bool EvaluateVersionConditional(Expression expr)
{
if (expr is NameExpr)
{
var e = expr as NameExpr;
return Tags.Contains(e.Name);
}
if (expr is BinaryOperatorExpr)
{
var e = expr as BinaryOperatorExpr;
bool left = EvaluateVersionConditional(e.Left);
bool right = EvaluateVersionConditional(e.Right);
if (e.Op == TokenType.LogicalAnd)
return left && right;
if (e.Op == TokenType.LogicalOr)
return left || right;
Error.Create("Unsupported operator '{0}' in version condition", e.Op).At(e.Position).Throw();
}
if (expr is UnaryOperatorExpr)
{
var e = expr as UnaryOperatorExpr;
bool right = EvaluateVersionConditional(e.Right);
if (e.Op == TokenType.Bang)
return !right;
Error.Create("Unsupported operator '{0}' in version condition", e.Op).At(e.Position).Throw();
}
Error.Create("Syntax error").At(expr.Position).Throw();
return false;
}
ExpressionStatement ParseExpressionStatement(Expression expr)
{
Consume(TokenType.Semi);
return new ExpressionStatement { Expr = expr, Position = expr.Position };
}