Changes between Version 45 and Version 46 of HashSourceCodes

Timestamp:

Apr 21, 2013, 4:28:08 AM (11 years ago)

Author:

os

Comment:

add scala

HashSourceCodes

@@ -1562 +1562 @@
 end;
 }}}
+
+== Scala ==
+{{{
+import java.io.{FileInputStream, File}
+import java.nio.{LongBuffer, ByteOrder, ByteBuffer}
+import java.nio.channels.FileChannel.MapMode
+import scala.math._
+
+class OpenSubtitlesHasher {
+  private val hashChunkSize = 64L * 1024L
+
+  def computeHash(file: File) : String = {
+    val fileSize = file.length
+    val chunkSizeForFile = min(fileSize, hashChunkSize)
+
+    val fileChannel = new FileInputStream(file).getChannel
+
+    try {
+      val head = computeHashForChunk(fileChannel.map(MapMode.READ_ONLY, 0, chunkSizeForFile))
+      val tail = computeHashForChunk(fileChannel.map(MapMode.READ_ONLY, max(fileSize - hashChunkSize, 0), chunkSizeForFile))
+
+      "%016x".format(fileSize + head + tail)
+    } finally {
+      fileChannel.close()
+    }
+  }
+
+  private def computeHashForChunk(buffer: ByteBuffer) : Long = {
+    def doCompute(longBuffer: LongBuffer, hash: Long) : Long = {
+      longBuffer.hasRemaining match {
+        case false => hash
+        case true => doCompute(longBuffer, hash + longBuffer.get)
+      }
+    }
+    val longBuffer = buffer.order(ByteOrder.LITTLE_ENDIAN).asLongBuffer()
+    doCompute(longBuffer, 0L)
+  }
+}
+}}}