You can build an expression tree which contains a return statement(s) using Expression.Return method. For example, you have the following code.
Func<int, bool> myFunc = (x) =>
{
if (x == 5)
return true;
else
return false;
};
Here is the code that is required to build the same functionality using expression tree.
LabelTarget returnTarget = Expression.Label(typeof(bool));
ParameterExpression para = Expression.Parameter(typeof(int), "intvalue");
Expression test = Expression.Equal(para, Expression.Constant(5));
Expression iftrue = Expression.Return(returnTarget, Expression.Constant(true));
Expression iffalse = Expression.Return(returnTarget, Expression.Constant(false));
var ex = Expression.Block(
Expression.IfThenElse(test, iftrue, iffalse),
Expression.Label(returnTarget, Expression.Constant(false)));
var compiled = Expression.Lambda<Func<int, bool>>(
ex,
new ParameterExpression[] { para }
).Compile();
Console.WriteLine(compiled(5)); // prints "True"
This example shows how to create an expression that contains a return statement(s).