cc.factorie.util.ISAble.scala Maven / Gradle / Ivy

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FACTORIE is a toolkit for deployable probabilistic modeling, implemented as a software library in Scala. It provides its users with a succinct language for creating relational factor graphs, estimating parameters and performing inference.

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/* Copyright (C) 2008-2016 University of Massachusetts Amherst.
   This file is part of "FACTORIE" (Factor graphs, Imperative, Extensible)
   http://factorie.cs.umass.edu, http://github.com/factorie
   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. */
package cc.factorie.util

import java.io._
import java.net.URL
import java.nio.file.{Files, Path}

/**
 * @author johnsullivan
 * Typeclass for things that can become [[java.io.InputStream]] */
trait ISAble[-A] extends (A => InputStream)

object ISAble {
  implicit object IsIs extends ISAble[InputStream] {
    def apply(is:InputStream) = is
  }

  implicit object UrlIs extends ISAble[URL] {
    def apply(u:URL) = u.openStream()
  }

  implicit object FileIs extends ISAble[File] {
    def apply(f:File) = new FileInputStream(f)
  }

  implicit object PathIs extends ISAble[Path] {
    def apply(p:Path) = Files.newInputStream(p)
  }

  implicit object BytesIs extends ISAble[Array[Byte]] {
    def apply(arr:Array[Byte]) = new ByteArrayInputStream(arr)
  }

  def inputStreamOf[A](a:A)(implicit conv:ISAble[A]):InputStream = conv(a)
  def buffered[A](a:A, buf:Int = 8192)(implicit conv:ISAble[A]):BufferedInputStream = conv(a) match {
    case b:BufferedInputStream => b
    case is => new BufferedInputStream(is, buf)
  }
  def lines[A](a:A, charSet:String="UTF-8")(implicit conv:ISAble[A]):Iterator[String] = new Iterator[String] {
    private val rdr = new BufferedReader(new InputStreamReader(conv(a), charSet))
    private var nextLine = rdr.readLine()

    def next() = {
      val res = nextLine
      nextLine = rdr.readLine()
      if(nextLine == null) {
        rdr.close()
      }
      res
    }

    def hasNext = nextLine != null
  }
}