public static Expression <Func <T, TResult> > ReplaceParameterByConstant <T, TResult>(Expression <Func <T, object, bool> > predicate, object constant)
{
var body = predicate.Body;
var substitutionVisitor = new VariableSubstitutionVisitor(predicate.Parameters[1], Expression.Constant(constant, constant.GetType()));
var visitedBody = substitutionVisitor.Visit(body).Reduce();
return(Expression.Lambda <Func <T, TResult> >(visitedBody, predicate.Parameters[0]));
}
public static Expression <Func <T, TResult> > ReplaceParameterByConstant <T, TConstant1, TConstant2, TResult>(Expression <Func <T, TConstant1, TConstant2, bool> > predicate,
TConstant1 constant1, TConstant2 constant2)
{
var body = predicate.Body;
var substitutionVisitor = new VariableSubstitutionVisitor(predicate.Parameters[1], Expression.Constant(constant1, typeof(TConstant1)));
var visitedBody = substitutionVisitor.Visit(body).Reduce();
var newLambda = Expression.Lambda <Func <T, TConstant2, TResult> >(visitedBody, predicate.Parameters[0], predicate.Parameters[2]);
return(ReplaceParameterByConstant <T, TConstant2, TResult>(newLambda, constant2));
}