1 files changed, 75 insertions, 0 deletions
diff --git a/core/source/core/scala/com/rockymadden/stringmetric/phonetic/RefinedSoundexAlgorithm.scala b/core/source/core/scala/com/rockymadden/stringmetric/phonetic/RefinedSoundexAlgorithm.scala
new file mode 100755
index 0000000..f22bde1
--- /dev/null
+++ b/core/source/core/scala/com/rockymadden/stringmetric/phonetic/RefinedSoundexAlgorithm.scala
@@ -0,0 +1,75 @@
+package com.rockymadden.stringmetric.phonetic
+
+import com.rockymadden.stringmetric.{StringAlgorithm, StringFilter}
+import com.rockymadden.stringmetric.Alphabet.Alpha
+import scala.annotation.{switch, tailrec}
+
+/** An implementation of the refined Soundex algorithm. */
+class RefinedSoundexAlgorithm extends StringAlgorithm[DummyImplicit, String] { this: StringFilter =>
+	final override def compute(charArray: Array[Char])(implicit di: DummyImplicit): Option[Array[Char]] = {
+		val fca = filter(charArray)
+
+		if (fca.length == 0 || !(Alpha isSuperset fca.head)) None
+		else Some(transcode(fca, Array(fca.head.toLower)))
+	}
+
+	final override def compute(string: String)(implicit di: DummyImplicit): Option[String] =
+		compute(string.toCharArray).map(_.mkString)
+
+	@tailrec
+	private[this] def transcode(i: Array[Char], o: Array[Char]): Array[Char] = {
+		if (i.length == 0) o
+		else {
+			val c = i.head.toLower
+			val m2 = (mc: Char) => (mc: @switch) match {
+				case 'a' | 'e' | 'h' | 'i' | 'o' | 'u' | 'w' | 'y' => '0'
+				case 'b' | 'p' => '1'
+				case 'f' | 'v' => '2'
+				case 'c' | 'k' | 's' => '3'
+				case 'g' | 'j' => '4'
+				case 'q' | 'x' | 'z' => '5'
+				case 'd' | 't' => '6'
+				case 'l' => '7'
+				case 'm' | 'n' => '8'
+				case 'r' => '9'
+				case _ => '\0'
+			}
+			val m1 = (mc: Char, pc: Char) => (mc: @switch) match {
+				case 'a' | 'e' | 'h' | 'i' | 'o' | 'u' | 'w' | 'y' if pc != '0' => '0'
+				case 'b' | 'p' if pc != '1' => '1'
+				case 'f' | 'v' if pc != '2' => '2'
+				case 'c' | 'k' | 's' if pc != '3' => '3'
+				case 'g' | 'j' if pc != '4' => '4'
+				case 'q' | 'x' | 'z' if pc != '5' => '5'
+				case 'd' | 't' if pc != '6' => '6'
+				case 'l' if pc != '7' => '7'
+				case 'm' | 'n' if pc != '8' => '8'
+				case 'r' if pc != '9' => '9'
+				case _ => '\0'
+			}
+			val a =
+				// Code twice.
+				if (o.length == 1) m2(c)
+				// Code once.
+				else m1(
+					c,
+					(o.last: @switch) match {
+						case '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' => o.last
+						case _ => m2(o.last)
+					}
+				)
+
+			transcode(i.tail, if (a != '\0') o :+ a else o)
+		}
+	}
+}
+
+object RefinedSoundexAlgorithm {
+	private lazy val self = apply()
+
+	def apply(): RefinedSoundexAlgorithm = new RefinedSoundexAlgorithm with StringFilter
+
+	def compute(charArray: Array[Char]) = self.compute(charArray)
+
+	def compute(string: String) = self.compute(string)
+}