+++ /dev/null
-// 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 })
-}
+++ /dev/null
-// 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)
-}