrealloc (dst->trns, dst->trns_cap, sizeof *dst->trns);
 158     }
 159
 160   for (i = 0; i < src->trns_cnt; i++)
 161     {
 162       struct transformation *d = &dst->trns[i + dst->trns_cnt];
 163       const struct transformation *s = &src->trns[i];
 164       *d = *s;
 165       d->idx_ofs += src->trns_cnt;
 166     }
 167   dst->trns_cnt += src->trns_cnt;
 168
 169   src->trns_cnt = 0;
 170   trns_chain_destroy (src);
 171 }
 172
 173 /* Returns the index that a transformation execution function may
 174    return to "jump" to the next transformation to be added. */
 175 size_t
 176 trns_chain_next (struct trns_chain *chain)
 177 {
 178   return chain->trns_cnt;
 179 }
 180
 181 /* Executes the given CHAIN of transformations on *C,
 182    passing CASE_NR as the case number.
 183    *C may be replaced by a new case.
 184    Returns the result code that caused the transformations to
 185    terminate, or TRNS_CONTINUE if the transformations finished
 186    due to "falling off the end" of the set of transformations. */
 187 enum trns_result
 188 trns_chain_execute (const struct trns_chain *chain, enum trns_result start,
 189                     struct ccase **c, casenumber case_nr)
 190 {
 191   size_t i;
 192
 193   assert (chain->finalized);
 194   for (i = start < 0 ? 0 : start; i < chain->trns_cnt; )
 195     {
 196       struct transformation *trns = &chain->trns[i];
 197       int retval = trns->execute (trns->aux, c, case_nr);
 198       if (retval == TRNS_CONTINUE)
 199         i++;
 200       else if (retval >= 0)
 201         i = retval + trns->idx_ofs;
 202       else
 203         return retval == TRNS_END_CASE ? i + 1 : retval;
 204     }
 205
 206   return TRNS_CONTINUE;
 207 }