Implement execution for stack manipulating opcodes

Author: Joon-Mo Yang

vm/src/executor.rs

@@ -43,11 +43,13 @@ pub enum ScriptResult {
 #[derive(Debug, PartialEq)]
 pub enum RuntimeError {
  OutOfMemory,
+ IndexOutOfBound,
  StackUnderflow,
  TypeMismatch,
  InvalidResult,
 }
 
+#[derive(Clone)]
 struct Item(Vec<u8>);
 
 impl Item {
@@ -105,6 +107,20 @@ impl Stack {
  fn len(&self) -> usize {
  self.stack.len()
  }
+
+ fn get(&self, index: usize) -> Result<Item, RuntimeError> {
+ self.stack.get(index).cloned().ok_or(RuntimeError::IndexOutOfBound)
+ }
+
+ fn remove(&mut self, index: usize) -> Result<Item, RuntimeError> {
+ if index < self.stack.len() {
+ let item = self.stack.remove(index);
+ self.memory_usage -= item.len();
+ Ok(item)
+ } else {
+ Err(RuntimeError::IndexOutOfBound)
+ }
+ }
 }
 
 pub fn execute(
@@ -135,10 +151,24 @@ pub fn execute(
  stack.pop()?;
  }
  Instruction::PushB(blob) => stack.push(Item(blob.clone()))?,
- Instruction::Dup => unimplemented!(),
- Instruction::Swap => unimplemented!(),
- Instruction::Copy(..) => unimplemented!(),
- Instruction::Drop(..) => unimplemented!(),
+ Instruction::Dup => {
+ let top = stack.pop()?;
+ stack.push(top.clone())?;
+ stack.push(top)?;
+ }
+ Instruction::Swap => {
+ let first = stack.pop()?;
+ let second = stack.pop()?;
+ stack.push(first)?;
+ stack.push(second)?;
+ }
+ Instruction::Copy(index) => {
+ let item = stack.get(*index as usize)?;
+ stack.push(item)?
+ }
+ Instruction::Drop(index) => {
+ stack.remove(*index as usize)?;
+ }
  Instruction::ChkSig => {
  let pubkey = Public::from_slice(stack.pop()?.assert_len(64)?.as_ref());
  let signature = ECDSASignature::from(H520::from(stack.pop()?.assert_len(65)?.as_ref()));