Add block enter/exit methods

schala-lang/language/src/ast/visitor.rs

@@ -6,7 +6,8 @@ use crate::ast::*;
 
 pub trait ASTVisitor: Sized {
   fn ast(&mut self, _ast: &AST) {}
-  fn block(&mut self, _statements: &Vec<Statement>) {}
+  fn enter_block(&mut self, _statements: &Vec<Statement>) {}
+  fn exit_block(&mut self, _statements: &Vec<Statement>) {}
   fn statement(&mut self, _statement: &Statement) {}
   fn declaration(&mut self, _declaration: &Declaration) {}
   fn signature(&mut self, _signature: &Signature) {}
@@ -55,9 +56,17 @@ pub trait ExpressionVisitor {
   fn string_literal(&mut self, _value: &Rc<String>) -> Self::Output;
   fn binexp(&mut self, _op: &BinOp, _lhs_resul: Self::Output, _rhs_result: Self::Output) -> Self::Output;
   fn tuple_literal(&mut self, _items: Vec<Self::Output>) -> Self::Output;
+  fn visit_statement(&mut self) -> StatementVisitor<Output=Self::Output>;
   fn done(&mut self, kind: Self::Output, anno: Option<Self::Output>) -> Self::Output;
 }
 
+pub trait StatementVisitor {
+  type Output;
+
+  fn expression(&mut self) -> Self::Output;
+  fn declaration(&mut self, &Declaration) -> Self::Output;
+}
+
 pub fn dispatch_expression<T>(input: &Expression, visitor: &mut dyn ExpressionVisitor<Output=T>) -> Result<T, String> {
 
   let output = match input.kind {

schala-lang/language/src/ast/walker.rs

@@ -1,7 +1,7 @@
 #![allow(dead_code)]
 use std::rc::Rc;
 use crate::ast::*;
-use crate::ast::visitor::ASTVisitor;
+use crate::ast::visitor::{ASTVisitor, BlockEntry};
 use crate::util::deref_optional_box;
 
 pub fn walk_ast<V: ASTVisitor>(v: &mut V, ast: &AST) {
@@ -10,10 +10,12 @@ pub fn walk_ast<V: ASTVisitor>(v: &mut V, ast: &AST) {
 }
 
 fn walk_block<V: ASTVisitor>(v: &mut V, block: &Vec<Statement>) {
+  v.enter_block(&block);
   for s in block {
     v.statement(s);
     statement(v, s);
   }
+  v.exit_block(&block);
 }
 
 fn statement<V: ASTVisitor>(v: &mut V, statement: &Statement) {
@@ -44,7 +46,6 @@ fn declaration<V: ASTVisitor>(v: &mut V, decl: &Declaration) {
     },
     FuncDecl(sig, block) => {
       v.signature(&sig);
-      v.block(&block);
       walk_block(v, block);
     },
     TypeDecl { name, body, mutable  } => v.type_declaration(name, body, *mutable),
@@ -123,7 +124,6 @@ fn lambda<V: ASTVisitor>(v: &mut V, params: &Vec<FormalParam>, type_anno: Option
     formal_param(v, param);
   }
   v.type_annotation(type_anno);
-  v.block(body);
   walk_block(v, body);
 }
 
@@ -234,7 +234,6 @@ fn condition_arm<V: ASTVisitor>(v: &mut V, arm: &ConditionArm) {
     v.expression(guard);
     expression(v, guard);
   });
-  v.block(&arm.body);
   walk_block(v, &arm.body);
 }