feat(stack): Sha256 operator

Author: tmpolaczyk

stack/src/lib.rs

@@ -19,6 +19,7 @@ pub use scriptful::prelude::Item;
 pub enum MyOperator {
     Equal,
     Hash160,
+    Sha256,
     CheckMultiSig,
     CheckTimeLock,
     /// Stop script execution if top-most element of stack is not "true"
@@ -63,6 +64,16 @@ fn hash_160_operator(stack: &mut Stack<MyValue>) {
     }
 }
 
+fn sha_256_operator(stack: &mut Stack<MyValue>) {
+    let a = stack.pop();
+    if let MyValue::Bytes(bytes) = a {
+        let Sha256(h) = calculate_sha256(&bytes);
+        stack.push(MyValue::Bytes(h.to_vec()));
+    } else {
+        // TODO: hash other types?
+    }
+}
+
 fn check_multisig_operator(stack: &mut Stack<MyValue>) {
     let m = stack.pop();
     match m {
@@ -191,6 +202,7 @@ fn my_operator_system(
     match operator {
         MyOperator::Equal => equal_operator(stack),
         MyOperator::Hash160 => hash_160_operator(stack),
+        MyOperator::Sha256 => sha_256_operator(stack),
         MyOperator::CheckMultiSig => check_multisig_operator(stack),
         MyOperator::CheckTimeLock => check_timelock_operator(stack, context.block_timestamp),
         MyOperator::Verify => {