Program uses shunting yard algorithm to interpret C Preprocessor (#if, #elif) boolean expressions

Examples

c_eval function implements Parser(with Precedence of all operators such as defined ! | >> ...)
defined operator must take only an identifier
Below Expression will output a syntax error

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

expr = "~ defined(TEST)"
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) # False

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