diff options
Diffstat (limited to 'darray.h')
| -rw-r--r-- | darray.h | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/darray.h b/darray.h new file mode 100644 index 0000000000..ed6085fbcd --- /dev/null +++ b/darray.h @@ -0,0 +1,198 @@ +#ifndef RUBY_DARRAY_H +#define RUBY_DARRAY_H + +#include <stdint.h> +#include <stddef.h> +#include <stdlib.h> + +// Type for a dynamic array. Use to declare a dynamic array. +// It is a pointer so it fits in st_table nicely. Designed +// to be fairly type-safe. +// +// NULL is a valid empty dynamic array. +// +// Example: +// rb_darray(char) char_array = NULL; +// if (!rb_darray_append(&char_array, 'e')) abort(); +// printf("pushed %c\n", *rb_darray_ref(char_array, 0)); +// rb_darray_free(char_array); +// +#define rb_darray(T) struct { rb_darray_meta_t meta; T data[]; } * + +// Copy an element out of the array. Warning: not bounds checked. +// +// T rb_darray_get(rb_darray(T) ary, int32_t idx); +// +#define rb_darray_get(ary, idx) ((ary)->data[(idx)]) + +// Assign to an element. Warning: not bounds checked. +// +// void rb_darray_set(rb_darray(T) ary, int32_t idx, T element); +// +#define rb_darray_set(ary, idx, element) ((ary)->data[(idx)] = (element)) + +// Get a pointer to an element. Warning: not bounds checked. +// +// T *rb_darray_ref(rb_darray(T) ary, int32_t idx); +// +#define rb_darray_ref(ary, idx) (&((ary)->data[(idx)])) + +// Copy a new element into the array. Return 1 on success and 0 on failure. +// ptr_to_ary is evaluated multiple times. +// +// bool rb_darray_append(rb_darray(T) *ptr_to_ary, T element); +// +#define rb_darray_append(ptr_to_ary, element) ( \ + rb_darray_ensure_space((ptr_to_ary), sizeof(**(ptr_to_ary)), sizeof((*(ptr_to_ary))->data[0])) ? ( \ + rb_darray_set(*(ptr_to_ary), \ + (*(ptr_to_ary))->meta.size, \ + (element)), \ + ++((*(ptr_to_ary))->meta.size), \ + 1 \ + ) : 0) + +// Last element of the array +// +#define rb_darray_back(ary) ((ary)->data[(ary)->meta.size - 1]) + +// Remove the last element of the array. +// +#define rb_darray_pop_back(ary) ((ary)->meta.size--) + +// Remove element at idx and replace it by the last element +#define rb_darray_remove_unordered(ary, idx) do { \ + rb_darray_set(ary, idx, rb_darray_back(ary)); \ + rb_darray_pop_back(ary); \ +} while (0); + +// Iterate over items of the array in a for loop +// +#define rb_darray_foreach(ary, idx_name, elem_ptr_var) \ + for (int idx_name = 0; idx_name < rb_darray_size(ary) && ((elem_ptr_var) = rb_darray_ref(ary, idx_name)); ++idx_name) + +// Iterate over valid indicies in the array in a for loop +// +#define rb_darray_for(ary, idx_name) \ + for (int idx_name = 0; idx_name < rb_darray_size(ary); ++idx_name) + +// Make a dynamic array of a certain size. All bytes backing the elements are set to zero. +// Return 1 on success and 0 on failure. +// +// Note that NULL is a valid empty dynamic array. +// +// bool rb_darray_make(rb_darray(T) *ptr_to_ary, int32_t size); +// +#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])) + +// Set the size of the array to zero without freeing the backing memory. +// Allows reusing the same array. +// +#define rb_darray_clear(ary) (ary->meta.size = 0) + +typedef struct rb_darray_meta { + int32_t size; + int32_t capa; +} rb_darray_meta_t; + +// Get the size of the dynamic array. +// +static inline int32_t +rb_darray_size(const void *ary) +{ + const rb_darray_meta_t *meta = ary; + return meta ? meta->size : 0; +} + +// Get the capacity of the dynamic array. +// +static inline int32_t +rb_darray_capa(const void *ary) +{ + const rb_darray_meta_t *meta = ary; + return meta ? meta->capa : 0; +} + +// Free the dynamic array. +// +static inline void +rb_darray_free(void *ary) +{ + free(ary); +} + +// Internal function. Calculate buffer size on malloc heap. +static inline size_t +rb_darray_buffer_size(int32_t capacity, size_t header_size, size_t element_size) +{ + if (capacity == 0) return 0; + return header_size + (size_t)capacity * element_size; +} + +// Internal function +// Ensure there is space for one more element. Return 1 on success and 0 on failure. +// Note: header_size can be bigger than sizeof(rb_darray_meta_t) when T is __int128_t, for example. +static inline int +rb_darray_ensure_space(void *ptr_to_ary, size_t header_size, size_t element_size) +{ + rb_darray_meta_t **ptr_to_ptr_to_meta = ptr_to_ary; + rb_darray_meta_t *meta = *ptr_to_ptr_to_meta; + int32_t current_capa = rb_darray_capa(meta); + if (rb_darray_size(meta) < current_capa) return 1; + + int32_t new_capa; + // Calculate new capacity + if (current_capa == 0) { + new_capa = 1; + } + else { + int64_t doubled = 2 * (int64_t)current_capa; + new_capa = (int32_t)doubled; + if (new_capa != doubled) return 0; + } + + // Calculate new buffer size + size_t current_buffer_size = rb_darray_buffer_size(current_capa, header_size, element_size); + size_t new_buffer_size = rb_darray_buffer_size(new_capa, header_size, element_size); + if (new_buffer_size <= current_buffer_size) return 0; + + rb_darray_meta_t *doubled_ary = realloc(meta, new_buffer_size); + if (!doubled_ary) return 0; + + if (meta == NULL) { + // First allocation. Initialize size. On subsequence allocations + // realloc takes care of carrying over the size. + doubled_ary->size = 0; + } + + doubled_ary->capa = new_capa; + + // We don't have access to the type of the dynamic array in function context. + // Write out result with memcpy to avoid strict aliasing issue. + memcpy(ptr_to_ary, &doubled_ary, sizeof(doubled_ary)); + return 1; +} + +static inline int +rb_darray_make_impl(void *ptr_to_ary, int32_t array_size, size_t header_size, size_t element_size) +{ + rb_darray_meta_t **ptr_to_ptr_to_meta = ptr_to_ary; + if (array_size < 0) return 0; + if (array_size == 0) { + *ptr_to_ptr_to_meta = NULL; + return 1; + } + + size_t buffer_size = rb_darray_buffer_size(array_size, header_size, element_size); + rb_darray_meta_t *meta = calloc(buffer_size, 1); + if (!meta) return 0; + + meta->size = array_size; + meta->capa = array_size; + + // We don't have access to the type of the dynamic array in function context. + // Write out result with memcpy to avoid strict aliasing issue. + memcpy(ptr_to_ary, &meta, sizeof(meta)); + return 1; +} + +#endif /* RUBY_DARRAY_H */ |