Forgot to implement aritmetic operation OP_WITHIN

src/main/scala/org/scalacoin/script/arithmetic/ArithmeticInterpreter.scala

@@ -394,6 +394,34 @@ trait ArithmeticInterpreter extends ControlOperationsInterpreter {
   }
 
 
+  /**
+   * Returns 1 if x is within the specified range (left-inclusive), 0 otherwise.
+   * @param program
+   * @return
+   */
+  def opWithin(program : ScriptProgram) : ScriptProgram = {
+    require(program.script.headOption.isDefined && program.script.head == OP_WITHIN,
+      "Script top must be OP_WITHIN")
+    require(program.stack.size > 2, "Stack size must be 3 or more perform an OP_WITHIN")
+
+    val c = program.stack.head
+    val b = program.stack.tail.head
+    val a = program.stack.tail.tail.head
+
+    val isWithinRange = (a,b,c) match {
+      case (x : ScriptNumberOperation, y : ScriptNumber, z : ScriptNumber) => z >= x && z < y
+      case (x : ScriptNumber, y : ScriptNumberOperation, z : ScriptNumber) => z >= x && z < y.scriptNumber
+      case (x : ScriptNumber, y : ScriptNumber, z : ScriptNumberOperation) => z.scriptNumber >= x && z.scriptNumber < y
+      case (x : ScriptNumber, y : ScriptNumber, z : ScriptNumber) => z >= x && z < y
+      case (x,y,z) => z.toLong >= x.toLong && z.toLong < y.toLong
+    }
+
+    val newStackTop = if (isWithinRange) OP_1 else OP_0
+    ScriptProgramImpl(newStackTop :: program.stack.tail.tail.tail,
+      program.script.tail, program.transaction, program.altStack)
+  }
+
+
 
   /**
    * Wraps a scala number into a script token for the script language

src/main/scala/org/scalacoin/script/interpreter/ScriptInterpreter.scala

@@ -82,6 +82,7 @@ trait ScriptInterpreter extends CryptoInterpreter with StackInterpreter with Con
         case OP_GREATERTHANOREQUAL :: t => loop(opGreaterThanOrEqual(program))
         case OP_MIN :: t => loop(opMin(program))
         case OP_MAX :: t => loop(opMax(program))
+        case OP_WITHIN :: t => loop(opWithin(program))
         //bitwise operations
         case OP_EQUAL :: t => {
           val newProgram = opEqual(program)

src/test/scala/org/scalacoin/script/arithmetic/ArithmeticInterpreterTest.scala

@@ -338,4 +338,23 @@ class ArithmeticInterpreterTest extends FlatSpec with MustMatchers with Arithmet
 
     newProgram.stack must be (List(ScriptNumberImpl(1)))
   }
+
+  it must "evaluate an OP_WITHIN correctly" in {
+    val stack = List(OP_0,ScriptNumberImpl(2), ScriptNumberImpl(1))
+    val script = List(OP_WITHIN)
+    val program = ScriptProgramImpl(stack,script,TestUtil.transaction,List())
+    val newProgram = opWithin(program)
+    newProgram.stack must be (List(OP_0))
+    newProgram.script.isEmpty must be (true)
+
+
+    val stack1 = List(OP_0, ScriptNumberImpl(1),ScriptNumberImpl(0))
+    val script1 = List(OP_WITHIN)
+    val program1 = ScriptProgramImpl(stack1,script1,TestUtil.transaction,List())
+    val newProgram1 = opWithin(program1)
+    newProgram1.stack must be (List(OP_1))
+    newProgram1.script.isEmpty must be (true)
+  }
+
+
 }