From 94f2b0b8f48f5715975446c637a078008fb7e941 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Fri, 18 Mar 2022 12:57:53 -0700
Subject: Generalized Queue

---
 src/lib/queue.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 src/lib/queue.c

(limited to 'src/lib')

diff --git a/src/lib/queue.c b/src/lib/queue.c
new file mode 100644
index 0000000..1fc35f6
--- /dev/null
+++ b/src/lib/queue.c
@@ -0,0 +1,55 @@
+#include <lib/queue.h>
+
+void push_to_queue(struct Entry* e, struct Queue* q)
+{
+	q->end.next->next = e;
+	q->end.next = e;
+	e->next = &q->end;
+}
+
+void prepend_to_queue(struct Entry* e, struct Queue* q)
+{
+	e->next = q->start.next;
+	q->start.next = e;
+	if (e->next->entry_type == END_ENTRY)
+		q->end.next = e;
+}
+
+struct Entry* pop_from_queue(struct Queue* q)
+{
+	if (q->start.next->entry_type == END_ENTRY)
+		return 0;
+	struct Entry* e = q->start.next;
+	q->start.next = e->next;
+	if (e->next->entry_type == END_ENTRY)
+		q->end.next = &q->start;
+	return e;
+}
+
+struct Entry* remove_next_from_queue(struct Entry* e)
+{
+	struct Entry* prev = e;
+	struct Entry* remove = e->next;
+	struct Entry* next = remove->next;
+	if (remove->entry_type != VALUE_ENTRY)
+		return 0;
+	prev->next = next;
+	if (next->entry_type == END_ENTRY)
+		next->next = prev;
+	return remove;
+}
+
+struct Entry* find_value(void* value, struct Queue* q)
+{
+	struct Entry* prev;
+	struct Entry* entry;
+	prev = &q->start;
+	entry = prev->next;
+	while (entry->entry_type != END_ENTRY) {
+		if (entry->value == value)
+			return prev;
+		prev = entry;
+		entry = prev->next;
+	}
+	return 0;
+}
-- 
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