discrete-logic-parser

LogicParser

This is a node.js version of FellowHashbrown's PyLogic. If you don't have the time to read his, or want to know about mine, I'll break it down for you.

This is a node.js project for parsing and evaluating logical expressions such as those in Discrete Mathematics.

Process of Parsing

In order to parse a logical expression, LogicParser will use the parseExpression function in tree.js to iterate through the entire expression. It removes all the spaces beforehand because spaces don't necessarily matter in the parsing.

It will then return an object of information pertaining to the expression that will be stored as a LogicNode instance as the root of a LogicTree. Each value is then parsed through (recursively if needed) to create instances to use in the final evaluation.

Examples of Logical Expressions

When evaluating logical expressions, there is a function, makeTable(), that will generate a truth table for you with the order of the expressions in ascending order that way you can read it as you would write a normal truth table.

Here are some examples:

a ^ b

| a | b | a ^ b |
+---+---+-------+
| T | T |   T   |
| T | F |   F   |
| F | T |   F   |
| F | F |   F   |

~(a v b)

| a | b | ~(a v b) |
+---+---+----------+
| T | T |    F     |
| T | F |    F     |
| F | T |    F     |
| F | F |    T     |

a v b v c v d

| a | b | c | d | a v b | (a v b) v c | ((a v b) v c) v d |
+---+---+---+---+-------+-------------+-------------------+
| T | T | T | T |   T   |      T      |         T         |
| T | T | T | F |   T   |      T      |         T         |
| T | T | F | T |   T   |      T      |         T         |
| T | T | F | F |   T   |      T      |         T         |
| T | F | T | T |   T   |      T      |         T         |
| T | F | T | F |   T   |      T      |         T         |
| T | F | F | T |   T   |      T      |         T         |
| T | F | F | F |   T   |      T      |         T         |
| F | T | T | T |   T   |      T      |         T         |
| F | T | T | F |   T   |      T      |         T         |
| F | T | F | T |   T   |      T      |         T         |
| F | T | F | F |   T   |      T      |         T         |
| F | F | T | T |   F   |      T      |         T         |
| F | F | T | F |   F   |      T      |         T         |
| F | F | F | T |   F   |      F      |         T         |
| F | F | F | F |   F   |      F      |         F         |

As you can tell with that last one, parentheses are automatically added because each logical expression is parsed as a {left} {operator} {right} value.

Feedback, Suggestions and Bugs

Any feedback, suggestions, or bugs can be mentioned in my Discord Developer Server.