Ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e0ba6b95ab71a441357ed5484e33498)
darray.h
1#ifndef RUBY_DARRAY_H
2#define RUBY_DARRAY_H
3
4#include <stdint.h>
5#include <stddef.h>
6#include <stdlib.h>
7
8// Type for a dynamic array. Use to declare a dynamic array.
9// It is a pointer so it fits in st_table nicely. Designed
10// to be fairly type-safe.
11//
12// NULL is a valid empty dynamic array.
13//
14// Example:
15// rb_darray(char) char_array = NULL;
16// if (!rb_darray_append(&char_array, 'e')) abort();
17// printf("pushed %c\n", *rb_darray_ref(char_array, 0));
18// rb_darray_free(char_array);
19//
20#define rb_darray(T) struct { rb_darray_meta_t meta; T data[]; } *
21
22// Copy an element out of the array. Warning: not bounds checked.
23//
24// T rb_darray_get(rb_darray(T) ary, int32_t idx);
25//
26#define rb_darray_get(ary, idx) ((ary)->data[(idx)])
27
28// Assign to an element. Warning: not bounds checked.
29//
30// void rb_darray_set(rb_darray(T) ary, int32_t idx, T element);
31//
32#define rb_darray_set(ary, idx, element) ((ary)->data[(idx)] = (element))
33
34// Get a pointer to an element. Warning: not bounds checked.
35//
36// T *rb_darray_ref(rb_darray(T) ary, int32_t idx);
37//
38#define rb_darray_ref(ary, idx) (&((ary)->data[(idx)]))
39
40// Copy a new element into the array. Return 1 on success and 0 on failure.
41// ptr_to_ary is evaluated multiple times.
42//
43// bool rb_darray_append(rb_darray(T) *ptr_to_ary, T element);
44//
45#define rb_darray_append(ptr_to_ary, element) ( \
46 rb_darray_ensure_space((ptr_to_ary), sizeof(**(ptr_to_ary)), sizeof((*(ptr_to_ary))->data[0])) ? ( \
47 rb_darray_set(*(ptr_to_ary), \
48 (*(ptr_to_ary))->meta.size, \
49 (element)), \
50 ++((*(ptr_to_ary))->meta.size), \
51 1 \
52 ) : 0)
53
54// Last element of the array
55//
56#define rb_darray_back(ary) ((ary)->data[(ary)->meta.size - 1])
57
58// Remove the last element of the array.
59//
60#define rb_darray_pop_back(ary) ((ary)->meta.size--)
61
62// Remove element at idx and replace it by the last element
63#define rb_darray_remove_unordered(ary, idx) do { \
64 rb_darray_set(ary, idx, rb_darray_back(ary)); \
65 rb_darray_pop_back(ary); \
66} while (0);
67
68// Iterate over items of the array in a for loop
69//
70#define rb_darray_foreach(ary, idx_name, elem_ptr_var) \
71 for (int idx_name = 0; idx_name < rb_darray_size(ary) && ((elem_ptr_var) = rb_darray_ref(ary, idx_name)); ++idx_name)
72
73// Iterate over valid indicies in the array in a for loop
74//
75#define rb_darray_for(ary, idx_name) \
76 for (int idx_name = 0; idx_name < rb_darray_size(ary); ++idx_name)
77
78// Make a dynamic array of a certain size. All bytes backing the elements are set to zero.
79// Return 1 on success and 0 on failure.
80//
81// Note that NULL is a valid empty dynamic array.
82//
83// bool rb_darray_make(rb_darray(T) *ptr_to_ary, int32_t size);
84//
85#define rb_darray_make(ptr_to_ary, size) rb_darray_make_impl((ptr_to_ary), size, sizeof(**(ptr_to_ary)), sizeof((*(ptr_to_ary))->data[0]))
86
87// Set the size of the array to zero without freeing the backing memory.
88// Allows reusing the same array.
89//
90#define rb_darray_clear(ary) (ary->meta.size = 0)
91
92typedef struct rb_darray_meta {
93 int32_t size;
94 int32_t capa;
96
97// Get the size of the dynamic array.
98//
99static inline int32_t
100rb_darray_size(const void *ary)
101{
102 const rb_darray_meta_t *meta = ary;
103 return meta ? meta->size : 0;
104}
105
106// Get the capacity of the dynamic array.
107//
108static inline int32_t
109rb_darray_capa(const void *ary)
110{
111 const rb_darray_meta_t *meta = ary;
112 return meta ? meta->capa : 0;
113}
114
115// Free the dynamic array.
116//
117static inline void
118rb_darray_free(void *ary)
119{
120 free(ary);
121}
122
123// Internal function. Calculate buffer size on malloc heap.
124static inline size_t
125rb_darray_buffer_size(int32_t capacity, size_t header_size, size_t element_size)
126{
127 if (capacity == 0) return 0;
128 return header_size + (size_t)capacity * element_size;
129}
130
131// Internal function
132// Ensure there is space for one more element. Return 1 on success and 0 on failure.
133// Note: header_size can be bigger than sizeof(rb_darray_meta_t) when T is __int128_t, for example.
134static inline int
135rb_darray_ensure_space(void *ptr_to_ary, size_t header_size, size_t element_size)
136{
137 rb_darray_meta_t **ptr_to_ptr_to_meta = ptr_to_ary;
138 rb_darray_meta_t *meta = *ptr_to_ptr_to_meta;
139 int32_t current_capa = rb_darray_capa(meta);
140 if (rb_darray_size(meta) < current_capa) return 1;
141
142 int32_t new_capa;
143 // Calculate new capacity
144 if (current_capa == 0) {
145 new_capa = 1;
146 }
147 else {
148 int64_t doubled = 2 * (int64_t)current_capa;
149 new_capa = (int32_t)doubled;
150 if (new_capa != doubled) return 0;
151 }
152
153 // Calculate new buffer size
154 size_t current_buffer_size = rb_darray_buffer_size(current_capa, header_size, element_size);
155 size_t new_buffer_size = rb_darray_buffer_size(new_capa, header_size, element_size);
156 if (new_buffer_size <= current_buffer_size) return 0;
157
158 rb_darray_meta_t *doubled_ary = realloc(meta, new_buffer_size);
159 if (!doubled_ary) return 0;
160
161 if (meta == NULL) {
162 // First allocation. Initialize size. On subsequence allocations
163 // realloc takes care of carrying over the size.
164 doubled_ary->size = 0;
165 }
166
167 doubled_ary->capa = new_capa;
168
169 // We don't have access to the type of the dynamic array in function context.
170 // Write out result with memcpy to avoid strict aliasing issue.
171 memcpy(ptr_to_ary, &doubled_ary, sizeof(doubled_ary));
172 return 1;
173}
174
175static inline int
176rb_darray_make_impl(void *ptr_to_ary, int32_t array_size, size_t header_size, size_t element_size)
177{
178 rb_darray_meta_t **ptr_to_ptr_to_meta = ptr_to_ary;
179 if (array_size < 0) return 0;
180 if (array_size == 0) {
181 *ptr_to_ptr_to_meta = NULL;
182 return 1;
183 }
184
185 size_t buffer_size = rb_darray_buffer_size(array_size, header_size, element_size);
186 rb_darray_meta_t *meta = calloc(buffer_size, 1);
187 if (!meta) return 0;
188
189 meta->size = array_size;
190 meta->capa = array_size;
191
192 // We don't have access to the type of the dynamic array in function context.
193 // Write out result with memcpy to avoid strict aliasing issue.
194 memcpy(ptr_to_ary, &meta, sizeof(meta));
195 return 1;
196}
197
198#endif /* RUBY_DARRAY_H */