From f79125e9df8335a9367251156702bd2ea2754c9e Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Sat, 17 Nov 2018 18:38:53 -0800
Subject: [PATCH] more modules

---
 schala-lang/language/src/ast_visitor.rs | 77 +++++++++++++++----------
 1 file changed, 46 insertions(+), 31 deletions(-)

diff --git a/schala-lang/language/src/ast_visitor.rs b/schala-lang/language/src/ast_visitor.rs
index 14be077..d3c09f8 100644
--- a/schala-lang/language/src/ast_visitor.rs
+++ b/schala-lang/language/src/ast_visitor.rs
@@ -7,24 +7,12 @@ pub fn dispatch<T, V: ASTVisitor<T>>(visitor: &mut V, ast: &AST) -> T {
     match statement {
       Statement::ExpressionStatement(expr) => {
         let ref mut expression_visitor = visitor.expression();
-        dispatch_expression(expression_visitor, expr);
+        ExpressionVisitor::dispatch(expression_visitor, expr);
       },
       Statement::Declaration(decl) => {
-        visitor.declaration(decl);
-        match decl {
-          Declaration::FuncSig(sig) => visitor.func_signature(sig),
-          Declaration::FuncDecl(sig, block) => visitor.func_declaration(sig, block),
-          _ => unimplemented!(),
-          /*
-          Declaration::TypeDecl { .. } => unimplemented!(),
-          Declaration::TypeAlias(..) => unimplemented!(), 
-          Declaration::Binding { .. } => unimplemented!(),
-          Declaration::Impl { .. } => unimplemented!(),
-          Declaration::Interface { .. } => unimplemented!(),
-          */
-        };
-        visitor.decl_done();
-      }
+        let ref mut declaration_visitor = visitor.declaration();
+        DeclarationVisitor::dispatch(declaration_visitor, decl);
+      },
     }
   }
   visitor.done()
@@ -32,6 +20,7 @@ pub fn dispatch<T, V: ASTVisitor<T>>(visitor: &mut V, ast: &AST) -> T {
 
 pub trait ASTVisitor<T> {
   type EV : ExpressionVisitor<T>;
+  type DV : DeclarationVisitor<T>;
 
   fn ast(&mut self, ast: &AST) {
   }
@@ -40,10 +29,37 @@ pub trait ASTVisitor<T> {
   fn statement(&mut self, statement: &Statement) {
   }
 
-  fn declaration(&mut self, statement: &Declaration) {
+  fn expression(&mut self) -> Self::EV;
+  fn declaration(&mut self) -> Self::DV;
+}
+
+pub trait ExpressionVisitor<T> {
+  fn dispatch(visitor: &mut Self, expr: &Expression) -> T {
+    visitor.expression(expr);
+    visitor.done()
+  }
+  fn expression(&mut self, expression: &Expression) {
+  }
+  fn done(&mut self) -> T;
+}
+
+pub trait DeclarationVisitor<T> {
+  fn dispatch(visitor: &mut Self, decl: &Declaration) -> T {
+    use self::Declaration::*;
+    match decl {
+      FuncSig(sig) => visitor.func_signature(sig),
+      FuncDecl(sig, block) => visitor.func_declaration(sig, block),
+      TypeDecl { name, body, mutable } => visitor.type_declaration(name, body, mutable),
+      TypeAlias(..) => unimplemented!(), 
+      Binding { .. } => unimplemented!(),
+      Impl { .. } => unimplemented!(),
+      Interface { .. } => unimplemented!(),
+    };
+    visitor.done()
   }
 
-  fn decl_done(&mut self) -> T;
+  fn declaration(&mut self, decl: &Declaration) {
+  }
 
   fn func_signature(&mut self, sig: &Signature) {
   }
@@ -51,17 +67,9 @@ pub trait ASTVisitor<T> {
   fn func_declaration(&mut self, sig: &Signature, block: &Vec<Statement>) {
   }
 
-  fn expression(&mut self) -> Self::EV;
-}
-
-pub fn dispatch_expression<T, V: ExpressionVisitor<T>>(visitor: &mut V, expr: &Expression) -> T {
-  visitor.expression(expr);
-  visitor.done()
-}
-
-pub trait ExpressionVisitor<T> {
-  fn expression(&mut self, expression: &Expression) {
+  fn type_declaration(&mut self, name: &TypeSingletonName, body: &TypeBody, mutable: &bool) {
   }
+
   fn done(&mut self) -> T;
 }
 
@@ -71,15 +79,16 @@ pub trait ExpressionVisitor<T> {
 struct NullVisitor { }
 impl ASTVisitor<()> for NullVisitor {
   type EV = NullVisitor;
+  type DV = NullVisitor;
   fn done(&mut self) -> () {
     ()
   }
 
-  fn decl_done(&mut self) -> () {
-    ()
+  fn expression(&mut self) -> Self::EV {
+    NullVisitor { }
   }
 
-  fn expression(&mut self) -> Self::EV {
+  fn declaration(&mut self) -> Self::DV {
     NullVisitor { }
   }
 }
@@ -90,3 +99,9 @@ impl ExpressionVisitor<()> for NullVisitor {
   }
 }
 
+impl DeclarationVisitor<()> for NullVisitor {
+  fn done(&mut self) -> () {
+    ()
+  }
+}
+