Advanced techniques for building Kotlin DSL(s) - droidcon NYC 2022

How to create Kotlin DSL that looks like the syntax of a programming language?
In this talk, I would like to talk about advanced techniques for creating Kotlin DSL.
As an example, we will see how to build a DSL that looks like a Starlark programming language, a Python dialect used for writing build scripts for Bazel build system. This DSL is a declarative code generator that builds an abstract syntax tree of a Starlark language and then generates a formatted code based on it.
However, all the concepts described in this talk are applicable to any kind of Kotlin DSL(s) including ones for Android projects.
The example project was presented at BazelCon 2021, a Google conference about Bazel build system: https://youtu.be/dz-CFEwJuko
In addition, there is a blog post that shows the capabilities of this DSL: https://proandroiddev.com/304fa8b3680c
The source code is available on GitHub: https://github.com/Morfly/airin

Transcript

1. Advanced techniques for building Kotlin DSL(s) Pavlo Stavytskyi
2. About me • Google Developer Expert, Android • Mobile Infrastructure at Lyft 2
3. Agenda
4. • A concrete example of a Kotlin DSL Agenda 4
5. • A concrete example of a Kotlin DSL • DSL components Agenda 5
6. Concrete DSL example
7. Concrete DSL example • Starlark code generator (Python dialect) 7
8. Concrete DSL example • Starlark code generator (Python dialect) • Replicate Starlark syntax in Kotlin 8
9. Concrete DSL example • Starlark code generator (Python dialect) • Replicate Starlark syntax in Kotlin • https://github.com/Morfly/airin → airin-starlark 9
10. Starlark code generator
11. // Starlark/Python SRC_FILES = ["MyClass.java"] android_binary( name = "app", srcs = ["MainActivity.java"] + SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 11
12. // Kotlin DSL val starlarkFile = BUILD.bazel { val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) } fileWriter.write(starlarkFile) Starlark code generator 12
13. // Kotlin DSL val starlarkFile = BUILD.bazel { val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) } fileWriter.write(starlarkFile) // Creates BUILD.bazel file Starlark code generator 13
14. Starlark code generator 14 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression list expression SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … MainActivity.java string literal
15. MainActivity.java string literal android_binary function call Starlark file name argument srcs argument manifest argument + binary expression list expression SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … MainActivity.java string literal // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 15 android_binary function call Starlark file name argument manifest argument + binary expression SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES …
16. Starlark file name argument srcs argument manifest argument + binary expression SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … MainActivity.java string literal android_binary function call // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 16 android_binary function call list expression MainActivity.java string literal
17. // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 17 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression MainActivity.java string literal SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … name argument app string literal list expression MainActivity.java string literal
18. // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 18 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression MainActivity.java string literal SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … manifest argument AndroidManifest.xml string literal list expression MainActivity.java string literal
19. // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 19 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression MainActivity.java string literal SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … srcs argument list expression MainActivity.java string literal
20. // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 20 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression MainActivity.java string literal SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … + binary expression list expression MainActivity.java string literal
21. // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 21 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression MainActivity.java string literal SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … list expression SRC_FILES reference MainActivity.java string literal
22. // Kotlin DSL val SRC_FILES by list["MyClass.java"] android_binary( name = "app", srcs = list["MainActivity.java"] `+` SRCS_FILES, manifest = "AndroidManifest.xml", ) Starlark code generator 22 android_binary function call Starlark file name argument srcs argument manifest argument + binary expression MainActivity.java string literal SRC_FILES reference app string literal AndroidManifest.xml string literal SRC_FILES … list expression SRC_FILES reference MainActivity.java string literal
23. class StarlarkFile(val statements: List<Node>): Node Starlark code generator 23
24. class StarlarkFile(val statements: List<Node>): Node class FunctionCall(val name: String, val arguments: List<Node>): Node Starlark code generator 24
25. class StarlarkFile(val statements: List<Node>): Node class FunctionCall(val name: String, val arguments: List<Node>): Node class Argument(val name: String, param: Node) Starlark code generator 25
26. class StarlarkFile(val statements: List<Node>): Node class FunctionCall(val name: String, val arguments: List<Node>): Node class Argument(val name: String, param: Node) class StringLiteral(val value: String): Node class ListExpression(val items: List<Node>): Node class ListReference(val name: String): Node class BinaryPlus(val left: Node, val right: Node): Node Starlark code generator 26
27. Starlark DSL components
28. // Kotlin DSL val starlarkFile = BUILD.bazel { ... } fileWriter.write(starlarkFile) Entering DSL context 28
29. // Kotlin DSL val starlarkFile = BUILD.bazel { ... } fileWriter.write(starlarkFile) Entering DSL context 29
30. // Implementation object BUILD Lambdas with receiver 30
31. // Implementation object BUILD inline fun BUILD.bazel(body: StarlarkFileContext.() -> Unit): StarlarkFile { val context = StarlarkFileContext() context.body() val nodes = context.nodes return StarlarkFile(path, nodes) } Lambdas with receiver 31
32. // Implementation object BUILD inline fun BUILD.bazel(body: StarlarkFileContext.() -> Unit): StarlarkFile { val context = StarlarkFileContext() context.body() val nodes = context.nodes return StarlarkFile(path, nodes) } Lambdas with receiver 32
33. // Implementation object BUILD inline fun BUILD.bazel(body: StarlarkFileContext.() -> Unit): StarlarkFile { val context = StarlarkFileContext() context.body() val nodes = context.nodes return StarlarkFile(path, nodes) } Lambdas with receiver 33
34. // Kotlin DSL val buildFile = BUILD.bazel { this: StarlarkFileContext -> android_binary( name = "app", srcs = list["MainActivity.java"], manifest = "AndroidManifest.xml", ) } Lambdas with receiver 34
35. // Kotlin DSL class StarlarkFileContext { fun android_binary(...) {...} } val buildFile = BUILD.bazel { this: StarlarkFileContext -> android_binary( name = "app", srcs = list["MainActivity.java"], manifest = "AndroidManifest.xml", ) } Lambdas with receiver 35
36. // Kotlin DSL class StarlarkFileContext { val statements = mutableListOf<Node>() fun android_binary(...) {...} } Lambdas with receiver 36
37. Function calls
38. // Starlark/Python android_binary( name = "app", srcs = ["MainActivity.java"], manifest = "AndroidManifest.xml", ) Function calls 38
39. // Starlark/Python android_binary( name = "app", srcs = ["MainActivity.java"], manifest = "AndroidManifest.xml", ) // Kotlin DSL android_binary( name = "app", srcs = list["MainActivity.java"], manifest = "AndroidManifest.xml", ) Function calls 39
40. // Implementation fun StarlarkFileContext.android_binary( val name: String, val srcs: List<String?>? = null, val manifest: String? = null, ) { ... } Function calls 40
41. // Implementation fun StarlarkFileContext.android_binary( val name: String, val srcs: List<String?>? = null, val manifest: String? = null, ) { val args = listOf( Argument("name", StringLiteral(name)), Argument("srcs", ListExpression(srcs)), Argument("manifest", StringLiteral(manifest)) ) statements += FunctionCall("android_binary", args) } Function calls 41
42. Indexed access operator
43. // Starlark/Python [1, 2, 3] Indexed access operator 43
44. // Starlark/Python [1, 2, 3] // Kotlin DSL list[1, 2, 3] Indexed access operator 44
45. // Implementation object _ListExpressionBuilder val list get() = _ListExpressionBuilder Indexed access operator 45
46. // Implementation object _ListExpressionBuilder val list get() = _ListExpressionBuilder operator fun <T> _ListExpressionBuilder.get(vararg args: T): List<T> { return ListExpression(listOf(*args)) } Indexed access operator 46
47. // Implementation object _ListExpressionBuilder val list get() = _ListExpressionBuilder operator fun <T> _ListExpressionBuilder.get(vararg args: T): List<T> { return ListExpression(listOf(*args)) } // Kotlin DSL list["MainActivity.java"] Indexed access operator 47
48. Property delegation
49. // Starlark/Python MY_STRING = "value" MY_LIST = [1, 2, 3] MY_DICT = {"key": "value"} Property delegation 49
50. // Starlark/Python MY_STRING = "value" MY_LIST = [1, 2, 3] MY_DICT = {"key": "value"} // Kotlin DSL val MY_STRING by "value" val MY_LIST by list[1, 2, 3] val MY_DICT by {"key" to "value"} Property delegation 50
51. // Starlark/Python MY_STRING = "value" MY_LIST = [1, 2, 3] MY_DICT = {"key": "value"} // Kotlin DSL val MY_STRING by "value" val MY_LIST by list[1, 2, 3] val MY_DICT by {"key" to "value"} Property delegation 51
52. // Starlark/Python MY_STRING = "value" MY_LIST = [1, 2, 3] MY_DICT = {"key": "value"} // Kotlin DSL val MY_STRING by "value" val MY_LIST by list[1, 2, 3] val MY_DICT by {"key" to "value"} Property delegation 52
53. // Starlark/Python MY_STRING = "value" MY_LIST = [1, 2, 3] MY_DICT = {"key": "value"} // Kotlin DSL val MY_STRING by "value" val MY_STRING = "value" val MY_LIST by list[1, 2, 3] val MY_DICT by {"key" to "value"} Property delegation 53
54. // Starlark/Python MY_STRING = "value" MY_LIST = [1, 2, 3] MY_DICT = {"key": "value"} // Kotlin DSL val MY_STRING: StringReference by "value" val MY_LIST: ListReference by list[1, 2, 3] val MY_DICT: DictionaryReference by {"key" to "value"} Property delegation 54
55. // Implementation class ListReference<out T>(val name: String) : List<T>, Node Property delegation 55
56. // Implementation class ListReference<out T>(val name: String) : List<T>, Node class DictionaryReference<K, V: Any>(val name: String) : Map<K, V>, Node Property delegation 56
57. // Implementation class ListReference<out T>(val name: String) : List<T>, Node class DictionaryReference<K, V: Any>(val name: String) : Map<K, V>, Node class StringReference(val name: String) : String, Node Property delegation 57
58. // Implementation class ListReference<out T>(val name: String) : List<T>, Node class DictionaryReference<K, V: Any>(val name: String) : Map<K, V>, Node class StringReference(val name: String) : CharSequence, Node Property delegation 58
59. // Kotlin DSL val NAME by "app" val SRCS by list["MainActivity.java"] val MANIFEST_VALUES by dict {"minSdkVersion" to "21"} android_binary( name = NAME, // String srcs = SRCS, // List manifest_values = MANIFEST_VALUES // Dictionary ) Property delegation 59
60. // Implementation fun StarlarkFileContext.android_binary( val name: CharSequence, val srcs: List<CharSequence?>? = null, val manifest_values: Map<CharSequence?, CharSequence?>? = null, ) {...} Property delegation 60
61. Making DSL customizable
62. Dynamic function args 62 // Starlark/Python android_binary( name = "app", srcs = ["MainActivity.java"], some_new_argument = {"key": "value"} )
63. Dynamic function args 63 // Starlark android_binary( name = "app", srcs = ["MainActivity.java"], some_new_argument = {"key": "value"} ) // Kotlin DSL android_binary { name = "app" srcs = list["MainActivity.java"] "some_new_argument" `=` {"key" to "value"} }
64. Dynamic function args 64 // Starlark android_binary( name = "app", srcs = ["MainActivity.java"], some_new_argument = {"key": "value"} ) // Kotlin DSL android_binary { name = "app" srcs = list["MainActivity.java"] "some_new_argument" `=` {"key" to "value"} }
65. Dynamic function args 65 // Starlark android_binary( name = "app", srcs = ["MainActivity.java"], some_new_argument = {"key": "value"} ) // Kotlin DSL android_binary { name = "app" srcs = list["MainActivity.java"] "some_new_argument" `=` {"key" to "value"} }
66. Dynamic function args 66 // Starlark android_binary( name = "app", srcs = ["MainActivity.java"], some_new_argument = {"key": "value"} ) // Kotlin DSL android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] "some_new_argument" `=` {"key" to "value"} }
67. Dynamic function args 67 // Implementation class AndroidBinaryContext { val args = linkedSetOf<Argument>() var name: CharSequence by args var srcs: ListType<CharSequence?>? by args var manifest: CharSequence? by args }
68. Dynamic function args 68 // Implementation class AndroidBinaryContext { val args = linkedSetOf<Argument>() var name: CharSequence by args var srcs: ListType<CharSequence?>? by args var manifest: CharSequence? by args infix fun CharSequence.`=`(value: CharSequence) { args = Argument(id = this, value = Expression(value, ::StringLiteral)) } }
69. Dynamic function args 69 // Implementation class AndroidBinaryContext { val args = linkedSetOf<Argument>() var name: CharSequence by args var srcs: ListType<CharSequence?>? by args var manifest: CharSequence? by args infix fun CharSequence.`=`(value: CharSequence) { args = Argument(id = this, value = Expression(value, ::StringLiteral)) } }
70. Dynamic function calls 70 // Starlark/Python some_new_function( name = "app", )
71. Dynamic function calls 71 // Starlark/Python some_new_function( name = "app", ) // Kotlin DSL "some_new_function" { "name" `=` "app" }
72. Dynamic function calls 72 // Implementation operator fun String.invoke(body: FunctionCallContext.() -> Unit) { val args = FunctionCallContext().apply(body).args statements += VoidFunctionCall(name, args) }
73. Dynamic function calls 73 // Implementation operator fun String.invoke(body: FunctionCallContext.() -> Unit) { val args = FunctionCallContext().apply(body).args statements += VoidFunctionCall(name, args) }
74. Dynamic function calls 74 // Implementation operator fun String.invoke(body: FunctionCallContext.() -> Unit) { val args = FunctionCallContext().apply(body).args statements += VoidFunctionCall(name, args) }
75. Combining elements
76. Concatenations 76 // Starlark/Python SOURCE_FILES = ["MainViewModel.java"] android_binary( name = "app", srcs = SOURCE_FILES + ["MainActivity.java"], )
77. Concatenations 77 // Starlark/Python SOURCE_FILES = ["MainViewModel.java"] android_binary( name = "app", srcs = SOURCE_FILES + ["MainActivity.java"], ) // Kotlin DSL val SOURCE_FILES by list["MainViewModel.java"] android_binary( name = "app", srcs = SOURCE_FILES `+` list["MainActivity.java"], )
78. Concatenations 78 // Starlark/Python SOURCE_FILES = ["MainViewModel.java"] android_binary( name = "app", srcs = SOURCE_FILES + ["MainActivity.java"], ) // Kotlin DSL val SOURCE_FILES by list["MainViewModel.java"] android_binary( name = "app", srcs = SOURCE_FILES `+` list["MainActivity.java"], srcs = SOURCE_FILES + list["MainActivity.java"], )
79. Concatenations 79 // Implementation infix fun <T> List<T>?.`+`(other: List<T>?): List<T> = ListBinaryOperation( left = Expression(this, ::ListExpression), operator = BinaryOperator.PLUS, right = Expression(other, ::ListExpression) )
80. Concatenations 80 // Implementation infix fun <T> List<T>?.`+`(other: List<T>?): List<T> = ListBinaryOperation( left = Expression(this, ::ListExpression), operator = BinaryOperator.PLUS, right = Expression(other, ::ListExpression) ) class ListBinaryOperation<T>( val left: Node, val operator: BinaryOperator, val right: Node ) : Node, List<T>
81. Concatenations 81 // Implementation infix fun <T> List<T>?.`+`(other: List<T>?): List<T> = ListBinaryOperation( left = Expression(this, ::ListExpression), operator = BinaryOperator.PLUS, right = Expression(other, ::ListExpression) ) class ListBinaryOperation<T>( val left: Node, val operator: BinaryOperator, val right: Node ) : Node, List<T>
82. Context conflicts
83. Context conflicts 83 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] } }
84. Context conflicts 84 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] android_binary {...} } }
85. Context conflicts 85 // Kotlin DSL @DslMarker annotation class LanguageScope
86. Context conflicts 86 // Kotlin DSL @DslMarker annotation class LanguageScope @LanguageScope class StarlarkFileContext @LanguageScope class AndroidBinaryContext
87. Context conflicts 87 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] android_binary {...} } }
88. Context conflicts 88 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] `+` list["MainViewModel.java"] } }
89. Context conflicts 89 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] `+` list["MainViewModel.java"] } }
90. Restructuring the DSL
91. Restructuring the DSL 91 // Kotlin DSL sealed interface ConcatenationsFeature { // implement `+` operators }
92. Restructuring the DSL 92 // Kotlin DSL sealed interface ConcatenationsFeature { // implement `+` operators } @LanguageScope class StarlarkFileContext: ConcatenationsFeature {...} @LanguageScope class AndroidBinaryContext: ConcatenationsFeature {...}
93. Restructuring the DSL 93 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> name = "app" srcs = list["MainActivity.java"] `+` list["MainViewModel.java"] } }
94. Restructuring the DSL 94 // Kotlin DSL BUILD.bazel { this: StarlarkFileContext -> android_binary { this: AndroidBinaryContext -> "manifest_values" `=` { this: DictionaryContext -> "key_" `+` "1" to "value_" `+` "1" } } }
95. Restructuring the DSL 95 // Kotlin DSL BUILD.bazel { android_binary { "manifest_values" `=` { this: DictionaryContext -> "key_" `+` "1" to "value_" `+` "1" } } }
96. Additional features
97. List comprehensions 97 // Starlark/Python SRCS = [file + ".java" for file in ["MainActivity"]]
98. List comprehensions 98 // Starlark/Python SRCS = [file + ".java" for file in ["MainActivity"]] // Kotlin DSL val SRCS by "file" `in` list["MainActivity"] take { it `+` ".java" }
99. List comprehensions 99 // Starlark/Python SRCS = [file + ".java" for file in ["MainActivity"]] // Kotlin DSL val SRCS by "file" `in` list["MainActivity"] take { it `+` ".java" }
100. List comprehensions 100 // Starlark/Python SRCS = [file + ".java" for file in ["MainActivity"]] // Kotlin DSL val SRCS by "file" `in` list["MainActivity"] take { it `+` ".java" }
101. List comprehensions 101 // Starlark/Python SRCS = [file + ".java" for file in ["MainActivity"]] // Kotlin DSL val SRCS by "file" `in` list["MainActivity"] take { it `+` ".java" }
102. List comprehensions 102 // Starlark/Python SRCS = [file + ".java" for file in ["MainActivity"]] // Kotlin DSL val SRCS by "file" `in` list["MainActivity"] take { it: CharSequence -> it `+` ".java" }
103. Applying KSP
104. // Starlark/Python android_binary( name = "app", srcs = ["MainActivity.java"], manifest = "AndroidManifest.xml", ) Applying KSP 104
105. class AndroidBinaryContext : FunctionCallContext() { var name: Name by fargs var custom_package: StringType? by fargs var manifest: Label? by fargs var manifest_values: DictionaryType<Key?, Value?>? by fargs var debug_key: Label? by fargs var enable_data_binding: BooleanType? by fargs var multidex: StringType? by fargs var incremental_dexing: NumberType? by fargs var crunch_png: BooleanType? by fargs var dex_shards: NumberType? by fargs var resource_files: ListType<Label?>? by fargs var srcs: ListType<Label?>? by fargs var plugins: ListType<Label?>? by fargs var deps: ListType<Label?>? by fargs var visibility: ListType<Label?>? by fargs var args: ListType<StringType?>? by fargs var env: DictionaryType<Key?, Value?>? by fargs var output_licenses: ListType<StringType?>? by fargs } fun BuildStatementsLibrary.`android_binary`(body: AndroidBinaryContext.() -> Unit): Unit = registerFunctionCallStatement("android_binary", AndroidBinaryContext(), body) Applying KSP 105
106. class AndroidBinaryContext : FunctionCallContext() { var name: Name by fargs var custom_package: StringType? by fargs var manifest: Label? by fargs var manifest_values: DictionaryType<Key?, Value?>? by fargs var debug_key: Label? by fargs var enable_data_binding: BooleanType? by fargs var multidex: StringType? by fargs var incremental_dexing: NumberType? by fargs var crunch_png: BooleanType? by fargs var dex_shards: NumberType? by fargs var resource_files: ListType<Label?>? by fargs var srcs: ListType<Label?>? by fargs var plugins: ListType<Label?>? by fargs var deps: ListType<Label?>? by fargs var visibility: ListType<Label?>? by fargs var args: ListType<StringType?>? by fargs var env: DictionaryType<Key?, Value?>? by fargs var output_licenses: ListType<StringType?>? by fargs } fun BuildStatementsLibrary.`android_binary`(body: AndroidBinaryContext.() -> Unit): Unit = registerFunctionCallStatement("android_binary", AndroidBinaryContext(), body) Applying KSP 106 fun BuildStatementsLibrary.`android_binary`( name: Name, custom_package: StringType? = UnspecifiedString, manifest: Label? = UnspecifiedString, manifest_values: DictionaryType<Key?, Value?>? = UnspecifiedDictionary, debug_key: Label? = UnspecifiedString, enable_data_binding: BooleanType? = UnspecifiedBoolean, multidex: StringType? = UnspecifiedString, incremental_dexing: NumberType? = UnspecifiedNumber, crunch_png: BooleanType? = UnspecifiedBoolean, dex_shards: NumberType? = UnspecifiedNumber, resource_files: ListType<Label?>? = UnspecifiedList, srcs: ListType<Label?>? = UnspecifiedList, plugins: ListType<Label?>? = UnspecifiedList, deps: ListType<Label?>? = UnspecifiedList, visibility: ListType<Label?>? = UnspecifiedList, args: ListType<StringType?>? = UnspecifiedList, env: DictionaryType<Key?, Value?>? = UnspecifiedDictionary, output_licenses: ListType<StringType?>? = UnspecifiedList ): Unit { val _args = linkedSetOf<Argument>().also { it += Argument("name", Expression(name, ::StringLiteral)) if (custom_package !== UnspecifiedString) it += Argument("custom_package", Expression(custom_package, ::StringLiteral)) if (manifest !== UnspecifiedString) it += Argument("manifest", Expression(manifest, ::StringLiteral)) if (manifest_values !== UnspecifiedDictionary) it += Argument("manifest_values", Expression(manifest_values, ::DictionaryExpression)) if (debug_key !== UnspecifiedString) it += Argument("debug_key", Expression(debug_key, ::StringLiteral)) if (enable_data_binding !== UnspecifiedBoolean) it += Argument("enable_data_binding", Expression(enable_data_binding, ::BooleanLiteral)) if (multidex !== UnspecifiedString) it += Argument("multidex", Expression(multidex, ::StringLiteral)) if (incremental_dexing !== UnspecifiedNumber) it += Argument("incremental_dexing", Expression(incremental_dexing, ::NumberLiteral)) if (crunch_png !== UnspecifiedBoolean) it += Argument("crunch_png", Expression(crunch_png, ::BooleanLiteral)) if (dex_shards !== UnspecifiedNumber) it += Argument("dex_shards", Expression(dex_shards, ::NumberLiteral)) if (resource_files !== UnspecifiedList) it += Argument("resource_files", Expression(resource_files, ::ListExpression)) if (srcs !== UnspecifiedList) it += Argument("srcs", Expression(srcs, ::ListExpression)) if (plugins !== UnspecifiedList) it += Argument("plugins", Expression(plugins, ::ListExpression)) if (deps !== UnspecifiedList) it += Argument("deps", Expression(deps, ::ListExpression)) if (visibility !== UnspecifiedList) it += Argument("visibility", Expression(visibility, ::ListExpression)) if (args !== UnspecifiedList) it += Argument("args", Expression(args, ::ListExpression)) if (env !== UnspecifiedDictionary) it += Argument("env", Expression(env, ::DictionaryExpression)) if (output_licenses !== UnspecifiedList) it += Argument("output_licenses", Expression(output_licenses, ::ListExpression)) } return registerFunctionCallStatement("android_binary", _args) }
107. // Kotlin DSL @LibraryFunction(name = "android_binary") private interface AndroidBinary { @Argument(required = true) val name: Name val manifest: CharSequence? val srcs: List<CharSequence?>? val deps: List<CharSequence?>? ... } Applying KSP 107
108. // Kotlin DSL @LibraryFunction(name = "android_binary") private interface AndroidBinary { @Argument(required = true) val name: Name val manifest: CharSequence? val srcs: List<CharSequence?>? val deps: List<CharSequence?>? ... } Applying KSP 108
109. How does it look like in practice?
110. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 110
111. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 111
112. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 112
113. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 113
114. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 114
115. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 115
116. // Starlark/Python VIEW_MODELS_WITH_RES_IMPORTS = ["MyViewModel.kt", ...] [ genrule( name = "modify_imports_in_" + file[0:-3], srcs = [file], outs = [file[0:-3] + "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import org.morfly.airin.sample.app.R/import org.morfly.airin.sample.app.viewmodels.R/g' > $(OUTS) """, ) for file in VIEW_MODELS_WITH_RES_IMPORTS ] Usage example 116
117. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 117
118. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 118
119. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 119
120. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 120
121. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 121
122. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 122
123. val VIEW_MODELS_WITH_RES_IMPORTS by list["MyViewModel.kt", ...] "file" `in` VIEW_MODELS_WITH_RES_IMPORTS take { file -> genrule( name = "modify_imports_in_" `+` file[0..-3], srcs = list[file], outs = list[file[0..-3] `+` "_synthetic.kt"], cmd = """ cat $(SRCS) | sed 's/import $packageName.R/import $packageName.viewmodels.R/g' > $(OUTS) """.trimIndent() ) } Usage example 123
124. Conclusions
125. Conclusions 125 • Apply Kotlin syntax elements in non-conventional ways
126. Conclusions 126 • Apply Kotlin syntax elements in non-conventional ways • Experiment!
127. Source code 127 • https://github.com/Morfly/airin → airin-starlark