use std::error::Error;
use crate::ast::*;

pub type VResult = Result<(), Box<dyn Error>>;

pub trait ASTVisitor {
  fn visit_expression(&mut self, _: &mut Expression) -> VResult {
    Ok(())
  }
}

pub trait Visitable {
  fn visit(&mut self, v: &mut dyn ASTVisitor) -> VResult;
}

impl Visitable for AST {
  fn visit(&mut self, v: &mut dyn ASTVisitor) -> VResult {
    for s in self.0.iter_mut() {
      s.node_mut().visit(v)?
    }
    Ok(())
  }
}

impl Visitable for Statement {
  fn visit(&mut self, _v: &mut dyn ASTVisitor) -> VResult {
    Ok(())
  }
}