Factor lowering a list of qubits into a helper function

fixes: #163

crates/oq3_semantics/src/syntax_to_semantics.rs

@@ -402,29 +402,19 @@ fn from_stmt(stmt: synast::Stmt, context: &mut Context) -> Option<asg::Stmt> {
  }
 
  synast::Stmt::Barrier(barrier) => {
- let gate_operands = barrier.qubit_list().map(|operands| {
- operands
- .gate_operands()
- .map(|qubit| from_gate_operand(qubit, context))
- .collect()
- });
- Some(asg::Stmt::Barrier(asg::Barrier::new(gate_operands)))
+ let gate_operands = from_qubit_list(barrier.qubit_list(), context);
+ Some(asg::Stmt::Barrier(asg::Barrier::new(Some(gate_operands))))
  }
 
  synast::Stmt::DelayStmt(delay_stmt) => {
- let gate_operands = delay_stmt.qubit_list().map(|operands| {
- operands
- .gate_operands()
- .map(|qubit| from_gate_operand(qubit, context))
- .collect()
- });
+ let gate_operands = from_qubit_list(delay_stmt.qubit_list(), context);
  let duration = from_expr(delay_stmt.designator().unwrap().expr(), context).unwrap();
  if !matches!(duration.get_type(), Type::Duration(_)) {
  context.insert_error(IncompatibleTypesError, &delay_stmt.designator().unwrap());
  }
  Some(asg::Stmt::Delay(asg::DelayStmt::new(
  duration,
- gate_operands.unwrap(),
+ gate_operands,
  )))
  }
 
@@ -753,13 +743,7 @@ fn from_gate_call_expr(
 ) -> Option<asg::Stmt> {
  // Warning, I think map overlooks None. This can cause a bug in the present case.
  // Because None means a coding error upstream. Better to blow up here.
- let gate_operands: Vec<_> = gate_call_expr
- .qubit_list()
- .unwrap()
- .gate_operands()
- .map(|qubit| from_gate_operand(qubit, context))
- .collect();
-
+ let gate_operands: Vec<_> = from_qubit_list(gate_call_expr.qubit_list(), context);
  let param_list = gate_call_expr
  .arg_list()
  .map(|ex| inner_expression_list(ex.expression_list().unwrap(), context));
@@ -855,6 +839,14 @@ fn from_expression_list(
  asg::ExpressionList::new(inner_expression_list(expression_list, context))
 }
 
+fn from_qubit_list(qubit_list: Option<synast::QubitList>, context: &mut Context) -> Vec<asg::TExpr> {
+ // Because None means a coding error upstream. Better to blow up here.
+ qubit_list.unwrap()
+ .gate_operands()
+ .map(|qubit| from_gate_operand(qubit, context))
+ .collect()
+}
+
 // Return a Vec of TExpr.
 fn inner_expression_list(
  expression_list: synast::ExpressionList,