Data commit

Task/Inverted-index/Scala/inverted-index.scala

@@ -0,0 +1,31 @@
+object InvertedIndex extends App {
+  import java.io.File
+
+  // indexer
+  val WORD = raw"(\w+)".r
+  def parse(s: String) = WORD.findAllIn(s).map(_.toString.toLowerCase)
+  def invertedIndex(files: Seq[File]): Map[String,Set[File]] = {
+    var i = Map[String,Set[File]]() withDefaultValue Set.empty
+    files.foreach{f => scala.io.Source.fromFile(f).getLines flatMap parse foreach
+      (w => i = i + (w -> (i(w) + f)))}
+    i
+  }
+
+  // user interface
+  args match {
+    case _ if args.length < 2 => println("Usage: InvertedIndex ALLSEARCHWORDS FILENAME...")
+    case Array(searchwords, filenames @ _*) =>
+      val queries = parse(searchwords).toList
+      val files = filenames.map(new File(_)).filter{f => if (!f.exists) println(s"Ignoring $f"); f.exists}
+      (queries, files) match {
+        case (q, _) if q.isEmpty => println("Missing search words")
+        case (_, f) if f.isEmpty => println("Missing extant files")
+        case _ => val index = invertedIndex(files)
+          println(s"""Searching for ${queries map ("\""+_+"\"") mkString " and "} in ${files.size} files:""")
+          queries.map(index).foldLeft(files.toSet)(_ intersect _) match {
+            case m if m.isEmpty => println("No matching files")
+            case m => println(m mkString "\n")
+          }
+      }
+  }
+}