/// <summary>
/// Performs a reverse <see cref="IExpressionNode.Resolve" /> operation, i.e. creates a <see cref="LambdaExpression" />
/// from a given resolved expression,
/// substituting all <see cref="QuerySourceReferenceExpression" /> objects by getting the referenced objects from the
/// lambda's input parameter.
/// </summary>
/// <param name="itemExpression">
/// The item expression representing the items passed to the generated <see cref="LambdaExpression" /> via its input
/// parameter.
/// </param>
/// <param name="resolvedExpression">
/// The resolved expression for which to generate a reverse resolved
/// <see cref="LambdaExpression" />.
/// </param>
/// <returns>
/// A <see cref="LambdaExpression" /> from the given resolved expression, substituting all
/// <see cref="QuerySourceReferenceExpression" />
/// objects by getting the referenced objects from the lambda's input parameter. The generated
/// <see cref="LambdaExpression" /> has exactly one
/// parameter which is of the type defined by <paramref name="itemExpression" />.
/// </returns>
public static LambdaExpression ReverseResolve(Expression itemExpression, Expression resolvedExpression)
{
ArgumentUtility.CheckNotNull("itemExpression", itemExpression);
ArgumentUtility.CheckNotNull("resolvedExpression", resolvedExpression);
var lambdaParameter = Expression.Parameter(itemExpression.Type, "input");
var visitor = new ReverseResolvingExpressionVisitor(itemExpression, lambdaParameter);
var result = visitor.Visit(resolvedExpression);
return(Expression.Lambda(result, lambdaParameter));
}
/// <summary>
/// Performs a reverse <see cref="IExpressionNode.Resolve" /> operation on a <see cref="LambdaExpression" />, i.e.
/// creates a new
/// <see cref="LambdaExpression" /> with an additional parameter from a given resolved <see cref="LambdaExpression" />,
/// substituting all <see cref="QuerySourceReferenceExpression" /> objects by getting the referenced objects from the
/// new input parameter.
/// </summary>
/// <param name="itemExpression">
/// The item expression representing the items passed to the generated <see cref="LambdaExpression" /> via its new
/// input parameter.
/// </param>
/// <param name="resolvedExpression">
/// The resolved <see cref="LambdaExpression" /> for which to generate a reverse resolved
/// <see cref="LambdaExpression" />.
/// </param>
/// <param name="parameterInsertionPosition">The position at which to insert the new parameter.</param>
/// <returns>
/// A <see cref="LambdaExpression" /> similar to the given resolved expression, substituting all
/// <see cref="QuerySourceReferenceExpression" />
/// objects by getting the referenced objects from an additional input parameter. The new input parameter is of the
/// type defined by
/// <paramref name="itemExpression" />.
/// </returns>
public static LambdaExpression ReverseResolveLambda(Expression itemExpression,
LambdaExpression resolvedExpression, int parameterInsertionPosition)
{
ArgumentUtility.CheckNotNull("itemExpression", itemExpression);
ArgumentUtility.CheckNotNull("resolvedExpression", resolvedExpression);
if (parameterInsertionPosition < 0 || parameterInsertionPosition > resolvedExpression.Parameters.Count)
{
throw new ArgumentOutOfRangeException("parameterInsertionPosition");
}
var lambdaParameter = Expression.Parameter(itemExpression.Type, "input");
var visitor = new ReverseResolvingExpressionVisitor(itemExpression, lambdaParameter);
var result = visitor.Visit(resolvedExpression.Body);
var parameters = new List <ParameterExpression>(resolvedExpression.Parameters);
parameters.Insert(parameterInsertionPosition, lambdaParameter);
return(Expression.Lambda(result, parameters.ToArray()));
}
