Merge branch 'master' of /home/john/Development/pspp-window-manager
[pspp-builds.git] / src / data / scratch-writer.c
1 /* PSPP - a program for statistical analysis.
2    Copyright (C) 2006, 2009 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/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 "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   size_t dict_value_cnt;
63
64   /* Get exclusive write access to handle. */
65   /* TRANSLATORS: this fragment will be interpolated into
66      messages in fh_lock() that identify types of files. */
67   lock = fh_lock (fh, FH_REF_SCRATCH, N_("scratch file"), FH_ACC_WRITE, true);
68   if (lock == NULL)
69     return NULL;
70
71   /* Create writer. */
72   writer = xmalloc (sizeof *writer);
73   writer->lock = lock;
74   writer->fh = fh_ref (fh);
75
76   writer->dict = dict_clone (dictionary);
77   dict_delete_scratch_vars (writer->dict);
78   if (dict_count_values (writer->dict, 0)
79       < dict_get_next_value_idx (writer->dict))
80     {
81       writer->compactor = case_map_to_compact_dict (writer->dict, 0);
82       dict_compact_values (writer->dict);
83     }
84   else
85     writer->compactor = NULL;
86   dict_value_cnt = dict_get_next_value_idx (writer->dict);
87   writer->subwriter = autopaging_writer_create (dict_value_cnt);
88
89   casewriter = casewriter_create (dict_value_cnt,
90                                   &scratch_writer_casewriter_class, writer);
91   taint_propagate (casewriter_get_taint (writer->subwriter),
92                    casewriter_get_taint (casewriter));
93   return casewriter;
94 }
95
96 /* Writes case C to WRITER. */
97 static void
98 scratch_writer_casewriter_write (struct casewriter *w UNUSED, void *writer_,
99                                  struct ccase *c)
100 {
101   struct scratch_writer *writer = writer_;
102   casewriter_write (writer->subwriter,
103                     case_map_execute (writer->compactor, c));
104 }
105
106 /* Closes WRITER. */
107 static void
108 scratch_writer_casewriter_destroy (struct casewriter *w UNUSED, void *writer_)
109 {
110   static unsigned int next_unique_id = 0x12345678;
111
112   struct scratch_writer *writer = writer_;
113   struct casereader *reader = casewriter_make_reader (writer->subwriter);
114   if (!casereader_error (reader))
115     {
116       /* Destroy previous contents of handle. */
117       struct scratch_handle *sh = fh_get_scratch_handle (writer->fh);
118       if (sh != NULL)
119         scratch_handle_destroy (sh);
120
121       /* Create new contents. */
122       sh = xmalloc (sizeof *sh);
123       sh->unique_id = ++next_unique_id;
124       sh->dictionary = writer->dict;
125       sh->casereader = reader;
126       fh_set_scratch_handle (writer->fh, sh);
127     }
128   else
129     {
130       casereader_destroy (reader);
131       dict_destroy (writer->dict);
132     }
133
134   fh_unlock (writer->lock);
135   fh_unref (writer->fh);
136   free (writer);
137 }
138
139 static const struct casewriter_class scratch_writer_casewriter_class =
140   {
141     scratch_writer_casewriter_write,
142     scratch_writer_casewriter_destroy,
143     NULL,
144   };