Examples > Exchange of words > Analysis step by step
The explanation of the rule can be demonstrated in detail, by executing the program step by step.
To do this, first click on the Tetra-Tab of the left block in the user interface.
Now you can execute the program step by step by means of the single node button:
After you have clicked the button for the first time, a tree view is opened below of the name of the Exchange production, which shows the syntax of the production. After a second click on the button, the tree will look like:
The node Exchange represents the whole production.
The node Rep0_of_Exchange represents the parenthesis "(...)+"
The node Alt0_of_Rep0_of_Exchange represents the set of alternatives.
Each alternative consist of two nodes: a node representing the text, which shall be recognized, and a node representing the semantic action.
At each further step the yellow mark walks to the next tree node, which leads to the recognition of the next section of source text. Every time a node, which represents a semantic action, is left, the corresponding instructions will be executed; that means here: the target text will be extended.
The stepwise execution of a program is carried out in the so-called debug mode, and the TextTransformer has to be set back into the normal mode. This is done with the reset button:
Thereby the output will be deleted too.