Move stuff around

README.md

@@ -70,6 +70,7 @@ https://rust-lang-nursery.github.io/rustc-guide/type-inference.html
 ### Parsing
 http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
 https://soc.github.io/languages/unified-condition-syntax
+http://www.lihaoyi.com/post/ZeroOverheadTreeProcessingwiththeVisitorPattern.html?a=1
 
 [Crafting Interpreters](http://www.craftinginterpreters.com/)
 

schala-lang/language/src/ast_visitor.rs

@@ -1,2 +1,157 @@
+use std::rc::Rc;
 
+use builtin::{PrefixOp, BinOp};
 use ast::*;
+
+pub fn dispatch<V: ASTVisitor>(visitor: &mut V, ast: &AST) {
+  for statement in ast.0.iter() {
+    match statement {
+      Statement::ExpressionStatement(e) => {
+        dispatch_expression(visitor, e);
+        visitor.expression(e);
+      },
+      Statement::Declaration(decl) => {
+        dispatch_declaration(visitor, decl);
+        visitor.declaration(decl);
+      },
+    };
+    visitor.statement(statement);
+  }
+  visitor.ast(ast)
+}
+
+fn dispatch_expression<V: ASTVisitor>(visitor: &mut V, expression: &Expression) {
+  match expression {
+    Expression(expr, maybe_anno) => {
+      match expr {
+        ExpressionType::NatLiteral(n) => visitor.nat_literal(n),
+        ExpressionType::FloatLiteral(f) => visitor.float_literal(f),
+        ExpressionType::StringLiteral(s) => visitor.string_literal(s),
+        ExpressionType::BoolLiteral(b) => visitor.bool_literal(b),
+        ExpressionType::BinExp(binop, lhs, rhs) => visitor.binop(binop, lhs, rhs),
+        ExpressionType::PrefixExp(prefix, expr) => visitor.prefixop(prefix, expr),
+        ExpressionType::TupleLiteral(v) => visitor.tuple_literal(v),
+        ExpressionType::Value(v) => visitor.value(v),
+        ExpressionType::NamedStruct { name, fields } => visitor.named_struct(name, fields),
+        ExpressionType::Call { f, arguments } => visitor.call(f, arguments),
+        ExpressionType::Index { indexee, indexers } => visitor.index(indexee, indexers),
+        ExpressionType::IfExpression { discriminator, body } => visitor.if_expression(discriminator, body),
+        ExpressionType::WhileExpression { condition, body } => visitor.while_expresssion(condition, body),
+        ExpressionType::ForExpression { enumerators, body } => visitor.for_expression(enumerators, body),
+        ExpressionType::Lambda { params, type_anno, body } => visitor.lambda_expression(params, type_anno, body),
+        ExpressionType::ListLiteral(items) => visitor.list_literal(items),
+      }
+      visitor.anno_expr(maybe_anno);
+      visitor.expr_kind(expr);
+    }
+  }
+}
+
+fn dispatch_declaration<V: ASTVisitor>(visitor: &mut V, declaration: &Declaration) {
+  match declaration {
+    Declaration::FuncSig(sig) => visitor.func_signature(sig),
+    Declaration::FuncDecl(sig, block) => visitor.func_declaration(sig, block),
+    Declaration::TypeDecl { name, body, mutable } => visitor.type_declaration(name, body, mutable),
+    Declaration::TypeAlias(alias, name) => visitor.type_alias(alias, name),
+    Declaration::Binding { name, constant, expr} => visitor.binding(name, constant, expr),
+    Declaration::Impl { type_name, interface_name, block } => visitor.impl_block(type_name, interface_name, block),
+    Declaration::Interface { name, signatures } => visitor.interface(name, signatures),
+  }
+}
+
+pub trait ASTVisitor {
+  fn ast(&mut self, _ast: &AST) { }
+  fn statement(&mut self, _stmt: &Statement) { }
+  fn expression(&mut self, _expr: &Expression) { }
+  fn anno_expr(&mut self, &Option<TypeIdentifier>) { }
+  fn expr_kind(&mut self, _expr: &ExpressionType) { }
+
+  fn nat_literal(&mut self, _n: &u64) { }
+  fn float_literal(&mut self, _f: &f64) { }
+  fn string_literal(&mut self, _s: &Rc<String>) { }
+  fn bool_literal(&mut self, _bool: &bool) { }
+  fn binop(&mut self, _binop: &BinOp, _lhs: &Expression, _rhs: &Expression) { }
+  fn prefixop(&mut self, prefix: &PrefixOp, _expr: &Expression) { }
+  fn tuple_literal(&mut self, _v: &Vec<Expression>) { }
+  fn value(&mut self, _v: &Rc<String>) { }
+  fn named_struct(&mut self, _name: &Rc<String>, _values: &Vec<(Rc<String>, Expression)>) { }
+  fn call(&mut self, _f: &Box<Expression>, _arguments: &Vec<Expression>) { }
+  fn index(&mut self, _indexee: &Box<Expression>, _indexers: &Vec<Expression>) { }
+  fn if_expression(&mut self, _discriminator: &Discriminator, _body: &IfExpressionBody) { }
+  fn while_expresssion(&mut self, _condition: &Option<Box<Expression>>, body: &Block) { }
+  fn for_expression(&mut self, _enumerators: &Vec<Enumerator>, _body: &Box<ForBody>) { }
+  fn lambda_expression(&mut self, _params: &Vec<FormalParam>, type_anno: &Option<TypeIdentifier>, body: &Block) { }
+  fn list_literal(&mut self, _items: &Vec<Expression>) { }
+
+
+  fn declaration(&mut self, _decl: &Declaration) { }
+  fn func_signature(&mut self, _sig: &Signature) { }
+  fn func_declaration(&mut self, _sig: &Signature, _block: &Vec<Statement>) { }
+  fn type_declaration(&mut self, _name: &TypeSingletonName, _body: &TypeBody, _mutable: &bool) { }
+  fn type_alias(&mut self, _alias: &Rc<String>, _name: &Rc<String>) { }
+  fn binding(&mut self, _name: &Rc<String>, _constant: &bool, _expr: &Expression) { }
+  fn impl_block(&mut self, _type_name: &TypeIdentifier, _interface_name: &Option<InterfaceName>, _block: &Vec<Declaration>) { }
+  fn interface(&mut self, name: &Rc<String>, signatures: &Vec<Signature>) { }
+}
+
+#[derive(Clone)]
+struct SchalaPrinter { 
+  s: String
+}
+
+impl SchalaPrinter {
+  fn new() -> SchalaPrinter {
+    SchalaPrinter {
+      s: format!("Schala source code:\n"),
+    }
+  }
+
+  fn done(self) -> String {
+    self.s
+  }
+}
+
+impl ASTVisitor for SchalaPrinter {
+  fn statement(&mut self, _: &Statement) {
+    self.s.push_str("\n");
+  }
+
+  fn expression(&mut self, _: &Expression) {
+    self.s.push_str("some_expr");
+  }
+
+  fn binding(&mut self, name: &Rc<String>, constant: &bool, _expr: &Expression) {
+    self.s.push_str(&format!("let{} {} = {}",
+                            if *constant { "" } else { " mut" }, 
+                            name,
+                            "some_expr"));
+  }
+}
+
+
+#[cfg(test)]
+mod visitor_tests {
+  use ::tokenizing::{Token, tokenize};
+  use ::parsing::ParseResult;
+  use ::ast::AST;
+  use super::*;
+
+  fn parse(input: &str) -> ParseResult<AST> {
+    let tokens = tokenize(input);
+    let mut parser = ::parsing::Parser::new(tokens);
+    parser.parse()
+  }
+
+  #[test]
+  fn test() {
+    let ast = parse("let a = 1 + 2; let b = 2 + 44;foo()").unwrap();
+    let mut pp = SchalaPrinter::new();
+    dispatch(&mut pp, &ast);
+    let result = pp.done();
+    assert_eq!(result, r#"Schala source code:
+let a = 1 + 2
+let b = 2 + 44
+foo()
+"#);
+  }
+}