The purpose of this program is to determine whether a word is accepted by a given DFA or NFA.
It has builtin a CLI with 3 options:
- Read a DFA
- Read a NFA
- Process a word - read from the STDIN a word and prints whether is it accepted or not.
- Both of them open a window to select a text file that contains the graph for the automata.
The automata expects the input to have this specific format:
node_number _ is_final _ next_node _ letter _ ...
Where:
- the node number - represents a positive integer for that specific node Note that the node 0 will be always consider the starting node!
- is_final - a boolean that marks if the node is a terminal one. This should be written as
ffor a final one andnfor a non-terminal one. - next_node - represents a positive integer for the next node adjacent
- letter - is the corresponding letter from the automata's alphabet(it could be also any symbol) that lies on the edge of the connection
- The three dots marks that we can have any number of nodes linked to this node.
Every node along with its content should be written on a different line.
The program accepts non-completed automata, but must have all nodes declared at least.
Suppose that we have this automata:
The input file for this would be:
0 n 0 1 1 0
1 f 2 0 0 1
2 n 3 2
3 f
But if we wanted a complete automata we would complete the edges with a -1 node that coresponds for the abort state.
0 n 0 1 1 0 -1 2
1 f 2 0 0 1 -1 2
2 n 3 2 -1 0 -1 1
3 f -1 0 -1 1 -1 2
The program simulates an automata behavior, taking one letter at a time and decides the next node.
It has implemented 2 main classes:
- Node class - that represents a node in the automata's graph
- FA class(stands for Finate Automata) - storing the component nodes
The DFA and NFA classes inherits from the FA and adds the main functionallity, validate_word method, which differs between them.
The word validation in a NFA is done by running a backtracking through all nondeterministic nodes, whereas in a DFA is a liniar lookup.
The adjacent nodes are stored as an array of indices that corresponds to the node.
Example:
0 coresponds to node 0, 1 to node 1, ...
The file selector is done using the tkinter module, the root windows is hidden.