src/data/scratch-writer.c

   1 /* PSPP - a program for statistical analysis.
   2    Copyright (C) 2006 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 "scratch-writer.h"
  20
  21 #include <stdlib.h>
  22
  23 #include <data/case.h>
  24 #include <data/casereader.h>
  25 #include <data/casewriter-provider.h>
  26 #include <data/casewriter.h>
  27 #include <data/dictionary.h>
  28 #include <data/file-handle-def.h>
  29 #include <data/scratch-handle.h>
  30 #include <libpspp/compiler.h>
  31 #include <libpspp/taint.h>
  32
  33 #include "xalloc.h"
  34
  35 /* A scratch file writer. */
  36 struct scratch_writer
  37   {
  38     struct scratch_handle *handle;      /* Underlying scratch handle. */
  39     struct file_handle *fh;             /* Underlying file handle. */
  40     struct dict_compactor *compactor;   /* Compacts into handle->dictionary. */
  41     struct casewriter *subwriter;       /* Data output. */
  42   };
  43
  44 static struct casewriter_class scratch_writer_casewriter_class;
  45
  46 /* Opens FH, which must have referent type FH_REF_SCRATCH, and
  47    returns a scratch_writer for it, or a null pointer on
  48    failure.  Cases stored in the scratch_writer will be expected
  49    to be drawn from DICTIONARY. */
  50 struct casewriter *
  51 scratch_writer_open (struct file_handle *fh,
  52                      const struct dictionary *dictionary)
  53 {
  54   struct scratch_handle *sh;
  55   struct scratch_writer *writer;
  56   struct dictionary *scratch_dict;
  57   struct dict_compactor *compactor;
  58   struct casewriter *casewriter;
  59
  60   if (!fh_open (fh, FH_REF_SCRATCH, "scratch file", "we"))
  61     return NULL;
  62
  63   /* Destroy previous contents of handle. */
  64   sh = fh_get_scratch_handle (fh);
  65   if (sh != NULL)
  66     scratch_handle_destroy (sh);
  67
  68   /* Copy the dictionary and compact if needed. */
  69   scratch_dict = dict_clone (dictionary);
  70   if (dict_compacting_would_shrink (scratch_dict))
  71     {
  72       compactor = dict_make_compactor (scratch_dict);
  73       dict_compact_values (scratch_dict);
  74     }
  75   else
  76     compactor = NULL;
  77
  78   /* Create new contents. */
  79   sh = xmalloc (sizeof *sh);
  80   sh->dictionary = scratch_dict;
  81   sh->casereader = NULL;
  82
  83   /* Create writer. */
  84   writer = xmalloc (sizeof *writer);
  85   writer->handle = sh;
  86   writer->fh = fh;
  87   writer->compactor = compactor;
  88   writer->subwriter = autopaging_writer_create (dict_get_next_value_idx (
  89                                                scratch_dict));
  90
  91   fh_set_scratch_handle (fh, sh);
  92   casewriter = casewriter_create (&scratch_writer_casewriter_class, writer);
  93   taint_propagate (casewriter_get_taint (writer->subwriter),
  94                    casewriter_get_taint (casewriter));
  95   return casewriter;
  96 }
  97
  98 /* Writes case C to WRITER. */
  99 static void
 100 scratch_writer_casewriter_write (struct casewriter *w UNUSED, void *writer_,
 101                                  struct ccase *c)
 102 {
 103   struct scratch_writer *writer = writer_;
 104   struct scratch_handle *handle = writer->handle;
 105   struct ccase tmp;
 106   if (writer->compactor)
 107     {
 108       case_create (&tmp, dict_get_next_value_idx (handle->dictionary));
 109       dict_compactor_compact (writer->compactor, &tmp, c);
 110       case_destroy (c);
 111     }
 112   else
 113     case_move (&tmp, c);
 114   casewriter_write (writer->subwriter, &tmp);
 115 }
 116
 117 /* Closes WRITER. */
 118 static void
 119 scratch_writer_casewriter_destroy (struct casewriter *w UNUSED, void *writer_)
 120 {
 121   struct scratch_writer *writer = writer_;
 122   struct casereader *reader = casewriter_make_reader (writer->subwriter);
 123   if (!casereader_error (reader))
 124     writer->handle->casereader = reader;
 125   fh_close (writer->fh, "scratch file", "we");
 126   free (writer);
 127 }
 128
 129 static struct casewriter_class scratch_writer_casewriter_class =
 130   {
 131     scratch_writer_casewriter_write,
 132     scratch_writer_casewriter_destroy,
 133     NULL,
 134   };