1 /* PSPP - a program for statistical analysis.
2    Copyright (C) 2007, 2009, 2010, 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 /* Casereader client interface.
18 
19    A casereader abstracts interfaces through which cases may be
20    read.  A casereader may be a front-end for a system file, a
21    portable file, a dataset, or anything else on which a
22    casereader interface has been overlaid.  Casereader layering,
23    in which a casereader acts as a filter or translator on top of
24    another casereader, is also supported.
25 
26    There is no central interface for obtaining casereaders: a
27    casereader for reading a system file is obtained from the
28    system file reading module, and so on.  Once a casereader has
29    been obtained, by whatever means, the interface to it is
30    uniform.  The most important functions for casereader usage
31    are:
32 
33      - casereader_read: Reads a case from the casereader.  The
34        case is consumed and cannot be read again.  The caller is
35        responsible for destroying the case.
36 
37      - casereader_clone: Makes a copy of a casereader.  May be
38        used to read one or a set of cases from a casereader
39        repeatedly.
40 
41      - casereader_destroy: Destroys a casereader.
42 
43    Casereaders can encounter error conditions, such as I/O
44    errors, as they read cases.  Error conditions prevent any more
45    cases from being read from the casereader.  Error conditions
46    are reported by casereader_error.  Error condition may be
47    propagated to or from a casereader with taint_propagate using
48    the casereader's taint object, which may be obtained with
49    casereader_get_taint. */
50 
51 #ifndef DATA_CASEREADER_H
52 #define DATA_CASEREADER_H 1
53 
54 #include "libpspp/compiler.h"
55 #include "data/case.h"
56 #include "data/missing-values.h"
57 
58 struct dictionary;
59 struct casereader;
60 struct casewriter;
61 struct subcase;
62 
63 struct ccase *casereader_read (struct casereader *);
64 bool casereader_destroy (struct casereader *);
65 
66 struct casereader *casereader_clone (const struct casereader *);
67 struct casereader *casereader_rename (struct casereader *);
68 void casereader_swap (struct casereader *, struct casereader *);
69 
70 struct ccase *casereader_peek (struct casereader *, casenumber);
71 bool casereader_is_empty (struct casereader *);
72 
73 bool casereader_error (const struct casereader *);
74 void casereader_force_error (struct casereader *);
75 const struct taint *casereader_get_taint (const struct casereader *);
76 
77 casenumber casereader_get_case_cnt (struct casereader *);
78 casenumber casereader_count_cases (const struct casereader *);
79 void casereader_truncate (struct casereader *, casenumber);
80 const struct caseproto *casereader_get_proto (const struct casereader *);
81 
82 casenumber casereader_advance (struct casereader *, casenumber);
83 void casereader_transfer (struct casereader *, struct casewriter *);
84 
85 struct casereader *casereader_create_empty (const struct caseproto *);
86 
87 struct casereader *
88 casereader_create_filter_func (struct casereader *,
89                                bool (*include) (const struct ccase *,
90                                                 void *aux),
91                                bool (*destroy) (void *aux),
92                                void *aux,
93                                struct casewriter *exclude);
94 struct casereader *
95 casereader_create_filter_weight (struct casereader *,
96                                  const struct dictionary *dict,
97                                  bool *warn_on_invalid,
98                                  struct casewriter *exclude);
99 struct casereader *
100 casereader_create_filter_missing (struct casereader *,
101                                   const struct variable *const*vars, size_t var_cnt,
102                                   enum mv_class,
103 				  casenumber *n_missing,
104                                   struct casewriter *exclude);
105 
106 struct casereader *
107 casereader_create_counter (struct casereader *, casenumber *counter,
108                            casenumber initial_value);
109 
110 struct casereader *
111 casereader_create_translator (struct casereader *,
112                               const struct caseproto *output_proto,
113                               struct ccase *(*translate) (struct ccase *,
114                                                           void *aux),
115                               bool (*destroy) (void *aux),
116                               void *aux);
117 
118 struct casereader *
119 casereader_translate_stateless (struct casereader *,
120                                 const struct caseproto *output_proto,
121                                 struct ccase *(*translate) (struct ccase *,
122                                                             casenumber idx,
123                                                             const void *aux),
124                                 bool (*destroy) (void *aux),
125                                 void *aux);
126 
127 struct casereader *casereader_project (struct casereader *,
128                                        const struct subcase *);
129 struct casereader *casereader_project_1 (struct casereader *, int column);
130 struct casereader *casereader_select (struct casereader *,
131                                       casenumber first, casenumber last,
132                                       casenumber by);
133 
134 /* A function which creates a numberic value from an existing case */
135 typedef double new_value_func (const struct ccase *, casenumber, void *);
136 
137 struct casereader *
138 casereader_create_append_numeric (struct casereader *subreader,
139 				  new_value_func func, void *aux,
140 				  void (*destroy) (void *aux));
141 
142 struct casereader *
143 casereader_create_arithmetic_sequence (struct casereader *,
144                                        double first, double increment);
145 
146 enum rank_error
147   {
148     RANK_ERR_NONE = 0,
149     RANK_ERR_NEGATIVE_WEIGHT = 0x01,
150     RANK_ERR_UNSORTED = 0x02
151   };
152 
153 
154 typedef void distinct_func (double v, casenumber n, double w, void *aux);
155 
156 struct casereader *
157 casereader_create_append_rank (struct casereader *,
158 			       const struct variable *v, const struct variable *w,
159 			       enum rank_error *err,
160 			       distinct_func *distinct_callback, void *aux);
161 
162 struct casereader *
163 casereader_create_distinct (struct casereader *input,
164 			    const struct variable *key,
165 			    const struct variable *weight);
166 
167 
168 #endif /* data/casereader.h */
169