/// <summary>
/// Gets a new specification function which corresponds to the logical
/// combination of the specified objects: <c>AND</c>.
/// </summary>
/// <returns>A specification function.</returns>
/// <param name="spec">A specification function.</param>
/// <param name="composeWith">A specification expression.</param>
/// <typeparam name="T">The generic type of the specifications.</typeparam>
public static ISpecificationFunction <T> And <T>(this ISpecificationFunction <T> spec, ISpecificationExpression <T> composeWith)
{
var func1 = GetFunction(spec);
var func2 = composeWith.GetFunction();
return(Spec.Func <T>(o => func1(o) && func2(o)));
}
/// <summary>
/// Filters a Linq queryable object using the predicate defined in a specification expression.
/// </summary>
/// <returns>A queryable object which is filtered by the specification predicate.</returns>
/// <param name="collection">A Linq queryable object.</param>
/// <param name="specification">A specification expression.</param>
/// <typeparam name="T">The generic type of the collection and the specification.</typeparam>
public static IEnumerable <T> Where <T>(this IEnumerable <T> collection, ISpecificationExpression <T> specification)
{
if (collection == null)
{
throw new ArgumentNullException(nameof(collection));
}
return(collection.Where(specification.GetFunction()));
}
/// <summary>
/// Gets a <c>System.Predicate<T></c> from a specification expression.
/// </summary>
/// <returns>A predicate instance matching the specification.</returns>
/// <param name="spec">A specification expression.</param>
/// <typeparam name="T">The generic type of the specification.</typeparam>
public static Predicate <T> AsPredicate <T>(this ISpecificationExpression <T> spec)
{
var func = spec.GetFunction();
return(o => func(o));
}
/// <summary>
/// Gets a value which indicates whether a specified value matches/satisfies the specification.
/// </summary>
/// <returns><c>true</c> if the value matches the specification; <c>false</c> otherwise.</returns>
/// <param name="spec">A specification expression.</param>
/// <param name="value">The value to test with the specification.</param>
/// <typeparam name="T">The generic type of the specification and the specific type of the value object.</typeparam>
public static bool Matches <T>(this ISpecificationExpression <T> spec, T value)
{
var func = spec.GetFunction();
return(func(value));
}
/// <summary>
/// Gets a specification function which copies the specified specification expression.
/// </summary>
/// <returns>A specification function.</returns>
/// <param name="spec">A specification expression.</param>
/// <typeparam name="T">The generic type of the specification.</typeparam>
public static ISpecificationFunction <T> AsSpecificationFunction <T>(this ISpecificationExpression <T> spec)
{
return(Spec.Func(spec.GetFunction()));
}
