Sequenceの話 ~kotlin.sequences.Sequence~

2016/07/01(金) 第3回 Kotlin 勉強会 @Sansanの発表した資料です

Transcript

1. Sequenceͷ࿩ @RyotaMurohoshi 2016/07/01'ୈ3ճ'Kotlinษڧձ'@SanSan
2. ໰୊ ࣍ͷίʔυΛ࣮ߦ͢ΔͱɺͲ͏දࣔ͞ΕΔͰ͠ΐ͏͔ʁ ೋͭͷબ୒ࢶ͔ΒબΜͰ͍ͩ͘͞
3. val list = listOf(1, 2, 3) val converted = list.map { println("map $it") it } println("--------") for(it in converted) println("for $it")
4. બ୒ࢶ1 map 1 map 2 map 3 -------- for 1 for 2 for 3
5. બ୒ࢶ2 -------- map 1 for 1 map 2 for 2 map 3 for 3
6. ͲͬͪͰ͠ΐ͏ʁ
7. ౴͑͸ બ୒ࢶ1
8. kotlin.collections.List<T>ͷmapϝιου͸ શཁૉΛଈ࠲ʹࣹӨ͠·͢
9. ͍ͭͮͯͷ໰୊ ࣍ͷίʔυΛ࣮ߦ͢ΔͱɺͲ͏දࣔ͞ΕΔͰ͠ΐ͏͔ʁ
10. val list = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9) val result = list .map { println("map $it") it } .filter { println("filter $it") it % 2 == 0 } .take(3) println("--------") for(it in result) println("for $it")
11. kotlin.collections.List<T>ͷfilterϝιου΋ mapϝιουͱಉ༷ʹଈ࠲ʹબ୒ॲཧ͕ߦΘΕ·͢ ɹ ͱ͍͏͜ͱ͸...
12. map 1 map 2 /* தུ */ map 9 filter 1 filter 2 /* தུ */ filter 9 -------- for 2 for 4 for 6
13. kotlin.collections.List<T>ͷ֤ϝιουͱ Java8ͷStream*API΍C#ͷLINQͷҧ͍ʹ஫ҙ
14. ࠷ޙͷ໰୊Ͱ͢
15. 100000ߦͷJSON'LinesϑΝΠϧ ͜ΕΛ1ߦͣͭdataΫϥεͷΦϒδΣΫτʹม׵͠ ͋Δ৚݅Λຬͨ͢ΦϒδΣΫτΛ ࠷ॳ͔Β10͚݅ͩ֬ೝද͍ࣔͨ͠
16. val lineList: List<String> = File("data.jsonlines").readLines() val result = lineList .map { convertToData(it) } .filter { filterData(it) } .take(10) for (it in result) { println(it) }
17. ໰୊ ɹ Կ͕Α͘ͳ͍Ͱ͔͢ʁ
18. ౴͑ 10݅ͷσʔλ͕ཉ͍͠ͷʹɺ 100000ߦͷσʔλɺ શͯಡΈࠐΜͰ͠·͍ͬͯΔ
19. ͦ͜ͰSequenceͰ͢Α
20. package kotlin.sequences public interface Sequence<out T> { public operator fun iterator(): Iterator<T> } ίϝϯτ͸ൈ͍ͯ·͕͢ɺҎԼΑΓ h"ps:/ /github.com/JetBrains/kotlin/blob/1.0.2/libraries/stdlib/src/kotlin/collec<ons/Sequence.kt
21. Sequences.ktʹ͸ map΍filterɺcountɺtakeͳͲ ଟ͘ͷ֦ுؔ਺͕ఆٛ͞Ε͍ͯ·͢
22. val list = listOf(1, 2, 3) val sequence = list.asSequence() // ஫໨ʂ val result = sequence .map { println("map $it") it } println("--------") for (it in result) println("for $it")
23. -------- map 1 for 1 map 2 for 2 map 3 for 3
24. ཁૉͷࣹӨ͸ forͰΠςϨʔτ͞ΕඞཁʹͳͬͨλΠϛϯάͰ ߦΘΕ·͢
25. // listOfͰͳ͘ɺsequenceOfʂ val sequence = sequenceOf(1, 2, 3, 4, 5, 6, 7, 8, 9) val converted = sequence .map { println("map $it") it } .filter { println("filter $it") it % 2 == 0 } .take(3) println("--------") for(it in converted) println("for $it")
26. -------- map 1 filter 1 map 2 filter 2 for 2 map 3 /*தུ*/ map 5 filter 5 map 6 filter 6 for 6
27. ϑΝΠϧͷྫ΋ݟͯΈ·͠ΐ͏ʂ
28. ͓͞Β͍ 100000ߦͷJSON'LinesϑΝΠϧ ͜ΕΛ1ߦͣͭdataΫϥεͷΦϒδΣΫτʹม׵͠ ͋Δ৚݅Λຬͨ͢ΦϒδΣΫτΛ ࠷ॳ͔Β10͚݅ͩ֬ೝද͍ࣔͨ͠
29. ໰୊఺͸ඞཁͳ͍ͷʹ ϑΝΠϧΛશ෦ಡΜͰ͠·͏͜ͱ
30. val result: List<PersonData> = File("data.jsonlines") .useLines { lineSequences: Sequence<String> -> lineSequences .map { convertToData(it) } .filter { filterData(it) } .take(10) .toList() } for (it in result) { println(it) }
31. ϙΠϯτʂʂʂ val result: List<PersonData> = File("data.jsonlines") .useLines { lineSequences: Sequence<String> -> /*ུ*/ } ͜ΕͰϑΝΠϧશ෦ΛಡΈࠐ·ͳ͍ʂʂʂ
32. ͱ͍͏͜ͱͰҰճ·ͱΊ
33. ৔໘ʹԠͯ͡ద੾ʹ࢖͓͏ʂ • List<T>ͷmap΍filterͱ͔͸ͦͷ৔ͰશཁૉΛॲཧ • Sequence<T>ͷmap΍filterͱ͔͸ඞཁʹͳͬͨཁૉΛॲཧ
34. ͱ͜ΖͰ...
35. Sequenceͷfilterͷ࣮૷͸...
36. public fun <T> Sequence<T>.filter(predicate: (T) -> Boolean): Sequence<T> { return FilteringSequence(this, true, predicate) }
37. ;Ή;ΉɺͳΔ΄Ͳ FilteringSequenceͷ࣮૷͸ʁ
38. internal class FilteringSequence<T>(private val sequence: Sequence<T>, private val sendWhen: Boolean = true, private val predicate: (T) -> Boolean ) : Sequence<T> { override fun iterator(): Iterator<T> = object : Iterator<T> { val iterator = sequence.iterator(); var nextState: Int = -1 // -1 for unknown, 0 for done, 1 for continue var nextItem: T? = null private fun calcNext() { while (iterator.hasNext()) { val item = iterator.next() if (predicate(item) == sendWhen) { nextItem = item nextState = 1 return } } nextState = 0 } override fun next(): T { if (nextState == -1) calcNext() if (nextState == 0) throw NoSuchElementException() val result = nextItem nextItem = null nextState = -1 return result as T } override fun hasNext(): Boolean { if (nextState == -1) calcNext() return nextState == 1 } } }
39. ͳ͛͐ʂʂʂ
40. IteratorΛ࣮૷ͨ͠ΦϒδΣΫτΛ࡞Βͳ͚Ε͹͍͚ͳ͍ ͍ͨ΁Μʂʂʂʂ
41. ΋͠Sequenceͷࣗ࡞֦ுؔ਺Λ࡞Δͱͨ͠Βɺ໘౗͍͘͞ʂʂʂ ɹ ͱ͜Ζ͕...
42. Kotlin'1.1Ͱ SequenceΛͭ͘Δϝιουָ͕ʹ ࡞Δ͜ͱ͕Ͱ͖ΔΑ͏ʹͳΓͦ͏ʂʂʂ
43. yield/generator 1.0ϦϦʔε࣌఺Ͱɺgenerator͸༧໿ޠʹͳΓ·ͨ͠Ͷ
44. yieldɺC#Ͱେ׆༂ʂʂʂ LINQ͸͜ͷyield͕׆༻͞Ε͍ͯΔʂ
45. ࣗݾ঺հ
46. • @RyotaMurohoshi • C#ɾUnity2(Unity෦2ӡӦ) • Unity༻ͷLINQϥΠϒϥϦ2UniLinq࡞੒ • KotlinͷLINQϥΠϒϥϦ2KotLinq࡞੒த
47. C#erͰ͢! LINQ͕޷͖Ͱ͢ʂ (Sequence.mapͱ͔ʹ͍ۙίϨΫγϣϯؔ਺܈)
48. C#ͰyieldΛ࢖ͬͯ filterʹ૬౰͢ΔॲཧΛߦ͏ʹ͸ʁ
49. C#Ͱfilterʹ૬౰͢ΔॲཧΛߦ͏ʹ͸ʁ public static IEnumerable<TSource> Filter<TSource> ( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) throw new ArgumentNullException (nameOf(source)); if (selector == null) throw new ArgumentNullException (nameOf(predicate)); return source.Filter_ (predicate); } public static IEnumerable<TSource> Filter_<TSource> ( this IEnumerable<TSource> source, Func<TSource,bool> predicate) { foreach (TSource element in source) if(predicate(element)) yield return element; }
50. େࣄͳ෦෼͸͜͜ʂ͜Μͳʹ୹͍ʂ public static IEnumerable<TSource> Filter_<TSource> ( this IEnumerable<TSource> source, Func<TSource,bool> predicate) { foreach (TSource element in source) if(predicate(element)) yield return element; } ࣮ࡍʹC#Ͱ࢖ΘΕΔɺWhere͸࠷దԽͷͨΊʹ΋ͬͱ৭ʑ΍ͬͯ·͢
51. yield࠷ߴʂ
52. Kotlinͷyield/generatorͨͷ͠ΈͰ͢Ͷʂ h"ps:/ /github.com/Kotlin/kotlin4corou6nes
53. ΋͔ͨ͠͠Β͜Μͳ෩ʹ୹͘ͳΔ͔ͳʁ public fun <T> Sequence<T>.filter(predicate: (T) -> Boolean): Sequence<T> = generate { for(it in this){ if(predicate(it)){ yield(it) } } }
54. ࣗ࡞Sequence֦ுؔ਺΋ॻ͖΍͘͢ͳΔ͔ͳʁ
55. એ఻ʂ
56. C#ͷLINQޓ׵ͷϥΠϒϥϦ KotLinq࡞͍ͬͯ·͢ʂʂʂ h"ps:/ /github.com/RyotaMurohoshi/KotLinq
57. KotLinq • (΄΅)LINQޓ׵ • IterableɺMapɺArrayɺSequence΁ͷ֦ு਺܈ • ࣹӨɺબ୒ͱ͔தؒૢ࡞ͷϝιουͰ͸SequenceΛฦ͢
58. ·ͱΊ • Sequenceɺ࢖͍Ͳ͜Ζ͕͋ͬͨΒͥͻʂ • yield/generator2ָ͠Έʂ • KotLinqΛ͓ٓ͘͠ئ͍͠·͢ʂ
59. ͓·͚
60. h"ps:/ /github.com/RyotaMurohoshi/Kollec8on
61. Μʁ
62. Kollec&on?
63. Kollec&on!!!?
64. ໊લม͑·͢ (΄ͱΜͲ࡞ͬͯͳ͍Ͱ͕͢)