Interpreter Without Environment Poltergeist

interpret.py

# Top level function that interprets an entire program. It creates the
# initial environment that's used for storing variables.

def interpret_program(model):
    # Make the initial environment (a dict).  The environment is
    # where you will create and store variables.
    env = {}
    for structure in model.statements:
        interpret(structure, env)

# Internal function to interpret a node in the environment.  You need
# to expand to cover all of the classes in the model.py file.

def interpret(node, env):
    # Expand to check for different node types
    if isinstance(node, Integer):
        return int(node.value)
    elif isinstance(node, Float):
        return node.value
    elif isinstance(node, BinaryOperator):
        if node.op == '*':
            return interpret(node.left, env) * interpret(node.right, env)
        elif node.op == '/':
            return interpret(node.left, env) / interpret(node.right, env)
        elif node.op == '+':
            return interpret(node.left, env) + interpret(node.right, env)
        elif node.op == '-':
            return interpret(node.left, env) - interpret(node.right, env)
    elif isinstance(node, Comparison):
        if node.op == '>':
            return interpret(node.left, env) > interpret(node.right, env)
        elif node.op == '<':
            return interpret(node.left, env) < interpret(node.right, env)
        elif node.op == '==':
            return interpret(node.left, env) == interpret(node.right, env)
        elif node.op == '>=':
            return interpret(node.left, env) >= interpret(node.right, env)
        elif node.op == '<=':
            return interpret(node.left, env) <= interpret(node.right, env)
        elif node.op == '!=':
            return interpret(node.left, env) != interpret(node.right, env)
    elif isinstance(node, Print):
        print(interpret(node.value, env))
    elif isinstance(node, VariableAssignment):
        env[str(node.name)] = {"value": interpret(node.value, env), "mutable": True}
        return Unit()
    elif isinstance(node, ConstantAssignment):
        env[str(node.name)] = {"value": interpret(node.value, env), "mutable": False}
        return Unit()
    elif isinstance(node, VariableDeclaration):
        env[str(node.name)] = {"value": None, "mutable": True}
        return Unit()
    elif isinstance(node, VariableReAssignment):
        if str(node.name) in env.keys():
            if not env[str(node.name)]['mutable']:
               raise RuntimeError("Cannot reassign the value of a constant")
            else:
                env[str(node.name)] = interpret(node.value, env)
        else:
            raise RuntimeError(f"{node.name} not found for reassignment")
        return Unit()
    elif isinstance(node, Name):
        if node.name in env.keys():
            return env.get(node.name).get('value')
        else:
            raise RuntimeError(f"'{node.name}' not defined")
    elif isinstance(node, Negative):
        # gotta check if its  type that can be negative
        return interpret(node.value, env) * -1
    elif isinstance(node, Conditional):
        if interpret(node.if_condition, env):
            result = interpret(node.if_block, env)
            if isinstance(result, Break):
                return Break()
        else:
            if node.else_block:
                result = interpret(node.else_block, env)
                if isinstance(result, Break):
                    return Break()
    elif isinstance(node, WhileLoop):
        if interpret(node.while_condition, env):
            result = interpret(node.while_block, env)
            if not isinstance(result, Break):
                interpret(node, env)
            else:
                return Unit()
    elif isinstance(node, Block):
        for statement in node.statements:
            maybe_flow_interruptor = interpret(statement, env)
            if isinstance(maybe_flow_interruptor, Continue):
                return Unit()
            elif isinstance(maybe_flow_interruptor, Break):
                return Break()
        return Unit()
    elif isinstance(node, CompoundExpression):
        final_statement = None
        for statement in node.statements:
            final_statement = interpret(statement, env)
        return final_statement
    elif isinstance(node, Break):
        return Break()
    elif isinstance(node, Continue):
        return Continue()
    elif isinstance(node, WabbitType):
        return Unit()
    elif isinstance(node, WabbitBoolean):
        return node.value
    elif isinstance(node, Character):
        return str(node.value)
    else:
        raise RuntimeError(f"Can't interpret {node}")