public override bool CanConvertFrom(Type fromType, Type toType, bool toNotNullable, NarrowingLevel level)
{
var nonNullable = Binders.GetNonNullableType(toType);
return(toType.IsAssignableFrom(fromType) ||
fromType == typeof(Builtins.Void) ||
toType == typeof(object) ||
toType == typeof(string) ||
nonNullable == typeof(bool) ||
Binders.IsNumber(nonNullable) && (Binders.IsNumber(fromType) || fromType == typeof(string)));
}
internal static Expression TryConvertExpression(Expression expression, Type toType, ParameterExpression succeeded)
{
var nonNullable = Binders.GetNonNullableType(toType);
if (toType == typeof(object))
{
return(InSuccess(Expression.Convert(expression, toType), succeeded));
}
else if (toType == expression.Type)
{
return(InSuccess(expression, succeeded));
}
else if (expression.Type == typeof(Builtins.Void))
{
if (toType == typeof(string))
{
return(InSuccess(Expression.Constant(string.Empty), succeeded));
}
else
{
return(InSuccess(Expression.Default(toType), succeeded));
}
}
else if (Binders.IsNumber(nonNullable))
{
if (Binders.IsNumber(expression.Type))
{
return(InSuccess(NewNullableOrThrough(Expression.Convert(expression, nonNullable), toType, nonNullable), succeeded));
}
else if (expression.Type == typeof(string))
{
ParameterExpression v;
Expression test;
if (Binders.IsInteger(nonNullable))
{
v = Expression.Variable(typeof(long));
test = Expression.Call(typeof(Binders).GetMethod("TryConvertInt64"), expression, v);
}
else if (Binders.IsFloatingPoint(nonNullable))
{
v = Expression.Variable(typeof(double));
test = Expression.Call(typeof(Binders).GetMethod("TryConvertDouble"), expression, v);
}
else
{
v = Expression.Variable(nonNullable);
test = Expression.Call(nonNullable.GetMethod("TryParse", new[] { typeof(string), nonNullable.MakeByRefType() }), expression, v);
}
if (succeeded != null)
{
test = Expression.Assign(succeeded, test);
}
return(Expression.Block(new[] { v },
Expression.Condition(test,
NewNullableOrThrough(v, toType, nonNullable),
Expression.Default(toType)
)
));
}
}
else if (toType == typeof(string))
{
if (expression.Type.IsValueType)
{
return(InSuccess(Expression.Call(expression, expression.Type.GetMethod("ToString", Type.EmptyTypes)), succeeded));
}
var v = Expression.Variable(expression.Type);
return(InSuccess(Expression.Block(new[] { v },
Expression.Condition(Expression.NotEqual(Expression.Assign(v, expression), Expression.Constant(null)),
Expression.Call(v, expression.Type.GetMethod("ToString", Type.EmptyTypes)),
Expression.Constant("null")
)
), succeeded));
}
else if (nonNullable == typeof(bool))
{
Expression exp;
if (Binders.IsNumber(expression.Type))
{
exp = Expression.NotEqual(expression, Expression.Default(expression.Type));
}
else if (expression.Type == typeof(string))
{
var v = Expression.Variable(typeof(long));
exp = Expression.Block(new[] { v },
Expression.AndAlso(
Expression.Call(typeof(long).GetMethod("TryParse", new[] { typeof(string), typeof(long).MakeByRefType() }), expression, v),
Expression.NotEqual(v, Expression.Constant(0L))
)
);
}
else if (!expression.Type.IsValueType)
{
exp = Expression.NotEqual(expression, Expression.Constant(null));
}
else if (expression.Type.IsGenericType && expression.Type.GetGenericTypeDefinition() == typeof(Nullable <>))
{
exp = Expression.Property(expression, "HasValue");
}
else
{
return(InSuccess(nonNullable == toType ? Expression.Constant(true) : Expression.Constant(new bool?(true)), succeeded));
}
return(InSuccess(NewNullableOrThrough(exp, toType, nonNullable), succeeded));
}
return(null);
}
internal static object ConvertInternal(object obj, Type toType)
{
Type fromType;
if (obj == null || (fromType = obj.GetType()) == typeof(Builtins.Void))
{
if (toType == typeof(string))
{
return(obj == null ? "null" : string.Empty);
}
else
{
return(toType.IsValueType ? toType.GetConstructor(Type.EmptyTypes).Invoke(null) : null);
}
}
if (toType == typeof(object) || toType == fromType)
{
return(obj);
}
if (toType == typeof(string))
{
return(obj.ToString());
}
var nonNullableTo = Binders.GetNonNullableType(toType);
if (Binders.IsNumber(nonNullableTo))
{
if (Binders.IsNumber(fromType))
{
var converted = System.Convert.ChangeType(obj, nonNullableTo);
if (nonNullableTo == toType)
{
return(converted);
}
else
{
return(Activator.CreateInstance(toType, converted));
}
}
else if (fromType == typeof(string))
{
var tryParse = nonNullableTo.GetMethod("TryParse", new[] { typeof(string), nonNullableTo.MakeByRefType() });
var argument = new[] { obj, null };
if ((bool)tryParse.Invoke(null, argument))
{
if (nonNullableTo == toType)
{
return(argument[1]);
}
else
{
return(Activator.CreateInstance(toType, argument[1]));
}
}
else
{
return(Activator.CreateInstance(toType));
}
}
}
else if (nonNullableTo == typeof(bool))
{
object converted;
if (Binders.IsNumber(fromType))
{
converted = System.Convert.ChangeType(obj, nonNullableTo);
}
else if (fromType == typeof(string))
{
long value;
converted = long.TryParse((string)obj, out value) && value != 0;
}
else if (!fromType.IsValueType)
{
converted = obj != null;
}
else if (fromType.IsGenericType && fromType.GetGenericTypeDefinition() == typeof(Nullable <>))
{
converted = fromType.GetProperty("HasValue").GetValue(obj);
}
else
{
converted = true;
}
if (nonNullableTo == toType)
{
return(converted);
}
else
{
return(new bool?((bool)converted));
}
}
return(NoValue);
}