89 lines
3.9 KiB
C#
89 lines
3.9 KiB
C#
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using System;
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using System.Linq.Expressions;
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namespace MyCode.Project.Infrastructure
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{
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/// <summary>
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/// Represents the base class for specifications.
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/// </summary>
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/// <typeparam name="T">The type of the object to which the specification is applied.</typeparam>
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public abstract class Specification<T> : ISpecification<T>
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{
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#region Public Methods
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/// <summary>
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/// Evaluates a LINQ expression to its corresponding specification.
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/// </summary>
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/// <param name="expression">The LINQ expression to be evaluated.</param>
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/// <returns>The specification which represents the same semantics as the given LINQ expression.</returns>
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public static Specification<T> Eval(Expression<Func<T, bool>> expression)
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{
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return new ExpressionSpecification<T>(expression);
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}
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#endregion
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#region ISpecification<T> Members
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/// <summary>
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/// Returns a <see cref="System.Boolean"/> value which indicates whether the specification
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/// is satisfied by the given object.
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/// </summary>
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/// <param name="obj">The object to which the specification is applied.</param>
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/// <returns>True if the specification is satisfied, otherwise false.</returns>
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public virtual bool IsSatisfiedBy(T obj)
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{
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return this.GetExpression().Compile()(obj);
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}
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/// <summary>
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/// Combines the current specification instance with another specification instance
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/// and returns the combined specification which represents that both the current and
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/// the given specification must be satisfied by the given object.
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/// </summary>
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/// <param name="other">The specification instance with which the current specification
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/// is combined.</param>
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/// <returns>The combined specification instance.</returns>
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public ISpecification<T> And(ISpecification<T> other)
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{
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return new AndSpecification<T>(this, other);
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}
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/// <summary>
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/// Combines the current specification instance with another specification instance
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/// and returns the combined specification which represents that either the current or
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/// the given specification should be satisfied by the given object.
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/// </summary>
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/// <param name="other">The specification instance with which the current specification
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/// is combined.</param>
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/// <returns>The combined specification instance.</returns>
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public ISpecification<T> Or(ISpecification<T> other)
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{
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return new OrSpecification<T>(this, other);
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}
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/// <summary>
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/// Combines the current specification instance with another specification instance
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/// and returns the combined specification which represents that the current specification
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/// should be satisfied by the given object but the specified specification should not.
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/// </summary>
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/// <param name="other">The specification instance with which the current specification
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/// is combined.</param>
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/// <returns>The combined specification instance.</returns>
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public ISpecification<T> AndNot(ISpecification<T> other)
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{
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return new AndNotSpecification<T>(this, other);
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}
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/// <summary>
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/// Reverses the current specification instance and returns a specification which represents
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/// the semantics opposite to the current specification.
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/// </summary>
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/// <returns>The reversed specification instance.</returns>
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public ISpecification<T> Not()
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{
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return new NotSpecification<T>(this);
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}
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/// <summary>
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/// Gets the LINQ expression which represents the current specification.
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/// </summary>
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/// <returns>The LINQ expression.</returns>
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public abstract Expression<Func<T, bool>> GetExpression();
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#endregion
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}
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}
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