Data stack

data_stack.h

#ifndef DATA_STACK_H	// Include guard
#define DATA_STACK_H

#include <stdlib.h>	// size_t, NULL, malloc, free

// Stack node
typedef struct data_stack_node{
	void* data;	// Userdata
	size_t data_len;	// Userdata byte length
	struct data_stack_node* prev;	// Reference to previous node
}data_stack_node_t;

// Stack container
typedef struct{
	data_stack_node_t* top;	// Top node of the stack
	size_t n;	// Number of stack nodes
}data_stack_t;

// Create a new stack
inline data_stack_t data_stack_new(){
	return (data_stack_t){NULL, 0};
}

// Free stack (optionally with node data)
inline void data_stack_free(data_stack_t* stack, int free_data){
	data_stack_node_t* node;
	while(stack->top){
		stack->top = (node = stack->top)->prev;
		if(free_data)
			free(node->data);
		free(node);
	}
}

// Push data on stack
inline void data_stack_push(data_stack_t* stack, void* data, size_t data_len){
	data_stack_node_t* node = malloc(sizeof(data_stack_node_t));
	if(node){
		node->data = data;
		node->data_len = data_len;
		node->prev = stack->top;
		stack->top = node;
		stack->n++;
	}
}

// Pop data from stack
inline void data_stack_pop(data_stack_t* stack, void** data, size_t* data_len){
	data_stack_node_t* node = stack->top;
	if(node){
		stack->top = node->prev;
		stack->n--;
		if(data)
			*data = node->data;
		if(data_len)
			*data_len = node->data_len;
		free(node);
	}
}

// Get stack size/number of data
inline size_t data_stack_size(data_stack_t* stack){
	return stack->n;
}

// Get stack data at given position
inline void data_stack_get(data_stack_t* stack, size_t i, void** data, size_t* data_len){
	data_stack_node_t* node = stack->top;
	i = stack->n - i;
	while(--i)
		node = node->prev;
	*data = node->data;
	*data_len = node->data_len;
}

// Set stack data at given position
inline void data_stack_set(data_stack_t* stack, size_t i, void* data, size_t data_len){
	data_stack_node_t* node = stack->top;
	i = stack->n - i;
	while(--i)
		node = node->prev;
	node->data = data;
	node->data_len = data_len;
}

#endif // DATA_STACK_H