Add container/list package.

This is imported from //cacheserving/gash/cache/list*.go,
but with style changes to suit the Go standard library.

R=r,rsc
APPROVED=r
DELTA=286  (286 added, 0 deleted, 0 changed)
OCL=29438
CL=29796

src/lib/Make.deps

 bignum.install: fmt.install
 bufio.install: io.install os.install utf8.install
+container/list.install:
 container/vector.install:
 crypto/aes.install: os.install
 crypto/block.install: fmt.install io.install os.install

src/lib/Makefile

@@ -16,6 +16,7 @@ GC=6g
 DIRS=\
 	bignum\
 	bufio\
+	container/list\
 	container/vector\
 	crypto/aes\
 	crypto/block\
@@ -65,6 +66,7 @@ DIRS=\
 TEST=\
 	bignum\
 	bufio\
+	container/list\
 	container/vector\
 	crypto/aes\
 	crypto/block\

src/lib/container/list/Makefile

+# 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.
+
+# DO NOT EDIT.  Automatically generated by gobuild.
+# gobuild -m >Makefile
+
+D=/container/
+
+O_arm=5
+O_amd64=6
+O_386=8
+OS=568vq
+
+O=$(O_$(GOARCH))
+GC=$(O)g -I_obj
+CC=$(O)c -FVw
+AS=$(O)a
+AR=6ar
+
+default: packages
+
+clean:
+	rm -rf *.[$(OS)] *.a [$(OS)].out _obj
+
+test: packages
+	gotest
+
+coverage: packages
+	gotest
+	6cov -g `pwd` | grep -v '_test\.go:'
+
+%.$O: %.go
+	$(GC) $*.go
+
+%.$O: %.c
+	$(CC) $*.c
+
+%.$O: %.s
+	$(AS) $*.s
+
+O1=\
+	list.$O\
+
+
+phases: a1
+_obj$D/list.a: phases
+
+a1: $(O1)
+	$(AR) grc _obj$D/list.a list.$O
+	rm -f $(O1)
+
+
+newpkg: clean
+	mkdir -p _obj$D
+	$(AR) grc _obj$D/list.a
+
+$(O1): newpkg
+$(O2): a1
+
+nuke: clean
+	rm -f $(GOROOT)/pkg$D/list.a
+
+packages: _obj$D/list.a
+
+install: packages
+	test -d $(GOROOT)/pkg && mkdir -p $(GOROOT)/pkg$D
+	cp _obj$D/list.a $(GOROOT)/pkg$D/list.a

src/lib/container/list/list.go

+// 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.
+
+// The list package implements a doubly linked list.
+package list
+
+// Element is an element in the linked list.
+type Element struct {
+	// Next and previous pointers in the doubly-linked list of elements.
+	// The front of the list has prev = nil, and the back has next = nil.
+	next, prev *Element;
+
+	// The contents of this list element.
+	Value interface {};
+}
+
+// List represents a doubly linked list.
+type List struct {
+	front, back *Element;
+}
+
+// Init initializes or clears a List.
+func (l *List) Init() *List {
+	l.front = nil;
+	l.back = nil;
+	return l
+}
+
+// New returns an initialized list.
+func New() *List {
+	return new(List).Init()
+}
+
+// Front returns the first element in the list.
+func (l *List) Front() *Element {
+	return l.front
+}
+
+// Back returns the last element in the list.
+func (l *List) Back() *Element {
+	return l.back
+}
+
+// Remove removes the element from the list.
+func (l *List) Remove(e *Element) {
+	if e.prev == nil {
+		l.front = e.next;
+	} else {
+		e.prev.next = e.next;
+	}
+	if e.next == nil {
+		l.back = e.prev;
+	} else {
+		e.next.prev = e.prev;
+	}
+
+	e.prev = nil;
+	e.next = nil;
+}
+
+func (l *List) insertFront(e *Element) {
+	e.prev = nil;
+	e.next = l.front;
+	l.front = e;
+	if e.next != nil {
+		e.next.prev = e;
+	} else {
+		l.back = e;
+	}
+}
+
+func (l *List) insertBack(e *Element) {
+	e.next = nil;
+	e.prev = l.back;
+	l.back = e;
+	if e.prev != nil {
+		e.prev.next = e;
+	} else {
+		l.front = e;
+	}
+}
+
+// PushFront inserts the value at the front of the list, and returns a new Element containing it.
+func (l *List) PushFront(value interface {}) *Element {
+	e := &Element{ nil, nil, value };
+	l.insertFront(e);
+	return e
+}
+
+// PushBack inserts the value at the back of the list, and returns a new Element containing it.
+func (l *List) PushBack(value interface {}) *Element {
+	e := &Element{ nil, nil, value };
+	l.insertBack(e);
+	return e
+}
+
+// MoveToFront moves the element to the front of the list.
+func (l *List) MoveToFront(e *Element) {
+	if l.front == e {
+		return
+	}
+	l.Remove(e);
+	l.insertFront(e);
+}
+
+// MoveToBack moves the element to the back of the list.
+func (l *List) MoveToBack(e *Element) {
+	if l.back == e {
+		return
+	}
+	l.Remove(e);
+	l.insertBack(e);
+}
+
+func (l *List) iterate(c chan <- *Element) {
+	var next *Element;
+	for e := l.front; e != nil; e = next {
+		// Save next in case reader of c changes e.
+		next = e.next;
+		c <- e;
+	}
+	close(c);
+}
+
+func (l *List) Iter() <-chan *Element {
+	c := make(chan *Element);
+	go l.iterate(c);
+	return c
+}

src/lib/container/list/list_test.go

+// 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.
+
+package list
+
+import (
+	"container/list";
+	"testing";
+)
+
+func checkListPointers(t *testing.T, l *List, es []*Element) {
+	if len(es) == 0 {
+		if l.front != nil || l.back != nil {
+			t.Errorf("l.front/l.back = %v/%v should be nil/nil", l.front, l.back);
+		}
+		return
+	}
+
+	if l.front != es[0] {
+		t.Errorf("l.front = %v, want %v", l.front, es[0]);
+	}
+	if last := es[len(es)-1]; l.back != last {
+		t.Errorf("l.back = %v, want %v", l.back, last);
+	}
+
+	for i := 0; i < len(es); i++ {
+		e := es[i];
+		var e_prev, e_next *Element = nil, nil;
+		if i > 0 {
+			e_prev = es[i-1];
+		}
+		if i < len(es) - 1 {
+			e_next = es[i+1];
+		}
+		if e.prev != e_prev {
+			t.Errorf("elt #%d (%v) has prev=%v, want %v", i, e, e.prev, e_prev);
+		}
+		if e.next != e_next {
+			t.Errorf("elt #%d (%v) has next=%v, want %v", i, e, e.next, e_next);
+		}
+	}
+}
+
+func TestList(t *testing.T) {
+	l := New();
+	checkListPointers(t, l, []*Element{});
+
+	// Single element list
+	e := l.PushFront("a");
+	checkListPointers(t, l, []*Element{ e });
+	l.MoveToFront(e);
+	checkListPointers(t, l, []*Element{ e });
+	l.MoveToBack(e);
+	checkListPointers(t, l, []*Element{ e });
+	l.Remove(e);
+	checkListPointers(t, l, []*Element{});
+
+	// Bigger list
+	e2 := l.PushFront(2);
+	e1 := l.PushFront(1);
+	e3 := l.PushBack(3);
+	e4 := l.PushBack("banana");
+	checkListPointers(t, l, []*Element{ e1, e2, e3, e4 });
+
+	l.Remove(e2);
+	checkListPointers(t, l, []*Element{ e1, e3, e4 });
+
+	l.MoveToFront(e3);  // move from middle
+	checkListPointers(t, l, []*Element{ e3, e1, e4 });
+
+	l.MoveToFront(e1);
+	l.MoveToBack(e3);  // move from middle
+	checkListPointers(t, l, []*Element{ e1, e4, e3 });
+
+	l.MoveToFront(e3);  // move from back
+	checkListPointers(t, l, []*Element{ e3, e1, e4 });
+	l.MoveToFront(e3);  // should be no-op
+	checkListPointers(t, l, []*Element{ e3, e1, e4 });
+
+	l.MoveToBack(e3);  // move from front
+	checkListPointers(t, l, []*Element{ e1, e4, e3 });
+	l.MoveToBack(e3);  // should be no-op
+	checkListPointers(t, l, []*Element{ e1, e4, e3 });
+
+	// Clear all elements by iterating
+	for e := range l.Iter() {
+		l.Remove(e);
+	}
+	checkListPointers(t, l, []*Element{});
+}