private object GetTag([NotNull] Expression tagExpression)
{
if (tagExpression == null)
{
throw new ArgumentNullException(nameof(tagExpression));
}
switch (tagExpression)
{
case ConstantExpression constant:
return(constant.Value);
case UnaryExpression unary:
if (unary.NodeType == ExpressionType.Convert)
{
return(GetTag(unary.Operand));
}
break;
}
// ReSharper disable once ConstantNullCoalescingCondition
var expression = Visit(tagExpression) ?? throw new BuildExpressionException($"Invalid tag expression {tagExpression}.", new InvalidOperationException());
if (_buildContext.TryCompile(Expression.Lambda(expression.Convert(typeof(object)), true), out var tagFunc, out var error))
{
return(((Func <object>)tagFunc)());
}
throw error;
}
private object GetTag([NotNull] Expression tagExpression)
{
if (tagExpression == null)
{
throw new ArgumentNullException(nameof(tagExpression));
}
object tag;
switch (tagExpression)
{
case ConstantExpression constant:
tag = constant.Value;
break;
default:
// ReSharper disable once ConstantNullCoalescingCondition
var expression = Visit(tagExpression) ?? throw new BuildExpressionException($"Invalid tag expression {tagExpression}.", new InvalidOperationException());
if (_buildContext.TryCompile(Expression.Lambda(expression, true), out var tagFunc, out var error))
{
tag = ((Func <object>)tagFunc)();
}
else
{
throw error;
}
break;
}
public bool TryBuildExpression(IBuildContext buildContext, ILifetime lifetime, out Expression expression, out Exception error)
{
var type = buildContext.Key.Type.Descriptor();
var keyComparer = buildContext.Key.Tag as IComparer <Key>;
if (!type.IsConstructedGenericType())
{
throw new BuildExpressionException($"Unsupported enumerable type {type}.", null);
}
var genericTypeArguments = type.GetGenericTypeArguments();
if (genericTypeArguments.Length != 1)
{
throw new BuildExpressionException($"Unsupported enumerable type {type}.", null);
}
var elementType = genericTypeArguments[0];
var allKeys = GetKeys(buildContext.Container, elementType);
if (keyComparer != null)
{
allKeys = allKeys.OrderBy(i => i, keyComparer);
}
var keys = allKeys.ToArray();
var positionVar = Expression.Variable(typeof(int));
var conditionExpression =
keys.Length < 5
? CreateConditions(buildContext, keys, elementType, positionVar)
: CreateSwitchCases(buildContext, keys, elementType, positionVar);
if (buildContext.TryCompile(Expression.Lambda(conditionExpression, positionVar, buildContext.ContainerParameter, buildContext.ArgsParameter), out var factory, out error))
{
var ctor = EnumerableTypeDescriptor.MakeGenericType(elementType).Descriptor().GetDeclaredConstructors().Single();
var enumerableExpression = Expression.New(ctor, Expression.Constant(factory), Expression.Constant(keys.Length), buildContext.ContainerParameter, buildContext.ArgsParameter);
expression = enumerableExpression;
return(true);
}
expression = default(Expression);
return(false);
}
