Simple Lex and Yacc Boolean Parser
A Boolean expression has the usual operators applied to logical values,represented by 0 (zero), the value FALSE, and 1 (one), the value TRUE. The values Logics can appear in the expression explicitly (0/1) or as variables. The variables are represented by the letter 'x' followed by a number, e.g., x1, x24. The program recognizes the following representation for Boolean operators: '+' - logical OR '.' - (dot) AND logical '!' - denial '=>' - implication '(' expression ')' - parentheses with the usual meaning.
For example, the expression Boolean: ¬ (x1 ∨ ¬x2) ∧ (¬x1 ∨ x3 ∨ ¬x4 ∨ x5) ∧ x4 x6 ∨ (¬x4 ∧ ¬x5)
It will have the following representation in the program: ! (x1 +! x2). (! x1 + x3 +! x4 + x5). x4 => x6 + (! x4.! x5)
The program also accepts the assignment of a Boolean value to a variable. The following is a small example of inputs and outputs of the program: input: x1 = 0 input: x2 = 1 input: x1 + !x2 output: 0 input: x3 = 0 input: x1 => x3 output: 1 input: x4 = (x2 + x3 + x1) . (!x2 + x3) input: x4 output: 0 input: (x1 + x3 + 1) . (!0 + x4) output: 1
Linux commands to compile:
user@machine:$ yacc -d BooleanParser.y
user@machine:$ flex BooleanParser.l
user@machine:$ gcc lex.yy.c y.tab.c
user@machine:$ ./a.out