visitMappingExpr method

Implementation

@override
Object? visitMappingExpr(Expr.Mapping expr) {
  Stmt.Functional mp;
  var func = evaluate(expr.lambda);
  if (func is! LoxFunction) {
    throw RuntimeError(
        expr.name, "Only func can be used as Mapping function");
  } else {
    mp = func.declaration;
  }
  Object? objects = evaluate(expr.callee);
  LoxFunction iterableFun = LoxFunction(mp, environment, false);
  switch (expr.name.lexeme) {
    case 'map':
      if (objects is! Iterable) {
        throw RuntimeError(expr.name, "Only iterable can map function");
      }
      return objects.map((i) {
        return iterableFun.call(this, [i], {});
      }).toList();
    case 'where':
      if (objects is! Iterable) {
        throw RuntimeError(expr.name, "Only iterable can use where function");
      }
      return objects.where((i) {
        return iterableFun.call(this, [i], {}) == true;
      }).toList();
    case 'sort':
      if (objects is! List) {
        throw RuntimeError(expr.name, "Only List can be sorted");
      }
      objects.sort((a, b) {
        return iterableFun.call(this, [a, b], {}) as int;
      });
      return null;
    case 'forEach':
      if (objects is! Iterable) {
        throw RuntimeError(
            expr.name, "Only iterable can use forEach function");
      }
      for (var i in objects) {
        iterableFun.call(this, [i], {});
      }
      return null;
  }
  throw RuntimeError(expr.name, "Only Array have mapping.");
}