public Expression <FunctionComponent> BuildRendererExpression()
{
var context = new ComponentBuilderContext(this);
var element = null as ElementBuilder;
try
{
// build element to be rendered
element = Render(context);
}
catch (Exception e)
{
context.OnException(e);
}
context.ThrowExceptions();
var body = new List <Expression>();
// declare and initialize variables step
var variables = context.Variables.OrderBy(x => x.Key).Select(x => x.Value).ToArray();
foreach (var variable in variables)
{
body.Add(Expression.Assign(variable.Name, variable.Value));
}
// return rendered element step
body.Add(element?.GetValue(context) ?? Expression.Constant(null, typeof(ofElement)));
return(Expression.Lambda <FunctionComponent>(Expression.Block(variables.Select(v => v.Name), body), context.Node));
}
public virtual Expression GetValue(ComponentBuilderContext context)
{
Expression expr = Expression.New(Constructor, Parameters.Select(p => Props[p.Name].GetValue(context)));
if (Assignee != null)
{
expr = Expression.Assign(Assignee, expr);
}
return(expr);
}
public Expression GetValue(ComponentBuilderContext context)
{
var items = _items.Select(x => x.GetValue(context));
var elementType = _type.GetElementType();
if (elementType != null)
{
return(Expression.NewArrayInit(elementType, items));
}
return(Expression.ListInit(Expression.New(_type), items));
}
public Expression GetValue(ComponentBuilderContext context)
{
if (_parameter.HasDefaultValue)
{
if (_parameter.DefaultValue == null && _parameter.ParameterType.IsValueType)
{
return(Expression.Default(_parameter.ParameterType));
}
return(Expression.Constant(_parameter.DefaultValue, _parameter.ParameterType));
}
throw new ArgumentException($"Parameter {_parameter} of constructor {_parameter.Member} in {_parameter.Member.DeclaringType} is required but no value was provided.");
}
public override Expression GetValue(ComponentBuilderContext context) => Expression.Constant(null, typeof(ofElement));
protected abstract ElementBuilder Render(ComponentBuilderContext context);