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Provide flatMapIndexed operation

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- similar to flatMap, but transform function takes index and element

#KT-36894
This commit is contained in:
Ilya Gorbunov
2020-06-19 16:16:55 +03:00
parent db93462bcf
commit 130987fa1e
20 changed files with 1216 additions and 74 deletions
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libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt
+66 -57
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@@ -311,7 +311,7 @@ object Mapping : TemplateGroupBase() {
doc { "Returns a single sequence of all elements from results of [transform] function being invoked on each element of original sequence." }
returns("Sequence<R>")
body {
"return FlatteningSequence(this, transform, { it.iterator() })"
"return FlatteningSequence(this, transform, Iterable<R>::iterator)"
}
}
}
@@ -338,7 +338,7 @@ object Mapping : TemplateGroupBase() {
doc { "Returns a single sequence of all elements from results of [transform] function being invoked on each element of original sequence." }
returns("Sequence<R>")
body {
"return FlatteningSequence(this, transform, { it.iterator() })"
"return FlatteningSequence(this, transform, Sequence<R>::iterator)"
}
}
}
@@ -396,70 +396,79 @@ object Mapping : TemplateGroupBase() {
}
}
val f_flatMapIndexed = fn("flatMapIndexed(transform: (index: Int, T) -> Iterable<R>)") {
includeDefault()
include(Maps, CharSequences, ArraysOfUnsigned)
} builder {
inlineOnly()
val f_flatMapIndexed = listOf(Iterables, Sequences).map { containerFamily ->
val containerClass = containerFamily.name.dropLast(1)
fn("flatMapIndexed(transform: (index: Int, T) -> $containerClass<R>)") {
when (containerFamily) {
Iterables -> include(Iterables, Sequences, ArraysOfObjects, ArraysOfPrimitives, ArraysOfUnsigned, CharSequences)
Sequences -> include(Sequences, Iterables, ArraysOfObjects)
}
} builder {
inlineOnly()
doc {
"""
Returns a single ${f.mapResult} of all elements yielded from results of [transform] function being invoked on each ${f.element}
and its index in the original ${f.collection}.
"""
}
sample("samples.collections.Collections.Transformations.flatMap")
typeParam("R")
returns("List<R>")
body {
"return flatMapIndexedTo(ArrayList<R>(), transform)"
}
specialFor(Sequences) {
inline(Inline.No)
signature("flatMapIndexed(transform: (index: Int, T) -> Sequence<R>)")
returns("Sequence<R>")
since("1.4")
doc {
"""
Returns a single ${f.mapResult} of all elements yielded from results of [transform] function being invoked on each ${f.element}
and its index in the original ${f.collection}.
"""
}
annotation("@OptIn(kotlin.experimental.ExperimentalTypeInference::class)")
annotation("@OverloadResolutionByLambdaReturnType")
if (family != ArraysOfUnsigned)
annotation("""@kotlin.jvm.JvmName("flatMapIndexed$containerClass")""")
sample("samples.collections.Collections.Transformations.flatMapIndexed")
typeParam("R")
returns("List<R>")
body {
"""
return sequence {
var index = 0
for (element in this@flatMapIndexed) {
val result = transform(checkIndexOverflow(index++), element)
for (r in result) yield(r)
}
"return flatMapIndexedTo(ArrayList<R>(), transform)"
}
specialFor(Sequences) {
inline(Inline.No)
returns("Sequence<R>")
body {
"return flatMapIndexed(this, transform, $containerClass<R>::iterator)"
}
"""
}
}
}
val f_flatMapIndexedTo = fn("flatMapIndexedTo(destination: C, transform: (index: Int, T) -> Iterable<R>)") {
includeDefault()
include(Maps, CharSequences, ArraysOfUnsigned)
} builder {
inlineOnly()
doc {
"""
Appends all elements yielded from results of [transform] function being invoked on each ${f.element}
and its index in the original ${f.collection}, to the given [destination].
"""
}
specialFor(Sequences) {
signature("flatMapIndexedTo(destination: C, transform: (index: Int, T) -> Sequence<R>)")
}
typeParam("R")
typeParam("C : MutableCollection<in R>")
returns("C")
body {
fun checkOverflow(value: String) = if (f == Sequences || f == Iterables) "checkIndexOverflow($value)" else value
"""
var index = 0
for (element in this) {
val list = transform(${checkOverflow("index++")}, element)
destination.addAll(list)
val f_flatMapIndexedTo = listOf(Iterables, Sequences).map { containerFamily ->
val containerClass = containerFamily.name.dropLast(1)
fn("flatMapIndexedTo(destination: C, transform: (index: Int, T) -> $containerClass<R>)") {
when (containerFamily) {
Iterables -> include(Iterables, Sequences, ArraysOfObjects, ArraysOfPrimitives, ArraysOfUnsigned, CharSequences)
Sequences -> include(Sequences, Iterables, ArraysOfObjects)
}
} builder {
inlineOnly()
since("1.4")
doc {
"""
Appends all elements yielded from results of [transform] function being invoked on each ${f.element}
and its index in the original ${f.collection}, to the given [destination].
"""
}
annotation("@OptIn(kotlin.experimental.ExperimentalTypeInference::class)")
annotation("@OverloadResolutionByLambdaReturnType")
if (family != ArraysOfUnsigned)
annotation("""@kotlin.jvm.JvmName("flatMapIndexed${containerClass}To")""")
typeParam("R")
typeParam("C : MutableCollection<in R>")
returns("C")
body {
fun checkOverflow(value: String) = if (f == Sequences || f == Iterables) "checkIndexOverflow($value)" else value
"""
var index = 0
for (element in this) {
val list = transform(${checkOverflow("index++")}, element)
destination.addAll(list)
}
return destination
"""
}
return destination
"""
}
}