June 2018 Update

Task/Inverted-index/Kotlin/inverted-index.kotlin

@@ -0,0 +1,58 @@
+// version 1.1.51
+
+import java.io.File
+
+val invIndex  = mutableMapOf<String, MutableList<Location>>()
+val fileNames = mutableListOf<String>()
+val splitter  = Regex("""\W+""")
+
+class Location(val fileName: String, val wordNum: Int) {
+    override fun toString() = "{$fileName, word number $wordNum}"
+}
+
+fun indexFile(fileName: String) {
+    if (fileName in fileNames) {
+        println("'$fileName' already indexed")
+        return
+    }
+    fileNames.add(fileName)
+    File(fileName).forEachLine { line ->
+        for ((i, w) in line.toLowerCase().split(splitter).withIndex()) {
+            var locations = invIndex[w]
+            if (locations == null) {
+                locations = mutableListOf<Location>()
+                invIndex.put(w, locations)
+            }
+            locations.add(Location(fileName, i + 1))
+        }
+    }
+    println("'$fileName' has been indexed")
+}
+
+fun findWord(word: String) {
+    val w = word.toLowerCase()
+    val locations = invIndex[w]
+    if (locations != null) {
+       println("\n'$word' found in the following locations:")
+       println(locations.map { "    $it" }.joinToString("\n"))
+    }
+    else println("\n'$word' not found")
+    println()
+}
+
+fun main(args: Array<String>) {
+    // files to be indexed entered as command line arguments
+    if (args.size == 0) {
+        println("No file names have been supplied")
+        return
+    }
+    for (arg in args) indexFile(arg)
+    println()
+    println("Enter word(s) to be searched for in these files or 'q' to quit")
+    while (true) {
+        print("  ? : ")
+        val word = readLine()!!
+        if (word.toLowerCase() == "q") return
+        findWord(word)
+    }
+}