This is a fun project to demonstrate how we can create a CFG using recursion
We always start with production rule that contains variable S. We keep adding text
of this production rule to our result until we encounter a variable. We then
pick a production rule that has this variable and recursively explores it. We
stop once there is no more production rule to explore.
Let's say we have the following set of production rules:
<S> = I am <a> happy
<a> = very
In the above example, we have two variables S and a and two production rules that are associated with
these variables. We start with S. We keep adding text of this production rule until we
encounter variable. Then we explore production rule that starts with a. After
adding all text of this production rule to our string variable, we don't have any variable
left, so we backtrack to the production rule that we were working on previously which was
S. we then add happy to our string variable and return it. As a result, we have I am very happy.
