from .nodes import *

class SymbolTable:
  """
   Symbol table for a current scope.
   It has functions:
    - hasname for checking for a name in current scope or above
    - addSymbol to add an object
  """
  def __init__(self, parent=None):
    self.parent = parent
    self.syms = {}

  def __repr__(self):
    return 'Symboltable with {0} symbols\n'.format(len(self.syms))

  def printTable(self, indent=0):
    for name in self.syms:
      print(self.syms[name])

  def getAllLocal(self, cls):
     """ Get all local objects of a specific type """
     r = []
     for key in self.syms.keys():
        sym = self.syms[key]
        if issubclass(type(sym), cls):
           r.append(sym)
     return r

  def getLocal(self, cls, name):
      if name in self.syms.keys():
         sym = self.syms[name]
         if isinstance(sym, cls):
            return sym
         else:
            Error('Wrong type found')
      else:
         Error('Symbol not found')

  # Retrieving of specific classes of items:
  def get(self, cls, name):
    if self.hasSymbol(name):
      sym = self.getSymbol(name)
      if issubclass(type(sym), cls):
        return sym
    raise SymbolException('type {0} undefined'.format(typename))

  def has(self, cls, name):
    if self.hasSymbol(name):
      sym = self.getSymbol(name)
      if issubclass(type(sym), cls):
        return True
    return False

  # Adding and retrieving of symbols in general:
  def addSymbol(self, sym):
    if sym.name in self.syms.keys():
      raise Exception('Symbol "{0}" redefined'.format(sym.name))
    else:
      self.syms[sym.name] = sym

  def getSymbol(self, name):
     if name in self.syms.keys():
      return self.syms[name]
     else:
      if self.parent:
        return self.parent.getSymbol(name)
      else:
         raise Exception('Symbol "{0}" undeclared!'.format(name))

  def hasSymbol(self, name):
    if name in self.syms.keys():
      return True
    else:
      if self.parent:
        return self.parent.hasSymbol(name)
      else:
        return False