Add an Iterable package with handy functions like All, Any and Map.

Add a Data method to vector.Vector.

R=r,rsc
APPROVED=rsc
DELTA=173  (170 added, 0 deleted, 3 changed)
OCL=26980
CL=27098

src/lib/container/Makefile

@@ -36,8 +36,10 @@ O1=\
 
 O2=\
 	intvector.$O\
+	iterable.$O\
 
 vector.a: a1 a2
+iterable.a: a1 a2
 
 a1:	$(O1)
 	$(AR) grc vector.a vector.$O
@@ -45,19 +47,21 @@ a1:	$(O1)
 
 a2:	$(O2)
 	$(AR) grc vector.a intvector.$O
+	$(AR) grc iterable.a iterable.$O
 	rm -f $(O2)
 
 newpkg: clean
 	$(AR) grc vector.a
+	$(AR) grc iterable.a
 
 $(O1): newpkg
 $(O2): a1
 
 nuke: clean
-	rm -f $(GOROOT)/pkg/vector.a
+	rm -f $(GOROOT)/pkg/vector.a $(GOROOT)/pkg/iterable.a
 
-packages: vector.a
+packages: vector.a iterable.a
 
 install: packages
 	cp vector.a $(GOROOT)/pkg/vector.a
-
+	cp iterable.a $(GOROOT)/pkg/iterable.a

src/lib/container/iterable.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 iterable package provides several traversal and searching methods.
+// It can be used on anything that satisfies the Iterable interface,
+// including vector, though certain functions, such as Map, can also be used on
+// something that would produce an infinite amount of data.
+package iterable
+
+import "vector"
+
+
+type Iterable interface {
+	// Iter should return a fresh channel each time it is called.
+	Iter() <-chan interface {}
+}
+
+
+// All tests whether f is true for every element of iter.
+func All(iter Iterable, f func(e interface {}) bool) bool {
+	for e := range iter.Iter() {
+		if !f(e) {
+			return false
+		}
+	}
+	return true
+}
+
+
+// Any tests whether f is true for at least one element of iter.
+func Any(iter Iterable, f func(e interface {}) bool) bool {
+	return !All(iter, func(e interface {}) bool { return !f(e) });
+}
+
+
+// Data returns a slice containing the elements of iter.
+func Data(iter Iterable) []interface {} {
+	vec := vector.New(0);
+	for e := range iter.Iter() {
+		vec.Push(e)
+	}
+	return vec.Data()
+}
+
+
+// mappedIterable is a helper struct that implements Iterable, returned by Map.
+type mappedIterable struct {
+	it Iterable;
+	f func(interface {}) interface {};
+}
+
+
+func (m mappedIterable) iterate(out chan<- interface {}) {
+	for e := range m.it.Iter() {
+		out <- m.f(e)
+	}
+	close(out)
+}
+
+
+func (m mappedIterable) Iter() <-chan interface {} {
+	ch := make(chan interface {});
+	go m.iterate(ch);
+	return ch;
+}
+
+
+// Map returns an Iterable that returns the result of applying f to each
+// element of iter.
+func Map(iter Iterable, f func(e interface {}) interface {}) Iterable {
+	return mappedIterable{ iter, f }
+}
+
+
+// TODO:
+// - Find, Filter
+// - Inject
+// - Partition
+// - Zip

src/lib/container/iterable_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 iterable
+
+import (
+	"iterable";
+	"testing";
+)
+
+type IntArray []int;
+
+func (arr IntArray) Iter() <-chan interface {} {
+	ch := make(chan interface {});
+	go func() {
+		for i, x := range arr {
+			ch <- x
+		}
+		close(ch)
+	}();
+	return ch
+}
+
+var oneToFive IntArray = []int{ 1, 2, 3, 4, 5 };
+
+func isNegative(n interface {}) bool {
+	return n.(int) < 0
+}
+func isPositive(n interface {}) bool {
+	return n.(int) > 0
+}
+func isAbove3(n interface {}) bool {
+	return n.(int) > 3
+}
+func isEven(n interface {}) bool {
+	return n.(int) % 2 == 0
+}
+func doubler(n interface {}) interface {} {
+	return n.(int) * 2
+}
+func addOne(n interface {}) interface {} {
+	return n.(int) + 1
+}
+
+
+func TestAll(t *testing.T) {
+	if !All(oneToFive, isPositive) {
+		t.Error("All(oneToFive, isPositive) == false")
+	}
+	if All(oneToFive, isAbove3) {
+		t.Error("All(oneToFive, isAbove3) == true")
+	}
+}
+
+
+func TestAny(t *testing.T) {
+	if Any(oneToFive, isNegative) {
+		t.Error("Any(oneToFive, isNegative) == true")
+	}
+	if !Any(oneToFive, isEven) {
+		t.Error("Any(oneToFive, isEven) == false")
+	}
+}
+
+
+func TestMap(t *testing.T) {
+	res := Data(Map(Map(oneToFive, doubler), addOne));
+	if len(res) != len(oneToFive) {
+		t.Fatal("len(res) = %v, want %v", len(res), len(oneToFive))
+	}
+	expected := []int{ 3, 5, 7, 9, 11 };
+	for i := range res {
+		if res[i].(int) != expected[i] {
+			t.Errorf("res[%v] = %v, want %v", i, res[i], expected[i])
+		}
+	}
+}

src/lib/container/vector.go

@@ -107,6 +107,16 @@ func (p *Vector) Last() Element {
 }
 
 
+// Data returns all the elements as a slice.
+func (p *Vector) Data() []Element {
+	arr := make([]Element, p.Len());
+	for i, v := range p.a {
+		arr[i] = v
+	}
+	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 Element) {