capybara/virtualenv/lib/python2.7/site-packages/pip/index.py
def egg_info_matches(
        egg_info, search_name, link,
        _egg_info_re=re.compile(r'([a-z0-9_.]+)-([a-z0-9_.!+-]+)', re.I)):
    """Pull the version part out of a string.

    :param egg_info: The string to parse. E.g. foo-2.1
    :param search_name: The name of the package this belongs to. None to
        infer the name. Note that this cannot unambiguously parse strings
        like foo-2-2 which might be foo, 2-2 or foo-2, 2.
    :param link: The link the string came from, for logging on failure.
    """
    match = _egg_info_re.search(egg_info)
    if not match:
        logger.debug('Could not parse version from link: %s', link)
        return None
    if search_name is None:
        full_match = match.group(0)
        return full_match[full_match.index('-'):]
    name = match.group(0).lower()
    # To match the "safe" name that pkg_resources creates:
    name = name.replace('_', '-')
    # project name and version must be separated by a dash
    look_for = search_name.lower() + "-"
    if name.startswith(look_for):
        return match.group(0)[len(look_for):]
    else:
        return None
def egg_info_matches(
        egg_info, search_name, link,
        _egg_info_re=re.compile(r'([a-z0-9_.]+)-([a-z0-9_.!+-]+)', re.I)):
    match = _egg_info_re.search(egg_info)
    if not match:
        logger.debug('Could not parse version from link: %s', link)
        return None
    if search_name is None:
        full_match = match.group(0)
        return full_match[full_match.index('-'):]
    name = match.group(0).lower()
    # To match the "safe" name that pkg_resources creates:
    name = name.replace('_', '-')
    # project name and version must be separated by a dash
    look_for = search_name.lower() + "-"
    if name.startswith(look_for):
        return match.group(0)[len(look_for):]
    else:
        return None
def egg_info_matches ( egg_info , search_name , link , _egg_info_re = re . compile ( r'([a-z0-9_.]+)-([a-z0-9_.!+-]+)' , re . I ) ) : match = _egg_info_re . search ( egg_info ) if not match : logger . debug ( 'Could not parse version from link: %s' , link ) return None if search_name is None : full_match = match . group ( 0 ) return full_match [ full_match . index ( '-' ) : ] name = match . group ( 0 ) . lower ( ) # To match the "safe" name that pkg_resources creates: name = name . replace ( '_' , '-' ) # project name and version must be separated by a dash look_for = search_name . lower ( ) + "-" if name . startswith ( look_for ) : return match . group ( 0 ) [ len ( look_for ) : ] else : return None
Pull the version part out of a string.

    :param egg_info: The string to parse. E.g. foo-2.1
    :param search_name: The name of the package this belongs to. None to
        infer the name. Note that this cannot unambiguously parse strings
        like foo-2-2 which might be foo, 2-2 or foo-2, 2.
    :param link: The link the string came from, for logging on failure.
Pull the version part out of a string .