interp_Pvar.py

from ast import *
from utils import input_int


class InterpPvar:
    def interp_exp(self, e, env):
        match e:
            case BinOp(left, Add(), right):
                l = self.interp_exp(left, env)
                r = self.interp_exp(right, env)
                return l + r
            case UnaryOp(USub(), v):
                return - self.interp_exp(v, env)
            case Name(id):
                return env[id]
            case Constant(value):
                return value
            case Call(Name('input_int'), []):
                return int(input())
            case _:
                raise Exception('error in InterpPvar.interp_exp, unhandled ' + repr(e))

    def interp_stmts(self, ss, env):
        if len(ss) == 0:
            return
        match ss[0]:
            case Assign([lhs], value):
                env[lhs.id] = self.interp_exp(value, env)
                return self.interp_stmts(ss[1:], env)
            case Expr(Call(Name('print'), [arg])):
                print(self.interp_exp(arg, env), end='')
                return self.interp_stmts(ss[1:], env)
            case Expr(value):
                self.interp_exp(value, env)
                return self.interp_stmts(ss[1:], env)
            case _:
                raise Exception('error in InterpPvar.interp_stmt, unhandled ' + repr(ss[0]))

    def interp_P(self, p):
        match p:
            case Module(body):
                self.interp_stmts(body, {})


if __name__ == "__main__":
    eight = Constant(8)
    neg_eight = UnaryOp(USub(), eight)
    read = Call(Name('input_int'), [])
    ast1_1 = BinOp(read, Add(), neg_eight)
    pr = Expr(Call(Name('print'), [ast1_1]))
    p = Module([pr])
    interp = InterpPvar()
    interp.interp_P(p)