1 files changed, 84 insertions, 0 deletions
diff --git a/include/stack.h b/include/stack.h
new file mode 100644
index 0000000..7e0f711
--- /dev/null
+++ b/include/stack.h
@@ -0,0 +1,84 @@
+#ifndef STACK_H
+#define STACK_H
+
+#include "./type.h"
+#include <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct stack {
+  stack_value_t *data;
+  stack_value_t *head;
+  uint_t size;
+  uint_t capacity;
+} stack_t;
+
+void stack_init(stack_t *);
+stack_t *stack_from_array(stack_value_t *, uint_t);
+void stack_push(stack_t *, stack_value_t);
+stack_value_t stack_pop(stack_t *);
+stack_value_t stack_peek(stack_t *);
+
+#endif
+
+#ifdef STACK_IMPLEMENTATION
+
+const stack_value_t ZERO = 0;
+
+void stack_init(stack_t *stack) {
+  if (stack->capacity == 0) {
+    stack->capacity = 16;
+  }
+
+  stack->size = 0;
+  stack->data = calloc(stack->capacity, sizeof(stack_value_t));
+  stack->head = stack->data;
+}
+
+stack_t *stack_from_array(stack_value_t *array, uint_t size) {
+  stack_t *stack = calloc(1, sizeof(stack_t));
+
+  stack->size = size;
+  stack->capacity = size;
+  stack->data = calloc(size, sizeof(stack_value_t));
+  memcpy(stack->data, array, sizeof(stack_value_t) * size);
+  stack->head = stack->data;
+
+  return stack;
+}
+
+void stack_push(stack_t *stack, stack_value_t x) {
+  if (stack->size == stack->capacity) {
+    stack->capacity *= 2;
+    stack->data = realloc(stack->data, sizeof(stack_value_t) * stack->capacity);
+    stack->head = &(stack->data[stack->size - 1]);
+  }
+
+  *stack->head = x;
+  stack->head++;
+  stack->size++;
+}
+
+stack_value_t stack_pop(stack_t *stack) {
+  if (stack->size == 0) {
+    return ZERO;
+  }
+
+  stack_value_t x = stack->head[-1];
+  stack->size--;
+  stack->head--;
+
+  return x;
+}
+
+stack_value_t stack_peek(stack_t *stack) {
+  if (stack->size == 0) {
+    return ZERO;
+  }
+
+  return stack->head[-1];
+}
+
+#endif
+\ No newline at end of file