How Kotlin implements features Java doesn't have

CA.kt #1
TwitterID変えました。@lvla0805 -> @MoyuruAizawa

Transcript

1. How Kotlin implements features Java doesn’t have @lvla0805
2. Ѫᖒ
   ๖ (Moyuru Aizawa) lvla lvla0805 - Kotlin engineer at CyberAgent, Inc. - FRESH!
3. Data Classes Sealed Classes Extension Functions Inline Functions Default Arguments Named Arguments Delegation Properties Auto Casts Type Alias Covariance Null Safety Elvis Operator Spread Operator Operator Overloading Type Inference DSL Support Type-Safe Builders Coroutines String Interpolation Rages Map Array Syntax Destructuring KDoc
5. Bytecode
6. NonNull / Nullable Extension Function Named Argument / Default Argument
7. NonNull / Nullable
8. fun nonNullInt(number: Int) { number.toString() } NonNull: Kotlin
9. public final nonNullInt(I)V L0 LINENUMBER 7 L0 ILOAD 1 INVOKESTATIC java/lang/String.valueOf (I)Ljava/lang/String; POP … NonNull: Bytecode
10. public final nonNullInt(I)V L0 LINENUMBER 7 L0 ILOAD 1 INVOKESTATIC java/lang/String.valueOf (I)Ljava/lang/String; POP … NonNull: Bytecode
11. public final void nonNullInt(int number) { String.valueOf(number); } NonNull: Java
12. fun nullableInt(number: Int?) { number?.toString() } Nullable: Kotlin
13. public final nullableInt(Ljava/lang/Integer;)V @Lorg/jetbrains/annotations/Nullable;() // invisible, parameter 0 L0 LINENUMBER 7 L0 ALOAD 1 DUP IFNULL L1 INVOKEVIRTUAL java/lang/Integer.intValue ()I INVOKESTATIC java/lang/String.valueOf (I)Ljava/lang/String; POP GOTO L2 L1 POP … Nullable: Bytecode
14. public final nullableInt(Ljava/lang/Integer;)V @Lorg/jetbrains/annotations/Nullable;() // invisible, parameter 0 L0 LINENUMBER 7 L0 ALOAD 1 DUP IFNULL L1 INVOKEVIRTUAL java/lang/Integer.intValue ()I INVOKESTATIC java/lang/String.valueOf (I)Ljava/lang/String; POP GOTO L2 L1 POP … Nullable: Bytecode
15. public final nullableInt(Ljava/lang/Integer;)V @Lorg/jetbrains/annotations/Nullable;() // invisible, parameter 0 L0 LINENUMBER 7 L0 ALOAD 1 DUP IFNULL L1 INVOKEVIRTUAL java/lang/Integer.intValue ()I INVOKESTATIC java/lang/String.valueOf (I)Ljava/lang/String; POP GOTO L2 L1 POP … Nullable: Bytecode
16. public final void nullableInt(@Nullable Integer number) { if(number != null) { String.valueOf(number.intValue()); } } Nullable: Java
17. fun nonNullString(string: String) { string.length } NonNull: Kotlin
18. public final nonNullString(Ljava/lang/String;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 ALOAD 1 LDC "string" INVOKESTATIC kotlin/jvm/internal/Intrinsics.checkParameterIsNotNull (Ljava/lang/Object;Ljava/lang/String;)V L1 LINENUMBER 7 L1 ALOAD 1 INVOKEVIRTUAL java/lang/String.length ()I POP … NonNull: Bytecode
19. public final nonNullString(Ljava/lang/String;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 ALOAD 1 LDC "string" INVOKESTATIC kotlin/jvm/internal/Intrinsics.checkParameterIsNotNull (Ljava/lang/Object;Ljava/lang/String;)V L1 LINENUMBER 7 L1 ALOAD 1 INVOKEVIRTUAL java/lang/String.length ()I POP … NonNull
20. public final nonNullString(Ljava/lang/String;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 ALOAD 1 LDC "string" INVOKESTATIC kotlin/jvm/internal/Intrinsics.checkParameterIsNotNull (Ljava/lang/Object;Ljava/lang/String;)V L1 LINENUMBER 7 L1 ALOAD 1 INVOKEVIRTUAL java/lang/String.length ()I POP … NonNull: Bytecode
21. public final void nonNullString(@NotNull String string) { Intrinsics.checkParameterIsNotNull(string, "string"); string.length(); } NonNull: Java
22. private fun nonNullString(string: String) { string.length } NonNull: Kotlin
23. private final nonNullString(Ljava/lang/String;)V L0 LINENUMBER 7 L0 ALOAD 1 INVOKEVIRTUAL java/lang/String.length ()I POP NonNull: Bytecode
24. private fun nullableString(string: String?) { string?.length } Nullable: Kotlin
25. private final static nullableString(Ljava/lang/String;)V L0 LINENUMBER 2 L0 ALOAD 0 DUP IFNULL L1 INVOKEVIRTUAL java/lang/String.length ()I POP GOTO L2 L1 POP L2 L3 LINENUMBER 3 L3 RETURN … Nullable: Bytecode
26. private final void nullableString(String string) { if(string != null) { string.length(); } } Nullable: Java
27. Conclusion of NonNull/Nullable Primitive NonNull -> Primitive Primitive Nullable -> BoxType ClassType NonNull -> ClassType, Check Null ClassType Nullable -> ClassType Safe Call -> IFNULL
28. Extension Function
29. fun String.println() { println(this) } "Hello World".println() // out: Hello World Extension Function
30. Package Level Extension Function
31. // in StringExtension.kt fun String.println() { println(this) } Package Level Extension Function: Kotlin
32. public final class StringExtensionKt { public final static println(Ljava/lang/String;)V … } Package Level Extension Function: Bytecode
33. public final class StringExtensionKt { public final static println(Ljava/lang/String;)V … } Package Level Extension Function: Bytecode
34. public final class StringExtensionKt { public final static println(Ljava/lang/String;)V … } Package Level Extension Function: Bytecode
35. public final class StringExtensionKt { public static final void println(@NotNull String $receiver) { Intrinsics.checkParameterIsNotNull($receiver, "$receiver"); System.out.println($receiver); } } Package Level Extension Function: Java
36. Class Level Extension Function
37. class Foo { fun String.println() { println(this) } } Class Level Extension Function: Kotlin
38. public final class Foo { public final println(Ljava/lang/String;)V … } Class Level Extension Function: Bytecode
39. Extension Function Package Level Extension Function -> Static Method Class Level Extension Function -> Method
40. Package Level Extension Function Package Level Extension Function -> Static Method
41. Package Level Extension Function Public Package Level Extension Function -> Public Static Method Private Package Level Extension Function -> Private Static Method
42. Scope of Package Level Extension Public Package Level Extension Function -> Anywhere Private Package Level Extension Function -> Same file
43. Private Package Level Extension Function Private Package Level Extension Function -> Private Static Method
44. // in Bar.kt private fun Foo.doSomething() { } class Foo { init { doSomething() } } Private Package Level Extension Function: Kotlin
45. public final class FooKt { private final static doSomething(LFoo;)V … public final static synthetic access$doSomething(LFoo;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 LINENUMBER 1 L0 ALOAD 0 INVOKESTATIC FooKt.doSomething (LFoo;)V RETURN L1 LOCALVARIABLE $receiver LFoo; L0 L1 0 MAXSTACK = 1 MAXLOCALS = 1 Private Package Level Extension Function: Bytecode
46. public final class FooKt { private final static doSomething(LFoo;)V … public final static synthetic access$doSomething(LFoo;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 LINENUMBER 1 L0 ALOAD 0 INVOKESTATIC FooKt.doSomething (LFoo;)V RETURN L1 LOCALVARIABLE $receiver LFoo; L0 L1 0 MAXSTACK = 1 MAXLOCALS = 1 Private Package Level Extension Function: Bytecode
47. public final class FooKt { private final static doSomething(LFoo;)V … public final static synthetic access$doSomething(LFoo;)V @Lorg/jetbrains/annotations/NotNull;() // invisible, parameter 0 L0 LINENUMBER 1 L0 ALOAD 0 INVOKESTATIC FooKt.doSomething (LFoo;)V RETURN L1 LOCALVARIABLE $receiver LFoo; L0 L1 0 MAXSTACK = 1 MAXLOCALS = 1 Private Package Level Extension Function: Bytecode
48. Conclusion of Extension Function Package Level Extension Function -> Static Method Class Level Extension Function -> Method Call Private Package Level Extension Function from inside a class of same file -> Private Static Method and Accessor Method
49. Named Argument Default Argument
50. fun foo(one: String, two: String, three: String) { } foo(three = "tres", one = "uno", two = "dos") Named Argument: Kotlin
51. LDC "tres" LDC "uno" LDC "dos" ASTORE 1 ASTORE 2 ASTORE 3 ALOAD 2 ALOAD 1 ALOAD 3 INVOKEVIRTUAL Foo.foo (Ljava/lang/String;Ljava/lang/String;Ljava/lang/ String;)V Named Argument: Bytecode
52. LDC "tres" LDC "uno" LDC "dos" ASTORE 1 ASTORE 2 ASTORE 3 ALOAD 2 ALOAD 1 ALOAD 3 INVOKEVIRTUAL Foo.foo (Ljava/lang/String;Ljava/lang/String;Ljava/lang/ String;)V Named Argument: Bytecode
53. LDC "tres" LDC "uno" LDC "dos" ASTORE 1 ASTORE 2 ASTORE 3 ALOAD 2 ALOAD 1 ALOAD 3 INVOKEVIRTUAL Foo.foo (Ljava/lang/String;Ljava/lang/String;Ljava/lang/ String;)V Named Argument: Bytecode
54. LDC "tres" LDC "uno" LDC "dos" ASTORE 1 ASTORE 2 ASTORE 3 ALOAD 2 ALOAD 1 ALOAD 3 INVOKEVIRTUAL Foo.foo (Ljava/lang/String;Ljava/lang/String;Ljava/lang/ String;)V Named Argument: Bytecode
55. String var1 = "dos"; String var2 = "uno"; String var3 = "tres"; this.foo(var2, var1, var3); Named Argument: Java
56. fun foo(one: String = “one", two: String = “two", three: String = "three") { } foo() foo("uno") foo("uno", "dos") foo("uno", "dos", "tres") foo(two = "dos") Default Argument: Kotlin
57. fun foo(one: String = “one", two: String = “two", three: String = "three") { } foo(two = "dos") Default Argument: Kotlin
58. ‣ public static void foo(String, String, String) ‣ public static void foo$default(String, String, String, int, Object) Default Argument: Java
59. foo(two = "dos") Default Argument: Kotlin
60. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
61. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
62. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
63. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
64. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
65. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
66. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
67. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 0 1 1
68. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 101
69. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java
70. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java var1: null var2: “dos” var3: null
71. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 101 001 101
 and 001 001 var1: null var2: “dos” var3: null
72. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 101 001 101
 and 001 001 var1: “one” var2: “dos” var3: null
73. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 101 010 101
 and 010 000 var1: “one” var2: “dos” var3: null
74. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 101 100 101
 and 100 100 var1: “one” var2: “dos” var3: null
75. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java 101 100 101
 and 100 100 var1: “one” var2: “dos” var3: “three”
76. public static void foo$default( String var1, String var2, String var3, int var4, Object var5) { if((var4 & 1) != 0) { var1 = "one"; } if((var4 & 2) != 0) { var2 = "two"; } if((var4 & 4) != 0) { var3 = "three"; } foo(var1, var2, var3); } foo$default((String)null, "dos", (String)null, 5, (Object)null); Default Argument: Java “one”“dos”“three”
77. Thank you