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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.generic
/** The base trait of all builders.
* A builder lets one construct a collection incrementally, by adding
* elements to the builder with += and then converting to the required
* collection type with `result`.
*/
trait Builder[-Elem, +To] extends Growable[Elem] {
/** Adds a single element to the builder.
* @param elem The element to be added
*/
def +=(elem: Elem): this.type
/** Clear the contents of this builder
*/
def clear()
/** Returns collection resulting from this builder. The buffer's contents
* are undefined afterwards.
*/
def result(): To
/** Give a hint how many elements are expected to be added
* when the next `result` is called.
*/
def sizeHint(size: Int) {}
/** Create a new builder which is the same as the current builder except
* that a given function is applied to the current builder's result.
* @param f the function to apply to the builder's result
*/
def mapResult[NewTo](f: To => NewTo): Builder[Elem, NewTo] =
new Builder[Elem, NewTo] with Proxy {
val self = Builder.this
def +=(x: Elem): this.type = { self += x; this }
def clear() = self.clear()
override def ++=(xs: Iterator[Elem]): this.type = { self ++= xs; this }
override def ++=(xs: Traversable[Elem]): this.type = { self ++= xs; this }
def result: NewTo = f(self.result)
}
}
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