Program uses shunting yard algorithm to interpret C Preprocessor #if boolean expressions

• It holds a Precedence Dictionary

Examples

• c_eval function has a lexer, parser and eval loop
• defined operator cannot take only a number, it must take an identifier
• Below Expression will output a syntax error

expr = "!defined(456)"
c_eval(expr)

expr = "F > 12.3"
c_eval(expr)

expr = "!defined(AAA) && F > H +"
c_eval(expr)

• If there is an identifier in this expression, it means it has not defined and treated as 0 in eval loop
• For Example below, B will be treated as 0

expr = "!defined(B) && 123 > 1257"
c_eval(expr)
Outputs : False

• Also FOO and F Treated as 0

expr = "!defined(FOO) && 123678 > 1257 || F + 12"
print(c_eval(expr))
Outputs : True