SymbolTable.py

#!/usr/bin/python
from errors import UndeclaredVariableError

class VariableSymbol:
    def __init__(self, name, type):
        self.name = name
        self.type = type # MatrixType, IntType, FloatType, String

class Scope:
    def __init__(self, parent, level):
        self.parent = parent
        self.level = level
        self.symbols = dict()

    def put(self, name, type):
        self.symbols[name] = VariableSymbol(name, type)
    
    def get(self, name):
        if name in self.symbols:
            return self.symbols[name]
        
        if self.parent == None:
            raise UndeclaredVariableError()
        
        return self.parent.get(name)
         
    def get_parent(self):
        return self.parent
    
class SymbolTable:
    def __init__(self):
        self.global_scope = Scope(None, 0)
        self.current_scope = self.global_scope

    def push_scope(self):
        self.current_scope = Scope(self.current_scope, self.current_scope.level+1)

    def pop_scope(self):
        self.current_scope = self.current_scope.get_parent()

    def get(self, name):
        return self.current_scope.get(name)
    
    def put(self, name, type):
        self.current_scope.put(name, type)