From 154874afda4a8df885e51c01f7681f04fb0b8e61 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sat, 9 Apr 2022 09:43:53 +0200
Subject: neue Verzeichnisstruktur

---
 src/stack.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 src/stack.c

(limited to 'src/stack.c')

diff --git a/src/stack.c b/src/stack.c
new file mode 100644
index 0000000..48b9eba
--- /dev/null
+++ b/src/stack.c
@@ -0,0 +1,110 @@
+/* Standard C */
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* Project */
+#include "util.h"
+
+/* --8<-- stack_type */
+typedef int T;
+
+struct stack_item {
+	struct stack_item *next;
+	T                  data;
+};
+
+struct stack {
+	struct stack_item *head;
+};
+/* -->8-- */
+
+/* --8<-- stack_init */
+void
+stack_init(struct stack *stack)
+{
+	stack->head = NULL;
+}
+/* -->8-- */
+
+/* --8<-- stack_push */
+void
+stack_push(struct stack *stack, T data)
+{
+	struct stack_item *new_item;
+
+	if ( (new_item = malloc(sizeof *new_item)) != NULL ) {
+		new_item->data = data;
+		new_item->next = stack->head;
+		stack->head    = new_item;
+	}
+	else
+		ERROR("out of memory");
+}
+/* -->8-- */
+
+/* --8<-- stack_pop */
+bool
+stack_pop(struct stack *stack, T *data)
+{
+	if ( stack->head ) {
+		struct stack_item *next = stack->head->next;
+
+		if ( data ) {
+			*data = stack->head->data;
+		}
+		free(stack->head);
+		stack->head = next;
+
+		return true;
+	}
+	else
+		return false;
+}
+/* -->8-- */
+
+/* --8<-- stack_empty */
+bool
+stack_empty(struct stack *stack)
+{
+	return stack->head == NULL;
+}
+/* -->8-- */
+
+/* --8<-- stack_free */
+void
+stack_free(struct stack *stack)
+{
+	struct stack_item *item, *next;
+
+	for ( item = stack->head; item; item = next ) {
+		next = item->next;
+		free(item);
+	}
+}
+/* -->8-- */
+
+int
+main()
+{
+	struct stack stack[1];
+
+	stack_init(stack);
+
+	for ( int i = 0; i != 10; ++i )
+		stack_push(stack, i);
+
+	/*
+	while ( !stack_empty(stack) ) {
+		int i;
+		if ( stack_pop(stack, &i) )
+			printf("%d\n", i);
+		else
+			ERROR("this shouldn't happen!");
+	}
+	*/
+
+	stack_free(stack);
+
+	return EXIT_SUCCESS;
+}
-- 
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