RiGrammar grammar = new RiGrammar(this, "myGrammar.g");
String text = grammar.expand();
println("Expanded: "+text);

RiTa grammar files are plain text files (generally ending with the '.g' extension and residing in the 'data' folder) that follow the format below:

     {
      <start>
      <token1> | <token2> | <token3>
    }

    {
      <token2>
      terminal1 | 
      terminal2 | <token1>
      # this is a comment 
    }
    ...

• expand() which simply begins at the <start> state and generates a string of terminals from the grammar.

• expandFrom(String) which begins with the argument String (which can consist of both non-terminals and terminals,) and expands from there. Notice that expand() is simply a convenient version of expandFrom("<start>");.

• expandWith(String, String) takes 2 String arguments, the 1st (a terminal) is guaranteed to be substituted for the 2nd (a non-terminal). Once this subsitution is made, the algorithm then works backwards (up the tree from the leaf) ensuring that the terminal (arg1) appears in the output string. For example, with the grammar fragment above, one might call:

        grammar.expandWith("hello", "<token2>");
   

  assuring not only that <token2>will be used at least once in the generation process, but that when it is, it will be replaced by the terminal "hello".

• Grammar files should be placed in the 'data' directory of a processing sketch, along with images, fonts, and other resources.

• A RiGrammar object will assign (by default) equal weights to all choices in a rule. One can adjust the weights by adding 'multipliers' as follows. In the production below, 'terminal1' will be chosen twice as often as the 2 other choices.

     {
       <token2>
       [2] terminal1 | 
       terminal2 | <token1> | 
     }

RiGrammar(parent, grammarFileName);