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[pspp] / src / data / scratch-writer.c
1 /* PSPP - a program for statistical analysis.
2    Copyright (C) 2006, 2009, 2011 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/scratch-writer.h"
20
21 #include <stdlib.h>
22
23 #include "data/case.h"
24 #include "data/case-map.h"
25 #include "data/casereader.h"
26 #include "data/casewriter-provider.h"
27 #include "data/casewriter.h"
28 #include "data/dictionary.h"
29 #include "data/file-handle-def.h"
30 #include "data/scratch-handle.h"
31 #include "data/variable.h"
32 #include "libpspp/compiler.h"
33 #include "libpspp/taint.h"
34
35 #include "gl/xalloc.h"
36
37 #define N_(msgid) (msgid)
38
39 /* A scratch file writer. */
40 struct scratch_writer
41   {
42     struct file_handle *fh;             /* Underlying file handle. */
43     struct fh_lock *lock;               /* Exclusive access to file handle. */
44     struct dictionary *dict;            /* Dictionary for subwriter. */
45     struct case_map *compactor;         /* Compacts into dictionary. */
46     struct casewriter *subwriter;       /* Data output. */
47   };
48
49 static const struct casewriter_class scratch_writer_casewriter_class;
50
51 /* Opens FH, which must have referent type FH_REF_SCRATCH, and
52    returns a scratch_writer for it, or a null pointer on
53    failure.  Cases stored in the scratch_writer will be expected
54    to be drawn from DICTIONARY. */
55 struct casewriter *
56 scratch_writer_open (struct file_handle *fh,
57                      const struct dictionary *dictionary)
58 {
59   struct scratch_writer *writer;
60   struct casewriter *casewriter;
61   struct fh_lock *lock;
62
63   /* Get exclusive write access to handle. */
64   /* TRANSLATORS: this fragment will be interpolated into
65      messages in fh_lock() that identify types of files. */
66   lock = fh_lock (fh, FH_REF_SCRATCH, N_("scratch file"), FH_ACC_WRITE, true);
67   if (lock == NULL)
68     return NULL;
69
70   /* Create writer. */
71   writer = xmalloc (sizeof *writer);
72   writer->lock = lock;
73   writer->fh = fh_ref (fh);
74
75   writer->dict = dict_clone (dictionary);
76   dict_delete_scratch_vars (writer->dict);
77   if (dict_count_values (writer->dict, 0)
78       < dict_get_next_value_idx (writer->dict))
79     {
80       writer->compactor = case_map_to_compact_dict (writer->dict, 0);
81       dict_compact_values (writer->dict);
82     }
83   else
84     writer->compactor = NULL;
85   writer->subwriter = autopaging_writer_create (dict_get_proto (writer->dict));
86
87   casewriter = casewriter_create (dict_get_proto (writer->dict),
88                                   &scratch_writer_casewriter_class, writer);
89   taint_propagate (casewriter_get_taint (writer->subwriter),
90                    casewriter_get_taint (casewriter));
91   return casewriter;
92 }
93
94 /* Writes case C to WRITER. */
95 static void
96 scratch_writer_casewriter_write (struct casewriter *w UNUSED, void *writer_,
97                                  struct ccase *c)
98 {
99   struct scratch_writer *writer = writer_;
100   casewriter_write (writer->subwriter,
101                     case_map_execute (writer->compactor, c));
102 }
103
104 /* Closes WRITER. */
105 static void
106 scratch_writer_casewriter_destroy (struct casewriter *w UNUSED, void *writer_)
107 {
108   static unsigned int next_unique_id = 0x12345678;
109
110   struct scratch_writer *writer = writer_;
111   struct casereader *reader = casewriter_make_reader (writer->subwriter);
112   if (!casereader_error (reader))
113     {
114       /* Destroy previous contents of handle. */
115       struct scratch_handle *sh = fh_get_scratch_handle (writer->fh);
116       if (sh != NULL)
117         scratch_handle_destroy (sh);
118
119       /* Create new contents. */
120       sh = xmalloc (sizeof *sh);
121       sh->unique_id = ++next_unique_id;
122       sh->dictionary = writer->dict;
123       sh->casereader = reader;
124       fh_set_scratch_handle (writer->fh, sh);
125     }
126   else
127     {
128       casereader_destroy (reader);
129       dict_destroy (writer->dict);
130     }
131
132   fh_unlock (writer->lock);
133   fh_unref (writer->fh);
134   free (writer);
135 }
136
137 static const struct casewriter_class scratch_writer_casewriter_class =
138   {
139     scratch_writer_casewriter_write,
140     scratch_writer_casewriter_destroy,
141     NULL,
142   };