feat(init): function support (#1285)

* add lowering stage after annotation stage
* add support for function-local variable initializations

Author: mhasel

compiler/plc_ast/src/ast.rs

@@ -256,6 +256,7 @@ pub enum PouType {
     Action,
     Class,
     Method { owner_class: String },
+    Init,
 }
 
 impl Display for PouType {
@@ -267,6 +268,7 @@ impl Display for PouType {
             PouType::Action => write!(f, "Action"),
             PouType::Class => write!(f, "Class"),
             PouType::Method { .. } => write!(f, "Method"),
+            PouType::Init => write!(f, "Init"),
         }
     }
 }

compiler/plc_ast/src/lib.rs

@@ -5,6 +5,7 @@
 pub mod ast;
 pub mod control_statements;
 pub mod literals;
+pub mod mut_visitor;
 mod pre_processor;
 pub mod provider;
 pub mod visitor;