Introduce "Call chain on collection should be converted into 'Sequence'"

So #KT-15476 Fixed

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/.inspection

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.collections.ConvertCallChainIntoSequenceInspection

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/all.kt

@@ -0,0 +1,35 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Pair<List<Int>, List<Int>>> {
+    return list
+            .<caret>chunked(1)
+            .distinct()
+            .distinctBy { it }
+            .drop(1)
+            .dropWhile { true }
+            .filter { true }
+            .filterIndexed { index, list -> true }
+            .filterIsInstance<Int>()
+            .filterNot { true }
+            .filterNotNull()
+            .map { it }
+            .mapIndexed { index, i -> i }
+            .mapIndexedNotNull { index, i -> i }
+            .mapNotNull { it }
+            .minus(1)
+            .minusElement(1)
+            .onEach {}
+            .plus(1)
+            .plusElement(1)
+            .requireNoNulls()
+            .sorted()
+            .sortedBy { it }
+            .sortedByDescending { it }
+            .sortedDescending()
+            .sortedWith(Comparator { o1, o2 -> 0 })
+            .take(1)
+            .takeWhile { true }
+            .windowed(1, 1, true)
+            .zipWithNext()
+            .zipWithNext { a, b -> a }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/all.kt.after

@@ -0,0 +1,37 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Pair<List<Int>, List<Int>>> {
+    return list
+            .asSequence()
+            .chunked(1)
+            .distinct()
+            .distinctBy { it }
+            .drop(1)
+            .dropWhile { true }
+            .filter { true }
+            .filterIndexed { index, list -> true }
+            .filterIsInstance<Int>()
+            .filterNot { true }
+            .filterNotNull()
+            .map { it }
+            .mapIndexed { index, i -> i }
+            .mapIndexedNotNull { index, i -> i }
+            .mapNotNull { it }
+            .minus(1)
+            .minusElement(1)
+            .onEach {}
+            .plus(1)
+            .plusElement(1)
+            .requireNoNulls()
+            .sorted()
+            .sortedBy { it }
+            .sortedByDescending { it }
+            .sortedDescending()
+            .sortedWith(Comparator { o1, o2 -> 0 })
+            .take(1)
+            .takeWhile { true }
+            .windowed(1, 1, true)
+            .zipWithNext()
+            .zipWithNext { a, b -> a }
+            .toList()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/comment.kt

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): Int {
+    return list // comment1
+            .<caret>filter { it > 1 } // comment2
+            .map { it * 2 } // comment3
+            .sum() // comment4
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/comment.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): Int {
+    return list // comment1
+            .asSequence()
+            .filter { it > 1 } // comment2
+            .map { it * 2 } // comment3
+            .sum() // comment4
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/comment2.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list // comment1
+            .<caret>filter { it > 1 } // comment2
+            .map { it * 2 } // comment3
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/comment2.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list // comment1
+            .asSequence()
+            .filter { it > 1 } // comment2
+            .map { it * 2 }
+            .toList() // comment3
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/noTargetCallChain.kt

@@ -0,0 +1,6 @@
+// PROBLEM: none
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list.<caret>filter { it > 1 }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/noTargetCallChain2.kt

@@ -0,0 +1,6 @@
+// PROBLEM: none
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list.filter { it > 2 }.dropLast(1).<caret>filter { it > 2 }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/noTargetCallChain3.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .reversed()
+            .map { it + 1 }
+            .<caret>map { it + 1 }
+            .dropLast(1)
+            .takeLast(2)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/nullable.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>?): List<Int>? {
+    return list
+            ?.<caret>filter { it > 1 }
+            ?.map { it * 2 }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/nullable.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>?): List<Int>? {
+    return list
+            ?.asSequence()
+            ?.filter { it > 1 }
+            ?.map { it * 2 }
+            ?.toList()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/nullable2.kt

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>?): List<Int>? {
+    return list?.filter { it > 1 }!!.<caret>filter { it > 2 }.filter { it > 3 }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/nullable2.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>?): List<Int>? {
+    return list?.filter { it > 1 }!!.asSequence().filter { it > 2 }.filter { it > 3 }.toList()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/return.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .<caret>filter { it > 1 }
+            .mapNotNull {
+                if (it == 2) return emptyList()
+                it * 2
+            }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/returnAtLabels.kt

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .<caret>filter { it > 1 }
+            .mapNotNull {
+                if (it == 2) return@mapNotNull null
+                it * 2
+            }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/returnAtLabels.kt.after

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .asSequence()
+            .filter { it > 1 }
+            .mapNotNull {
+                if (it == 2) return@mapNotNull null
+                it * 2
+            }
+            .toList()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple.kt

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(): List<Int> {
+    return listOf(1, 2, 3).<caret>filter { it > 1 }.map { it * 2 }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(): List<Int> {
+    return listOf(1, 2, 3).asSequence().filter { it > 1 }.map { it * 2 }.toList()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple2.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .filter<caret> { it > 1 }
+            .map { it * 2 }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple2.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .asSequence()
+            .filter { it > 1 }
+            .map { it * 2 }
+            .toList()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple3.kt

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .reversed()
+            .<caret>map { it + 1 }
+            .map { it + 1 }
+            .dropLast(1)
+            .takeLast(2)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple3.kt.after

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>): List<Int> {
+    return list
+            .reversed()
+            .asSequence()
+            .map { it + 1 }
+            .map { it + 1 }
+            .toList()
+            .dropLast(1)
+            .takeLast(2)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple4.kt

@@ -0,0 +1,11 @@
+// WITH_RUNTIME
+
+fun test(foo: Foo): List<Int> {
+    return foo.getList()
+            .<caret>filter { it > 1 }
+            .map { it * 2 }
+}
+
+class Foo {
+    fun getList(): List<Int> = listOf(1, 2, 3)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/simple4.kt.after

@@ -0,0 +1,13 @@
+// WITH_RUNTIME
+
+fun test(foo: Foo): List<Int> {
+    return foo.getList()
+            .asSequence()
+            .filter { it > 1 }
+            .map { it * 2 }
+            .toList()
+}
+
+class Foo {
+    fun getList(): List<Int> = listOf(1, 2, 3)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination.kt

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+
+fun test(): Int {
+    return listOf(1, 2, 3)
+            .<caret>filter { it > 1 }
+            .map { it * 2 }
+            .sum()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+
+fun test(): Int {
+    return listOf(1, 2, 3)
+            .asSequence()
+            .filter { it > 1 }
+            .map { it * 2 }
+            .sum()
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination2.kt

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+
+fun test(): Int {
+    return listOf(1, 2, 3)
+            .<caret>filter { it > 1 }
+            .map { it * 2 }
+            .binarySearch(4)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination2.kt.after

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun test(): Int {
+    return listOf(1, 2, 3)
+            .asSequence()
+            .filter { it > 1 }
+            .map { it * 2 }
+            .toList()
+            .binarySearch(4)
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination3.kt

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun test(): Int {
+    return listOf(1, 2, 3)
+            .<caret>filter { it > 1 }
+            .map { it * 2 }
+            .let {
+                it.binarySearch(1)
+            }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination3.kt.after

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+
+fun test(): Int {
+    return listOf(1, 2, 3)
+            .asSequence()
+            .filter { it > 1 }
+            .map { it * 2 }
+            .toList()
+            .let {
+                it.binarySearch(1)
+            }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination4.kt

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+
+fun test(list: List<List<Int>>): List<Int> {
+    return list
+            .<caret>filter { it.count() > 2 }
+            .map { it + it }
+            .flatMap { it + it }
+}

idea/testData/inspectionsLocal/collections/convertCallChainIntoSequence/termination4.kt.after

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+
+fun test(list: List<List<Int>>): List<Int> {
+    return list
+            .asSequence()
+            .filter { it.count() > 2 }
+            .map { it + it }
+            .toList()
+            .flatMap { it + it }
+}