One of key features of the Builder Application is the Grammar Test Window. After the grammar has been successfully compiled by the Builder, the developer can check how Deterministic Finite Automata and LALR algorithms will analyze any number of test cases.
To test the behavior of the algorithms, a local embedded implementation of the Visual Basic 6 Engine is used. Although different implementations of the Engine exist, the behavior of the LALR and DFA algorithms is constant. Regardless of whether an Engine is written for Visual Basic, C++ or Java, the parse tables will create the same number of reductions and will accept or reject the same information. As a result, the specific details on how the Visual Basic 6 Engine was implemented, will have no effect on testing.
The Grammar Test Window contains three separate "tabs". The first tab allows the developer to enter or load a test string. In the screenshot below, a very simple LISP program is being tested.
The controls on the Test Window are simular to those you will find on your DVD (or VCR) player.
You start the test, by clicking on the "Start" button. At this point, you can then click either the "Step" button to parse the test string and pause each time a token is read. This allows you to watch how the test string is interpreted by your grammar step-by-step. The "Parse All" button will parse the rest of the test string and will not stop until either an error occurs or the test string is accepted.The "Stop" button can be used at any time to to quit the test.
The first tab contains a list of the parse actions performed by the LALR Parsing Engine.
If the test string is successfully parsed, the GOLD Builder draws a parse tree for the user to review. This tree can be saved to formatted text.
