1 files changed, 57 insertions, 0 deletions
diff --git a/core/src/main/scala/com/rockymadden/stringmetric/phonetic/SoundexAlgorithm.scala b/core/src/main/scala/com/rockymadden/stringmetric/phonetic/SoundexAlgorithm.scala
new file mode 100755
index 0000000..b211908
--- /dev/null
+++ b/core/src/main/scala/com/rockymadden/stringmetric/phonetic/SoundexAlgorithm.scala
@@ -0,0 +1,57 @@
+package com.rockymadden.stringmetric.phonetic
+
+import com.rockymadden.stringmetric.Algorithm.StringAlgorithm
+
+case object SoundexAlgorithm extends StringAlgorithm {
+	import com.rockymadden.stringmetric.Alphabet.Alpha
+
+	override def compute(a: Array[Char]): Option[Array[Char]] =
+		if (a.length == 0 || !(Alpha isSuperset a.head)) None
+		else {
+			val fc = a.head.toLower
+
+			Some(transcode(a.tail, fc, Array(fc)).padTo(4, '0'))
+		}
+
+	override def compute(string: String): Option[String] = compute(string.toCharArray).map(_.mkString)
+
+	@annotation.tailrec
+	private val transcode: ((Array[Char], Char, Array[Char]) => Array[Char]) = (i, pc, o) =>
+		if (i.length == 0) o
+		else {
+			val c = i.head.toLower
+			val m2 = (mc: Char) => (mc: @annotation.switch) match {
+				case 'b' | 'f' | 'p' | 'v' => '1'
+				case 'c' | 'g' | 'j' | 'k' | 'q' | 's' | 'x' | 'z' => '2'
+				case 'd' | 't' => '3'
+				case 'l' => '4'
+				case 'm' | 'n' => '5'
+				case 'r' => '6'
+				case _ => '\0'
+			}
+			val m1 = (mc: Char, pc: Char) => (mc: @annotation.switch) match {
+				case 'b' | 'f' | 'p' | 'v' if pc != '1' => '1'
+				case 'c' | 'g' | 'j' | 'k' | 'q' | 's' | 'x' | 'z' if pc != '2' => '2'
+				case 'd' | 't' if pc != '3' => '3'
+				case 'l' if pc != '4' => '4'
+				case 'm' | 'n' if pc != '5' => '5'
+				case 'r' if pc != '6' => '6'
+				case _ => '\0'
+			}
+			val a = pc match {
+				// Code twice.
+				case 'a' | 'e' | 'i' | 'o' | 'u' | 'y' => m2(c)
+				// Code once.
+				case _ => m1(
+					c,
+					(o.last: @annotation.switch) match {
+						case '1' | '2' | '3' | '4' | '5' | '6' => o.last
+						case _ => m2(o.last)
+					}
+				)
+			}
+
+			if (o.length == 3 && a != '\0') o :+ a
+			else transcode(i.tail, c, if (a != '\0') o :+ a else o)
+		}
+}