Return &[T] rather than Vec<T> and similar in getters (#75)

There are several return types in asg.rs that are improved.
This causes a bit of a change in the API. So validate.rs is updated
External users, that is the qiskit importer, will likely need to
be updated.

crates/oq3_semantics/src/asg.rs

@@ -47,7 +47,7 @@ impl Program {
         }
     }
 
-    pub fn stmts(&self) -> &Vec<Stmt> {
+    pub fn stmts(&self) -> &[Stmt] {
         &self.stmts
     }
 
@@ -67,8 +67,8 @@ impl Program {
         self.version = Some(version);
     }
 
-    pub fn version(&self) -> &Option<OpenQASMVersion> {
-        &self.version
+    pub fn version(&self) -> Option<&OpenQASMVersion> {
+        self.version.as_ref()
     }
 
     // FIXME: must exist idiomatic rust for managing these modes
@@ -158,11 +158,11 @@ impl TExpr {
     }
 
     pub fn get_type(&self) -> &Type {
-        &(self.ty)
+        &self.ty
     }
 
     pub fn expression(&self) -> &Expr {
-        &(self.expression)
+        &self.expression
     }
 }
 
@@ -270,7 +270,7 @@ impl AnnotatedStmt {
         &self.stmt
     }
 
-    pub fn annotations(&self) -> &Vec<Annotation> {
+    pub fn annotations(&self) -> &[Annotation] {
         &self.annotations
     }
 }
@@ -346,6 +346,10 @@ impl HardwareQubit {
         }
     }
 
+    pub fn identifier(&self) -> &str {
+        &self.identifier
+    }
+
     pub fn to_texpr(self) -> TExpr {
         TExpr::new(Expr::HardwareQubit(self), Type::HardwareQubit)
     }
@@ -458,8 +462,8 @@ impl DeclareClassical {
         &self.name
     }
 
-    pub fn initializer(&self) -> &Option<Box<TExpr>> {
-        &self.initializer
+    pub fn initializer(&self) -> Option<&TExpr> {
+        self.initializer.as_deref()
     }
 
     pub fn to_stmt(self) -> Stmt {
@@ -536,11 +540,11 @@ impl GateDeclaration {
         &self.name
     }
 
-    pub fn params(&self) -> &Option<Vec<SymbolIdResult>> {
-        &self.params
+    pub fn params(&self) -> Option<&[SymbolIdResult]> {
+        self.params.as_deref()
     }
 
-    pub fn qubits(&self) -> &Vec<SymbolIdResult> {
+    pub fn qubits(&self) -> &[SymbolIdResult] {
         &self.qubits
     }
 
@@ -586,8 +590,8 @@ impl Barrier {
         Barrier { qubits }
     }
 
-    pub fn qubits(&self) -> &Option<Vec<TExpr>> {
-        &self.qubits
+    pub fn qubits(&self) -> Option<&[TExpr]> {
+        self.qubits.as_deref()
     }
 }
 
@@ -648,12 +652,12 @@ impl GateCall {
         &self.name
     }
 
-    pub fn qubits(&self) -> &Vec<TExpr> {
+    pub fn qubits(&self) -> &[TExpr] {
         &self.qubits
     }
 
-    pub fn params(&self) -> &Option<Vec<TExpr>> {
-        &self.params
+    pub fn params(&self) -> Option<&[TExpr]> {
+        self.params.as_deref()
     }
 
     pub fn modifiers(&self) -> &[GateModifier] {
@@ -1110,8 +1114,8 @@ impl If {
         &self.then_branch
     }
 
-    pub fn else_branch(&self) -> &Option<Block> {
-        &self.else_branch
+    pub fn else_branch(&self) -> Option<&Block> {
+        self.else_branch.as_ref()
     }
 
     pub fn to_stmt(self) -> Stmt {

crates/oq3_semantics/src/validate.rs

@@ -39,7 +39,7 @@ impl<T: SymTrait> WalkSymbols<T> for Program {
     }
 }
 
-impl<V, T: SymTrait> WalkSymbols<T> for &Vec<V>
+impl<V, T: SymTrait> WalkSymbols<T> for &[V]
 where
     V: WalkSymbols<T>,
 {
@@ -59,7 +59,7 @@ where
     }
 }
 
-impl<V, T: SymTrait> WalkSymbols<T> for Box<V>
+impl<V, T: SymTrait> WalkSymbols<T> for &Box<V>
 where
     V: WalkSymbols<T>,
 {
@@ -68,7 +68,7 @@ where
     }
 }
 
-impl<T: SymTrait> WalkSymbols<T> for TExpr {
+impl<T: SymTrait> WalkSymbols<T> for &TExpr {
     fn walk_symbols(&self, context: &mut SymContext<T>) {
         self.expression().walk_symbols(context);
     }