ruby/darray.h at master · ruby/ruby

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	#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 */

ruby / ruby Public

ruby/darray.h