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exp/iterable: delete

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Package iterable has outlived its utility.

It is an interesting demonstration, but it encourages
people to use iteration over channels where simple
iteration over array indices or a linked list would be
cheaper, simpler, and have fewer races.

R=dsymonds, r
CC=golang-dev
https://golang.org/cl/2436041
This commit is contained in:
Russ Cox 2010-10-11 22:38:42 -04:00
parent f75129894c
commit e6ecf9765a
7 changed files with 4 additions and 836 deletions
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1
src/pkg/Makefile
View File

@ -63,7 +63,6 @@ DIRS=\
exp/draw\ exp/draw\
exp/draw/x11\ exp/draw/x11\
exp/eval\ exp/eval\
exp/iterable\
expvar\ expvar\
flag\ flag\
fmt\ fmt\

13
src/pkg/container/list/list.go
View File

@ -180,19 +180,6 @@ func (l *List) MoveToBack(e *Element) {
// Len returns the number of elements in the list. // Len returns the number of elements in the list.
func (l *List) Len() int { return l.len } func (l *List) Len() int { return l.len }
func (l *List) iterate(c chan<- interface{}) {
for e := l.front; e != nil; e = e.next {
c <- e.Value
}
close(c)
}
func (l *List) Iter() <-chan interface{} {
c := make(chan interface{})
go l.iterate(c)
return c
}
// PushBackList inserts each element of ol at the back of the list. // PushBackList inserts each element of ol at the back of the list.
func (l *List) PushBackList(ol *List) { func (l *List) PushBackList(ol *List) {
last := ol.Back() last := ol.Back()

7
src/pkg/container/list/list_test.go
View File

@ -116,8 +116,8 @@ func TestList(t *testing.T) {
// Check standard iteration. // Check standard iteration.
sum := 0 sum := 0
for e := range l.Iter() { for e := l.Front(); e != nil; e = e.Next() {
if i, ok := e.(int); ok { if i, ok := e.Value.(int); ok {
sum += i sum += i
} }
} }
@ -141,7 +141,8 @@ func checkList(t *testing.T, l *List, es []interface{}) {
return return
} }
i := 0 i := 0
for le := range l.Iter() { for e := l.Front(); e != nil; e = e.Next() {
le := e.Value.(int)
if le != es[i] { if le != es[i] {
t.Errorf("elt #%d has value=%v, want %v", i, le, es[i]) t.Errorf("elt #%d has value=%v, want %v", i, le, es[i])
} }

12
src/pkg/exp/iterable/Makefile
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@ -1,12 +0,0 @@
# 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.inc
TARG=exp/iterable
GOFILES=\
array.go\
iterable.go\
include ../../../Make.pkg

72
src/pkg/exp/iterable/array.go
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@ -1,72 +0,0 @@
// 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
// This file implements the Iterable interface on some primitive types.
type ByteArray []byte
func (a ByteArray) Iter() <-chan interface{} {
ch := make(chan interface{})
go func() {
for _, e := range a {
ch <- e
}
close(ch)
}()
return ch
}
type IntArray []int
func (a IntArray) Iter() <-chan interface{} {
ch := make(chan interface{})
go func() {
for _, e := range a {
ch <- e
}
close(ch)
}()
return ch
}
type FloatArray []float
func (a FloatArray) Iter() <-chan interface{} {
ch := make(chan interface{})
go func() {
for _, e := range a {
ch <- e
}
close(ch)
}()
return ch
}
type StringArray []string
func (a StringArray) Iter() <-chan interface{} {
ch := make(chan interface{})
go func() {
for _, e := range a {
ch <- e
}
close(ch)
}()
return ch
}
type UintArray []uint
func (a UintArray) Iter() <-chan interface{} {
ch := make(chan interface{})
go func() {
for _, e := range a {
ch <- e
}
close(ch)
}()
return ch
}

344
src/pkg/exp/iterable/iterable.go
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@ -1,344 +0,0 @@
// 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 (
"container/list"
"container/vector"
)
type Iterable interface {
// Iter should return a fresh channel each time it is called.
Iter() <-chan interface{}
}
func not(f func(interface{}) bool) func(interface{}) bool {
return func(e interface{}) bool { return !f(e) }
}
// All tests whether f is true for every element of iter.
func All(iter Iterable, f func(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(interface{}) bool) bool {
return !All(iter, not(f))
}
// Data returns a slice containing the elements of iter.
func Data(iter Iterable) []interface{} {
var v vector.Vector
for e := range iter.Iter() {
v.Push(e)
}
return v
}
// filteredIterable is a struct that implements Iterable with each element
// passed through a filter.
type filteredIterable struct {
it Iterable
f func(interface{}) bool
}
func (f *filteredIterable) iterate(out chan<- interface{}) {
for e := range f.it.Iter() {
if f.f(e) {
out <- e
}
}
close(out)
}
func (f *filteredIterable) Iter() <-chan interface{} {
ch := make(chan interface{})
go f.iterate(ch)
return ch
}
// Filter returns an Iterable that returns the elements of iter that satisfy f.
func Filter(iter Iterable, f func(interface{}) bool) Iterable {
return &filteredIterable{iter, f}
}
// Find returns the first element of iter that satisfies f.
// Returns nil if no such element is found.
func Find(iter Iterable, f func(interface{}) bool) interface{} {
for e := range Filter(iter, f).Iter() {
return e
}
return nil
}
// Injector is a type representing a function that takes two arguments,
// an accumulated value and an element, and returns the next accumulated value.
// See the Inject function.
type Injector func(interface{}, interface{}) interface{}
// Inject combines the elements of iter by repeatedly calling f with an
// accumulated value and each element in order. The starting accumulated value
// is initial, and after each call the accumulated value is set to the return
// value of f. For instance, to compute a sum:
// var arr IntArray = []int{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
// sum := iterable.Inject(arr, 0,
// func(ax interface {}, x interface {}) interface {} {
// return ax.(int) + x.(int) }).(int)
func Inject(iter Iterable, initial interface{}, f Injector) interface{} {
acc := initial
for e := range iter.Iter() {
acc = f(acc, e)
}
return acc
}
// 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(interface{}) interface{}) Iterable {
return &mappedIterable{iter, f}
}
// Partition(iter, f) returns Filter(iter, f) and Filter(iter, !f).
func Partition(iter Iterable, f func(interface{}) bool) (Iterable, Iterable) {
return Filter(iter, f), Filter(iter, not(f))
}
// A Func is a function that, when called, sends the
// iterable values on a channel.
type Func func(chan<- interface{})
// Iter creates and returns a new channel; it starts a
// goroutine running f to send values to the channel.
func (f Func) Iter() <-chan interface{} {
ch := make(chan interface{})
go f(ch)
return ch
}
// Take returns an Iterable that contains the first n elements of iter.
func Take(iter Iterable, n int) Iterable { return Slice(iter, 0, n) }
// TakeWhile returns an Iterable that contains elements from iter while f is true.
func TakeWhile(iter Iterable, f func(interface{}) bool) Iterable {
return Func(func(ch chan<- interface{}) {
for v := range iter.Iter() {
if !f(v) {
break
}
ch <- v
}
close(ch)
})
}
// Drop returns an Iterable that returns each element of iter after the first n elements.
func Drop(iter Iterable, n int) Iterable {
return Func(func(ch chan<- interface{}) {
m := n
for v := range iter.Iter() {
if m > 0 {
m--
continue
}
ch <- v
}
close(ch)
})
}
// DropWhile returns an Iterable that returns each element of iter after the initial sequence for which f returns true.
func DropWhile(iter Iterable, f func(interface{}) bool) Iterable {
return Func(func(ch chan<- interface{}) {
drop := true
for v := range iter.Iter() {
if drop {
if f(v) {
continue
}
drop = false
}
ch <- v
}
close(ch)
})
}
// Cycle repeats the values of iter in order infinitely.
func Cycle(iter Iterable) Iterable {
return Func(func(ch chan<- interface{}) {
for {
for v := range iter.Iter() {
ch <- v
}
}
})
}
// Chain returns an Iterable that concatenates all values from the specified Iterables.
func Chain(args []Iterable) Iterable {
return Func(func(ch chan<- interface{}) {
for _, e := range args {
for v := range e.Iter() {
ch <- v
}
}
close(ch)
})
}
// Zip returns an Iterable of []interface{} consisting of the next element from
// each input Iterable. The length of the returned Iterable is the minimum of
// the lengths of the input Iterables.
func Zip(args []Iterable) Iterable {
return Func(func(ch chan<- interface{}) {
defer close(ch)
if len(args) == 0 {
return
}
iters := make([]<-chan interface{}, len(args))
for i := 0; i < len(iters); i++ {
iters[i] = args[i].Iter()
}
for {
out := make([]interface{}, len(args))
for i, v := range iters {
out[i] = <-v
if closed(v) {
return
}
}
ch <- out
}
})
}
// ZipWith returns an Iterable containing the result of executing f using arguments read from a and b.
func ZipWith2(f func(c, d interface{}) interface{}, a, b Iterable) Iterable {
return Map(Zip([]Iterable{a, b}), func(a1 interface{}) interface{} {
arr := a1.([]interface{})
return f(arr[0], arr[1])
})
}
// ZipWith returns an Iterable containing the result of executing f using arguments read from a, b and c.
func ZipWith3(f func(d, e, f interface{}) interface{}, a, b, c Iterable) Iterable {
return Map(Zip([]Iterable{a, b, c}), func(a1 interface{}) interface{} {
arr := a1.([]interface{})
return f(arr[0], arr[1], arr[2])
})
}
// Slice returns an Iterable that contains the elements from iter
// with indexes in [start, stop).
func Slice(iter Iterable, start, stop int) Iterable {
return Func(func(ch chan<- interface{}) {
defer close(ch)
i := 0
for v := range iter.Iter() {
switch {
case i >= stop:
return
case i >= start:
ch <- v
}
i++
}
})
}
// Repeat generates an infinite stream of v.
func Repeat(v interface{}) Iterable {
return Func(func(ch chan<- interface{}) {
for {
ch <- v
}
})
}
// RepeatTimes generates a stream of n copies of v.
func RepeatTimes(v interface{}, n int) Iterable {
return Func(func(ch chan<- interface{}) {
for i := 0; i < n; i++ {
ch <- v
}
close(ch)
})
}
// Group is the type for elements returned by the GroupBy function.
type Group struct {
Key interface{} // key value for matching items
Vals Iterable // Iterable for receiving values in the group
}
// Key defines the interface required by the GroupBy function.
type Grouper interface {
// Return the key for the given value
Key(interface{}) interface{}
// Compute equality for the given keys
Equal(a, b interface{}) bool
}
// GroupBy combines sequences of logically identical values from iter using k
// to generate a key to compare values. Each value emitted by the returned
// Iterable is of type Group, which contains the key used for matching the
// values for the group, and an Iterable for retrieving all the values in the
// group.
func GroupBy(iter Iterable, k Grouper) Iterable {
return Func(func(ch chan<- interface{}) {
var curkey interface{}
var lst *list.List
// Basic strategy is to read one group at a time into a list prior to emitting the Group value
for v := range iter.Iter() {
kv := k.Key(v)
if lst == nil || !k.Equal(curkey, kv) {
if lst != nil {
ch <- Group{curkey, lst}
}
lst = list.New()
curkey = kv
}
lst.PushBack(v)
}
if lst != nil {
ch <- Group{curkey, lst}
}
close(ch)
})
}
// Unique removes duplicate values which occur consecutively using id to compute keys.
func Unique(iter Iterable, id Grouper) Iterable {
return Map(GroupBy(iter, id), func(v interface{}) interface{} { return v.(Group).Key })
}

391
src/pkg/exp/iterable/iterable_test.go
View File

@ -1,391 +0,0 @@
// 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 (
"container/vector"
"testing"
)
func TestArrayTypes(t *testing.T) {
// Test that conversion works correctly.
bytes := ByteArray([]byte{1, 2, 3})
if x := Data(bytes)[1].(byte); x != 2 {
t.Error("Data(bytes)[1].(byte) = %v, want 2", x)
}
uints := UintArray([]uint{1, 2, 3})
if x := Data(uints)[1].(uint); x != 2 {
t.Error("Data(uints)[1].(uint) = %v, want 2", x)
}
ints := IntArray([]int{1, 2, 3})
if x := Data(ints)[2].(int); x != 3 {
t.Error("Data(ints)[2].(int) = %v, want 3", x)
}
floats := FloatArray([]float{1, 2, 3})
if x := Data(floats)[0].(float); x != 1 {
t.Error("Data(floats)[0].(float) = %v, want 1", x)
}
strings := StringArray([]string{"a", "b", "c"})
if x := Data(strings)[1].(string); x != "b" {
t.Error(`Data(strings)[1].(string) = %q, want "b"`, x)
}
}
var (
oneToFive = IntArray{1, 2, 3, 4, 5}
sixToTen = IntArray{6, 7, 8, 9, 10}
elevenToTwenty = IntArray{11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
)
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 adder(acc interface{}, n interface{}) interface{} {
return acc.(int) + n.(int)
}
// A stream of the natural numbers: 0, 1, 2, 3, ...
type integerStream struct{}
func (i integerStream) Iter() <-chan interface{} {
ch := make(chan interface{})
go func() {
for i := 0; ; i++ {
ch <- i
}
}()
return ch
}
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 assertArraysAreEqual(t *testing.T, res []interface{}, expected []int) {
if len(res) != len(expected) {
t.Errorf("len(res) = %v, want %v", len(res), len(expected))
goto missing
}
for i := range res {
if v := res[i].(int); v != expected[i] {
t.Errorf("res[%v] = %v, want %v", i, v, expected[i])
goto missing
}
}
return
missing:
t.Errorf("res = %v\nwant %v", res, expected)
}
func TestFilter(t *testing.T) {
ints := integerStream{}
moreInts := Filter(ints, isAbove3).Iter()
res := make([]interface{}, 3)
for i := 0; i < 3; i++ {
res[i] = <-moreInts
}
assertArraysAreEqual(t, res, []int{4, 5, 6})
}
func TestFind(t *testing.T) {
ints := integerStream{}
first := Find(ints, isAbove3)
if first.(int) != 4 {
t.Errorf("Find(ints, isAbove3) = %v, want 4", first)
}
}
func TestInject(t *testing.T) {
res := Inject(oneToFive, 0, adder)
if res.(int) != 15 {
t.Errorf("Inject(oneToFive, 0, adder) = %v, want 15", res)
}
}
func TestMap(t *testing.T) {
res := Data(Map(Map(oneToFive, doubler), addOne))
assertArraysAreEqual(t, res, []int{3, 5, 7, 9, 11})
}
func TestPartition(t *testing.T) {
ti, fi := Partition(oneToFive, isEven)
assertArraysAreEqual(t, Data(ti), []int{2, 4})
assertArraysAreEqual(t, Data(fi), []int{1, 3, 5})
}
func TestTake(t *testing.T) {
res := Take(oneToFive, 2)
assertArraysAreEqual(t, Data(res), []int{1, 2})
assertArraysAreEqual(t, Data(res), []int{1, 2}) // second test to ensure that .Iter() returns a new channel
// take none
res = Take(oneToFive, 0)
assertArraysAreEqual(t, Data(res), []int{})
// try to take more than available
res = Take(oneToFive, 20)
assertArraysAreEqual(t, Data(res), oneToFive)
}
func TestTakeWhile(t *testing.T) {
// take some
res := TakeWhile(oneToFive, func(v interface{}) bool { return v.(int) <= 3 })
assertArraysAreEqual(t, Data(res), []int{1, 2, 3})
assertArraysAreEqual(t, Data(res), []int{1, 2, 3}) // second test to ensure that .Iter() returns a new channel
// take none
res = TakeWhile(oneToFive, func(v interface{}) bool { return v.(int) > 3000 })
assertArraysAreEqual(t, Data(res), []int{})
// take all
res = TakeWhile(oneToFive, func(v interface{}) bool { return v.(int) < 3000 })
assertArraysAreEqual(t, Data(res), oneToFive)
}
func TestDrop(t *testing.T) {
// drop none
res := Drop(oneToFive, 0)
assertArraysAreEqual(t, Data(res), oneToFive)
assertArraysAreEqual(t, Data(res), oneToFive) // second test to ensure that .Iter() returns a new channel
// drop some
res = Drop(oneToFive, 2)
assertArraysAreEqual(t, Data(res), []int{3, 4, 5})
assertArraysAreEqual(t, Data(res), []int{3, 4, 5}) // second test to ensure that .Iter() returns a new channel
// drop more than available
res = Drop(oneToFive, 88)
assertArraysAreEqual(t, Data(res), []int{})
}
func TestDropWhile(t *testing.T) {
// drop some
res := DropWhile(oneToFive, func(v interface{}) bool { return v.(int) < 3 })
assertArraysAreEqual(t, Data(res), []int{3, 4, 5})
assertArraysAreEqual(t, Data(res), []int{3, 4, 5}) // second test to ensure that .Iter() returns a new channel
// test case where all elements are dropped
res = DropWhile(oneToFive, func(v interface{}) bool { return v.(int) < 100 })
assertArraysAreEqual(t, Data(res), []int{})
// test case where none are dropped
res = DropWhile(oneToFive, func(v interface{}) bool { return v.(int) > 1000 })
assertArraysAreEqual(t, Data(res), oneToFive)
}
func TestCycle(t *testing.T) {
res := Cycle(oneToFive)
exp := []int{1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4}
// read the first nineteen values from the iterable
out := make([]interface{}, 19)
for i, it := 0, res.Iter(); i < 19; i++ {
out[i] = <-it
}
assertArraysAreEqual(t, out, exp)
res2 := Cycle(sixToTen)
exp2 := []int{6, 7, 8, 9, 10, 6, 7, 8, 9, 10, 6, 7, 8, 9, 10, 6, 7, 8, 9}
for i, it := 0, res2.Iter(); i < 19; i++ {
out[i] = <-it
}
assertArraysAreEqual(t, out, exp2)
// ensure first iterator was not harmed
for i, it := 0, res.Iter(); i < 19; i++ {
out[i] = <-it
}
assertArraysAreEqual(t, out, exp)
}
func TestChain(t *testing.T) {
exp := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
res := Chain([]Iterable{oneToFive, sixToTen, elevenToTwenty})
assertArraysAreEqual(t, Data(res), exp)
// reusing the same iterator should produce the same result again
assertArraysAreEqual(t, Data(res), exp)
// test short read from Chain
i := 0
out := make([]interface{}, 4)
for v := range res.Iter() {
out[i] = v
i++
if i == len(out) {
break
}
}
assertArraysAreEqual(t, out, exp[0:4])
// test zero length array
res = Chain([]Iterable{})
assertArraysAreEqual(t, Data(res), []int{})
}
func TestZipWith(t *testing.T) {
exp := []int{7, 9, 11, 13, 15}
// f with 2 args and 1 return value
f := func(a, b interface{}) interface{} { return a.(int) + b.(int) }
res := ZipWith2(f, oneToFive, sixToTen)
assertArraysAreEqual(t, Data(res), exp)
// test again to make sure returns new iter each time
assertArraysAreEqual(t, Data(res), exp)
// test a function with 3 args
f2 := func(a, b, c interface{}) interface{} { return a.(int) + b.(int) + c.(int) }
res = ZipWith3(f2, oneToFive, sixToTen, oneToFive)
exp = []int{8, 11, 14, 17, 20}
assertArraysAreEqual(t, Data(res), exp)
// test a function with multiple values returned
f3 := func(a, b interface{}) interface{} { return ([]interface{}{a.(int) + 1, b.(int) + 1}) }
res = ZipWith2(f3, oneToFive, sixToTen)
exp2 := [][]int{[]int{2, 7}, []int{3, 8}, []int{4, 9}, []int{5, 10}, []int{6, 11}}
i := 0
for v := range res.Iter() {
out := v.([]interface{})
assertArraysAreEqual(t, out, exp2[i])
i++
}
// test different length iterators--should stop after shortest is exhausted
res = ZipWith2(f, elevenToTwenty, oneToFive)
exp = []int{12, 14, 16, 18, 20}
assertArraysAreEqual(t, Data(res), exp)
}
func TestSlice(t *testing.T) {
out := Data(Slice(elevenToTwenty, 2, 6))
exp := []int{13, 14, 15, 16}
assertArraysAreEqual(t, out, exp)
// entire iterable
out = Data(Slice(elevenToTwenty, 0, len(elevenToTwenty)))
exp = []int{11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
assertArraysAreEqual(t, out, exp)
// empty slice at offset 0
exp = []int{}
out = Data(Slice(elevenToTwenty, 0, 0))
assertArraysAreEqual(t, out, exp)
// slice upper bound exceeds length of iterable
exp = []int{1, 2, 3, 4, 5}
out = Data(Slice(oneToFive, 0, 88))
assertArraysAreEqual(t, out, exp)
// slice upper bounce is lower than lower bound
exp = []int{}
out = Data(Slice(oneToFive, 93, 4))
assertArraysAreEqual(t, out, exp)
// slice lower bound is greater than len of iterable
exp = []int{}
out = Data(Slice(oneToFive, 93, 108))
assertArraysAreEqual(t, out, exp)
}
func TestRepeat(t *testing.T) {
res := Repeat(42)
i := 0
for v := range res.Iter() {
if v.(int) != 42 {
t.Fatal("Repeat returned the wrong value")
}
if i == 9 {
break
}
i++
}
}
func TestRepeatTimes(t *testing.T) {
res := RepeatTimes(84, 9)
exp := []int{84, 84, 84, 84, 84, 84, 84, 84, 84}
assertArraysAreEqual(t, Data(res), exp)
assertArraysAreEqual(t, Data(res), exp) // second time to ensure new iter is returned
// 0 repeat
res = RepeatTimes(7, 0)
exp = []int{}
assertArraysAreEqual(t, Data(res), exp)
// negative repeat
res = RepeatTimes(7, -3)
exp = []int{}
assertArraysAreEqual(t, Data(res), exp)
}
// a type that implements Key for ints
type intkey struct{}
func (v intkey) Key(a interface{}) interface{} {
return a
}
func (v intkey) Equal(a, b interface{}) bool { return a.(int) == b.(int) }
func TestGroupBy(t *testing.T) {
in := IntArray{1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5}
exp := [][]int{[]int{1}, []int{2, 2}, []int{3, 3, 3}, []int{4, 4, 4, 4}, []int{5, 5, 5, 5, 5}}
i := 0
for x := range GroupBy(in, intkey{}).Iter() {
gr := x.(Group)
if gr.Key.(int) != i+1 {
t.Fatal("group key wrong; expected", i+1, "but got", gr.Key.(int))
}
vals := Data(gr.Vals)
assertArraysAreEqual(t, vals, exp[i])
i++
}
if i != 5 {
t.Fatal("did not return expected number of groups")
}
// test 0 length Iterable
for _ = range GroupBy(IntArray([]int{}), &intkey{}).Iter() {
t.Fatal("iterator should be empty")
}
// test case with only uniques
var out vector.Vector
for x := range GroupBy(elevenToTwenty, intkey{}).Iter() {
out.Push(x.(Group).Key)
}
assertArraysAreEqual(t, out, elevenToTwenty)
}
func TestUnique(t *testing.T) {
in := IntArray([]int{1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5})
exp := []int{1, 2, 3, 4, 5}
res := Unique(in, intkey{})
assertArraysAreEqual(t, Data(res), exp)
assertArraysAreEqual(t, Data(res), exp) // second time to ensure new iter is returned
// test case with only uniques
res = Unique(elevenToTwenty, intkey{})
assertArraysAreEqual(t, Data(res), elevenToTwenty)
}