Checker is a base class for all checkers - it makes all children classes to have same methods.

finder.py

class Checker:
    @staticmethod
    def is_this_type(expr):
        raise NotImplementedError()

    def does_match(self, value):
        raise NotImplementedError()


class NameChecker(Checker):
    @staticmethod
    def is_this_type(expr):
        """
        Check if the expr is in a name checker format
        """

    def __init__(self, expr):
        self.expr = expr

    def does_match(self, value):
        "Check if value matches to the expr"


class SizeChecker(Checker):
    @staticmethod
    def is_this_type(expr):
        """
        Check if the expr is in a size checker format
        """

    def __init__(self, expr):
        self.expr = expr

    def does_match(self, value):
        "Check if value matches to the expr"


class TypeChecker(Checker):
    @staticmethod
    def is_this_type(expr):
        """
        Check if the expr is in a type checker format
        """

    def __init__(self, expr):
        self.expr = expr

    def does_match(self, value):
        "Check if value matches to the expr"


class CreateTimeChecker(Checker):
    @staticmethod
    def is_this_type(expr):
        """
        Check if the expr is in a creation time checker format
        """

    def __init__(self, expr):
        self.expr = expr

    def does_match(self, value):
        "Check if value matches to the expr"


class Finder:
    checkers = [NameChecker, SizeChecker, TypeChecker, CreateTimeChecker]

    def __init__(self, path, expression):
        self.current_checkers = []
        exps = [e.strip() for e in expression.split('|')]
        for exp in exps:
            found = False
            for ch in self.checkers:
                if ch.is_this_type(exp):
                    found = True
                    self.current_checkers.append(ch(exp))
                    break
            if not found:
                raise ValueError("Invalid pattern '{}'.".format(exp))

    def find(self, current_path, results):
        """
        Check if content files match the expressions and check it's inner folders
        """