Parse version to major, minor, patch, pre-release, build parts.

    :param version: version string
    :return: dictionary with the keys 'build', 'major', 'minor', 'patch',
             and 'prerelease'. The prerelease or build keys can be None
             if not provided
    :rtype: dict

    >>> import semver
    >>> ver = semver.parse('3.4.5-pre.2+build.4')
    >>> ver['major']
    3
    >>> ver['minor']
    4
    >>> ver['patch']
    5
    >>> ver['prerelease']
    'pre.2'
    >>> ver['build']
    'build.4'

def parse(version):
    """Parse version to major, minor, patch, pre-release, build parts.

    :param version: version string
    :return: dictionary with the keys 'build', 'major', 'minor', 'patch',
             and 'prerelease'. The prerelease or build keys can be None
             if not provided
    :rtype: dict

    >>> import semver
    >>> ver = semver.parse('3.4.5-pre.2+build.4')
    >>> ver['major']
    3
    >>> ver['minor']
    4
    >>> ver['patch']
    5
    >>> ver['prerelease']
    'pre.2'
    >>> ver['build']
    'build.4'
    """
    match = _REGEX.match(version)
    if match is None:
        raise ValueError('%s is not valid SemVer string' % version)

    version_parts = match.groupdict()

    version_parts['major'] = int(version_parts['major'])
    version_parts['minor'] = int(version_parts['minor'])
    version_parts['patch'] = int(version_parts['patch'])

    return version_parts