Adding control flow operations

src/main/scala/org/scalacoin/script/Constants.scala

@@ -4,13 +4,13 @@ package org.scalacoin.script
  * Created by chris on 1/6/16.
  */
 
-trait ScriptOperation
-
-sealed trait Constant extends ScriptOperation {
+trait ScriptOperation {
   def opCode : Int
   def hex : String = Integer.toHexString(opCode)
 }
 
+sealed trait Constant extends ScriptOperation
+
 /**
  * An empty array of bytes is pushed onto the stack. (This is not a no-op: an item is added to the stack.)
  */

src/main/scala/org/scalacoin/script/control/ControlOperations.scala

@@ -0,0 +1,65 @@
+package org.scalacoin.script.control
+
+import org.scalacoin.script.ScriptOperation
+
+/**
+ * Created by chris on 1/6/16.
+ */
+sealed trait ControlOperations extends ScriptOperation
+
+/**
+ * Does nothing
+ */
+case object OP_NOP extends ControlOperations {
+  override def opCode = 97
+}
+
+/**
+ * If the top stack value is not 0, the statements are executed. The top stack value is removed.
+ */
+case object OP_IF extends ControlOperations {
+  override def opCode = 99
+}
+
+
+/**
+ * If the top stack value is 0, the statements are executed. The top stack value is removed.
+ */
+case object OP_NOTIF extends ControlOperations {
+  override def opCode = 100
+}
+
+/**
+ * If the preceding OP_IF or OP_NOTIF or OP_ELSE was not executed then these statements are and
+ * if the preceding OP_IF or OP_NOTIF or OP_ELSE was executed then these statements are not.
+ */
+case object OP_ELSE extends ControlOperations {
+  override def opCode = 103
+}
+
+/**
+ * Ends an if/else block. All blocks must end, or the transaction is invalid.
+ * An OP_ENDIF without OP_IF earlier is also invalid.
+ */
+case object OP_ENDIF extends ControlOperations {
+ override def opCode = 104
+}
+
+/**
+ * Marks transaction as invalid if top stack value is not true.
+ */
+case object OP_VERIFY extends ControlOperations {
+  override def opCode = 105
+}
+
+/**
+ * Marks transaction as invalid. A standard way of attaching extra data to transactions is to add a zero-value
+ * output with a scriptPubKey consisting of OP_RETURN followed by exactly one pushdata op.
+ * Such outputs are provably unspendable, reducing their cost to the network.
+ * Currently it is usually considered non-standard
+ * (though valid) for a transaction to have more than one OP_RETURN output or an OP_RETURN output
+ * with more than one pushdata op.
+ */
+case object OP_RETURN extends ControlOperations {
+  override def opCode = 106
+}

src/test/scala/org/scalacoin/script/control/ControlOperationsTest.scala

@@ -0,0 +1,33 @@
+package org.scalacoin.script.control
+
+import org.scalatest.{MustMatchers, FlatSpec}
+
+/**
+ * Created by chris on 1/6/16.
+ */
+class ControlOperationsTest extends FlatSpec with MustMatchers {
+
+  "ControlOperations" must "define an OP_IF" in {
+    OP_IF.opCode must be (99)
+  }
+
+  it must "define an OP_NOTIF" in {
+    OP_NOTIF.opCode must be (100)
+  }
+
+  it must "define an OP_ELSE" in {
+    OP_ELSE.opCode must be (103)
+  }
+
+  it must "define an OP_ENDIF" in {
+    OP_ENDIF.opCode must be (104)
+  }
+
+  it must "define an OP_VERIFY" in {
+    OP_VERIFY.opCode must be (105)
+  }
+
+  it must "define an OP_RETURN" in {
+    OP_RETURN.opCode must be (106)
+  }
+}