org.neo4j.cypher.internal.runtime.Counter.scala Maven / Gradle / Ivy
/*
* Copyright (c) 2018-2020 "Graph Foundation"
* Graph Foundation, Inc. [https://graphfoundation.org]
*
* Copyright (c) 2002-2020 "Neo4j,"
* Neo4j Sweden AB [http://neo4j.com]
*
* This file is part of ONgDB.
*
* ONgDB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
package org.neo4j.cypher.internal.runtime
object Counter {
def apply(initialCount: Long = 0) = new Counter(initialCount)
}
class Counter(initialCount: Long) {
self =>
private var _count: Long = initialCount
def counted = _count
def reset(newValue: Long = 0) = {
_count = newValue
self
}
def +=(amount: Long): Long = {
_count += amount
_count
}
def -=(amount: Long) = self += (-amount)
def values = map(identity)
def map[T](f: Long => T) = new CountingIterator[T] {
override def hasNext = true
override def next() = f(self += 1)
}
def track[T](tracked: Iterator[T]) = new CountingIterator[T] {
override def hasNext = tracked.hasNext
override def next() = {
val result = tracked.next()
self += 1
result
}
}
trait CountingIterator[T] extends Iterator[T] {
inner =>
def counted = self.counted
def tick(): Unit = next()
def limit(maxCount: Long)(thunk: Long => T) = new CountingIterator[T] {
override def hasNext = inner.hasNext
override def next() = if (counted >= maxCount) thunk(self += 1) else inner.next()
}
}
}