feat: add stack implementation

src/include/stack.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include <stdbool.h>
+
+#include "types/err.h"
+#include "types/stack.h"
+
+/**
+ * Initializes the given stack.
+ *
+ * @param stack  The stack to be initialized.
+ */
+void
+stack_init(stack_t* stack);
+
+/**
+ * Push a new value on the stack.
+ *
+ * @param stack  The stack where tbe value will be pushed.
+ * @param value  The value to push on the stack.
+ *
+ * @return  The index of the new value inside the stack.
+ */
+unsigned int
+stack_push(stack_t* stack, void* value);
+
+/**
+ * Pop a value from the stack.
+ *
+ * @param stack  The stack from where the value will be poped.
+ * @param value  Pointer for where the poped value will be saved.
+ *
+ * @return  ERR_EMPTY on stack is empty.
+ * @return  ERR_OK on value is poped successful.
+ */
+error_code_t
+stack_pop(stack_t* stack, void** value);
+
+/**
+ * Check if the given stack is empty.
+ *
+ * @param stack  The stack to check.
+ *
+ * @return  true on stack is empty.
+ * @return  false if stack has values.
+ */
+bool
+stack_isempty(stack_t* stack);

src/include/types/stack.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#define STACK_INITIAL_LENGTH   20
+#define STACK_LENGTH_INCREMENT 50
+
+/**
+ * A struct representing a dynamic stack. Each value on the stack is a `void *`.
+ */
+typedef struct stack
+{
+  void** values;        ///< Array of values on the stack.
+  unsigned int length;  ///< Number of elements on the stack.
+  unsigned int _size;   ///< Current number of elements that fits on the stack.
+} stack_t;

src/types/stack.c

@@ -0,0 +1,44 @@
+#include <stdlib.h>
+
+#include "stack.h"
+#include "types/err.h"
+
+void
+stack_init(stack_t* stack)
+{
+  stack->length = 0;
+
+  stack->values = malloc(sizeof(void*) * STACK_INITIAL_LENGTH);
+  stack->_size = STACK_INITIAL_LENGTH;
+}
+
+unsigned int
+stack_push(stack_t* stack, void* value)
+{
+  if (stack->length >= stack->_size) {
+    stack->_size += STACK_LENGTH_INCREMENT;
+    stack->values = realloc(stack->values, sizeof(void*) * stack->_size);
+  }
+
+  stack->values[stack->length] = value;
+
+  return stack->length++;
+}
+
+error_code_t
+stack_pop(stack_t* stack, void** value)
+{
+  if (stack_isempty(stack)) {
+    return ERR_EMPTY;
+  }
+
+  *value = stack->values[--stack->length];
+
+  return ERR_OK;
+}
+
+bool
+stack_isempty(stack_t* stack)
+{
+  return stack->length == 0;
+}