Implementing OP_HASH160, OP_DUP and adding in some util functions

src/main/scala/org/scalacoin/script/crypto/CryptoInterpreter.scala

@@ -0,0 +1,33 @@
+package org.scalacoin.script.crypto
+
+import org.scalacoin.script.ScriptOperation
+import org.scalacoin.util.ScalacoinUtil
+
+
+/**
+ * Created by chris on 1/6/16.
+ */
+trait CryptoInterpreter extends ScalacoinUtil {
+
+  def hash160(stack : List[String], script : List[ScriptOperation]) : (List[String], List[ScriptOperation]) = {
+    require(stack.headOption.isDefined, "The top of the stack must be defined")
+    require(script.headOption.isDefined && script.head == OP_HASH160, "Script operation must be OP_HASH160")
+    val stackTop = stack.head
+    val hash = sha256Hash160(stackTop)
+    (hash :: stack, script.tail)
+  }
+
+
+  /**
+   * Does the following computation
+   * RIPEMD160(SHA256(hex))
+   * @param hex
+   * @return
+   */
+  private def sha256Hash160(hex : String) = {
+    val bytes = decodeHex(hex)
+    val hash = org.bitcoinj.core.Utils.sha256hash160(bytes)
+    encodeHex(hash)
+
+  }
+}

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

@@ -0,0 +1,16 @@
+package org.scalacoin.script.interpreter
+
+import org.scalacoin.script.ScriptOperation
+import org.scalacoin.script.stack.OP_DUP
+
+import scala.collection.immutable.Stack
+
+/**
+ * Created by chris on 1/6/16.
+ */
+trait ScriptInterpreter {
+
+
+
+
+}

src/main/scala/org/scalacoin/script/stack/StackInterpreter.scala

@@ -0,0 +1,24 @@
+package org.scalacoin.script.stack
+
+import org.scalacoin.script.ScriptOperation
+
+/**
+ * Created by chris on 1/6/16.
+ */
+trait StackInterpreter {
+  /**
+   * Duplicates the element on top of the stack
+   * expects the first element in script to be the OP_DUP operation
+   * @param stack
+   * @param script
+   * @return
+   */
+  def opDup(stack : List[String], script : List[ScriptOperation]) : (List[String], List[ScriptOperation]) = {
+    require(script.headOption.isDefined && script.head == OP_DUP, "Top of the script stack must be OP_DUP")
+    require(stack.headOption.isDefined, "Cannot duplicate the top element on an empty stack")
+    stack match {
+      case h :: t => (h :: stack, script.tail)
+      case Nil => throw new RuntimeException("Received an empty stack! Cannot duplicate an element on an empty stack")
+    }
+  }
+}

src/test/scala/org/scalacoin/script/interpreter/ScriptInterpreterTest.scala

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+package org.scalacoin.script.interpreter
+
+import org.scalacoin.script.stack.OP_DUP
+import org.scalatest.{MustMatchers, FlatSpec}
+
+/**
+ * Created by chris on 1/6/16.
+ */
+class ScriptInterpreterTest extends FlatSpec with MustMatchers with ScriptInterpreter {
+
+
+
+}

src/test/scala/org/scalacoin/script/stack/StackInterpreterTest.scala

@@ -0,0 +1,37 @@
+package org.scalacoin.script.stack
+
+import org.scalatest.{FlatSpec, MustMatchers}
+
+/**
+ * Created by chris on 1/6/16.
+ */
+class StackInterpreterTest extends FlatSpec with MustMatchers with StackInterpreter {
+
+  "StackInterpreter" must "duplicate elements on top of the stack" in {
+    val stack = List("Hello","World")
+    val script = List(OP_DUP)
+    val (newStack,newScript) = opDup(stack,script)
+
+    newStack.head must be ("Hello")
+    newStack(1) must be ("Hello")
+    newStack(2) must be ("World")
+  }
+
+  it must "throw an exception when calling opDup without an OP_DUP on top of the script stack" in {
+
+    intercept[IllegalArgumentException] {
+      val stack = List("Hello","World")
+      val script = List()
+      val (newStack,newScript) = opDup(stack,script)
+    }
+  }
+
+  it must "throw an exception when calling opDup without an element on top of the stack" in {
+
+    intercept[IllegalArgumentException] {
+      val stack = List()
+      val script = List(OP_DUP)
+      val (newStack,newScript) = opDup(stack,script)
+    }
+  }
+}