Library versioning example

library_versioning.py

"""Library versioning using the default Python syntax

Example:
    >>> is_compatible("pyblish<=1", (0, 9, 0))
    True
    >>> is_compatible("pyblish>=1.1, <2.1", (2, 0, 0))
    True

"""

import re
import operator


def is_compatible(requirement, version):
    """Return whether or not `requirement` is compatible with `version`

    Example:
        >>> is_compatible("pyblish<=1", (0, 9, 0))
        True
        >>> is_compatible("pyblish>=1, <1.3", (1, 2, 0))
        True
        >>> is_compatible("pyblish>=0.9.9", (1, 0, 0))
        True
        >>> is_compatible("pyblish>=1.1, <2.1", (2, 0, 0))
        True
        >>> is_compatible("pyblish==1.0.0", (1, 0, 0))
        True
        >>> is_compatible("pyblish==1.0.0", (1, 0, 1))
        False

    """

    results = list()

    for operator_string, requirement_string in parse_requirements(requirement):
        operator = operators[operator_string]
        required = string_to_tuple(requirement_string)
        result = operator(version, required)

        results.append(result)

    return all(results)


def parse_requirements(line):
    """From pkg_utils.parse_requirements

    Example:
        >>> parse_requirements("pyblish==1.0.0")
        [('==', '1.0.0')]
        >>> parse_requirements("pyblish>=1.1.0")
        [('>=', '1.1.0')]
        >>> parse_requirements("pyblish>=1.1.0, <1.2")
        [('>=', '1.1.0'), ('<', '1.2')]

    """

    LINE_END = re.compile(r"\s*(#.*)?$")
    DISTRO = re.compile(r"\s*((\w|[-.])+)")
    VERSION = re.compile(r"\s*(<=?|>=?|==|!=)\s*((\w|[-.])+)")
    COMMA = re.compile(r"\s*,")

    match = DISTRO.match(line)
    p = match.end()
    specs = list()

    while not LINE_END.match(line, p):
        match = VERSION.match(line, p)
        if not match:
            raise ValueError(
                "Expected version spec in",
                line, "at", line[p:])

        specs.append(match.group(*(1, 2)))
        p = match.end()

        match = COMMA.match(line, p)
        if match:
            p = match.end()  # Skip comma
        elif not LINE_END.match(line, p):
            raise ValueError(
                "Expected ',' or end-of-list in",
                line, "at", line[p:])

    return specs


def string_to_tuple(version):
    """Convert version as string to tuple

    Example:
        >>> string_to_tuple("1.0.0")
        (1, 0, 0)
        >>> string_to_tuple("2.5")
        (2, 5)

    """

    return tuple(map(int, version.split(".")))


operators = {"<":   operator.lt,
             "<=":  operator.le,
             "==":  operator.eq,
             "!=":  operator.ne,
             ">=":  operator.ge,
             ">":   operator.gt}


if __name__ == '__main__':
    import doctest
    doctest.testmod()