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package breeze.util

/*
 Copyright 2012 David Hall

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

import java.util.Arrays

/**
 * Array operations on generic arrays, a little faster in general, I hope.
 * @author dlwh
 */

object ArrayUtil {

  def fill[V](a: Array[V], offset: Int, length: Int, v: V) {
    a match {
      case x: Array[Double] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Double])
      case x: Array[Int] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Int])
      case x: Array[Float] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Float])
      case x: Array[Long] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Long])
      case x: Array[Short] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Short])
      case x: Array[Char] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Char])
      case x: Array[Byte] => Arrays.fill(x, offset, offset + length, v.asInstanceOf[Byte])
      case x: Array[_] => Arrays.fill(x.asInstanceOf[Array[AnyRef]], offset, offset + length, v.asInstanceOf[AnyRef])
      case _ => throw new RuntimeException("shouldn't be here!")
    }
  }


  def copyOf[V](a: Array[V], length: Int): Array[V] = {
    a match {
      case x: Array[Double] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[Int] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[Float] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[Long] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[Short] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[Char] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[Byte] => Arrays.copyOf(x, length).asInstanceOf[Array[V]]
      case x: Array[_] => Arrays.copyOf(x.asInstanceOf[Array[AnyRef]], length).asInstanceOf[Array[V]]
      case _ => throw new RuntimeException("shouldn't be here!")
    }
  }


  def copyOfRange[V, VU>:V](a: Array[V], from: Int, to: Int): Array[V] = {
    a match {
      case x: Array[Double] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[Int] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[Float] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[Long] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[Short] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[Char] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[Byte] => Arrays.copyOfRange(x, from, to).asInstanceOf[Array[V]]
      case x: Array[_] => Arrays.copyOfRange(x.asInstanceOf[Array[AnyRef]], from, to).asInstanceOf[Array[V]]
      case _ => throw new RuntimeException("shouldn't be here!")
    }
  }

  def newArrayLike[V](a: Array[V], length: Int): Array[V] = {
    a match {
      case x: Array[Double] => new Array[Double](length).asInstanceOf[Array[V]]
      case x: Array[Int] => new Array[Int](length).asInstanceOf[Array[V]]
      case x: Array[Float] => new Array[Float](length).asInstanceOf[Array[V]]
      case x: Array[Long] => new Array[Long](length).asInstanceOf[Array[V]]
      case x: Array[Short] => new Array[Short](length).asInstanceOf[Array[V]]
      case x: Array[Char] => new Array[Char](length).asInstanceOf[Array[V]]
      case x: Array[Byte] => new Array[Byte](length).asInstanceOf[Array[V]]
      case x: Array[_] =>
        implicit val man = ClassManifest.fromClass(x.getClass.getComponentType.asInstanceOf[Class[V]])
        new Array[V](length)
      case _ => throw new RuntimeException("shouldn't be here!")
    }
  }

  def equals(a: Array[_], b: Array[_]):Boolean = {
    val ac = a.getClass
    val bc = b.getClass
    if(ac != bc) false
    else {
      a match {
        case x: Array[Double] => Arrays.equals(a.asInstanceOf[Array[Double]], b.asInstanceOf[Array[Double]])
        case x: Array[Int] => Arrays.equals(a.asInstanceOf[Array[Int]], b.asInstanceOf[Array[Int]])
        case x: Array[Float] => Arrays.equals(a.asInstanceOf[Array[Float]], b.asInstanceOf[Array[Float]])
        case x: Array[Long] => Arrays.equals(a.asInstanceOf[Array[Long]], b.asInstanceOf[Array[Long]])
        case x: Array[Short] => Arrays.equals(a.asInstanceOf[Array[Short]], b.asInstanceOf[Array[Short]])
        case x: Array[Char] => Arrays.equals(a.asInstanceOf[Array[Char]], b.asInstanceOf[Array[Char]])
        case x: Array[Byte] => Arrays.equals(a.asInstanceOf[Array[Byte]], b.asInstanceOf[Array[Byte]])
        case x: Array[_] => Arrays.equals(a.asInstanceOf[Array[AnyRef]], b.asInstanceOf[Array[AnyRef]])
        case _ => throw new RuntimeException("shouldn't be here!")
      }
    }


  }

}