Merge branch 'nchengyeeshen-fifo-queue'

Author: zyedidia

README.md

@@ -24,6 +24,7 @@ information about each data structure.
   for arrays of bytes, but this rope is generic.
 * [`stack`](./stack): a LIFO stack.
 * [`trie`](./trie): a ternary search trie.
+* [`queue`](./queue): a First In First Out (FIFO) queue.
 
 The package also includes support for iterators, in the `iter` subpackage.
 Most data structures provide an iterator API, which can be used with some

queue/README.md

@@ -0,0 +1,86 @@
+<!-- Code generated by gomarkdoc. DO NOT EDIT -->
+
+# queue
+
+```go
+import "github.com/zyedidia/generic/queue"
+```
+
+Package queue provides an implementation of a First In First Out \(FIFO\) queue\. The FIFO queue is implemented using a doubly\-linked list found in the 'list' package\.
+
+## Index
+
+- [type FIFOQueue](<#type-fifoqueue>)
+  - [func New[T any]() *FIFOQueue[T]](<#func-new>)
+  - [func (q *FIFOQueue[T]) Dequeue() T](<#func-badrecv-dequeue>)
+  - [func (q *FIFOQueue[T]) Empty() bool](<#func-badrecv-empty>)
+  - [func (q *FIFOQueue[T]) Enqueue(value T)](<#func-badrecv-enqueue>)
+  - [func (q *FIFOQueue[T]) Iter() iter.Iter[T]](<#func-badrecv-iter>)
+  - [func (q *FIFOQueue[T]) Peek() T](<#func-badrecv-peek>)
+
+
+## type [FIFOQueue](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L12-L14>)
+
+FIFOQueue is a simple First In First Out \(FIFO\) queue\.
+
+```go
+type FIFOQueue[T any] struct {
+    // contains filtered or unexported fields
+}
+```
+
+### func [New](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L17>)
+
+```go
+func New[T any]() *FIFOQueue[T]
+```
+
+New returns an empty First In First Out \(FIFO\) queue\.
+
+### func \(\*BADRECV\) [Dequeue](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L31>)
+
+```go
+func (q *FIFOQueue[T]) Dequeue() T
+```
+
+Dequeue removes and returns the item at the front of the queue\.
+
+A panic occurs if the queue is Empty\.
+
+### func \(\*BADRECV\) [Empty](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L46>)
+
+```go
+func (q *FIFOQueue[T]) Empty() bool
+```
+
+Empty returns true if the queue is empty\.
+
+### func \(\*BADRECV\) [Enqueue](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L24>)
+
+```go
+func (q *FIFOQueue[T]) Enqueue(value T)
+```
+
+Enqueue inserts 'value' to the end of the queue\.
+
+### func \(\*BADRECV\) [Iter](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L52>)
+
+```go
+func (q *FIFOQueue[T]) Iter() iter.Iter[T]
+```
+
+Iter returns a forward iterator\, returning items starting from the front to the back of the queue\.
+
+### func \(\*BADRECV\) [Peek](<https://github.com/nchengyeeshen/generic/blob/master/queue/fifo_queue.go#L41>)
+
+```go
+func (q *FIFOQueue[T]) Peek() T
+```
+
+Peek returns the item at the front of the queue without removing it\.
+
+A panic occurs if the queue is Empty\.
+
+
+
+Generated by [gomarkdoc](<https://github.com/princjef/gomarkdoc>)

queue/queue.go

@@ -0,0 +1,54 @@
+// Package queue provides an implementation of a First In First Out (FIFO)
+// queue. The FIFO queue is implemented using the doubly-linked list from the
+// 'list' package.
+package queue
+
+import (
+	"github.com/zyedidia/generic/iter"
+	"github.com/zyedidia/generic/list"
+)
+
+// Queue is a simple First In First Out (FIFO) queue.
+type Queue[T any] struct {
+	list *list.List[T]
+}
+
+// New returns an empty First In First Out (FIFO) queue.
+func New[T any]() *Queue[T] {
+	return &Queue[T]{
+		list: list.New[T](),
+	}
+}
+
+// Enqueue inserts 'value' to the end of the queue.
+func (q *Queue[T]) Enqueue(value T) {
+	q.list.PushBack(value)
+}
+
+// Dequeue removes and returns the item at the front of the queue.
+//
+// A panic occurs if the queue is Empty.
+func (q *Queue[T]) Dequeue() T {
+	value := q.list.Front.Value
+	q.list.Remove(q.list.Front)
+
+	return value
+}
+
+// Peek returns the item at the front of the queue without removing it.
+//
+// A panic occurs if the queue is Empty.
+func (q *Queue[T]) Peek() T {
+	return q.list.Front.Value
+}
+
+// Empty returns true if the queue is empty.
+func (q *Queue[T]) Empty() bool {
+	return q.list.Front == nil
+}
+
+// Iter returns a forward iterator, returning items starting from the front to
+// the back of the queue.
+func (q *Queue[T]) Iter() iter.Iter[T] {
+	return q.list.Front.Iter()
+}

queue/queue_test.go

@@ -0,0 +1,215 @@
+package queue
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/zyedidia/generic/list"
+)
+
+func TestQueueEmpty(t *testing.T) {
+	cases := []struct {
+		name  string
+		queue *Queue[int]
+		want  bool
+	}{
+		{
+			name:  "empty queue",
+			queue: emptyQueue(),
+			want:  true,
+		},
+		{
+			name:  "non-empty queue",
+			queue: nonEmptyQueue(),
+			want:  false,
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got := c.queue.Empty()
+
+			if got != c.want {
+				t.Errorf("got %v, want %v", got, c.want)
+			}
+		})
+	}
+}
+
+func TestQueuePeek(t *testing.T) {
+	t.Run("panics on empty queue", func(t *testing.T) {
+		defer func() {
+			if err := recover(); err == nil {
+				t.Error("peeking on empty queue did not panic")
+			}
+		}()
+
+		emptyQueue().Peek()
+	})
+
+	t.Run("non-empty queue", func(t *testing.T) {
+		got := nonEmptyQueue().Peek()
+		want := 1
+
+		if got != want {
+			t.Errorf("got %v, want %v", got, want)
+		}
+	})
+}
+
+func TestQueueEnqueue(t *testing.T) {
+	t.Run("empty queue", func(t *testing.T) {
+		q := emptyQueue()
+
+		q.Enqueue(1)
+
+		if q.list.Front == nil {
+			t.Error("front is nil")
+		}
+
+		if q.list.Front.Value != 1 {
+			t.Errorf("got %v, want %v for front value", q.list.Front.Value, 1)
+		}
+
+		if q.list.Back == nil {
+			t.Error("back is nil")
+		}
+
+		if q.list.Front != q.list.Back {
+			t.Error(("front and back are not the same"))
+		}
+	})
+
+	t.Run("non-empty queue", func(t *testing.T) {
+		q := nonEmptyQueue()
+
+		q.Enqueue(3)
+
+		if q.list.Front.Value != 1 {
+			t.Errorf("got %v, want %v for front value", q.list.Front.Value, 1)
+		}
+
+		if q.list.Back == nil {
+			t.Error("back is nil")
+		}
+
+		if q.list.Back.Value != 3 {
+			t.Errorf("got %v, want %v for back value", q.list.Back.Value, 3)
+		}
+	})
+}
+
+func TestQueueDequeue(t *testing.T) {
+	t.Run("panics on empty queue", func(t *testing.T) {
+		defer func() {
+			if err := recover(); err == nil {
+				t.Error("dequeue on empty queue did not panic")
+			}
+		}()
+
+		emptyQueue().Dequeue()
+	})
+
+	t.Run("non-empty queue", func(t *testing.T) {
+		q := nonEmptyQueue()
+
+		// Non-empty after dequeue
+		got := q.Dequeue()
+
+		if got != 1 {
+			t.Errorf("got %v, want %v", got, 1)
+		}
+
+		if q.list.Front.Value == 1 {
+			t.Error("front of queue is still 1 after dequeue")
+		}
+
+		if q.Empty() {
+			t.Error("queue is empty")
+		}
+
+		// Empty after dequeue
+		got = q.Dequeue()
+
+		if got != 2 {
+			t.Errorf("got %v, want %v", got, 2)
+		}
+
+		if !q.Empty() {
+			t.Error("queue is not empty")
+		}
+	})
+}
+
+func TestQueueIter(t *testing.T) {
+	q := nonEmptyQueue()
+
+	i := 1
+	q.Iter().For(func(item int) {
+		if item != i {
+			t.Errorf("got %v, want %v", item, i)
+		}
+		i++
+	})
+}
+
+func ExampleQueue_Enqueue() {
+	q := New[int]()
+	q.Enqueue(1)
+}
+
+func ExampleQueue_Peek() {
+	q := New[int]()
+	q.Enqueue(1)
+
+	fmt.Println(q.Peek())
+	// Output: 1
+}
+
+func ExampleQueue_Dequeue() {
+	q := New[int]()
+	q.Enqueue(1)
+
+	fmt.Println(q.Dequeue())
+	// Output: 1
+}
+
+func ExampleQueue_Iter() {
+	q := New[int]()
+	q.Enqueue(1)
+	q.Enqueue(2)
+
+	q.Iter().For(func(i int) {
+		fmt.Println(i)
+	})
+	// Output:
+	// 1
+	// 2
+}
+
+func ExampleQueue_Empty_empty() {
+	q := New[int]()
+
+	fmt.Println(q.Empty())
+	// Output: true
+}
+
+func ExampleQueue_Empty_nonempty() {
+	q := New[int]()
+	q.Enqueue(1)
+
+	fmt.Println(q.Empty())
+	// Output: false
+}
+
+func emptyQueue() *Queue[int] {
+	return New[int]()
+}
+
+func nonEmptyQueue() *Queue[int] {
+	q := New[int]()
+	q.list.Front = &list.Node[int]{Value: 1}
+	q.list.Front.Next = &list.Node[int]{Value: 2, Prev: q.list.Front}
+	q.list.Back = q.list.Front.Next
+	return q
+}