From b7490382464e35eca05d772b3c406e1698976e80 Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Thu, 3 Apr 2008 16:38:21 -0700
Subject: [PATCH] Add a rudimentary vector container to ameliorate the
 inability to allocate dynamic arrays.

SVN=114931
---
 src/lib/container/vector.go | 132 ++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 src/lib/container/vector.go

diff --git a/src/lib/container/vector.go b/src/lib/container/vector.go
new file mode 100644
index 0000000000..4b7c8ec0c0
--- /dev/null
+++ b/src/lib/container/vector.go
@@ -0,0 +1,132 @@
+// 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 vector
+
+export Vector, New;
+
+/*
+	import vector "vector"
+	v := vector.New();
+	v.Insert(0, new(Foo));
+	v.Append(new(Foo));
+	v.Delete(0);
+	for i := 0; i < v.Len(); i++ { f(v.At(i)); }
+*/
+
+type Element interface {
+}
+
+type Vector struct {
+	nalloc int;
+	nelem int;
+	elem *[]Element;
+}
+
+// BUG: workaround for non-constant allocation.
+// i must be a power of 10.
+func Alloc(i int) *[]Element {
+	print "Alloc ", i, "\n";
+	switch i {
+	case 1:
+		return new([1]Element);
+	case 10:
+		return new([10]Element);
+	case 100:
+		return new([100]Element);
+	case 1000:
+		return new([1000]Element);
+	}
+	print "bad size ", i, "\n";
+	panic "not known size\n";
+}
+
+func is_pow10(i int) bool {
+	switch i {
+	case 1, 10, 100, 1000:
+		return true;
+	}
+	return false;
+}
+
+func New() *Vector {
+	v := new(Vector);
+	v.nelem = 0;
+	v.nalloc = 1;
+	v.elem = Alloc(v.nalloc);
+	return v;
+}
+
+func (v *Vector) Len() int {
+	return v.nelem;
+}
+
+func (v *Vector) At(i int) Element {
+	if i < 0 || i >= v.nelem {
+		//return nil;  // BUG
+		panic "At out of range\n";
+	}
+	return v.elem[i];
+}
+
+func (v *Vector) Delete(i int) {
+	if i < 0 || i >= v.nelem {
+		panic "Delete out of range\n";
+	}
+	for j := i+1; j < v.nelem; j++ {
+		v.elem[j-1] = v.elem[j];
+	}
+	v.nelem--;
+	v.elem[v.nelem] = nil;
+}
+
+func (v *Vector) Insert(i int, e Element) {
+	if i > v.nelem {
+		panic "Del too large\n";
+	}
+	if v.nelem == v.nalloc && is_pow10(v.nalloc) {
+		n := Alloc(v.nalloc * 10);
+		for j := 0; j < v.nalloc; j++ {
+			n[j] = v.elem[j];
+		}
+		v.elem = n;
+		v.nalloc *= 10;
+	}
+	// make a hole
+	for j := v.nelem; j > i; j-- {
+		v.elem[j] = v.elem[j-1];
+	}
+	v.elem[i] = e;
+	v.nelem++;
+}
+
+func (v *Vector) Append(e Element) {
+	v.Insert(v.nelem, e);
+}
+
+/*
+type I struct { val int; };  // BUG: can't be local;
+
+func Test() {
+	i0 := new(I); i0.val = 0;
+	i1 := new(I); i1.val = 11;
+	i2 := new(I); i2.val = 222;
+	i3 := new(I); i3.val = 3333;
+	i4 := new(I); i4.val = 44444;
+	v := New();
+	print "hi\n";
+	v.Insert(0, i4);
+	v.Insert(0, i3);
+	v.Insert(0, i2);
+	v.Insert(0, i1);
+	v.Insert(0, i0);
+	for i := 0; i < v.Len(); i++ {
+		var x *I;
+		x = v.At(i);
+		print i, " ", x.val, "\n";  // BUG: can't use I(v.At(i))
+	}
+}
+
+export Test;
+*/