/// <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 ReverseResolvingExpressionTreeVisitor(itemExpression, lambdaParameter);
var result = visitor.VisitExpression(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 ReverseResolvingExpressionTreeVisitor(itemExpression, lambdaParameter);
var result = visitor.VisitExpression(resolvedExpression.Body);
var parameters = new List <ParameterExpression> (resolvedExpression.Parameters);
parameters.Insert(parameterInsertionPosition, lambdaParameter);
return(Expression.Lambda(result, parameters.ToArray()));
}
