started implementing interpreter pattern.
This commit is contained in:
tylerlaberge
59
pypatterns/behavioral/interpreter.py
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59
pypatterns/behavioral/interpreter.py
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from abc import ABCMeta, abstractmethod
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class Context(object):
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"""
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Context class as part of the Interpreter design pattern.
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"""
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def __init__(self, in_data):
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self.in_data = in_data
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self.out_data = None
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class Expression(object, metaclass=ABCMeta):
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"""
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Abstract Expression class as part of the Interpreter design pattern.
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"""
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@abstractmethod
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def interpret(self, context):
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"""
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Abstract interpret method.
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@param context: The context to interpret.
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@type context: Context
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"""
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pass
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class NonTerminalExpression(Expression, metaclass=ABCMeta):
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"""
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Base class for the NonTerminalExpression class as part of the Interpreter design pattern.
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"""
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def __init__(self, **expressions):
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"""
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Initialize a new NonTerminalExpression instance.
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@param expressions: A dict of Expressions that are used in this NonTerminalExpressions production.
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@type expressions: dict
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"""
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self.expressions = expressions
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class TerminalExpression(Expression, metaclass=ABCMeta):
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"""
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Base class for the TerminalExpression class as part of the Interpreter design pattern.
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"""
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def __init__(self, literal):
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"""
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Initialize a new TerminalExpression instance.
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@param literal: A literal representing this TerminalExpression.
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"""
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self.literal = literal
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247
tests/behavioral_tests/test_interpreter.py
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247
tests/behavioral_tests/test_interpreter.py
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from abc import ABCMeta, abstractmethod
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from unittest import TestCase
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from pypatterns.behavioral.interpreter import Context, Expression, NonTerminalExpression, TerminalExpression
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class ContextTestCase(TestCase):
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"""
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Unit testing class for the Context class.
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"""
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def setUp(self):
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"""
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Initialize testing data.
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"""
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self.context = Context('foo')
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def test_in_data(self):
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"""
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Test the in data attribute.
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@raise AssertionError: If the test fails.
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"""
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self.assertEquals('foo', self.context.in_data)
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try:
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self.context.in_data = 'bar'
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except AttributeError:
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raise AssertionError
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else:
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self.assertEquals('bar', self.context.in_data)
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def test_out_data(self):
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"""
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Test the out data attribute.
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@raise AssertionError: If the test fails.
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"""
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try:
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self.context.out_data = 'bar'
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except AttributeError:
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raise AssertionError
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else:
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self.assertEquals('bar', self.context.out_data)
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class ExpressionTestCase(TestCase):
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"""
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Unit testing class for the Expression class.
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"""
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def setUp(self):
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"""
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Initialize testing data.
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"""
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class ConcreteExpression(Expression):
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def interpret(self, context):
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context.out_data = str(context.in_data).upper()
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self.concrete_expression = ConcreteExpression()
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self.context = Context('foo')
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def test_interpret(self):
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"""
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Test the interpret method.
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@raise AssertionError: If the test fails.
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"""
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self.concrete_expression.interpret(self.context)
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self.assertEquals('FOO', self.context.out_data)
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class NonTerminalExpressionTestCase(TestCase):
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"""
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Unit testing class for the NonTerminalExpression class.
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"""
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def setUp(self):
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"""
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Initialize testing data.
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"""
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class RomanTerminalExpression(TerminalExpression, metaclass=ABCMeta):
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def interpret(self, context):
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return self.literal
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class RomanExpression(NonTerminalExpression, metaclass=ABCMeta):
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def interpret(self, context):
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if context.out_data is None:
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context.out_data = 0
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if len(context.in_data) == 0:
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return
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if context.in_data.startswith(self.nine()):
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context.out_data += 9 * self.multiplier()
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context.in_data = context.in_data[2:]
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elif context.in_data.startswith(self.four()):
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context.out_data += 4 * self.multiplier()
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context.in_data = context.in_data[2:]
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elif context.in_data.startswith(self.five()):
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context.out_data += 5 * self.multiplier()
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context.in_data = context.in_data[1:]
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while context.in_data.startswith(self.one()):
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context.out_data += 1 * self.multiplier()
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context.in_data = context.in_data[1:]
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@abstractmethod
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def one(self):
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pass
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@abstractmethod
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def four(self):
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pass
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@abstractmethod
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def five(self):
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pass
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@abstractmethod
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def nine(self):
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pass
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@abstractmethod
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def multiplier(self):
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pass
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class ThousandExpression(RomanExpression):
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def __init__(self):
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one_terminal = RomanTerminalExpression('M')
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four_terminal = RomanTerminalExpression(' ')
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five_terminal = RomanTerminalExpression(' ')
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nine_terminal = RomanTerminalExpression(' ')
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super().__init__(one=one_terminal, four=four_terminal, five=five_terminal, nine=nine_terminal)
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def one(self):
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return self.expressions['one'].interpret(None)
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def four(self):
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return self.expressions['four'].interpret(None)
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def five(self):
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return self.expressions['five'].interpret(None)
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def nine(self):
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return self.expressions['nine'].interpret(None)
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def multiplier(self):
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return 1000
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class HundredExpression(RomanExpression):
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def __init__(self):
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one_terminal = RomanTerminalExpression('C')
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four_terminal = RomanTerminalExpression('CD')
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five_terminal = RomanTerminalExpression('D')
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nine_terminal = RomanTerminalExpression('CM')
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super().__init__(one=one_terminal, four=four_terminal, five=five_terminal, nine=nine_terminal)
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def one(self):
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return self.expressions['one'].interpret(None)
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def four(self):
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return self.expressions['four'].interpret(None)
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def five(self):
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return self.expressions['five'].interpret(None)
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def nine(self):
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return self.expressions['nine'].interpret(None)
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def multiplier(self):
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return 100
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class TenExpression(RomanExpression):
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def __init__(self):
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one_terminal = RomanTerminalExpression('X')
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four_terminal = RomanTerminalExpression('XL')
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five_terminal = RomanTerminalExpression('L')
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nine_terminal = RomanTerminalExpression('XC')
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super().__init__(one=one_terminal, four=four_terminal, five=five_terminal, nine=nine_terminal)
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def one(self):
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return self.expressions['one'].interpret(None)
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def four(self):
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return self.expressions['four'].interpret(None)
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def five(self):
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return self.expressions['five'].interpret(None)
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def nine(self):
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return self.expressions['nine'].interpret(None)
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def multiplier(self):
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return 10
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class OneExpression(RomanExpression):
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def __init__(self):
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one_terminal = RomanTerminalExpression('I')
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four_terminal = RomanTerminalExpression('IV')
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five_terminal = RomanTerminalExpression('V')
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nine_terminal = RomanTerminalExpression('IX')
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super().__init__(one=one_terminal, four=four_terminal, five=five_terminal, nine=nine_terminal)
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def one(self):
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return self.expressions['one'].interpret(None)
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def four(self):
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return self.expressions['four'].interpret(None)
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def five(self):
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return self.expressions['five'].interpret(None)
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def nine(self):
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return self.expressions['nine'].interpret(None)
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def multiplier(self):
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return 1
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self.roman = "MCMXXVIII"
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self.context = Context(self.roman)
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self.expressions = [ThousandExpression(), HundredExpression(), TenExpression(), OneExpression()]
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def test_interpret(self):
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"""
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Test the interpret method.
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@raise AssertionError: If the test fails.
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"""
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for exp in self.expressions:
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exp.interpret(self.context)
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self.assertEquals(1928, int(self.context.out_data))
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