additions to array container:

- added Slice, Cut, InsertArray, AppendArray
- renamed Remove -> Delete (so we have: Insert, Delete, Cut)
- more factoring of code
- extra tests (could use some more)

R=r,rsc
DELTA=179  (127 added, 22 deleted, 30 changed)
OCL=23648
CL=23685

src/lib/container/array/array.go

@@ -4,13 +4,47 @@
 
 package array
 
-type Element interface {
+type (
+	Element interface {};
+	Array struct {
+		a []Element
+	}
+)
+
+
+func copy(dst, src []Element) {
+	for i := 0; i < len(src); i++ {
+		dst[i] = src[i]
+	}
 }
 
 
-type Array struct {
-	// TODO do not export field
-	a []Element
+// Insert n elements at position i.
+func expand(a []Element, i, n int) []Element {
+	// 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
+		b := make([]Element, len1, capb);
+		copy(b, a);
+		a = b
+	}
+
+	// make a hole
+	for j := len0-1; j >= i ; j-- {
+		a[j+n] = a[j]
+	}
+	return a
 }
 
 
@@ -61,52 +95,65 @@ func (p *Array) Last() Element {
 
 
 func (p *Array) Insert(i int, x Element) {
+	p.a = expand(p.a, i, 1);
+	p.a[i] = x;
+}
+
+
+func (p *Array) Delete(i int) Element {
 	a := p.a;
 	n := len(a);
 
-	// grow array by doubling its capacity
-	if n == cap(a) {
-		b := make([]Element, 2*n);
-		for j := n-1; j >= 0; j-- {
-			b[j] = a[j];
-		}
-		a = b
-	}
+	x := a[i];
+	copy(a[i : n-1], a[i+1 : n]);
+	a[n-1] = nil;  // support GC, nil out entry
+	p.a = a[0 : n-1];
+
+	return x
+}
 
-	// make a hole
-	a = a[0 : n+1];
-	for j := n; j > i; j-- {
-		a[j] = a[j-1]
-	}
 
-	a[i] = x;
-	p.a = a
+func (p *Array) InsertArray(i int, x *Array) {
+	p.a = expand(p.a, i, len(x.a));
+	copy(p.a[i : i + len(x.a)], x.a);
 }
 
 
-func (p *Array) Remove(i int) Element {
+func (p *Array) Cut(i, j int) {
 	a := p.a;
 	n := len(a);
+	m := n - (j - i);
 
-	x := a[i];
-	for j := i+1; j < n; j++ {
-		a[j-1] = a[j]
+	copy(a[i : m], a[j : n]);
+	for k := m; k < n; k++ {
+		a[k] = nil  // support GC, nil out entries
 	}
 
-	a[n-1] = nil;  // support GC, nil out entry
-	p.a = a[0 : n-1];
+	p.a = a[0 : m];
+}
 
-	return x
+
+func (p *Array) Slice(i, j int) *Array {
+	s := New(j - i);  // will fail in Init() if j < j
+	copy(s.a, p.a[i : j]);
+	return s;
 }
 
 
+// Convenience wrappers
+
 func (p *Array) Push(x Element) {
 	p.Insert(len(p.a), x)
 }
 
 
 func (p *Array) Pop() Element {
-	return p.Remove(len(p.a) - 1)
+	return p.Delete(len(p.a) - 1)
+}
+
+
+func (p *Array) AppendArray(x *Array) {
+	p.InsertArray(len(p.a), x);
 }
 
 

src/lib/container/array/array_test.go

@@ -24,7 +24,7 @@ func TestNew(t *testing.T) {
 }
 
 
-func Val(i int) int {
+func val(i int) int {
 	return i*991 - 1234
 }
 
@@ -34,34 +34,34 @@ func TestAccess(t *testing.T) {
 	var a array.Array;
 	a.Init(n);
 	for i := 0; i < n; i++ {
-		a.Set(i, Val(i));
+		a.Set(i, val(i));
 	}
 	for i := 0; i < n; i++ {
-		if a.At(i).(int) != Val(i) { t.Error(i) }
+		if a.At(i).(int) != val(i) { t.Error(i) }
 	}
 }
 
 
-func TestInsertRemoveClear(t *testing.T) {
+func TestInsertDeleteClear(t *testing.T) {
 	const n = 100;
 	a := array.New(0);
 
 	for i := 0; i < n; i++ {
-		if a.Len() != i { t.Errorf("A wrong len %d (expected %d)", a.Len(), i) }
-		a.Insert(0, Val(i));
-		if a.Last().(int) != Val(0) { t.Error("B") }
+		if a.Len() != i { t.Errorf("A) wrong len %d (expected %d)", a.Len(), i) }
+		a.Insert(0, val(i));
+		if a.Last().(int) != val(0) { t.Error("B") }
 	}
 	for i := n-1; i >= 0; i-- {
-		if a.Last().(int) != Val(0) { t.Error("C") }
-		if a.Remove(0).(int) != Val(i) { t.Error("D") }
-		if a.Len() != i { t.Errorf("E wrong len %d (expected %d)", a.Len(), i) }
+		if a.Last().(int) != val(0) { t.Error("C") }
+		if a.Delete(0).(int) != val(i) { t.Error("D") }
+		if a.Len() != i { t.Errorf("E) wrong len %d (expected %d)", a.Len(), i) }
 	}
 
-	if a.Len() != 0 { t.Errorf("F wrong len %d (expected 0)", a.Len()) }
+	if a.Len() != 0 { t.Errorf("F) wrong len %d (expected 0)", a.Len()) }
 	for i := 0; i < n; i++ {
-		a.Push(Val(i));
-		if a.Len() != i+1 { t.Errorf("G wrong len %d (expected %d)", a.Len(), i+1) }
-		if a.Last().(int) != Val(i) { t.Error("H") }
+		a.Push(val(i));
+		if a.Len() != i+1 { t.Errorf("G) wrong len %d (expected %d)", a.Len(), i+1) }
+		if a.Last().(int) != val(i) { t.Error("H") }
 	}
 	a.Init(0);
 	if a.Len() != 0 { t.Errorf("I wrong len %d (expected 0)", a.Len()) }
@@ -70,17 +70,76 @@ func TestInsertRemoveClear(t *testing.T) {
 	for j := 0; j < m; j++ {
 		a.Push(j);
 		for i := 0; i < n; i++ {
-			x := Val(i);
+			x := val(i);
 			a.Push(x);
 			if a.Pop().(int) != x { t.Error("J") }
-			if a.Len() != j+1 { t.Errorf("K wrong len %d (expected %d)", a.Len(), j+1) }
+			if a.Len() != j+1 { t.Errorf("K) wrong len %d (expected %d)", a.Len(), j+1) }
 		}
 	}
-	if a.Len() != m { t.Errorf("L wrong len %d (expected %d)", a.Len(), m) }
+	if a.Len() != m { t.Errorf("L) wrong len %d (expected %d)", a.Len(), m) }
+}
+
+
+func verify_slice(t *testing.T, x *array.Array, elt, i, j int) {
+	for k := i; k < j; k++ {
+		if x.At(k).(int) != elt {
+			t.Errorf("M) wrong [%d] element %d (expected %d)", k, x.At(k).(int), elt)
+		}
+	}
+
+	s := x.Slice(i, j);
+	for k, n := 0, j-i; k < n; k++ {
+		if s.At(k).(int) != elt {
+			t.Errorf("N) wrong [%d] element %d (expected %d)", k, x.At(k).(int), elt)
+		}
+	}
+}
+
+
+func verify_pattern(t *testing.T, x *array.Array, a, b, c int) {
+	n := a + b + c;
+	if x.Len() != n {
+		t.Errorf("O) wrong len %d (expected %d)", x.Len(), n)
+	}
+	verify_slice(t, x, 0, 0, a);
+	verify_slice(t, x, 1, a, a + b);
+	verify_slice(t, x, 0, a + b, n);
+}
+
+
+func make_array(elt, len int) *array.Array {
+	x := array.New(len);
+	for i := 0; i < len; i++ {
+		x.Set(i, elt);
+	}
+	return x;
+}
+
+
+func TestInsertArray(t *testing.T) {
+	// 1
+	a := make_array(0, 0);
+	b := make_array(1, 10);
+	a.InsertArray(0, b);
+	verify_pattern(t, a, 0, 10, 0);
+	// 2
+	a = make_array(0, 10);
+	b = make_array(1, 0);
+	a.InsertArray(5, b);
+	verify_pattern(t, a, 5, 0, 5);
+	// 3
+	a = make_array(0, 10);
+	b = make_array(1, 3);
+	a.InsertArray(3, b);
+	verify_pattern(t, a, 3, 3, 7);
+	// 4
+	a = make_array(0, 10);
+	b = make_array(1, 1000);
+	a.InsertArray(8, b);
+	verify_pattern(t, a, 8, 1000, 2);
 }
 
 
-/* currently doesn't compile due to linker bug
 func TestSorting(t *testing.T) {
 	const n = 100;
 	a := array.NewIntArray(n);
@@ -89,4 +148,3 @@ func TestSorting(t *testing.T) {
 	}
 	if sort.IsSorted(a) { t.Error("not sorted") }
 }
-*/

src/lib/container/array/intarray.go

@@ -43,8 +43,8 @@ func (p *IntArray) Insert(i int, x int) {
 }
 
 
-func (p *IntArray) Remove(i int) int {
-	return p.Array.Remove(i).(int)
+func (p *IntArray) Delete(i int) int {
+	return p.Array.Delete(i).(int)
 }
 
 

test/vectors.go

@@ -50,7 +50,7 @@ func test1() {
 	}
 
 	for v.Len() > 10 {
-		v.Remove(10);
+		v.Delete(10);
 	}
 }