From 7346d12d6c68e150c9d156958c33fa72826eead1 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Fri, 30 Mar 2018 14:52:11 +0700
Subject: [PATCH] use Genny to generate typed lists, based on Go standard
 library code

---
 codecov.yml                                 |   1 +
 internal/ackhandler/_gen.go                 |   7 -
 internal/ackhandler/gen.go                  |   3 +
 internal/ackhandler/packet.go               |   1 -
 internal/ackhandler/packet_linkedlist.go    |  45 ++--
 internal/utils/_gen.go                      |   7 -
 internal/utils/byteinterval_linkedlist.go   |  45 ++--
 internal/utils/gen.go                       |   4 +
 internal/utils/linkedlist/README.md         |  11 +
 internal/utils/linkedlist/linkedlist.go     | 218 ++++++++++++++++++++
 internal/utils/packet_interval.go           |   1 -
 internal/utils/packetinterval_linkedlist.go |  45 ++--
 internal/utils/streamframe_interval.go      |   1 -
 13 files changed, 309 insertions(+), 80 deletions(-)
 delete mode 100644 internal/ackhandler/_gen.go
 create mode 100644 internal/ackhandler/gen.go
 delete mode 100644 internal/utils/_gen.go
 create mode 100644 internal/utils/gen.go
 create mode 100644 internal/utils/linkedlist/README.md
 create mode 100644 internal/utils/linkedlist/linkedlist.go

diff --git a/codecov.yml b/codecov.yml
index 560f7ab4..f077c1ad 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -10,6 +10,7 @@ coverage:
     - internal/ackhandler/packet_linkedlist.go
     - internal/utils/byteinterval_linkedlist.go
     - internal/utils/packetinterval_linkedlist.go
+    - internal/utils/linkedlist/linkedlist.go
   status:
     project:
       default:
diff --git a/internal/ackhandler/_gen.go b/internal/ackhandler/_gen.go
deleted file mode 100644
index 154515b2..00000000
--- a/internal/ackhandler/_gen.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package main
-
-import (
-	_ "github.com/clipperhouse/linkedlist"
-	_ "github.com/clipperhouse/slice"
-	_ "github.com/clipperhouse/stringer"
-)
diff --git a/internal/ackhandler/gen.go b/internal/ackhandler/gen.go
new file mode 100644
index 00000000..32235f81
--- /dev/null
+++ b/internal/ackhandler/gen.go
@@ -0,0 +1,3 @@
+package ackhandler
+
+//go:generate genny -pkg ackhandler -in ../utils/linkedlist/linkedlist.go -out packet_linkedlist.go gen Item=Packet
diff --git a/internal/ackhandler/packet.go b/internal/ackhandler/packet.go
index 3638b193..650eebb9 100644
--- a/internal/ackhandler/packet.go
+++ b/internal/ackhandler/packet.go
@@ -8,7 +8,6 @@ import (
 )
 
 // A Packet is a packet
-// +gen linkedlist
 type Packet struct {
 	PacketNumber    protocol.PacketNumber
 	PacketType      protocol.PacketType
diff --git a/internal/ackhandler/packet_linkedlist.go b/internal/ackhandler/packet_linkedlist.go
index a827b214..bb74f4ef 100644
--- a/internal/ackhandler/packet_linkedlist.go
+++ b/internal/ackhandler/packet_linkedlist.go
@@ -1,13 +1,10 @@
-// Generated by: main
-// TypeWriter: linkedlist
-// Directive: +gen on Packet
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
 
 package ackhandler
 
-// List is a modification of http://golang.org/pkg/container/list/
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
+// Linked list implementation from the Go standard library.
 
 // PacketElement is an element of a linked list.
 type PacketElement struct {
@@ -41,8 +38,7 @@ func (e *PacketElement) Prev() *PacketElement {
 	return nil
 }
 
-// PacketList represents a doubly linked list.
-// The zero value for PacketList is an empty list ready to use.
+// PacketList is a linked list of Packets.
 type PacketList struct {
 	root PacketElement // sentinel list element, only &root, root.prev, and root.next are used
 	len  int           // current list length excluding (this) sentinel element
@@ -63,7 +59,7 @@ func NewPacketList() *PacketList { return new(PacketList).Init() }
 // The complexity is O(1).
 func (l *PacketList) Len() int { return l.len }
 
-// Front returns the first element of list l or nil.
+// Front returns the first element of list l or nil if the list is empty.
 func (l *PacketList) Front() *PacketElement {
 	if l.len == 0 {
 		return nil
@@ -71,7 +67,7 @@ func (l *PacketList) Front() *PacketElement {
 	return l.root.next
 }
 
-// Back returns the last element of list l or nil.
+// Back returns the last element of list l or nil if the list is empty.
 func (l *PacketList) Back() *PacketElement {
 	if l.len == 0 {
 		return nil
@@ -79,7 +75,7 @@ func (l *PacketList) Back() *PacketElement {
 	return l.root.prev
 }
 
-// lazyInit lazily initializes a zero PacketList value.
+// lazyInit lazily initializes a zero List value.
 func (l *PacketList) lazyInit() {
 	if l.root.next == nil {
 		l.Init()
@@ -98,7 +94,7 @@ func (l *PacketList) insert(e, at *PacketElement) *PacketElement {
 	return e
 }
 
-// insertValue is a convenience wrapper for insert(&PacketElement{Value: v}, at).
+// insertValue is a convenience wrapper for insert(&Element{Value: v}, at).
 func (l *PacketList) insertValue(v Packet, at *PacketElement) *PacketElement {
 	return l.insert(&PacketElement{Value: v}, at)
 }
@@ -116,10 +112,11 @@ func (l *PacketList) remove(e *PacketElement) *PacketElement {
 
 // Remove removes e from l if e is an element of list l.
 // It returns the element value e.Value.
+// The element must not be nil.
 func (l *PacketList) Remove(e *PacketElement) Packet {
 	if e.list == l {
 		// if e.list == l, l must have been initialized when e was inserted
-		// in l or l == nil (e is a zero PacketElement) and l.remove will crash
+		// in l or l == nil (e is a zero Element) and l.remove will crash
 		l.remove(e)
 	}
 	return e.Value
@@ -139,46 +136,51 @@ func (l *PacketList) PushBack(v Packet) *PacketElement {
 
 // InsertBefore inserts a new element e with value v immediately before mark and returns e.
 // If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
 func (l *PacketList) InsertBefore(v Packet, mark *PacketElement) *PacketElement {
 	if mark.list != l {
 		return nil
 	}
-	// see comment in PacketList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	return l.insertValue(v, mark.prev)
 }
 
 // InsertAfter inserts a new element e with value v immediately after mark and returns e.
 // If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
 func (l *PacketList) InsertAfter(v Packet, mark *PacketElement) *PacketElement {
 	if mark.list != l {
 		return nil
 	}
-	// see comment in PacketList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	return l.insertValue(v, mark)
 }
 
 // MoveToFront moves element e to the front of list l.
 // If e is not an element of l, the list is not modified.
+// The element must not be nil.
 func (l *PacketList) MoveToFront(e *PacketElement) {
 	if e.list != l || l.root.next == e {
 		return
 	}
-	// see comment in PacketList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	l.insert(l.remove(e), &l.root)
 }
 
 // MoveToBack moves element e to the back of list l.
 // If e is not an element of l, the list is not modified.
+// The element must not be nil.
 func (l *PacketList) MoveToBack(e *PacketElement) {
 	if e.list != l || l.root.prev == e {
 		return
 	}
-	// see comment in PacketList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	l.insert(l.remove(e), l.root.prev)
 }
 
 // MoveBefore moves element e to its new position before mark.
 // If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
 func (l *PacketList) MoveBefore(e, mark *PacketElement) {
 	if e.list != l || e == mark || mark.list != l {
 		return
@@ -187,7 +189,8 @@ func (l *PacketList) MoveBefore(e, mark *PacketElement) {
 }
 
 // MoveAfter moves element e to its new position after mark.
-// If e is not an element of l, or e == mark, the list is not modified.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
 func (l *PacketList) MoveAfter(e, mark *PacketElement) {
 	if e.list != l || e == mark || mark.list != l {
 		return
@@ -196,7 +199,7 @@ func (l *PacketList) MoveAfter(e, mark *PacketElement) {
 }
 
 // PushBackList inserts a copy of an other list at the back of list l.
-// The lists l and other may be the same.
+// The lists l and other may be the same. They must not be nil.
 func (l *PacketList) PushBackList(other *PacketList) {
 	l.lazyInit()
 	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
@@ -205,7 +208,7 @@ func (l *PacketList) PushBackList(other *PacketList) {
 }
 
 // PushFrontList inserts a copy of an other list at the front of list l.
-// The lists l and other may be the same.
+// The lists l and other may be the same. They must not be nil.
 func (l *PacketList) PushFrontList(other *PacketList) {
 	l.lazyInit()
 	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
diff --git a/internal/utils/_gen.go b/internal/utils/_gen.go
deleted file mode 100644
index 154515b2..00000000
--- a/internal/utils/_gen.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package main
-
-import (
-	_ "github.com/clipperhouse/linkedlist"
-	_ "github.com/clipperhouse/slice"
-	_ "github.com/clipperhouse/stringer"
-)
diff --git a/internal/utils/byteinterval_linkedlist.go b/internal/utils/byteinterval_linkedlist.go
index 545fc203..096023ef 100644
--- a/internal/utils/byteinterval_linkedlist.go
+++ b/internal/utils/byteinterval_linkedlist.go
@@ -1,13 +1,10 @@
-// Generated by: main
-// TypeWriter: linkedlist
-// Directive: +gen on ByteInterval
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
 
 package utils
 
-// List is a modification of http://golang.org/pkg/container/list/
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
+// Linked list implementation from the Go standard library.
 
 // ByteIntervalElement is an element of a linked list.
 type ByteIntervalElement struct {
@@ -41,8 +38,7 @@ func (e *ByteIntervalElement) Prev() *ByteIntervalElement {
 	return nil
 }
 
-// ByteIntervalList represents a doubly linked list.
-// The zero value for ByteIntervalList is an empty list ready to use.
+// ByteIntervalList is a linked list of ByteIntervals.
 type ByteIntervalList struct {
 	root ByteIntervalElement // sentinel list element, only &root, root.prev, and root.next are used
 	len  int                 // current list length excluding (this) sentinel element
@@ -63,7 +59,7 @@ func NewByteIntervalList() *ByteIntervalList { return new(ByteIntervalList).Init
 // The complexity is O(1).
 func (l *ByteIntervalList) Len() int { return l.len }
 
-// Front returns the first element of list l or nil.
+// Front returns the first element of list l or nil if the list is empty.
 func (l *ByteIntervalList) Front() *ByteIntervalElement {
 	if l.len == 0 {
 		return nil
@@ -71,7 +67,7 @@ func (l *ByteIntervalList) Front() *ByteIntervalElement {
 	return l.root.next
 }
 
-// Back returns the last element of list l or nil.
+// Back returns the last element of list l or nil if the list is empty.
 func (l *ByteIntervalList) Back() *ByteIntervalElement {
 	if l.len == 0 {
 		return nil
@@ -79,7 +75,7 @@ func (l *ByteIntervalList) Back() *ByteIntervalElement {
 	return l.root.prev
 }
 
-// lazyInit lazily initializes a zero ByteIntervalList value.
+// lazyInit lazily initializes a zero List value.
 func (l *ByteIntervalList) lazyInit() {
 	if l.root.next == nil {
 		l.Init()
@@ -98,7 +94,7 @@ func (l *ByteIntervalList) insert(e, at *ByteIntervalElement) *ByteIntervalEleme
 	return e
 }
 
-// insertValue is a convenience wrapper for insert(&ByteIntervalElement{Value: v}, at).
+// insertValue is a convenience wrapper for insert(&Element{Value: v}, at).
 func (l *ByteIntervalList) insertValue(v ByteInterval, at *ByteIntervalElement) *ByteIntervalElement {
 	return l.insert(&ByteIntervalElement{Value: v}, at)
 }
@@ -116,10 +112,11 @@ func (l *ByteIntervalList) remove(e *ByteIntervalElement) *ByteIntervalElement {
 
 // Remove removes e from l if e is an element of list l.
 // It returns the element value e.Value.
+// The element must not be nil.
 func (l *ByteIntervalList) Remove(e *ByteIntervalElement) ByteInterval {
 	if e.list == l {
 		// if e.list == l, l must have been initialized when e was inserted
-		// in l or l == nil (e is a zero ByteIntervalElement) and l.remove will crash
+		// in l or l == nil (e is a zero Element) and l.remove will crash
 		l.remove(e)
 	}
 	return e.Value
@@ -139,46 +136,51 @@ func (l *ByteIntervalList) PushBack(v ByteInterval) *ByteIntervalElement {
 
 // InsertBefore inserts a new element e with value v immediately before mark and returns e.
 // If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
 func (l *ByteIntervalList) InsertBefore(v ByteInterval, mark *ByteIntervalElement) *ByteIntervalElement {
 	if mark.list != l {
 		return nil
 	}
-	// see comment in ByteIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	return l.insertValue(v, mark.prev)
 }
 
 // InsertAfter inserts a new element e with value v immediately after mark and returns e.
 // If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
 func (l *ByteIntervalList) InsertAfter(v ByteInterval, mark *ByteIntervalElement) *ByteIntervalElement {
 	if mark.list != l {
 		return nil
 	}
-	// see comment in ByteIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	return l.insertValue(v, mark)
 }
 
 // MoveToFront moves element e to the front of list l.
 // If e is not an element of l, the list is not modified.
+// The element must not be nil.
 func (l *ByteIntervalList) MoveToFront(e *ByteIntervalElement) {
 	if e.list != l || l.root.next == e {
 		return
 	}
-	// see comment in ByteIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	l.insert(l.remove(e), &l.root)
 }
 
 // MoveToBack moves element e to the back of list l.
 // If e is not an element of l, the list is not modified.
+// The element must not be nil.
 func (l *ByteIntervalList) MoveToBack(e *ByteIntervalElement) {
 	if e.list != l || l.root.prev == e {
 		return
 	}
-	// see comment in ByteIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	l.insert(l.remove(e), l.root.prev)
 }
 
 // MoveBefore moves element e to its new position before mark.
 // If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
 func (l *ByteIntervalList) MoveBefore(e, mark *ByteIntervalElement) {
 	if e.list != l || e == mark || mark.list != l {
 		return
@@ -187,7 +189,8 @@ func (l *ByteIntervalList) MoveBefore(e, mark *ByteIntervalElement) {
 }
 
 // MoveAfter moves element e to its new position after mark.
-// If e is not an element of l, or e == mark, the list is not modified.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
 func (l *ByteIntervalList) MoveAfter(e, mark *ByteIntervalElement) {
 	if e.list != l || e == mark || mark.list != l {
 		return
@@ -196,7 +199,7 @@ func (l *ByteIntervalList) MoveAfter(e, mark *ByteIntervalElement) {
 }
 
 // PushBackList inserts a copy of an other list at the back of list l.
-// The lists l and other may be the same.
+// The lists l and other may be the same. They must not be nil.
 func (l *ByteIntervalList) PushBackList(other *ByteIntervalList) {
 	l.lazyInit()
 	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
@@ -205,7 +208,7 @@ func (l *ByteIntervalList) PushBackList(other *ByteIntervalList) {
 }
 
 // PushFrontList inserts a copy of an other list at the front of list l.
-// The lists l and other may be the same.
+// The lists l and other may be the same. They must not be nil.
 func (l *ByteIntervalList) PushFrontList(other *ByteIntervalList) {
 	l.lazyInit()
 	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
diff --git a/internal/utils/gen.go b/internal/utils/gen.go
new file mode 100644
index 00000000..bb839be6
--- /dev/null
+++ b/internal/utils/gen.go
@@ -0,0 +1,4 @@
+package utils
+
+//go:generate genny -pkg utils -in linkedlist/linkedlist.go -out byteinterval_linkedlist.go gen Item=ByteInterval
+//go:generate genny -pkg utils -in linkedlist/linkedlist.go -out packetinterval_linkedlist.go gen Item=PacketInterval
diff --git a/internal/utils/linkedlist/README.md b/internal/utils/linkedlist/README.md
new file mode 100644
index 00000000..15b46dce
--- /dev/null
+++ b/internal/utils/linkedlist/README.md
@@ -0,0 +1,11 @@
+# Usage
+
+This is the Go standard library implementation of a linked list 
+(https://golang.org/src/container/list/list.go), modified such that genny
+(https://github.com/cheekybits/genny) can be used to generate a typed linked
+list.
+
+To generate, run
+```
+genny -pkg $PACKAGE -in linkedlist.go -out $OUTFILE gen Item=$TYPE
+```
diff --git a/internal/utils/linkedlist/linkedlist.go b/internal/utils/linkedlist/linkedlist.go
new file mode 100644
index 00000000..74b815a8
--- /dev/null
+++ b/internal/utils/linkedlist/linkedlist.go
@@ -0,0 +1,218 @@
+package linkedlist
+
+import "github.com/cheekybits/genny/generic"
+
+// Linked list implementation from the Go standard library.
+
+// Item is a generic type.
+type Item generic.Type
+
+// ItemElement is an element of a linked list.
+type ItemElement struct {
+	// Next and previous pointers in the doubly-linked list of elements.
+	// To simplify the implementation, internally a list l is implemented
+	// as a ring, such that &l.root is both the next element of the last
+	// list element (l.Back()) and the previous element of the first list
+	// element (l.Front()).
+	next, prev *ItemElement
+
+	// The list to which this element belongs.
+	list *ItemList
+
+	// The value stored with this element.
+	Value Item
+}
+
+// Next returns the next list element or nil.
+func (e *ItemElement) Next() *ItemElement {
+	if p := e.next; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// Prev returns the previous list element or nil.
+func (e *ItemElement) Prev() *ItemElement {
+	if p := e.prev; e.list != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+// ItemList is a linked list of Items.
+type ItemList struct {
+	root ItemElement // sentinel list element, only &root, root.prev, and root.next are used
+	len  int         // current list length excluding (this) sentinel element
+}
+
+// Init initializes or clears list l.
+func (l *ItemList) Init() *ItemList {
+	l.root.next = &l.root
+	l.root.prev = &l.root
+	l.len = 0
+	return l
+}
+
+// NewItemList returns an initialized list.
+func NewItemList() *ItemList { return new(ItemList).Init() }
+
+// Len returns the number of elements of list l.
+// The complexity is O(1).
+func (l *ItemList) Len() int { return l.len }
+
+// Front returns the first element of list l or nil if the list is empty.
+func (l *ItemList) Front() *ItemElement {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.next
+}
+
+// Back returns the last element of list l or nil if the list is empty.
+func (l *ItemList) Back() *ItemElement {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.prev
+}
+
+// lazyInit lazily initializes a zero List value.
+func (l *ItemList) lazyInit() {
+	if l.root.next == nil {
+		l.Init()
+	}
+}
+
+// insert inserts e after at, increments l.len, and returns e.
+func (l *ItemList) insert(e, at *ItemElement) *ItemElement {
+	n := at.next
+	at.next = e
+	e.prev = at
+	e.next = n
+	n.prev = e
+	e.list = l
+	l.len++
+	return e
+}
+
+// insertValue is a convenience wrapper for insert(&Element{Value: v}, at).
+func (l *ItemList) insertValue(v Item, at *ItemElement) *ItemElement {
+	return l.insert(&ItemElement{Value: v}, at)
+}
+
+// remove removes e from its list, decrements l.len, and returns e.
+func (l *ItemList) remove(e *ItemElement) *ItemElement {
+	e.prev.next = e.next
+	e.next.prev = e.prev
+	e.next = nil // avoid memory leaks
+	e.prev = nil // avoid memory leaks
+	e.list = nil
+	l.len--
+	return e
+}
+
+// Remove removes e from l if e is an element of list l.
+// It returns the element value e.Value.
+// The element must not be nil.
+func (l *ItemList) Remove(e *ItemElement) Item {
+	if e.list == l {
+		// if e.list == l, l must have been initialized when e was inserted
+		// in l or l == nil (e is a zero Element) and l.remove will crash
+		l.remove(e)
+	}
+	return e.Value
+}
+
+// PushFront inserts a new element e with value v at the front of list l and returns e.
+func (l *ItemList) PushFront(v Item) *ItemElement {
+	l.lazyInit()
+	return l.insertValue(v, &l.root)
+}
+
+// PushBack inserts a new element e with value v at the back of list l and returns e.
+func (l *ItemList) PushBack(v Item) *ItemElement {
+	l.lazyInit()
+	return l.insertValue(v, l.root.prev)
+}
+
+// InsertBefore inserts a new element e with value v immediately before mark and returns e.
+// If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
+func (l *ItemList) InsertBefore(v Item, mark *ItemElement) *ItemElement {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in List.Remove about initialization of l
+	return l.insertValue(v, mark.prev)
+}
+
+// InsertAfter inserts a new element e with value v immediately after mark and returns e.
+// If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
+func (l *ItemList) InsertAfter(v Item, mark *ItemElement) *ItemElement {
+	if mark.list != l {
+		return nil
+	}
+	// see comment in List.Remove about initialization of l
+	return l.insertValue(v, mark)
+}
+
+// MoveToFront moves element e to the front of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *ItemList) MoveToFront(e *ItemElement) {
+	if e.list != l || l.root.next == e {
+		return
+	}
+	// see comment in List.Remove about initialization of l
+	l.insert(l.remove(e), &l.root)
+}
+
+// MoveToBack moves element e to the back of list l.
+// If e is not an element of l, the list is not modified.
+// The element must not be nil.
+func (l *ItemList) MoveToBack(e *ItemElement) {
+	if e.list != l || l.root.prev == e {
+		return
+	}
+	// see comment in List.Remove about initialization of l
+	l.insert(l.remove(e), l.root.prev)
+}
+
+// MoveBefore moves element e to its new position before mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *ItemList) MoveBefore(e, mark *ItemElement) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.insert(l.remove(e), mark.prev)
+}
+
+// MoveAfter moves element e to its new position after mark.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
+func (l *ItemList) MoveAfter(e, mark *ItemElement) {
+	if e.list != l || e == mark || mark.list != l {
+		return
+	}
+	l.insert(l.remove(e), mark)
+}
+
+// PushBackList inserts a copy of an other list at the back of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *ItemList) PushBackList(other *ItemList) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
+		l.insertValue(e.Value, l.root.prev)
+	}
+}
+
+// PushFrontList inserts a copy of an other list at the front of list l.
+// The lists l and other may be the same. They must not be nil.
+func (l *ItemList) PushFrontList(other *ItemList) {
+	l.lazyInit()
+	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
+		l.insertValue(e.Value, &l.root)
+	}
+}
diff --git a/internal/utils/packet_interval.go b/internal/utils/packet_interval.go
index f49b0c42..62cc8b9c 100644
--- a/internal/utils/packet_interval.go
+++ b/internal/utils/packet_interval.go
@@ -3,7 +3,6 @@ package utils
 import "github.com/lucas-clemente/quic-go/internal/protocol"
 
 // PacketInterval is an interval from one PacketNumber to the other
-// +gen linkedlist
 type PacketInterval struct {
 	Start protocol.PacketNumber
 	End   protocol.PacketNumber
diff --git a/internal/utils/packetinterval_linkedlist.go b/internal/utils/packetinterval_linkedlist.go
index e3431d68..b461e85a 100644
--- a/internal/utils/packetinterval_linkedlist.go
+++ b/internal/utils/packetinterval_linkedlist.go
@@ -1,13 +1,10 @@
-// Generated by: main
-// TypeWriter: linkedlist
-// Directive: +gen on PacketInterval
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
 
 package utils
 
-// List is a modification of http://golang.org/pkg/container/list/
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
+// Linked list implementation from the Go standard library.
 
 // PacketIntervalElement is an element of a linked list.
 type PacketIntervalElement struct {
@@ -41,8 +38,7 @@ func (e *PacketIntervalElement) Prev() *PacketIntervalElement {
 	return nil
 }
 
-// PacketIntervalList represents a doubly linked list.
-// The zero value for PacketIntervalList is an empty list ready to use.
+// PacketIntervalList is a linked list of PacketIntervals.
 type PacketIntervalList struct {
 	root PacketIntervalElement // sentinel list element, only &root, root.prev, and root.next are used
 	len  int                   // current list length excluding (this) sentinel element
@@ -63,7 +59,7 @@ func NewPacketIntervalList() *PacketIntervalList { return new(PacketIntervalList
 // The complexity is O(1).
 func (l *PacketIntervalList) Len() int { return l.len }
 
-// Front returns the first element of list l or nil.
+// Front returns the first element of list l or nil if the list is empty.
 func (l *PacketIntervalList) Front() *PacketIntervalElement {
 	if l.len == 0 {
 		return nil
@@ -71,7 +67,7 @@ func (l *PacketIntervalList) Front() *PacketIntervalElement {
 	return l.root.next
 }
 
-// Back returns the last element of list l or nil.
+// Back returns the last element of list l or nil if the list is empty.
 func (l *PacketIntervalList) Back() *PacketIntervalElement {
 	if l.len == 0 {
 		return nil
@@ -79,7 +75,7 @@ func (l *PacketIntervalList) Back() *PacketIntervalElement {
 	return l.root.prev
 }
 
-// lazyInit lazily initializes a zero PacketIntervalList value.
+// lazyInit lazily initializes a zero List value.
 func (l *PacketIntervalList) lazyInit() {
 	if l.root.next == nil {
 		l.Init()
@@ -98,7 +94,7 @@ func (l *PacketIntervalList) insert(e, at *PacketIntervalElement) *PacketInterva
 	return e
 }
 
-// insertValue is a convenience wrapper for insert(&PacketIntervalElement{Value: v}, at).
+// insertValue is a convenience wrapper for insert(&Element{Value: v}, at).
 func (l *PacketIntervalList) insertValue(v PacketInterval, at *PacketIntervalElement) *PacketIntervalElement {
 	return l.insert(&PacketIntervalElement{Value: v}, at)
 }
@@ -116,10 +112,11 @@ func (l *PacketIntervalList) remove(e *PacketIntervalElement) *PacketIntervalEle
 
 // Remove removes e from l if e is an element of list l.
 // It returns the element value e.Value.
+// The element must not be nil.
 func (l *PacketIntervalList) Remove(e *PacketIntervalElement) PacketInterval {
 	if e.list == l {
 		// if e.list == l, l must have been initialized when e was inserted
-		// in l or l == nil (e is a zero PacketIntervalElement) and l.remove will crash
+		// in l or l == nil (e is a zero Element) and l.remove will crash
 		l.remove(e)
 	}
 	return e.Value
@@ -139,46 +136,51 @@ func (l *PacketIntervalList) PushBack(v PacketInterval) *PacketIntervalElement {
 
 // InsertBefore inserts a new element e with value v immediately before mark and returns e.
 // If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
 func (l *PacketIntervalList) InsertBefore(v PacketInterval, mark *PacketIntervalElement) *PacketIntervalElement {
 	if mark.list != l {
 		return nil
 	}
-	// see comment in PacketIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	return l.insertValue(v, mark.prev)
 }
 
 // InsertAfter inserts a new element e with value v immediately after mark and returns e.
 // If mark is not an element of l, the list is not modified.
+// The mark must not be nil.
 func (l *PacketIntervalList) InsertAfter(v PacketInterval, mark *PacketIntervalElement) *PacketIntervalElement {
 	if mark.list != l {
 		return nil
 	}
-	// see comment in PacketIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	return l.insertValue(v, mark)
 }
 
 // MoveToFront moves element e to the front of list l.
 // If e is not an element of l, the list is not modified.
+// The element must not be nil.
 func (l *PacketIntervalList) MoveToFront(e *PacketIntervalElement) {
 	if e.list != l || l.root.next == e {
 		return
 	}
-	// see comment in PacketIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	l.insert(l.remove(e), &l.root)
 }
 
 // MoveToBack moves element e to the back of list l.
 // If e is not an element of l, the list is not modified.
+// The element must not be nil.
 func (l *PacketIntervalList) MoveToBack(e *PacketIntervalElement) {
 	if e.list != l || l.root.prev == e {
 		return
 	}
-	// see comment in PacketIntervalList.Remove about initialization of l
+	// see comment in List.Remove about initialization of l
 	l.insert(l.remove(e), l.root.prev)
 }
 
 // MoveBefore moves element e to its new position before mark.
 // If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
 func (l *PacketIntervalList) MoveBefore(e, mark *PacketIntervalElement) {
 	if e.list != l || e == mark || mark.list != l {
 		return
@@ -187,7 +189,8 @@ func (l *PacketIntervalList) MoveBefore(e, mark *PacketIntervalElement) {
 }
 
 // MoveAfter moves element e to its new position after mark.
-// If e is not an element of l, or e == mark, the list is not modified.
+// If e or mark is not an element of l, or e == mark, the list is not modified.
+// The element and mark must not be nil.
 func (l *PacketIntervalList) MoveAfter(e, mark *PacketIntervalElement) {
 	if e.list != l || e == mark || mark.list != l {
 		return
@@ -196,7 +199,7 @@ func (l *PacketIntervalList) MoveAfter(e, mark *PacketIntervalElement) {
 }
 
 // PushBackList inserts a copy of an other list at the back of list l.
-// The lists l and other may be the same.
+// The lists l and other may be the same. They must not be nil.
 func (l *PacketIntervalList) PushBackList(other *PacketIntervalList) {
 	l.lazyInit()
 	for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() {
@@ -205,7 +208,7 @@ func (l *PacketIntervalList) PushBackList(other *PacketIntervalList) {
 }
 
 // PushFrontList inserts a copy of an other list at the front of list l.
-// The lists l and other may be the same.
+// The lists l and other may be the same. They must not be nil.
 func (l *PacketIntervalList) PushFrontList(other *PacketIntervalList) {
 	l.lazyInit()
 	for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() {
diff --git a/internal/utils/streamframe_interval.go b/internal/utils/streamframe_interval.go
index 3c8325b2..ec16d251 100644
--- a/internal/utils/streamframe_interval.go
+++ b/internal/utils/streamframe_interval.go
@@ -3,7 +3,6 @@ package utils
 import "github.com/lucas-clemente/quic-go/internal/protocol"
 
 // ByteInterval is an interval from one ByteCount to the other
-// +gen linkedlist
 type ByteInterval struct {
 	Start protocol.ByteCount
 	End   protocol.ByteCount