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Provide dropLast and takeLastWhile methods. Optimize special cases of drop/take/dropLast/takeLast (when n is equal to zero or size of collection).

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This commit is contained in:
Ilya Gorbunov
2015-06-01 22:23:59 +03:00
parent 9f85fa9720
commit a1d8e9d633
5 changed files with 481 additions and 73 deletions
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libraries/stdlib/src/generated/_Filtering.kt
+322 -62
View File
@@ -15,6 +15,8 @@ import java.util.Collections // TODO: it's temporary while we have java.util.Col
*/
public fun <T> Array<out T>.drop(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<T>(size() - n)
@@ -29,6 +31,8 @@ public fun <T> Array<out T>.drop(n: Int): List<T> {
*/
public fun BooleanArray.drop(n: Int): List<Boolean> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Boolean>(size() - n)
@@ -43,6 +47,8 @@ public fun BooleanArray.drop(n: Int): List<Boolean> {
*/
public fun ByteArray.drop(n: Int): List<Byte> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Byte>(size() - n)
@@ -57,6 +63,8 @@ public fun ByteArray.drop(n: Int): List<Byte> {
*/
public fun CharArray.drop(n: Int): List<Char> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Char>(size() - n)
@@ -71,6 +79,8 @@ public fun CharArray.drop(n: Int): List<Char> {
*/
public fun DoubleArray.drop(n: Int): List<Double> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Double>(size() - n)
@@ -85,6 +95,8 @@ public fun DoubleArray.drop(n: Int): List<Double> {
*/
public fun FloatArray.drop(n: Int): List<Float> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Float>(size() - n)
@@ -99,6 +111,8 @@ public fun FloatArray.drop(n: Int): List<Float> {
*/
public fun IntArray.drop(n: Int): List<Int> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Int>(size() - n)
@@ -113,6 +127,8 @@ public fun IntArray.drop(n: Int): List<Int> {
*/
public fun LongArray.drop(n: Int): List<Long> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Long>(size() - n)
@@ -127,6 +143,8 @@ public fun LongArray.drop(n: Int): List<Long> {
*/
public fun ShortArray.drop(n: Int): List<Short> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0)
return toList()
if (n >= size())
return emptyList()
val list = ArrayList<Short>(size() - n)
@@ -141,6 +159,7 @@ public fun ShortArray.drop(n: Int): List<Short> {
*/
public fun <T> Iterable<T>.drop(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return toList()
val list: ArrayList<T>
if (this is Collection<*>) {
val resultSize = size() - n
@@ -169,7 +188,7 @@ public fun <T> Iterable<T>.drop(n: Int): List<T> {
*/
public fun <T> Sequence<T>.drop(n: Int): Sequence<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
return DropSequence(this, n)
return if (n == 0) this else DropSequence(this, n)
}
@@ -179,7 +198,7 @@ deprecated("Migrate to using Sequence<T> and respective functions")
*/
public fun <T> Stream<T>.drop(n: Int): Stream<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
return DropStream(this, n)
return if (n == 0) this else DropStream(this, n)
}
/**
@@ -189,6 +208,94 @@ public fun String.drop(n: Int): String {
return substring(Math.min(n, length()))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun <T> Array<out T>.dropLast(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun BooleanArray.dropLast(n: Int): List<Boolean> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun ByteArray.dropLast(n: Int): List<Byte> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun CharArray.dropLast(n: Int): List<Char> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun DoubleArray.dropLast(n: Int): List<Double> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun FloatArray.dropLast(n: Int): List<Float> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun IntArray.dropLast(n: Int): List<Int> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun LongArray.dropLast(n: Int): List<Long> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun ShortArray.dropLast(n: Int): List<Short> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last [n] elements.
*/
public fun <T> List<T>.dropLast(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((size() - n).coerceAtLeast(0))
}
/**
* Returns a string with the last [n] characters removed.
*/
public fun String.dropLast(n: Int): String {
require(n >= 0, { "Requested element count $n is less than zero." })
return take((length() - n).coerceAtLeast(0))
}
/**
* Returns a list containing all elements except last elements that satisfy the given [predicate].
*/
@@ -1090,11 +1197,12 @@ public fun String.slice(indices: Iterable<Int>): String {
*/
public fun <T> Array<out T>.take(n: Int): List<T> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<T>(realN)
val list = ArrayList<T>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1106,11 +1214,12 @@ public fun <T> Array<out T>.take(n: Int): List<T> {
*/
public fun BooleanArray.take(n: Int): List<Boolean> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Boolean>(realN)
val list = ArrayList<Boolean>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1122,11 +1231,12 @@ public fun BooleanArray.take(n: Int): List<Boolean> {
*/
public fun ByteArray.take(n: Int): List<Byte> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Byte>(realN)
val list = ArrayList<Byte>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1138,11 +1248,12 @@ public fun ByteArray.take(n: Int): List<Byte> {
*/
public fun CharArray.take(n: Int): List<Char> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Char>(realN)
val list = ArrayList<Char>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1154,11 +1265,12 @@ public fun CharArray.take(n: Int): List<Char> {
*/
public fun DoubleArray.take(n: Int): List<Double> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Double>(realN)
val list = ArrayList<Double>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1170,11 +1282,12 @@ public fun DoubleArray.take(n: Int): List<Double> {
*/
public fun FloatArray.take(n: Int): List<Float> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Float>(realN)
val list = ArrayList<Float>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1186,11 +1299,12 @@ public fun FloatArray.take(n: Int): List<Float> {
*/
public fun IntArray.take(n: Int): List<Int> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Int>(realN)
val list = ArrayList<Int>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1202,11 +1316,12 @@ public fun IntArray.take(n: Int): List<Int> {
*/
public fun LongArray.take(n: Int): List<Long> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Long>(realN)
val list = ArrayList<Long>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1218,11 +1333,12 @@ public fun LongArray.take(n: Int): List<Long> {
*/
public fun ShortArray.take(n: Int): List<Short> {
require(n >= 0, "Requested element count $n is less than zero.")
if (n == 0) return emptyList()
if (n >= size()) return toList()
var count = 0
val realN = Math.min(n, size())
val list = ArrayList<Short>(realN)
val list = ArrayList<Short>(n)
for (item in this) {
if (count++ == realN)
if (count++ == n)
break;
list.add(item)
}
@@ -1234,8 +1350,10 @@ public fun ShortArray.take(n: Int): List<Short> {
*/
public fun <T> Iterable<T>.take(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
if (this is Collection<T> && n >= size()) return toList()
var count = 0
val list = ArrayList<T>(Math.min(n, collectionSizeOrDefault(n)))
val list = ArrayList<T>(n)
for (item in this) {
if (count++ == n)
break
@@ -1249,7 +1367,7 @@ public fun <T> Iterable<T>.take(n: Int): List<T> {
*/
public fun <T> Sequence<T>.take(n: Int): Sequence<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
return TakeSequence(this, n)
return if (n == 0) emptySequence() else TakeSequence(this, n)
}
@@ -1259,7 +1377,7 @@ deprecated("Migrate to using Sequence<T> and respective functions")
*/
public fun <T> Stream<T>.take(n: Int): Stream<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
return TakeStream(this, n)
return if (n == 0) emptyStream() else TakeStream(this, n)
}
/**
@@ -1275,10 +1393,11 @@ public fun String.take(n: Int): String {
*/
public fun <T> Array<out T>.takeLast(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<T>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<T>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1288,10 +1407,11 @@ public fun <T> Array<out T>.takeLast(n: Int): List<T> {
*/
public fun BooleanArray.takeLast(n: Int): List<Boolean> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Boolean>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Boolean>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1301,10 +1421,11 @@ public fun BooleanArray.takeLast(n: Int): List<Boolean> {
*/
public fun ByteArray.takeLast(n: Int): List<Byte> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Byte>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Byte>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1314,10 +1435,11 @@ public fun ByteArray.takeLast(n: Int): List<Byte> {
*/
public fun CharArray.takeLast(n: Int): List<Char> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Char>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Char>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1327,10 +1449,11 @@ public fun CharArray.takeLast(n: Int): List<Char> {
*/
public fun DoubleArray.takeLast(n: Int): List<Double> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Double>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Double>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1340,10 +1463,11 @@ public fun DoubleArray.takeLast(n: Int): List<Double> {
*/
public fun FloatArray.takeLast(n: Int): List<Float> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Float>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Float>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1353,10 +1477,11 @@ public fun FloatArray.takeLast(n: Int): List<Float> {
*/
public fun IntArray.takeLast(n: Int): List<Int> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Int>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Int>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1366,10 +1491,11 @@ public fun IntArray.takeLast(n: Int): List<Int> {
*/
public fun LongArray.takeLast(n: Int): List<Long> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Long>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Long>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1379,10 +1505,11 @@ public fun LongArray.takeLast(n: Int): List<Long> {
*/
public fun ShortArray.takeLast(n: Int): List<Short> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<Short>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<Short>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1392,10 +1519,11 @@ public fun ShortArray.takeLast(n: Int): List<Short> {
*/
public fun <T> List<T>.takeLast(n: Int): List<T> {
require(n >= 0, { "Requested element count $n is less than zero." })
if (n == 0) return emptyList()
val size = size()
val realN = Math.min(n, size)
val list = ArrayList<T>(realN)
for (index in size - realN .. size - 1)
if (n >= size) return toList()
val list = ArrayList<T>(n)
for (index in size - n .. size - 1)
list.add(this[index])
return list
}
@@ -1409,6 +1537,138 @@ public fun String.takeLast(n: Int): String {
return substring(length - Math.min(n, length), length)
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun <T> Array<out T>.takeLastWhile(predicate: (T) -> Boolean): List<T> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun BooleanArray.takeLastWhile(predicate: (Boolean) -> Boolean): List<Boolean> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun ByteArray.takeLastWhile(predicate: (Byte) -> Boolean): List<Byte> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun CharArray.takeLastWhile(predicate: (Char) -> Boolean): List<Char> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun DoubleArray.takeLastWhile(predicate: (Double) -> Boolean): List<Double> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun FloatArray.takeLastWhile(predicate: (Float) -> Boolean): List<Float> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun IntArray.takeLastWhile(predicate: (Int) -> Boolean): List<Int> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun LongArray.takeLastWhile(predicate: (Long) -> Boolean): List<Long> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun ShortArray.takeLastWhile(predicate: (Short) -> Boolean): List<Short> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a list containing last elements satisfying the given [predicate].
*/
public inline fun <T> List<T>.takeLastWhile(predicate: (T) -> Boolean): List<T> {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return drop(index + 1)
}
}
return toList()
}
/**
* Returns a string containing last characters that satisfy the given [predicate].
*/
public inline fun String.takeLastWhile(predicate: (Char) -> Boolean): String {
for (index in lastIndex downTo 0) {
if (!predicate(this[index])) {
return substring(index + 1)
}
}
return this
}
/**
* Returns a list containing first elements satisfying the given [predicate].
*/
libraries/stdlib/src/kotlin/collections/Sequence.kt
+3
View File
@@ -70,6 +70,9 @@ public fun <T> sequenceOf(progression: Progression<T>): Sequence<T> = object : S
*/
public fun <T> emptySequence(): Sequence<T> = EmptySequence
deprecated("Remove in M13 with streams.")
private fun <T> emptyStream(): Stream<T> = EmptySequence
private object EmptySequence : Sequence<Nothing> {
override fun iterator(): Iterator<Nothing> = EmptyIterator
}