rpython/env.py

   1 from mal_types import MalType, MalSym, MalList, throw_str
   2
   3 # Environment
   4 class Env():
   5     def __init__(self, outer=None, binds=None, exprs=None):
   6         self.data = {}
   7         self.outer = outer or None
   8
   9         if binds:
  10             assert isinstance(binds, MalList) and isinstance(exprs, MalList)
  11             for i in range(len(binds)):
  12                 bind = binds[i]
  13                 if not isinstance(bind, MalSym):
  14                     throw_str("env bind value is not a symbol")
  15                 if bind.value == u"&":
  16                     bind = binds[i+1]
  17                     if not isinstance(bind, MalSym):
  18                         throw_str("env bind value is not a symbol")
  19                     self.data[bind.value] = exprs.slice(i)
  20                     break
  21                 else:
  22                     self.data[bind.value] = exprs[i]
  23
  24     def find(self, key):
  25         assert isinstance(key, MalSym)
  26         if key.value in self.data: return self
  27         elif self.outer:           return self.outer.find(key)
  28         else:                      return None
  29
  30     def set(self, key, value):
  31         assert isinstance(key, MalSym)
  32         assert isinstance(value, MalType)
  33         self.data[key.value] = value
  34         return value
  35
  36     def get(self, key):
  37         assert isinstance(key, MalSym)
  38         env = self.find(key)
  39         if not env: throw_str("'" + str(key.value) + "' not found")
  40         return env.data[key.value]