Metadata-Version: 1.0
Name: py-pattern-matching
Version: 0.1
Summary: Data-structure pattern matching and unpacking for Python
Home-page: https://github.com/eallik/py-pattern-matching
Author: Erik Allik
Author-email: eallik@gmail.com
License: UNKNOWN
Description: Usage
        =====
        
        Call the `patternmatching.match()` function with two arguments:
        
        * Argument 1: the pattern to match against
        * Argument 2: the data structure to match
        
        * Optional argument `flatten`: `True` to have the matched values
          flattened, i.e. returned as a flat tuple regardless of their position
          in the structure of the matched data.
        
        Return value:
            if flatten is true:
                match_ok, [matched_value, matched_value, matched_value, ...]
            if flatten is not true:
                match_ok, matched_data_structure
        
        Caveat:
            if all matched values in the pattern are ignored, `match()` does not return a `tuple` but a boolean.
            YES:
                `match_ok = match(PATTERN, DATA)`
            NO:
                `match_ok, = match(PATTERN, DATA)`
        
        
        Built-in match object
        =====================
        
        * ANY
        * IS_INSTANCE
        
        Any match object can be wrapped with `IGNORE()` to ignore the value
        matched by the match object in the returned values.
        
        `IGNORE` itself can be used as a shortcut for `IGNORE(ANY)`.
        
            assert True == match(IGNORE, 123)
        
        
        Usage in (unit) tests (but also anywhere else)
        ==============================================
        
        Comparing the return values of functions is tedious if you can't
        simply use the `==` operator. For example when a function returns a
        tuple and you only care about some parts of the tuple and not the
        entire tuple:
        
            retval = some_function_under_test()
            assert retval and isinstance(retval, tuple) \
                and len(retval) == 3 and retval[0] == 'foo' \
                and isinstance(retval[1], tuple) and len(retval[1]) == 2 \
                and isinstance(retval[1][1], SomeException)
        
        With pattern matching:
        
            retval = some_function_under_test()
            assert retval == ('foo', (ANY, IS_INSTANCE(SomeException)), ANY)
        
        
        Examples
        ========
        
        MATCH OK
        --------
        
        match_ok, value = match(ANY, 'foobar')
        assert match_ok and value == 'foobar'
        
        match_ok = match(IGNORE(ANY), 'foobar')
        assert match_ok
        
        match_ok, value1, value2 match((ANY, ANY), ('foo', 'bar'))
        assert match_ok and value1 == 'foo' and value2 == 'bar'
        
        match_ok, (value1, value2) = match((ANY, ANY), ('foo', 'bar'), flatten=False)
        assert match_ok and value1 == 'foo' and value2 == 'bar'
        
        match_ok, (value1, ) = match((ANY, IGNORE(ANY)), ('foo', 'whatev'))
        assert match_ok and value1 == 'foo'
        
        match_ok, value1, value2 = match(('foo', ANY, ANY), ('foo', 1, 2))
        assert match_ok and value1 == 1 and value2 == 2
        
        match_ok, value1, value2, value3 = match(('foo', ANY, (ANY, ANY)), ('foo', 1, (2, 3)))
        assert match_ok and value1 == 1 and value2 == 2 and value3 = 3
        
        match_ok, (value1, (value2, value3)) = match(('foo', ANY, (ANY, ANY)), ('foo', 1, (2, 3)), flatten=False)
        assert match_ok and value1 == 1 and value2 == 2 and value3 = 3
        
        NO MATCH
        --------
        
        match_ok = match(3, 4)
        assert not match_ok
        
        # notice how you can still successfully do unpacking of return values and just ignore `value` if the match failed
        match_ok, value = match(IS_INSTANCE(unicode), '123132')
        assert not match_ok
        
        # notice how you can still successfully do unpacking of return values and just ignore `value` if the match failed
        match_ok, (value1, (value2, value3)) = match(('foo', (ANY, (ANY, ANY))), ('not-foo', (1, (2, 3))))
        assert not match_ok
        
        # ...even when the structure of the data completely mismatches
        match_ok, (value1, (value2, value3)) = match(('foo', (ANY, (ANY, ANY))), ('foo', 'blabla'))
        assert not match_ok
        
        # ...don't rely on `value1`, `value2` and `value3` being `None` though--the matcher can still return whatever it wants there; you have to check `match_ok` yourself.
        
Platform: UNKNOWN
