interp_Lif.py

from ast import *
from interp_Lvar import InterpLvar
from utils import *

class InterpLif(InterpLvar):

  def interp_cmp(self, cmp):
    match cmp:
      case Lt():
        return lambda x, y: x < y
      case LtE():
        return lambda x, y: x <= y
      case Gt():
        return lambda x, y: x > y
      case GtE():
        return lambda x, y: x >= y
      case Eq():
        return lambda x, y: x == y
      case NotEq():
        return lambda x, y: x != y

  def interp_exp(self, e, env):
    match e:
      case IfExp(test, body, orelse):
        match self.interp_exp(test, env):
          case True:
            return self.interp_exp(body, env)
          case False:
            return self.interp_exp(orelse, env)
      case UnaryOp(Not(), v):
        return not self.interp_exp(v, env)
      case BoolOp(And(), values):
        left = values[0]; right = values[1]
        match self.interp_exp(left, env):
          case True:
            return self.interp_exp(right, env)
          case False:
            return False
      case BoolOp(Or(), values):
        left = values[0]; right = values[1]
        match self.interp_exp(left, env):
          case True:
            return True
          case False:
            return self.interp_exp(right, env)
      case Compare(left, [cmp], [right]):
        l = self.interp_exp(left, env)
        r = self.interp_exp(right, env)
        return self.interp_cmp(cmp)(l, r)
      case Let(Name(x), rhs, body):
        v = self.interp_exp(rhs, env)
        new_env = dict(env)
        new_env[x] = v
        return self.interp_exp(body, new_env)
      case _:
        return super().interp_exp(e, env)

  def interp_stmts(self, ss, env):
    if len(ss) == 0:
      return
    match ss[0]:
      case If(test, body, orelse):
        match self.interp_exp(test, env):
          case True:
            return self.interp_stmts(body + ss[1:], env)
          case False:
            return self.interp_stmts(orelse + ss[1:], env)
      case _:
        return super().interp_stmts(ss, env)