Experimental alternative implementation of the vector package

R=gri
CC=rsc
https://golang.org/cl/178048

12 files changed, 2152 insertions, 0 deletions

diff --git a/src/pkg/Makefile b/src/pkg/Makefile
index f37502d58d..70c3c6540e 100644
--- a/src/pkg/Makefile
+++ b/src/pkg/Makefile
@@ -57,6 +57,7 @@ DIRS=\
 	exp/exception\
 	exp/iterable\
 	exp/parser\
+	exp/vector\
 	expvar\
 	flag\
 	fmt\
diff --git a/src/pkg/exp/vector/Makefile b/src/pkg/exp/vector/Makefile
new file mode 100644
index 0000000000..a9a5715b02
--- /dev/null
+++ b/src/pkg/exp/vector/Makefile
@@ -0,0 +1,69 @@
+# 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.
+
+include ../../../Make.$(GOARCH)
+
+TARG=exp/vector
+GOFILES=\
+	defs.go\
+	intvector.go\
+	stringvector.go\
+	vector.go\
+
+generate: vector.go vector_test.go
+	< vector.go cat\
+	| gofmt -r='Vector -> IntVector'\
+	| gofmt -r='interface{} -> int'\
+	> intvector.go\
+	
+	< vector.go cat\
+	| gofmt -r='Vector -> StringVector'\
+	| gofmt -r='interface{} -> string'\
+	> stringvector.go\
+	
+	< vector_test.go cat\
+	| gofmt -r='Vector -> IntVector'\
+	| gofmt -r='zero -> intzero'\
+	| gofmt -r='elem2Value -> elem2IntValue'\
+	| gofmt -r='intf2Value -> intf2IntValue'\
+	| gofmt -r='int2Value -> int2IntValue'\
+	| gofmt -r='TestZeroLenExp -> TestIntZeroLenExp'\
+	| gofmt -r='TestResizeExp -> TestIntResizeExp'\
+	| gofmt -r='TestResize2Exp -> TestIntResize2Exp'\
+	| gofmt -r='checkZeroExp -> checkIntZeroExp'\
+	| gofmt -r='TestTrailingElementsExp -> TestIntTrailingElementsExp'\
+	| gofmt -r='TestAccessExp -> TestIntAccessExp'\
+	| gofmt -r='TestInsertDeleteClearExp -> TestIntInsertDeleteClearExp'\
+	| gofmt -r='verify_sliceExp -> verify_sliceIntExp'\
+	| gofmt -r='verify_patternExp -> verify_patternIntExp'\
+	| gofmt -r='make_vectorExp -> make_vectorIntExp'\
+	| gofmt -r='TestInsertVectorExp -> TestIntInsertVectorExp'\
+	| gofmt -r='TestDoExp -> TestIntDoExp'\
+	| gofmt -r='TestIterExp -> TestIntIterExp'\
+	| gofmt -r='TestVectorData -> TestIntVectorData'\
+	> intvector_test.go\
+	
+	< vector_test.go cat\
+	| gofmt -r='Vector -> StringVector'\
+	| gofmt -r='zero -> strzero'\
+	| gofmt -r='int2Value -> int2StrValue'\
+	| gofmt -r='intf2Value -> intf2StrValue'\
+	| gofmt -r='elem2Value -> elem2StrValue'\
+	| gofmt -r='TestZeroLenExp -> TestStrZeroLenExp'\
+	| gofmt -r='TestResizeExp -> TestStrResizeExp'\
+	| gofmt -r='TestResize2Exp -> TestStrResize2Exp'\
+	| gofmt -r='checkZeroExp -> checkStrZeroExp'\
+	| gofmt -r='TestTrailingElementsExp -> TestStrTrailingElementsExp'\
+	| gofmt -r='TestAccessExp -> TestStrAccessExp'\
+	| gofmt -r='TestInsertDeleteClearExp -> TestStrInsertDeleteClearExp'\
+	| gofmt -r='verify_sliceExp -> verify_sliceStrExp'\
+	| gofmt -r='verify_patternExp -> verify_patternStrExp'\
+	| gofmt -r='make_vectorExp -> make_vectorStrExp'\
+	| gofmt -r='TestInsertVectorExp -> TestStrInsertVectorExp'\
+	| gofmt -r='TestDoExp -> TestStrDoExp'\
+	| gofmt -r='TestIterExp -> TestStrIterExp'\
+	| gofmt -r='TestVectorData -> TestStrVectorData'\
+	> stringvector_test.go
+
+include ../../../Make.pkg
diff --git a/src/pkg/exp/vector/defs.go b/src/pkg/exp/vector/defs.go
new file mode 100644
index 0000000000..0607a50c6d
--- /dev/null
+++ b/src/pkg/exp/vector/defs.go
@@ -0,0 +1,78 @@
+// 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 vector package implements containers for managing sequences
+// of elements. Vectors grow and shrink dynamically as necessary.
+package vector
+
+
+// Vector is a container for numbered sequences of elements of type interface{}.
+// A vector's length and capacity adjusts automatically as necessary.
+// The zero value for Vector is an empty vector ready to use.
+type Vector []interface{}
+
+
+// IntVector is a container for numbered sequences of elements of type int.
+// A vector's length and capacity adjusts automatically as necessary.
+// The zero value for IntVector is an empty vector ready to use.
+type IntVector []int
+
+
+// StringVector is a container for numbered sequences of elements of type string.
+// A vector's length and capacity adjusts automatically as necessary.
+// The zero value for StringVector is an empty vector ready to use.
+type StringVector []string
+
+
+// Initial underlying array size
+const initialSize = 8
+
+
+// Partial sort.Interface support
+
+// LessInterface provides partial support of the sort.Interface.
+type LessInterface interface {
+	Less(y interface{}) bool
+}
+
+
+// Less returns a boolean denoting whether the i'th element is less than the j'th element.
+func (p *Vector) Less(i, j int) bool { return (*p)[i].(LessInterface).Less((*p)[j]) }
+
+
+// sort.Interface support
+
+// Less returns a boolean denoting whether the i'th element is less than the j'th element.
+func (p *IntVector) Less(i, j int) bool { return (*p)[i] < (*p)[j] }
+
+
+// Less returns a boolean denoting whether the i'th element is less than the j'th element.
+func (p *StringVector) Less(i, j int) bool { return (*p)[i] < (*p)[j] }
+
+
+// Do calls function f for each element of the vector, in order.
+// The behavior of Do is undefined if f changes *p.
+func (p *Vector) Do(f func(elem interface{})) {
+	for _, e := range *p {
+		f(e)
+	}
+}
+
+
+// Do calls function f for each element of the vector, in order.
+// The behavior of Do is undefined if f changes *p.
+func (p *IntVector) Do(f func(elem interface{})) {
+	for _, e := range *p {
+		f(e)
+	}
+}
+
+
+// Do calls function f for each element of the vector, in order.
+// The behavior of Do is undefined if f changes *p.
+func (p *StringVector) Do(f func(elem interface{})) {
+	for _, e := range *p {
+		f(e)
+	}
+}
diff --git a/src/pkg/exp/vector/intvector.go b/src/pkg/exp/vector/intvector.go
new file mode 100644
index 0000000000..374287a764
--- /dev/null
+++ b/src/pkg/exp/vector/intvector.go
@@ -0,0 +1,212 @@
+// 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
+
+
+func (p *IntVector) realloc(length, capacity int) (b []int) {
+	if capacity < initialSize {
+		capacity = initialSize
+	}
+	b = make(IntVector, length, capacity)
+	copy(b, *p)
+	*p = b
+	return
+}
+
+
+// Insert n elements at position i.
+func (p *IntVector) Expand(i, n int) {
+	a := *p
+
+	// make sure we have enough space
+	len0 := len(a)
+	len1 := len0 + n
+	if len1 <= cap(a) {
+		// enough space - just expand
+		a = a[0:len1]
+	} else {
+		// not enough space - double capacity
+		capb := cap(a) * 2
+		if capb < len1 {
+			// still not enough - use required length
+			capb = len1
+		}
+		// capb >= len1
+		a = p.realloc(len1, capb)
+	}
+
+	// make a hole
+	for j := len0 - 1; j >= i; j-- {
+		a[j+n] = a[j]
+	}
+
+	*p = a
+}
+
+
+// Insert n elements at the end of a vector.
+func (p *IntVector) Extend(n int) { p.Expand(len(*p), n) }
+
+
+// Resize changes the length and capacity of a vector.
+// If the new length is shorter than the current length, Resize discards
+// trailing elements. If the new length is longer than the current length,
+// Resize adds the respective zero values for the additional elements. The capacity
+// parameter is ignored unless the new length or capacity is longer than the current
+// capacity. The resized vector's capacity may be larger than the requested capacity.
+func (p *IntVector) Resize(length, capacity int) *IntVector {
+	a := *p
+
+	if length > cap(a) || capacity > cap(a) {
+		// not enough space or larger capacity requested explicitly
+		a = p.realloc(length, capacity)
+	} else if length < len(a) {
+		// clear trailing elements
+		for i := range a[length:] {
+			var zero int
+			a[length+i] = zero
+		}
+	}
+
+	*p = a[0:length]
+	return p
+}
+
+
+// Len returns the number of elements in the vector.
+// Same as len(*p).
+func (p *IntVector) Len() int { return len(*p) }
+
+
+// Cap returns the capacity of the vector; that is, the
+// maximum length the vector can grow without resizing.
+// Same as cap(*p).
+func (p *IntVector) Cap() int { return cap(*p) }
+
+
+// At returns the i'th element of the vector.
+func (p *IntVector) At(i int) int { return (*p)[i] }
+
+
+// Set sets the i'th element of the vector to value x.
+func (p *IntVector) Set(i int, x int) { (*p)[i] = x }
+
+
+// Last returns the element in the vector of highest index.
+func (p *IntVector) Last() int { return (*p)[len(*p)-1] }
+
+
+// Data returns all the elements as a slice.
+func (p *IntVector) Data() []int {
+	arr := make(IntVector, len(*p))
+	copy(arr, *p)
+	return arr
+}
+
+
+// Insert inserts into the vector an element of value x before
+// the current element at index i.
+func (p *IntVector) Insert(i int, x int) {
+	p.Expand(i, 1)
+	(*p)[i] = x
+}
+
+
+// Delete deletes the i'th element of the vector.  The gap is closed so the old
+// element at index i+1 has index i afterwards.
+func (p *IntVector) Delete(i int) {
+	a := *p
+	n := len(a)
+
+	copy(a[i:n-1], a[i+1:n])
+	var zero int
+	a[n-1] = zero // support GC, zero out entry
+	*p = a[0 : n-1]
+}
+
+
+// InsertVector inserts into the vector the contents of the vector
+// x such that the 0th element of x appears at index i after insertion.
+func (p *IntVector) InsertVector(i int, x *IntVector) {
+	b := *x
+
+	p.Expand(i, len(b))
+	copy((*p)[i:i+len(b)], b)
+}
+
+
+// Cut deletes elements i through j-1, inclusive.
+func (p *IntVector) Cut(i, j int) {
+	a := *p
+	n := len(a)
+	m := n - (j - i)
+
+	copy(a[i:m], a[j:n])
+	for k := m; k < n; k++ { //TODO(bflm) don't zero out the elements unless it's a Vector.
+		var zero int
+		a[k] = zero // support GC, zero out entries
+	}
+
+	*p = a[0:m]
+}
+
+
+// Slice returns a new sub-vector by slicing the old one to extract slice [i:j].
+// The elements are copied. The original vector is unchanged.
+func (p *IntVector) Slice(i, j int) *IntVector {
+	var s IntVector
+	s.realloc(j-i, 0) // will fail in Init() if j < i
+	copy(s, (*p)[i:j])
+	return &s
+}
+
+
+// Convenience wrappers
+
+// Push appends x to the end of the vector.
+func (p *IntVector) Push(x int) { p.Insert(len(*p), x) }
+
+
+// Pop deletes the last element of the vector.
+func (p *IntVector) Pop() int {
+	a := *p
+
+	i := len(a) - 1
+	x := a[i]
+	var zero int
+	a[i] = zero // support GC, zero out entry
+	*p = a[0:i]
+	return x
+}
+
+
+// AppendVector appends the entire vector x to the end of this vector.
+func (p *IntVector) AppendVector(x *IntVector) {
+	p.InsertVector(len(*p), x)
+}
+
+
+// Swap exchanges the elements at indexes i and j.
+func (p *IntVector) Swap(i, j int) {
+	a := *p
+	a[i], a[j] = a[j], a[i]
+}
+
+
+// Iterate over all elements; driver for range
+func (p *IntVector) iterate(c chan<- int) {
+	for _, v := range *p {
+		c <- v
+	}
+	close(c)
+}
+
+
+// Channel iterator for range.
+func (p *IntVector) Iter() <-chan int {
+	c := make(chan int)
+	go p.iterate(c)
+	return c
+}
diff --git a/src/pkg/exp/vector/intvector_test.go b/src/pkg/exp/vector/intvector_test.go
new file mode 100644
index 0000000000..ef4386bf2b
--- /dev/null
+++ b/src/pkg/exp/vector/intvector_test.go
@@ -0,0 +1,389 @@
+// 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
+
+
+import "testing"
+
+
+func TestIntZeroLenExp(t *testing.T) {
+	a := new(IntVector)
+	if a.Len() != 0 {
+		t.Errorf("%T: B1) expected 0, got %d", a, a.Len())
+	}
+	if len(*a) != 0 {
+		t.Errorf("%T: B2) expected 0, got %d", a, len(*a))
+	}
+	var b IntVector
+	if b.Len() != 0 {
+		t.Errorf("%T: B3) expected 0, got %d", b, b.Len())
+	}
+	if len(b) != 0 {
+		t.Errorf("%T: B4) expected 0, got %d", b, len(b))
+	}
+}
+
+
+func TestIntResizeExp(t *testing.T) {
+	var a IntVector
+	checkSizeExp(t, &a, 0, 0)
+	checkSizeExp(t, a.Resize(0, 5), 0, 5)
+	checkSizeExp(t, a.Resize(1, 0), 1, 5)
+	checkSizeExp(t, a.Resize(10, 0), 10, 10)
+	checkSizeExp(t, a.Resize(5, 0), 5, 10)
+	checkSizeExp(t, a.Resize(3, 8), 3, 10)
+	checkSizeExp(t, a.Resize(0, 100), 0, 100)
+	checkSizeExp(t, a.Resize(11, 100), 11, 100)
+}
+
+
+func TestIntResize2Exp(t *testing.T) {
+	var a IntVector
+	checkSizeExp(t, &a, 0, 0)
+	a.Push(int2IntValue(1))
+	a.Push(int2IntValue(2))
+	a.Push(int2IntValue(3))
+	a.Push(int2IntValue(4))
+	checkSizeExp(t, &a, 4, 4)
+	checkSizeExp(t, a.Resize(10, 0), 10, 10)
+	for i := 4; i < a.Len(); i++ {
+		if a.At(i) != intzero {
+			t.Errorf("%T: expected a.At(%d) == %v; found %v!", a, i, intzero, a.At(i))
+		}
+	}
+	for i := 4; i < len(a); i++ {
+		if a[i] != intzero {
+			t.Errorf("%T: expected a[%d] == %v; found %v", a, i, intzero, a[i])
+		}
+	}
+}
+
+
+func checkIntZeroExp(t *testing.T, a *IntVector, i int) {
+	for j := 0; j < i; j++ {
+		if a.At(j) == intzero {
+			t.Errorf("%T: 1 expected a.At(%d) == %d; found %v", a, j, j, a.At(j))
+		}
+		if (*a)[j] == intzero {
+			t.Errorf("%T: 2 expected (*a)[%d] == %d; found %v", a, j, j, (*a)[j])
+		}
+	}
+	for ; i < a.Len(); i++ {
+		if a.At(i) != intzero {
+			t.Errorf("%T: 3 expected a.At(%d) == %v; found %v", a, i, intzero, a.At(i))
+		}
+		if (*a)[i] != intzero {
+			t.Errorf("%T: 4 expected (*a)[%d] == %v; found %v", a, i, intzero, (*a)[i])
+		}
+	}
+}
+
+
+func TestIntTrailingElementsExp(t *testing.T) {
+	var a IntVector
+	for i := 0; i < 10; i++ {
+		a.Push(int2IntValue(i + 1))
+	}
+	checkIntZeroExp(t, &a, 10)
+	checkSizeExp(t, &a, 10, 16)
+	checkSizeExp(t, a.Resize(5, 0), 5, 16)
+	checkSizeExp(t, a.Resize(10, 0), 10, 16)
+	checkIntZeroExp(t, &a, 5)
+}
+
+
+func TestIntAccessExp(t *testing.T) {
+	const n = 100
+	var a IntVector
+	a.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		a.Set(i, int2IntValue(valExp(i)))
+	}
+	for i := 0; i < n; i++ {
+		if elem2IntValue(a.At(i)) != int2IntValue(valExp(i)) {
+			t.Error(i)
+		}
+	}
+	var b IntVector
+	b.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		b[i] = int2IntValue(valExp(i))
+	}
+	for i := 0; i < n; i++ {
+		if elem2IntValue(b[i]) != int2IntValue(valExp(i)) {
+			t.Error(i)
+		}
+	}
+}
+
+
+func TestIntInsertDeleteClearExp(t *testing.T) {
+	const n = 100
+	var a IntVector
+
+	for i := 0; i < n; i++ {
+		if a.Len() != i {
+			t.Errorf("T%: A) wrong Len() %d (expected %d)", a, a.Len(), i)
+		}
+		if len(a) != i {
+			t.Errorf("T%: A) wrong len() %d (expected %d)", a, len(a), i)
+		}
+		a.Insert(0, int2IntValue(valExp(i)))
+		if elem2IntValue(a.Last()) != int2IntValue(valExp(0)) {
+			t.Error("T%: B", a)
+		}
+	}
+	for i := n - 1; i >= 0; i-- {
+		if elem2IntValue(a.Last()) != int2IntValue(valExp(0)) {
+			t.Error("T%: C", a)
+		}
+		if elem2IntValue(a.At(0)) != int2IntValue(valExp(i)) {
+			t.Error("T%: D", a)
+		}
+		if elem2IntValue(a[0]) != int2IntValue(valExp(i)) {
+			t.Error("T%: D2", a)
+		}
+		a.Delete(0)
+		if a.Len() != i {
+			t.Errorf("T%: E) wrong Len() %d (expected %d)", a, a.Len(), i)
+		}
+		if len(a) != i {
+			t.Errorf("T%: E) wrong len() %d (expected %d)", a, len(a), i)
+		}
+	}
+
+	if a.Len() != 0 {
+		t.Errorf("T%: F) wrong Len() %d (expected 0)", a, a.Len())
+	}
+	if len(a) != 0 {
+		t.Errorf("T%: F) wrong len() %d (expected 0)", a, len(a))
+	}
+	for i := 0; i < n; i++ {
+		a.Push(int2IntValue(valExp(i)))
+		if a.Len() != i+1 {
+			t.Errorf("T%: G) wrong Len() %d (expected %d)", a, a.Len(), i+1)
+		}
+		if len(a) != i+1 {
+			t.Errorf("T%: G) wrong len() %d (expected %d)", a, len(a), i+1)
+		}
+		if elem2IntValue(a.Last()) != int2IntValue(valExp(i)) {
+			t.Error("T%: H", a)
+		}
+	}
+	a.Resize(0, 0)
+	if a.Len() != 0 {
+		t.Errorf("T%: I wrong Len() %d (expected 0)", a, a.Len())
+	}
+	if len(a) != 0 {
+		t.Errorf("T%: I wrong len() %d (expected 0)", a, len(a))
+	}
+
+	const m = 5
+	for j := 0; j < m; j++ {
+		a.Push(int2IntValue(j))
+		for i := 0; i < n; i++ {
+			x := valExp(i)
+			a.Push(int2IntValue(x))
+			if elem2IntValue(a.Pop()) != int2IntValue(x) {
+				t.Error("T%: J", a)
+			}
+			if a.Len() != j+1 {
+				t.Errorf("T%: K) wrong Len() %d (expected %d)", a, a.Len(), j+1)
+			}
+			if len(a) != j+1 {
+				t.Errorf("T%: K) wrong len() %d (expected %d)", a, len(a), j+1)
+			}
+		}
+	}
+	if a.Len() != m {
+		t.Errorf("T%: L) wrong Len() %d (expected %d)", a, a.Len(), m)
+	}
+	if len(a) != m {
+		t.Errorf("T%: L) wrong len() %d (expected %d)", a, len(a), m)
+	}
+}
+
+
+func verify_sliceIntExp(t *testing.T, x *IntVector, elt, i, j int) {
+	for k := i; k < j; k++ {
+		if elem2IntValue(x.At(k)) != int2IntValue(elt) {
+			t.Errorf("T%: M) wrong [%d] element %v (expected %v)", x, k, elem2IntValue(x.At(k)), int2IntValue(elt))
+		}
+	}
+
+	s := x.Slice(i, j)
+	for k, n := 0, j-i; k < n; k++ {
+		if elem2IntValue(s.At(k)) != int2IntValue(elt) {
+			t.Errorf("T%: N) wrong [%d] element %v (expected %v)", x, k, elem2IntValue(x.At(k)), int2IntValue(elt))
+		}
+	}
+}
+
+
+func verify_patternIntExp(t *testing.T, x *IntVector, a, b, c int) {
+	n := a + b + c
+	if x.Len() != n {
+		t.Errorf("T%: O) wrong Len() %d (expected %d)", x, x.Len(), n)
+	}
+	if len(*x) != n {
+		t.Errorf("T%: O) wrong len() %d (expected %d)", x, len(*x), n)
+	}
+	verify_sliceIntExp(t, x, 0, 0, a)
+	verify_sliceIntExp(t, x, 1, a, a+b)
+	verify_sliceIntExp(t, x, 0, a+b, n)
+}
+
+
+func make_vectorIntExp(elt, len int) *IntVector {
+	x := new(IntVector).Resize(len, 0)
+	for i := 0; i < len; i++ {
+		x.Set(i, int2IntValue(elt))
+	}
+	return x
+}
+
+
+func TestIntInsertVectorExp(t *testing.T) {
+	// 1
+	a := make_vectorIntExp(0, 0)
+	b := make_vectorIntExp(1, 10)
+	a.InsertVector(0, b)
+	verify_patternIntExp(t, a, 0, 10, 0)
+	// 2
+	a = make_vectorIntExp(0, 10)
+	b = make_vectorIntExp(1, 0)
+	a.InsertVector(5, b)
+	verify_patternIntExp(t, a, 5, 0, 5)
+	// 3
+	a = make_vectorIntExp(0, 10)
+	b = make_vectorIntExp(1, 3)
+	a.InsertVector(3, b)
+	verify_patternIntExp(t, a, 3, 3, 7)
+	// 4
+	a = make_vectorIntExp(0, 10)
+	b = make_vectorIntExp(1, 1000)
+	a.InsertVector(8, b)
+	verify_patternIntExp(t, a, 8, 1000, 2)
+}
+
+
+func TestIntDoExp(t *testing.T) {
+	const n = 25
+	const salt = 17
+	a := new(IntVector).Resize(n, 0)
+	for i := 0; i < n; i++ {
+		a.Set(i, int2IntValue(salt*i))
+	}
+	count := 0
+	a.Do(func(e interface{}) {
+		i := intf2IntValue(e)
+		if i != int2IntValue(count*salt) {
+			t.Error(tname(a), "value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(a), "should visit", n, "values; did visit", count)
+	}
+
+	b := new(IntVector).Resize(n, 0)
+	for i := 0; i < n; i++ {
+		(*b)[i] = int2IntValue(salt * i)
+	}
+	count = 0
+	b.Do(func(e interface{}) {
+		i := intf2IntValue(e)
+		if i != int2IntValue(count*salt) {
+			t.Error(tname(b), "b) value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(b), "b) should visit", n, "values; did visit", count)
+	}
+
+	var c IntVector
+	c.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		c[i] = int2IntValue(salt * i)
+	}
+	count = 0
+	c.Do(func(e interface{}) {
+		i := intf2IntValue(e)
+		if i != int2IntValue(count*salt) {
+			t.Error(tname(c), "c) value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(c), "c) should visit", n, "values; did visit", count)
+	}
+
+}
+
+
+func TestIntIterExp(t *testing.T) {
+	const Len = 100
+	x := new(IntVector).Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		x.Set(i, int2IntValue(i*i))
+	}
+	i := 0
+	for v := range x.Iter() {
+		if elem2IntValue(v) != int2IntValue(i*i) {
+			t.Error(tname(x), "Iter expected", i*i, "got", elem2IntValue(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(x), "Iter stopped at", i, "not", Len)
+	}
+	y := new(IntVector).Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		(*y)[i] = int2IntValue(i * i)
+	}
+	i = 0
+	for v := range y.Iter() {
+		if elem2IntValue(v) != int2IntValue(i*i) {
+			t.Error(tname(y), "y, Iter expected", i*i, "got", elem2IntValue(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(y), "y, Iter stopped at", i, "not", Len)
+	}
+	var z IntVector
+	z.Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		z[i] = int2IntValue(i * i)
+	}
+	i = 0
+	for v := range z.Iter() {
+		if elem2IntValue(v) != int2IntValue(i*i) {
+			t.Error(tname(z), "z, Iter expected", i*i, "got", elem2IntValue(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(z), "z, Iter stopped at", i, "not", Len)
+	}
+}
+
+func TestIntVectorData(t *testing.T) {
+	// verify Data() returns a slice of a copy, not a slice of the original vector
+	const Len = 10
+	var src IntVector
+	for i := 0; i < Len; i++ {
+		src.Push(int2IntValue(i * i))
+	}
+	dest := src.Data()
+	for i := 0; i < Len; i++ {
+		src[i] = int2IntValue(-1)
+		v := elem2IntValue(dest[i])
+		if v != int2IntValue(i*i) {
+			t.Error(tname(src), "expected", i*i, "got", v)
+		}
+	}
+}
diff --git a/src/pkg/exp/vector/nogen_test.go b/src/pkg/exp/vector/nogen_test.go
new file mode 100644
index 0000000000..e0399f7813
--- /dev/null
+++ b/src/pkg/exp/vector/nogen_test.go
@@ -0,0 +1,76 @@
+// 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
+
+
+import (
+	"fmt"
+	"sort"
+	"testing"
+)
+
+var (
+	zero    interface{}
+	intzero int
+	strzero string
+)
+
+
+func int2Value(x int) int       { return x }
+func int2IntValue(x int) int    { return x }
+func int2StrValue(x int) string { return string(x) }
+
+
+func elem2Value(x interface{}) int  { return x.(int) }
+func elem2IntValue(x int) int       { return x }
+func elem2StrValue(x string) string { return x }
+
+
+func intf2Value(x interface{}) int       { return x.(int) }
+func intf2IntValue(x interface{}) int    { return x.(int) }
+func intf2StrValue(x interface{}) string { return x.(string) }
+
+
+type VectorInterfaceExp interface {
+	Len() int
+	Cap() int
+}
+
+
+func checkSizeExp(t *testing.T, v VectorInterfaceExp, len, cap int) {
+	if v.Len() != len {
+		t.Errorf("%T expected len = %d; found %d", v, len, v.Len())
+	}
+	if v.Cap() < cap {
+		t.Errorf("%T expected cap >= %d; found %d", v, cap, v.Cap())
+	}
+}
+
+
+func valExp(i int) int { return i*991 - 1234 }
+
+
+func TestSortingExp(t *testing.T) {
+	const n = 100
+
+	a := new(IntVector).Resize(n, 0)
+	for i := n - 1; i >= 0; i-- {
+		a.Set(i, n-1-i)
+	}
+	if sort.IsSorted(a) {
+		t.Error("int vector not sorted")
+	}
+
+	b := new(StringVector).Resize(n, 0)
+	for i := n - 1; i >= 0; i-- {
+		b.Set(i, fmt.Sprint(n-1-i))
+	}
+	if sort.IsSorted(b) {
+		t.Error("string vector not sorted")
+	}
+}
+
+
+func tname(x interface{}) string { return fmt.Sprintf("%T: ", x) }
diff --git a/src/pkg/exp/vector/numbers_test.go b/src/pkg/exp/vector/numbers_test.go
new file mode 100644
index 0000000000..9a7e2780e6
--- /dev/null
+++ b/src/pkg/exp/vector/numbers_test.go
@@ -0,0 +1,122 @@
+// 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
+
+import (
+	"fmt"
+	"malloc"
+	"strings"
+	"testing"
+)
+
+
+const memTestN = 1000000
+
+
+func s(n uint64) string {
+	str := fmt.Sprintf("%d", n)
+	lens := len(str)
+	a := make([]string, (lens+2)/3)
+	start := lens
+	for i, _ := range a {
+		start -= 3
+		if start < 0 {
+			start = 0
+		}
+		a[len(a)-i-1] = str[start:lens]
+		lens -= 3
+	}
+	return strings.Join(a, " ")
+}
+
+
+func TestVectorNums(t *testing.T) {
+	var v Vector
+	c := int(0)
+	malloc.GC()
+	m0 := *malloc.GetStats()
+	v.Resize(memTestN, memTestN)
+	for i := 0; i < memTestN; i++ {
+		v.Set(i, c)
+	}
+	malloc.GC()
+	m := *malloc.GetStats()
+	v.Resize(0, 0)
+	malloc.GC()
+	n := m.Alloc - m0.Alloc
+	t.Logf("%T.Push(%#v), n = %s: Alloc/n = %.2f\n", v, c, s(memTestN), float(n)/memTestN)
+}
+
+
+func TestIntVectorNums(t *testing.T) {
+	var v IntVector
+	c := int(0)
+	malloc.GC()
+	m0 := *malloc.GetStats()
+	v.Resize(memTestN, memTestN)
+	for i := 0; i < memTestN; i++ {
+		v.Set(i, c)
+	}
+	malloc.GC()
+	m := *malloc.GetStats()
+	v.Resize(0, 0)
+	malloc.GC()
+	n := m.Alloc - m0.Alloc
+	t.Logf("%T.Push(%#v), n = %s: Alloc/n = %.2f\n", v, c, s(memTestN), float(n)/memTestN)
+}
+
+
+func TestStringVectorNums(t *testing.T) {
+	var v StringVector
+	c := ""
+	malloc.GC()
+	m0 := *malloc.GetStats()
+	v.Resize(memTestN, memTestN)
+	for i := 0; i < memTestN; i++ {
+		v.Set(i, c)
+	}
+	malloc.GC()
+	m := *malloc.GetStats()
+	v.Resize(0, 0)
+	malloc.GC()
+	n := m.Alloc - m0.Alloc
+	t.Logf("%T.Push(%#v), n = %s: Alloc/n = %.2f\n", v, c, s(memTestN), float(n)/memTestN)
+}
+
+
+func BenchmarkVectorNums(b *testing.B) {
+	c := int(0)
+	var v Vector
+	b.StopTimer()
+	malloc.GC()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		v.Push(c)
+	}
+}
+
+
+func BenchmarkIntVectorNums(b *testing.B) {
+	c := int(0)
+	var v IntVector
+	b.StopTimer()
+	malloc.GC()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		v.Push(c)
+	}
+}
+
+
+func BenchmarkStringVectorNums(b *testing.B) {
+	c := ""
+	var v StringVector
+	b.StopTimer()
+	malloc.GC()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		v.Push(c)
+	}
+}
diff --git a/src/pkg/exp/vector/nums.sh b/src/pkg/exp/vector/nums.sh
new file mode 100755
index 0000000000..22bf4dca5d
--- /dev/null
+++ b/src/pkg/exp/vector/nums.sh
@@ -0,0 +1,5 @@
+# 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.
+
+gotest -v -match Nums -benchmarks Nums
diff --git a/src/pkg/exp/vector/stringvector.go b/src/pkg/exp/vector/stringvector.go
new file mode 100644
index 0000000000..5a54a07e11
--- /dev/null
+++ b/src/pkg/exp/vector/stringvector.go
@@ -0,0 +1,212 @@
+// 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
+
+
+func (p *StringVector) realloc(length, capacity int) (b []string) {
+	if capacity < initialSize {
+		capacity = initialSize
+	}
+	b = make(StringVector, length, capacity)
+	copy(b, *p)
+	*p = b
+	return
+}
+
+
+// Insert n elements at position i.
+func (p *StringVector) Expand(i, n int) {
+	a := *p
+
+	// make sure we have enough space
+	len0 := len(a)
+	len1 := len0 + n
+	if len1 <= cap(a) {
+		// enough space - just expand
+		a = a[0:len1]
+	} else {
+		// not enough space - double capacity
+		capb := cap(a) * 2
+		if capb < len1 {
+			// still not enough - use required length
+			capb = len1
+		}
+		// capb >= len1
+		a = p.realloc(len1, capb)
+	}
+
+	// make a hole
+	for j := len0 - 1; j >= i; j-- {
+		a[j+n] = a[j]
+	}
+
+	*p = a
+}
+
+
+// Insert n elements at the end of a vector.
+func (p *StringVector) Extend(n int) { p.Expand(len(*p), n) }
+
+
+// Resize changes the length and capacity of a vector.
+// If the new length is shorter than the current length, Resize discards
+// trailing elements. If the new length is longer than the current length,
+// Resize adds the respective zero values for the additional elements. The capacity
+// parameter is ignored unless the new length or capacity is longer than the current
+// capacity. The resized vector's capacity may be larger than the requested capacity.
+func (p *StringVector) Resize(length, capacity int) *StringVector {
+	a := *p
+
+	if length > cap(a) || capacity > cap(a) {
+		// not enough space or larger capacity requested explicitly
+		a = p.realloc(length, capacity)
+	} else if length < len(a) {
+		// clear trailing elements
+		for i := range a[length:] {
+			var zero string
+			a[length+i] = zero
+		}
+	}
+
+	*p = a[0:length]
+	return p
+}
+
+
+// Len returns the number of elements in the vector.
+// Same as len(*p).
+func (p *StringVector) Len() int { return len(*p) }
+
+
+// Cap returns the capacity of the vector; that is, the
+// maximum length the vector can grow without resizing.
+// Same as cap(*p).
+func (p *StringVector) Cap() int { return cap(*p) }
+
+
+// At returns the i'th element of the vector.
+func (p *StringVector) At(i int) string { return (*p)[i] }
+
+
+// Set sets the i'th element of the vector to value x.
+func (p *StringVector) Set(i int, x string) { (*p)[i] = x }
+
+
+// Last returns the element in the vector of highest index.
+func (p *StringVector) Last() string { return (*p)[len(*p)-1] }
+
+
+// Data returns all the elements as a slice.
+func (p *StringVector) Data() []string {
+	arr := make(StringVector, len(*p))
+	copy(arr, *p)
+	return arr
+}
+
+
+// Insert inserts into the vector an element of value x before
+// the current element at index i.
+func (p *StringVector) Insert(i int, x string) {
+	p.Expand(i, 1)
+	(*p)[i] = x
+}
+
+
+// Delete deletes the i'th element of the vector.  The gap is closed so the old
+// element at index i+1 has index i afterwards.
+func (p *StringVector) Delete(i int) {
+	a := *p
+	n := len(a)
+
+	copy(a[i:n-1], a[i+1:n])
+	var zero string
+	a[n-1] = zero // support GC, zero out entry
+	*p = a[0 : n-1]
+}
+
+
+// InsertVector inserts into the vector the contents of the vector
+// x such that the 0th element of x appears at index i after insertion.
+func (p *StringVector) InsertVector(i int, x *StringVector) {
+	b := *x
+
+	p.Expand(i, len(b))
+	copy((*p)[i:i+len(b)], b)
+}
+
+
+// Cut deletes elements i through j-1, inclusive.
+func (p *StringVector) Cut(i, j int) {
+	a := *p
+	n := len(a)
+	m := n - (j - i)
+
+	copy(a[i:m], a[j:n])
+	for k := m; k < n; k++ { //TODO(bflm) don't zero out the elements unless it's a Vector.
+		var zero string
+		a[k] = zero // support GC, zero out entries
+	}
+
+	*p = a[0:m]
+}
+
+
+// Slice returns a new sub-vector by slicing the old one to extract slice [i:j].
+// The elements are copied. The original vector is unchanged.
+func (p *StringVector) Slice(i, j int) *StringVector {
+	var s StringVector
+	s.realloc(j-i, 0) // will fail in Init() if j < i
+	copy(s, (*p)[i:j])
+	return &s
+}
+
+
+// Convenience wrappers
+
+// Push appends x to the end of the vector.
+func (p *StringVector) Push(x string) { p.Insert(len(*p), x) }
+
+
+// Pop deletes the last element of the vector.
+func (p *StringVector) Pop() string {
+	a := *p
+
+	i := len(a) - 1
+	x := a[i]
+	var zero string
+	a[i] = zero // support GC, zero out entry
+	*p = a[0:i]
+	return x
+}
+
+
+// AppendVector appends the entire vector x to the end of this vector.
+func (p *StringVector) AppendVector(x *StringVector) {
+	p.InsertVector(len(*p), x)
+}
+
+
+// Swap exchanges the elements at indexes i and j.
+func (p *StringVector) Swap(i, j int) {
+	a := *p
+	a[i], a[j] = a[j], a[i]
+}
+
+
+// Iterate over all elements; driver for range
+func (p *StringVector) iterate(c chan<- string) {
+	for _, v := range *p {
+		c <- v
+	}
+	close(c)
+}
+
+
+// Channel iterator for range.
+func (p *StringVector) Iter() <-chan string {
+	c := make(chan string)
+	go p.iterate(c)
+	return c
+}
diff --git a/src/pkg/exp/vector/stringvector_test.go b/src/pkg/exp/vector/stringvector_test.go
new file mode 100644
index 0000000000..cfa6947754
--- /dev/null
+++ b/src/pkg/exp/vector/stringvector_test.go
@@ -0,0 +1,389 @@
+// 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
+
+
+import "testing"
+
+
+func TestStrZeroLenExp(t *testing.T) {
+	a := new(StringVector)
+	if a.Len() != 0 {
+		t.Errorf("%T: B1) expected 0, got %d", a, a.Len())
+	}
+	if len(*a) != 0 {
+		t.Errorf("%T: B2) expected 0, got %d", a, len(*a))
+	}
+	var b StringVector
+	if b.Len() != 0 {
+		t.Errorf("%T: B3) expected 0, got %d", b, b.Len())
+	}
+	if len(b) != 0 {
+		t.Errorf("%T: B4) expected 0, got %d", b, len(b))
+	}
+}
+
+
+func TestStrResizeExp(t *testing.T) {
+	var a StringVector
+	checkSizeExp(t, &a, 0, 0)
+	checkSizeExp(t, a.Resize(0, 5), 0, 5)
+	checkSizeExp(t, a.Resize(1, 0), 1, 5)
+	checkSizeExp(t, a.Resize(10, 0), 10, 10)
+	checkSizeExp(t, a.Resize(5, 0), 5, 10)
+	checkSizeExp(t, a.Resize(3, 8), 3, 10)
+	checkSizeExp(t, a.Resize(0, 100), 0, 100)
+	checkSizeExp(t, a.Resize(11, 100), 11, 100)
+}
+
+
+func TestStrResize2Exp(t *testing.T) {
+	var a StringVector
+	checkSizeExp(t, &a, 0, 0)
+	a.Push(int2StrValue(1))
+	a.Push(int2StrValue(2))
+	a.Push(int2StrValue(3))
+	a.Push(int2StrValue(4))
+	checkSizeExp(t, &a, 4, 4)
+	checkSizeExp(t, a.Resize(10, 0), 10, 10)
+	for i := 4; i < a.Len(); i++ {
+		if a.At(i) != strzero {
+			t.Errorf("%T: expected a.At(%d) == %v; found %v!", a, i, strzero, a.At(i))
+		}
+	}
+	for i := 4; i < len(a); i++ {
+		if a[i] != strzero {
+			t.Errorf("%T: expected a[%d] == %v; found %v", a, i, strzero, a[i])
+		}
+	}
+}
+
+
+func checkStrZeroExp(t *testing.T, a *StringVector, i int) {
+	for j := 0; j < i; j++ {
+		if a.At(j) == strzero {
+			t.Errorf("%T: 1 expected a.At(%d) == %d; found %v", a, j, j, a.At(j))
+		}
+		if (*a)[j] == strzero {
+			t.Errorf("%T: 2 expected (*a)[%d] == %d; found %v", a, j, j, (*a)[j])
+		}
+	}
+	for ; i < a.Len(); i++ {
+		if a.At(i) != strzero {
+			t.Errorf("%T: 3 expected a.At(%d) == %v; found %v", a, i, strzero, a.At(i))
+		}
+		if (*a)[i] != strzero {
+			t.Errorf("%T: 4 expected (*a)[%d] == %v; found %v", a, i, strzero, (*a)[i])
+		}
+	}
+}
+
+
+func TestStrTrailingElementsExp(t *testing.T) {
+	var a StringVector
+	for i := 0; i < 10; i++ {
+		a.Push(int2StrValue(i + 1))
+	}
+	checkStrZeroExp(t, &a, 10)
+	checkSizeExp(t, &a, 10, 16)
+	checkSizeExp(t, a.Resize(5, 0), 5, 16)
+	checkSizeExp(t, a.Resize(10, 0), 10, 16)
+	checkStrZeroExp(t, &a, 5)
+}
+
+
+func TestStrAccessExp(t *testing.T) {
+	const n = 100
+	var a StringVector
+	a.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		a.Set(i, int2StrValue(valExp(i)))
+	}
+	for i := 0; i < n; i++ {
+		if elem2StrValue(a.At(i)) != int2StrValue(valExp(i)) {
+			t.Error(i)
+		}
+	}
+	var b StringVector
+	b.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		b[i] = int2StrValue(valExp(i))
+	}
+	for i := 0; i < n; i++ {
+		if elem2StrValue(b[i]) != int2StrValue(valExp(i)) {
+			t.Error(i)
+		}
+	}
+}
+
+
+func TestStrInsertDeleteClearExp(t *testing.T) {
+	const n = 100
+	var a StringVector
+
+	for i := 0; i < n; i++ {
+		if a.Len() != i {
+			t.Errorf("T%: A) wrong Len() %d (expected %d)", a, a.Len(), i)
+		}
+		if len(a) != i {
+			t.Errorf("T%: A) wrong len() %d (expected %d)", a, len(a), i)
+		}
+		a.Insert(0, int2StrValue(valExp(i)))
+		if elem2StrValue(a.Last()) != int2StrValue(valExp(0)) {
+			t.Error("T%: B", a)
+		}
+	}
+	for i := n - 1; i >= 0; i-- {
+		if elem2StrValue(a.Last()) != int2StrValue(valExp(0)) {
+			t.Error("T%: C", a)
+		}
+		if elem2StrValue(a.At(0)) != int2StrValue(valExp(i)) {
+			t.Error("T%: D", a)
+		}
+		if elem2StrValue(a[0]) != int2StrValue(valExp(i)) {
+			t.Error("T%: D2", a)
+		}
+		a.Delete(0)
+		if a.Len() != i {
+			t.Errorf("T%: E) wrong Len() %d (expected %d)", a, a.Len(), i)
+		}
+		if len(a) != i {
+			t.Errorf("T%: E) wrong len() %d (expected %d)", a, len(a), i)
+		}
+	}
+
+	if a.Len() != 0 {
+		t.Errorf("T%: F) wrong Len() %d (expected 0)", a, a.Len())
+	}
+	if len(a) != 0 {
+		t.Errorf("T%: F) wrong len() %d (expected 0)", a, len(a))
+	}
+	for i := 0; i < n; i++ {
+		a.Push(int2StrValue(valExp(i)))
+		if a.Len() != i+1 {
+			t.Errorf("T%: G) wrong Len() %d (expected %d)", a, a.Len(), i+1)
+		}
+		if len(a) != i+1 {
+			t.Errorf("T%: G) wrong len() %d (expected %d)", a, len(a), i+1)
+		}
+		if elem2StrValue(a.Last()) != int2StrValue(valExp(i)) {
+			t.Error("T%: H", a)
+		}
+	}
+	a.Resize(0, 0)
+	if a.Len() != 0 {
+		t.Errorf("T%: I wrong Len() %d (expected 0)", a, a.Len())
+	}
+	if len(a) != 0 {
+		t.Errorf("T%: I wrong len() %d (expected 0)", a, len(a))
+	}
+
+	const m = 5
+	for j := 0; j < m; j++ {
+		a.Push(int2StrValue(j))
+		for i := 0; i < n; i++ {
+			x := valExp(i)
+			a.Push(int2StrValue(x))
+			if elem2StrValue(a.Pop()) != int2StrValue(x) {
+				t.Error("T%: J", a)
+			}
+			if a.Len() != j+1 {
+				t.Errorf("T%: K) wrong Len() %d (expected %d)", a, a.Len(), j+1)
+			}
+			if len(a) != j+1 {
+				t.Errorf("T%: K) wrong len() %d (expected %d)", a, len(a), j+1)
+			}
+		}
+	}
+	if a.Len() != m {
+		t.Errorf("T%: L) wrong Len() %d (expected %d)", a, a.Len(), m)
+	}
+	if len(a) != m {
+		t.Errorf("T%: L) wrong len() %d (expected %d)", a, len(a), m)
+	}
+}
+
+
+func verify_sliceStrExp(t *testing.T, x *StringVector, elt, i, j int) {
+	for k := i; k < j; k++ {
+		if elem2StrValue(x.At(k)) != int2StrValue(elt) {
+			t.Errorf("T%: M) wrong [%d] element %v (expected %v)", x, k, elem2StrValue(x.At(k)), int2StrValue(elt))
+		}
+	}
+
+	s := x.Slice(i, j)
+	for k, n := 0, j-i; k < n; k++ {
+		if elem2StrValue(s.At(k)) != int2StrValue(elt) {
+			t.Errorf("T%: N) wrong [%d] element %v (expected %v)", x, k, elem2StrValue(x.At(k)), int2StrValue(elt))
+		}
+	}
+}
+
+
+func verify_patternStrExp(t *testing.T, x *StringVector, a, b, c int) {
+	n := a + b + c
+	if x.Len() != n {
+		t.Errorf("T%: O) wrong Len() %d (expected %d)", x, x.Len(), n)
+	}
+	if len(*x) != n {
+		t.Errorf("T%: O) wrong len() %d (expected %d)", x, len(*x), n)
+	}
+	verify_sliceStrExp(t, x, 0, 0, a)
+	verify_sliceStrExp(t, x, 1, a, a+b)
+	verify_sliceStrExp(t, x, 0, a+b, n)
+}
+
+
+func make_vectorStrExp(elt, len int) *StringVector {
+	x := new(StringVector).Resize(len, 0)
+	for i := 0; i < len; i++ {
+		x.Set(i, int2StrValue(elt))
+	}
+	return x
+}
+
+
+func TestStrInsertVectorExp(t *testing.T) {
+	// 1
+	a := make_vectorStrExp(0, 0)
+	b := make_vectorStrExp(1, 10)
+	a.InsertVector(0, b)
+	verify_patternStrExp(t, a, 0, 10, 0)
+	// 2
+	a = make_vectorStrExp(0, 10)
+	b = make_vectorStrExp(1, 0)
+	a.InsertVector(5, b)
+	verify_patternStrExp(t, a, 5, 0, 5)
+	// 3
+	a = make_vectorStrExp(0, 10)
+	b = make_vectorStrExp(1, 3)
+	a.InsertVector(3, b)
+	verify_patternStrExp(t, a, 3, 3, 7)
+	// 4
+	a = make_vectorStrExp(0, 10)
+	b = make_vectorStrExp(1, 1000)
+	a.InsertVector(8, b)
+	verify_patternStrExp(t, a, 8, 1000, 2)
+}
+
+
+func TestStrDoExp(t *testing.T) {
+	const n = 25
+	const salt = 17
+	a := new(StringVector).Resize(n, 0)
+	for i := 0; i < n; i++ {
+		a.Set(i, int2StrValue(salt*i))
+	}
+	count := 0
+	a.Do(func(e interface{}) {
+		i := intf2StrValue(e)
+		if i != int2StrValue(count*salt) {
+			t.Error(tname(a), "value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(a), "should visit", n, "values; did visit", count)
+	}
+
+	b := new(StringVector).Resize(n, 0)
+	for i := 0; i < n; i++ {
+		(*b)[i] = int2StrValue(salt * i)
+	}
+	count = 0
+	b.Do(func(e interface{}) {
+		i := intf2StrValue(e)
+		if i != int2StrValue(count*salt) {
+			t.Error(tname(b), "b) value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(b), "b) should visit", n, "values; did visit", count)
+	}
+
+	var c StringVector
+	c.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		c[i] = int2StrValue(salt * i)
+	}
+	count = 0
+	c.Do(func(e interface{}) {
+		i := intf2StrValue(e)
+		if i != int2StrValue(count*salt) {
+			t.Error(tname(c), "c) value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(c), "c) should visit", n, "values; did visit", count)
+	}
+
+}
+
+
+func TestStrIterExp(t *testing.T) {
+	const Len = 100
+	x := new(StringVector).Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		x.Set(i, int2StrValue(i*i))
+	}
+	i := 0
+	for v := range x.Iter() {
+		if elem2StrValue(v) != int2StrValue(i*i) {
+			t.Error(tname(x), "Iter expected", i*i, "got", elem2StrValue(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(x), "Iter stopped at", i, "not", Len)
+	}
+	y := new(StringVector).Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		(*y)[i] = int2StrValue(i * i)
+	}
+	i = 0
+	for v := range y.Iter() {
+		if elem2StrValue(v) != int2StrValue(i*i) {
+			t.Error(tname(y), "y, Iter expected", i*i, "got", elem2StrValue(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(y), "y, Iter stopped at", i, "not", Len)
+	}
+	var z StringVector
+	z.Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		z[i] = int2StrValue(i * i)
+	}
+	i = 0
+	for v := range z.Iter() {
+		if elem2StrValue(v) != int2StrValue(i*i) {
+			t.Error(tname(z), "z, Iter expected", i*i, "got", elem2StrValue(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(z), "z, Iter stopped at", i, "not", Len)
+	}
+}
+
+func TestStrVectorData(t *testing.T) {
+	// verify Data() returns a slice of a copy, not a slice of the original vector
+	const Len = 10
+	var src StringVector
+	for i := 0; i < Len; i++ {
+		src.Push(int2StrValue(i * i))
+	}
+	dest := src.Data()
+	for i := 0; i < Len; i++ {
+		src[i] = int2StrValue(-1)
+		v := elem2StrValue(dest[i])
+		if v != int2StrValue(i*i) {
+			t.Error(tname(src), "expected", i*i, "got", v)
+		}
+	}
+}
diff --git a/src/pkg/exp/vector/vector.go b/src/pkg/exp/vector/vector.go
new file mode 100644
index 0000000000..68df23f41c
--- /dev/null
+++ b/src/pkg/exp/vector/vector.go
@@ -0,0 +1,210 @@
+// 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
+
+
+func (p *Vector) realloc(length, capacity int) (b []interface{}) {
+	if capacity < initialSize {
+		capacity = initialSize
+	}
+	b = make(Vector, length, capacity)
+	copy(b, *p)
+	*p = b
+	return
+}
+
+
+// Insert n elements at position i.
+func (p *Vector) Expand(i, n int) {
+	a := *p
+
+	// make sure we have enough space
+	len0 := len(a)
+	len1 := len0 + n
+	if len1 <= cap(a) {
+		// enough space - just expand
+		a = a[0:len1]
+	} else {
+		// not enough space - double capacity
+		capb := cap(a) * 2
+		if capb < len1 {
+			// still not enough - use required length
+			capb = len1
+		}
+		// capb >= len1
+		a = p.realloc(len1, capb)
+	}
+
+	// make a hole
+	for j := len0 - 1; j >= i; j-- {
+		a[j+n] = a[j]
+	}
+
+	*p = a
+}
+
+
+// Insert n elements at the end of a vector.
+func (p *Vector) Extend(n int) { p.Expand(len(*p), n) }
+
+
+// Resize changes the length and capacity of a vector.
+// If the new length is shorter than the current length, Resize discards
+// trailing elements. If the new length is longer than the current length,
+// Resize adds the respective zero values for the additional elements. The capacity
+// parameter is ignored unless the new length or capacity is longer than the current
+// capacity. The resized vector's capacity may be larger than the requested capacity.
+func (p *Vector) Resize(length, capacity int) *Vector {
+	a := *p
+
+	if length > cap(a) || capacity > cap(a) {
+		// not enough space or larger capacity requested explicitly
+		a = p.realloc(length, capacity)
+	} else if length < len(a) {
+		// clear trailing elements
+		for i := range a[length:] {
+			var zero interface{}
+			a[length+i] = zero
+		}
+	}
+
+	*p = a[0:length]
+	return p
+}
+
+
+// Len returns the number of elements in the vector.
+// Same as len(*p).
+func (p *Vector) Len() int { return len(*p) }
+
+
+// Cap returns the capacity of the vector; that is, the
+// maximum length the vector can grow without resizing.
+// Same as cap(*p).
+func (p *Vector) Cap() int { return cap(*p) }
+
+
+// At returns the i'th element of the vector.
+func (p *Vector) At(i int) interface{} { return (*p)[i] }
+
+
+// Set sets the i'th element of the vector to value x.
+func (p *Vector) Set(i int, x interface{}) { (*p)[i] = x }
+
+
+// Last returns the element in the vector of highest index.
+func (p *Vector) Last() interface{} { return (*p)[len(*p)-1] }
+
+
+// Data returns all the elements as a slice.
+func (p *Vector) Data() []interface{} {
+	arr := make(Vector, len(*p))
+	copy(arr, *p)
+	return arr
+}
+
+
+// Insert inserts into the vector an element of value x before
+// the current element at index i.
+func (p *Vector) Insert(i int, x interface{}) {
+	p.Expand(i, 1)
+	(*p)[i] = x
+}
+
+
+// Delete deletes the i'th element of the vector.  The gap is closed so the old
+// element at index i+1 has index i afterwards.
+func (p *Vector) Delete(i int) {
+	a := *p
+	n := len(a)
+
+	copy(a[i:n-1], a[i+1:n])
+	var zero interface{}
+	a[n-1] = zero // support GC, zero out entry
+	*p = a[0 : n-1]
+}
+
+
+// InsertVector inserts into the vector the contents of the vector
+// x such that the 0th element of x appears at index i after insertion.
+func (p *Vector) InsertVector(i int, x *Vector) {
+	b := *x
+
+	p.Expand(i, len(b))
+	copy((*p)[i:i+len(b)], b)
+}
+
+
+// Cut deletes elements i through j-1, inclusive.
+func (p *Vector) Cut(i, j int) {
+	a := *p
+	n := len(a)
+	m := n - (j - i)
+
+	copy(a[i:m], a[j:n])
+	for k := m; k < n; k++ { //TODO(bflm) don't zero out the elements unless it's a Vector.
+		var zero interface{}
+		a[k] = zero // support GC, zero out entries
+	}
+
+	*p = a[0:m]
+}
+
+
+// Slice returns a new sub-vector by slicing the old one to extract slice [i:j].
+// The elements are copied. The original vector is unchanged.
+func (p *Vector) Slice(i, j int) *Vector {
+	var s Vector
+	s.realloc(j-i, 0) // will fail in Init() if j < i
+	copy(s, (*p)[i:j])
+	return &s
+}
+
+
+// Convenience wrappers
+
+// Push appends x to the end of the vector.
+func (p *Vector) Push(x interface{}) { p.Insert(len(*p), x) }
+
+
+// Pop deletes the last element of the vector.
+func (p *Vector) Pop() interface{} {
+	a := *p
+
+	i := len(a) - 1
+	x := a[i]
+	var zero interface{}
+	a[i] = zero // support GC, zero out entry
+	*p = a[0:i]
+	return x
+}
+
+
+// AppendVector appends the entire vector x to the end of this vector.
+func (p *Vector) AppendVector(x *Vector) { p.InsertVector(len(*p), x) }
+
+
+// Swap exchanges the elements at indexes i and j.
+func (p *Vector) Swap(i, j int) {
+	a := *p
+	a[i], a[j] = a[j], a[i]
+}
+
+
+// Iterate over all elements; driver for range
+func (p *Vector) iterate(c chan<- interface{}) {
+	for _, v := range *p {
+		c <- v
+	}
+	close(c)
+}
+
+
+// Channel iterator for range.
+func (p *Vector) Iter() <-chan interface{} {
+	c := make(chan interface{})
+	go p.iterate(c)
+	return c
+}
diff --git a/src/pkg/exp/vector/vector_test.go b/src/pkg/exp/vector/vector_test.go
new file mode 100644
index 0000000000..ed2cfd5bd0
--- /dev/null
+++ b/src/pkg/exp/vector/vector_test.go
@@ -0,0 +1,389 @@
+// 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
+
+
+import "testing"
+
+
+func TestZeroLenExp(t *testing.T) {
+	a := new(Vector)
+	if a.Len() != 0 {
+		t.Errorf("%T: B1) expected 0, got %d", a, a.Len())
+	}
+	if len(*a) != 0 {
+		t.Errorf("%T: B2) expected 0, got %d", a, len(*a))
+	}
+	var b Vector
+	if b.Len() != 0 {
+		t.Errorf("%T: B3) expected 0, got %d", b, b.Len())
+	}
+	if len(b) != 0 {
+		t.Errorf("%T: B4) expected 0, got %d", b, len(b))
+	}
+}
+
+
+func TestResizeExp(t *testing.T) {
+	var a Vector
+	checkSizeExp(t, &a, 0, 0)
+	checkSizeExp(t, a.Resize(0, 5), 0, 5)
+	checkSizeExp(t, a.Resize(1, 0), 1, 5)
+	checkSizeExp(t, a.Resize(10, 0), 10, 10)
+	checkSizeExp(t, a.Resize(5, 0), 5, 10)
+	checkSizeExp(t, a.Resize(3, 8), 3, 10)
+	checkSizeExp(t, a.Resize(0, 100), 0, 100)
+	checkSizeExp(t, a.Resize(11, 100), 11, 100)
+}
+
+
+func TestResize2Exp(t *testing.T) {
+	var a Vector
+	checkSizeExp(t, &a, 0, 0)
+	a.Push(int2Value(1))
+	a.Push(int2Value(2))
+	a.Push(int2Value(3))
+	a.Push(int2Value(4))
+	checkSizeExp(t, &a, 4, 4)
+	checkSizeExp(t, a.Resize(10, 0), 10, 10)
+	for i := 4; i < a.Len(); i++ {
+		if a.At(i) != zero {
+			t.Errorf("%T: expected a.At(%d) == %v; found %v!", a, i, zero, a.At(i))
+		}
+	}
+	for i := 4; i < len(a); i++ {
+		if a[i] != zero {
+			t.Errorf("%T: expected a[%d] == %v; found %v", a, i, zero, a[i])
+		}
+	}
+}
+
+
+func checkZeroExp(t *testing.T, a *Vector, i int) {
+	for j := 0; j < i; j++ {
+		if a.At(j) == zero {
+			t.Errorf("%T: 1 expected a.At(%d) == %d; found %v", a, j, j, a.At(j))
+		}
+		if (*a)[j] == zero {
+			t.Errorf("%T: 2 expected (*a)[%d] == %d; found %v", a, j, j, (*a)[j])
+		}
+	}
+	for ; i < a.Len(); i++ {
+		if a.At(i) != zero {
+			t.Errorf("%T: 3 expected a.At(%d) == %v; found %v", a, i, zero, a.At(i))
+		}
+		if (*a)[i] != zero {
+			t.Errorf("%T: 4 expected (*a)[%d] == %v; found %v", a, i, zero, (*a)[i])
+		}
+	}
+}
+
+
+func TestTrailingElementsExp(t *testing.T) {
+	var a Vector
+	for i := 0; i < 10; i++ {
+		a.Push(int2Value(i + 1))
+	}
+	checkZeroExp(t, &a, 10)
+	checkSizeExp(t, &a, 10, 16)
+	checkSizeExp(t, a.Resize(5, 0), 5, 16)
+	checkSizeExp(t, a.Resize(10, 0), 10, 16)
+	checkZeroExp(t, &a, 5)
+}
+
+
+func TestAccessExp(t *testing.T) {
+	const n = 100
+	var a Vector
+	a.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		a.Set(i, int2Value(valExp(i)))
+	}
+	for i := 0; i < n; i++ {
+		if elem2Value(a.At(i)) != int2Value(valExp(i)) {
+			t.Error(i)
+		}
+	}
+	var b Vector
+	b.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		b[i] = int2Value(valExp(i))
+	}
+	for i := 0; i < n; i++ {
+		if elem2Value(b[i]) != int2Value(valExp(i)) {
+			t.Error(i)
+		}
+	}
+}
+
+
+func TestInsertDeleteClearExp(t *testing.T) {
+	const n = 100
+	var a Vector
+
+	for i := 0; i < n; i++ {
+		if a.Len() != i {
+			t.Errorf("T%: A) wrong Len() %d (expected %d)", a, a.Len(), i)
+		}
+		if len(a) != i {
+			t.Errorf("T%: A) wrong len() %d (expected %d)", a, len(a), i)
+		}
+		a.Insert(0, int2Value(valExp(i)))
+		if elem2Value(a.Last()) != int2Value(valExp(0)) {
+			t.Error("T%: B", a)
+		}
+	}
+	for i := n - 1; i >= 0; i-- {
+		if elem2Value(a.Last()) != int2Value(valExp(0)) {
+			t.Error("T%: C", a)
+		}
+		if elem2Value(a.At(0)) != int2Value(valExp(i)) {
+			t.Error("T%: D", a)
+		}
+		if elem2Value(a[0]) != int2Value(valExp(i)) {
+			t.Error("T%: D2", a)
+		}
+		a.Delete(0)
+		if a.Len() != i {
+			t.Errorf("T%: E) wrong Len() %d (expected %d)", a, a.Len(), i)
+		}
+		if len(a) != i {
+			t.Errorf("T%: E) wrong len() %d (expected %d)", a, len(a), i)
+		}
+	}
+
+	if a.Len() != 0 {
+		t.Errorf("T%: F) wrong Len() %d (expected 0)", a, a.Len())
+	}
+	if len(a) != 0 {
+		t.Errorf("T%: F) wrong len() %d (expected 0)", a, len(a))
+	}
+	for i := 0; i < n; i++ {
+		a.Push(int2Value(valExp(i)))
+		if a.Len() != i+1 {
+			t.Errorf("T%: G) wrong Len() %d (expected %d)", a, a.Len(), i+1)
+		}
+		if len(a) != i+1 {
+			t.Errorf("T%: G) wrong len() %d (expected %d)", a, len(a), i+1)
+		}
+		if elem2Value(a.Last()) != int2Value(valExp(i)) {
+			t.Error("T%: H", a)
+		}
+	}
+	a.Resize(0, 0)
+	if a.Len() != 0 {
+		t.Errorf("T%: I wrong Len() %d (expected 0)", a, a.Len())
+	}
+	if len(a) != 0 {
+		t.Errorf("T%: I wrong len() %d (expected 0)", a, len(a))
+	}
+
+	const m = 5
+	for j := 0; j < m; j++ {
+		a.Push(int2Value(j))
+		for i := 0; i < n; i++ {
+			x := valExp(i)
+			a.Push(int2Value(x))
+			if elem2Value(a.Pop()) != int2Value(x) {
+				t.Error("T%: J", a)
+			}
+			if a.Len() != j+1 {
+				t.Errorf("T%: K) wrong Len() %d (expected %d)", a, a.Len(), j+1)
+			}
+			if len(a) != j+1 {
+				t.Errorf("T%: K) wrong len() %d (expected %d)", a, len(a), j+1)
+			}
+		}
+	}
+	if a.Len() != m {
+		t.Errorf("T%: L) wrong Len() %d (expected %d)", a, a.Len(), m)
+	}
+	if len(a) != m {
+		t.Errorf("T%: L) wrong len() %d (expected %d)", a, len(a), m)
+	}
+}
+
+
+func verify_sliceExp(t *testing.T, x *Vector, elt, i, j int) {
+	for k := i; k < j; k++ {
+		if elem2Value(x.At(k)) != int2Value(elt) {
+			t.Errorf("T%: M) wrong [%d] element %v (expected %v)", x, k, elem2Value(x.At(k)), int2Value(elt))
+		}
+	}
+
+	s := x.Slice(i, j)
+	for k, n := 0, j-i; k < n; k++ {
+		if elem2Value(s.At(k)) != int2Value(elt) {
+			t.Errorf("T%: N) wrong [%d] element %v (expected %v)", x, k, elem2Value(x.At(k)), int2Value(elt))
+		}
+	}
+}
+
+
+func verify_patternExp(t *testing.T, x *Vector, a, b, c int) {
+	n := a + b + c
+	if x.Len() != n {
+		t.Errorf("T%: O) wrong Len() %d (expected %d)", x, x.Len(), n)
+	}
+	if len(*x) != n {
+		t.Errorf("T%: O) wrong len() %d (expected %d)", x, len(*x), n)
+	}
+	verify_sliceExp(t, x, 0, 0, a)
+	verify_sliceExp(t, x, 1, a, a+b)
+	verify_sliceExp(t, x, 0, a+b, n)
+}
+
+
+func make_vectorExp(elt, len int) *Vector {
+	x := new(Vector).Resize(len, 0)
+	for i := 0; i < len; i++ {
+		x.Set(i, int2Value(elt))
+	}
+	return x
+}
+
+
+func TestInsertVectorExp(t *testing.T) {
+	// 1
+	a := make_vectorExp(0, 0)
+	b := make_vectorExp(1, 10)
+	a.InsertVector(0, b)
+	verify_patternExp(t, a, 0, 10, 0)
+	// 2
+	a = make_vectorExp(0, 10)
+	b = make_vectorExp(1, 0)
+	a.InsertVector(5, b)
+	verify_patternExp(t, a, 5, 0, 5)
+	// 3
+	a = make_vectorExp(0, 10)
+	b = make_vectorExp(1, 3)
+	a.InsertVector(3, b)
+	verify_patternExp(t, a, 3, 3, 7)
+	// 4
+	a = make_vectorExp(0, 10)
+	b = make_vectorExp(1, 1000)
+	a.InsertVector(8, b)
+	verify_patternExp(t, a, 8, 1000, 2)
+}
+
+
+func TestDoExp(t *testing.T) {
+	const n = 25
+	const salt = 17
+	a := new(Vector).Resize(n, 0)
+	for i := 0; i < n; i++ {
+		a.Set(i, int2Value(salt*i))
+	}
+	count := 0
+	a.Do(func(e interface{}) {
+		i := intf2Value(e)
+		if i != int2Value(count*salt) {
+			t.Error(tname(a), "value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(a), "should visit", n, "values; did visit", count)
+	}
+
+	b := new(Vector).Resize(n, 0)
+	for i := 0; i < n; i++ {
+		(*b)[i] = int2Value(salt * i)
+	}
+	count = 0
+	b.Do(func(e interface{}) {
+		i := intf2Value(e)
+		if i != int2Value(count*salt) {
+			t.Error(tname(b), "b) value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(b), "b) should visit", n, "values; did visit", count)
+	}
+
+	var c Vector
+	c.Resize(n, 0)
+	for i := 0; i < n; i++ {
+		c[i] = int2Value(salt * i)
+	}
+	count = 0
+	c.Do(func(e interface{}) {
+		i := intf2Value(e)
+		if i != int2Value(count*salt) {
+			t.Error(tname(c), "c) value at", count, "should be", count*salt, "not", i)
+		}
+		count++
+	})
+	if count != n {
+		t.Error(tname(c), "c) should visit", n, "values; did visit", count)
+	}
+
+}
+
+
+func TestIterExp(t *testing.T) {
+	const Len = 100
+	x := new(Vector).Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		x.Set(i, int2Value(i*i))
+	}
+	i := 0
+	for v := range x.Iter() {
+		if elem2Value(v) != int2Value(i*i) {
+			t.Error(tname(x), "Iter expected", i*i, "got", elem2Value(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(x), "Iter stopped at", i, "not", Len)
+	}
+	y := new(Vector).Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		(*y)[i] = int2Value(i * i)
+	}
+	i = 0
+	for v := range y.Iter() {
+		if elem2Value(v) != int2Value(i*i) {
+			t.Error(tname(y), "y, Iter expected", i*i, "got", elem2Value(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(y), "y, Iter stopped at", i, "not", Len)
+	}
+	var z Vector
+	z.Resize(Len, 0)
+	for i := 0; i < Len; i++ {
+		z[i] = int2Value(i * i)
+	}
+	i = 0
+	for v := range z.Iter() {
+		if elem2Value(v) != int2Value(i*i) {
+			t.Error(tname(z), "z, Iter expected", i*i, "got", elem2Value(v))
+		}
+		i++
+	}
+	if i != Len {
+		t.Error(tname(z), "z, Iter stopped at", i, "not", Len)
+	}
+}
+
+func TestVectorData(t *testing.T) {
+	// verify Data() returns a slice of a copy, not a slice of the original vector
+	const Len = 10
+	var src Vector
+	for i := 0; i < Len; i++ {
+		src.Push(int2Value(i * i))
+	}
+	dest := src.Data()
+	for i := 0; i < Len; i++ {
+		src[i] = int2Value(-1)
+		v := elem2Value(dest[i])
+		if v != int2Value(i*i) {
+			t.Error(tname(src), "expected", i*i, "got", v)
+		}
+	}
+}