Constants (true/false) in FormulaNode

[jurajsic]

Currently the constants true/false are not represented in FormulaNode in any way and to check if it is there, we need to check for the name of the node. In #169 I added function is_constant(), is_true() and is_false(), but they also only check for the name of the node. Maybe we should add an option to enum of the node representing a constant operand true/false.

[martinhruska]

Agree, add it as an option to enum.

[jurajsic]

We will add true/false to enum. What is needed to be done:

1. Fix parsing from .mata format to IntermediateAut so that \true/\false (according to true/false in mata format #168) is saved into node with correct option in enum.
2. Change functions is_constant(), is_true() and is_false() to check for the enum.
3. Check if we need to add checks for constants in current code whenever IntermediateAut is used. Probably in Nfa::construct(), Afa::construct() and in mintermization.

[Adda0]

@jurajsic What is the status of this issue? Considering we are revising the Mata file format, we should also have a look at this issue.

[jurajsic]

Haven't touched it at all.