public static Expression Replace(Expression ex, IEnumerable <KeyValuePair <string, Expression> > namedParameters)
{
var visitor = new ReplaceVisitor();
foreach (var p in namedParameters)
{
visitor.NamedParams.Add(p.Key, p.Value);
}
return(visitor.Visit(ex));
}
public void PredicateCombineTest()
{
Expression <Func <RootClass, NestedClass> > lambda1 = x => x.Nested;
Expression <Func <NestedClass, bool> > lambda2 = x => x.Property == 5;
Expression <Func <RootClass, bool> > expected = x => x.Nested.Property == 5;
var replaceVisitor = new ReplaceVisitor(lambda2, lambda1);
var result = replaceVisitor.Visit(lambda2);
result.ToString().Should().BeEquivalentTo(expected.ToString());
}
public void MethodCombineTest()
{
Expression <Func <RootClass, NestedClass> > lambda1 = x => x.Nested;
Expression <Func <NestedClass, int> > lambda2 = x => Helper.GetProperty(x);
Expression <Func <RootClass, int> > expected = x => Helper.GetProperty(x.Nested);
var replaceVisitor = new ReplaceVisitor(lambda2, lambda1);
var result = replaceVisitor.Visit(lambda2);
result.ToString().Should().BeEquivalentTo(expected.ToString());
}
internal static Expression <Func <T, bool> > OrElse <T>(this Expression <Func <T, bool> > exp1, Expression <Func <T, bool> > exp2)
{
var parameter = Expression.Parameter(typeof(T), "t");
var leftVisitor = new ReplaceVisitor(exp1.Parameters[0], parameter);
var left = leftVisitor.Visit(exp1.Body);
var rightVisitor = new ReplaceVisitor(exp2.Parameters[0], parameter);
var right = rightVisitor.Visit(exp2.Body);
return(Expression.Lambda <Func <T, bool> >(
Expression.OrElse(left, right), parameter));
}
public static Expression Replace(LambdaExpression ex, params Expression[] parameters)
{
var visitor = new ReplaceVisitor();
for (int i = 0; i < parameters.Length; i++)
{
visitor.Params.Add(ex.Parameters[i], parameters[i]);
}
var result = visitor.Visit(ex.Body);
if (result.CanReduce)
{
result = result.Reduce();
}
return(result);
}
internal static Expression <Func <T, bool> > AndAlso <T>(this Expression <Func <T, bool> > exp1, Expression <Func <T, bool> > exp2)
{
if (exp1 == null)
{
return(exp2);
}
var parameter = Expression.Parameter(typeof(T));
var leftVisitor = new ReplaceVisitor(exp1.Parameters[0], parameter);
var left = leftVisitor.Visit(exp1.Body);
var rightVisitor = new ReplaceVisitor(exp2.Parameters[0], parameter);
var right = rightVisitor.Visit(exp2.Body);
return(Expression.Lambda <Func <T, bool> >(
Expression.AndAlso(left, right), parameter));
}
public Expression Join(Expression beforeExpression)
{
if (_argumentIndex == -1)
{
throw new InvalidOperationException("cannot join not splitted expression");
}
var arguments = new Expression[_afterExpression.Arguments.Count];
for (int i = 0; i < arguments.Length; i++)
{
arguments[i] = _afterExpression.Arguments[i];
}
arguments[_argumentIndex] = beforeExpression;
MethodCallExpression newAfterExpression = Expression.Call(_afterExpression.Object, _afterExpression.Method, arguments);
var visitor = new ReplaceVisitor(_afterExpression, newAfterExpression);
return(visitor.Visit(_source));
}
public static IQueryable <T> InlineMatch <T>(this IQueryable <T> e)
{
var visitor = new ReplaceVisitor();
return(e.Provider.CreateQuery <T>(visitor.Visit(e.Expression)));
}
public static T InlineMatch <T>(this T e) where T : Expression
{
var visitor = new ReplaceVisitor();
return((T)visitor.Visit(e));
}
/// <summary>
/// Applies an expression as argument to a lambda.
/// </summary>
/// <param name="lambda">A lambda expression with 1 parameter</param>
/// <param name="ex">The expression to use as input for the lambda expression</param>
/// <returns>The expanded body of the LambdaExpression.</returns>
public static Expression ApplyTo(this LambdaExpression lambda, Expression ex)
{
var visitor = new ReplaceVisitor(lambda.Parameters[0], ex);
return(visitor.Visit(lambda.Body));
}
