1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000, 2007, 2009 Free Software Foundation, Inc.
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.
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.
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/>. */
18 #define DATA_VALUE_H 1
26 /* Maximum length of a "short" string, that is represented in
27 "union value" without a separate pointer.
29 This is an implementation detail of the "union value" code.
30 There is little reason for client code to use it. */
31 #define MAX_SHORT_STRING 8
33 /* A numeric or string value.
35 The client is responsible for keeping track of the value's
38 This structure is semi-opaque:
40 - If the value is a number, clients may access the 'f'
43 - Clients should not access other members directly.
48 char short_string[MAX_SHORT_STRING];
52 static inline void value_init (union value *, int width);
53 static inline bool value_needs_init (int width);
54 static inline bool value_try_init (union value *, int width);
55 static inline void value_destroy (union value *, int width);
57 static inline double value_num (const union value *);
58 static inline const char *value_str (const union value *, int width);
59 static inline char *value_str_rw (union value *, int width);
61 int compare_values (const void *, const void *, const void *var);
62 unsigned hash_value (const void *, const void *var);
64 static inline void value_copy (union value *, const union value *, int width);
65 void value_copy_rpad (union value *, int dst_width,
66 const union value *, int src_width,
68 void value_copy_str_rpad (union value *, int dst_width, const char *,
70 void value_copy_buf_rpad (union value *dst, int dst_width,
71 const char *src, size_t src_len, char pad);
72 void value_set_missing (union value *, int width);
73 int value_compare_3way (const union value *, const union value *, int width);
74 bool value_equal (const union value *, const union value *, int width);
75 size_t value_hash (const union value *, int width, unsigned int basis);
77 bool value_is_resizable (const union value *, int old_width, int new_width);
78 bool value_needs_resize (int old_width, int new_width);
79 void value_resize (union value *, int old_width, int new_width);
81 static inline void value_swap (union value *, union value *);
84 void value_init_pool (struct pool *, union value *, int width);
85 void value_resize_pool (struct pool *, union value *,
86 int old_width, int new_width);
88 /* Initializes V as a value of the given WIDTH, where 0
89 represents a numeric value and a positive integer represents a
90 string value WIDTH bytes long.
92 A WIDTH of -1 is ignored.
94 The contents of value V are indeterminate after
97 value_init (union value *v, int width)
99 if (width > MAX_SHORT_STRING)
100 v->long_string = xmalloc (width);
103 /* Returns true if a value of the given WIDTH actually needs to
104 have the value_init and value_destroy functions called, false
105 if those functions are no-ops for values of the given WIDTH.
107 Using this function is only a valuable optimization if a large
108 number of values of the given WIDTH are to be initialized*/
110 value_needs_init (int width)
112 return width > MAX_SHORT_STRING;
115 /* Same as value_init, except that failure to allocate memory
116 causes it to return false instead of terminating the
117 program. On success, returns true. */
119 value_try_init (union value *v, int width)
121 if (width > MAX_SHORT_STRING)
123 v->long_string = malloc (width);
124 return v->long_string != NULL;
130 /* Frees any memory allocated by value_init for V, which must
131 have the given WIDTH. */
133 value_destroy (union value *v, int width)
135 if (width > MAX_SHORT_STRING)
136 free (v->long_string);
139 /* Returns the numeric value in V, which must have width 0. */
141 value_num (const union value *v)
146 /* Returns the string value in V, which must have width WIDTH.
148 The returned value is not null-terminated.
150 It is important that WIDTH be the actual value that was passed
151 to value_init. Passing, e.g., a smaller value because only
152 that number of bytes will be accessed will not always work. */
153 static inline const char *
154 value_str (const union value *v, int width)
157 return (width > MAX_SHORT_STRING ? v->long_string : v->short_string);
160 /* Returns the string value in V, which must have width WIDTH.
162 The returned value is not null-terminated.
164 It is important that WIDTH be the actual value that was passed
165 to value_init. Passing, e.g., a smaller value because only
166 that number of bytes will be accessed will not always work. */
168 value_str_rw (union value *v, int width)
171 return (width > MAX_SHORT_STRING ? v->long_string : v->short_string);
174 /* Copies SRC to DST, given that they both contain data of the
177 value_copy (union value *dst, const union value *src, int width)
179 if (width <= MAX_SHORT_STRING)
182 memcpy (dst->long_string, src->long_string, width);
185 /* Exchanges the contents of A and B. */
187 value_swap (union value *a, union value *b)
189 union value tmp = *a;
194 #endif /* data/value.h */