def freeze(h, output_yaml, resolve, groups):
    """Output installed packages."""
    if not groups:
        groups = filter(lambda group: not group.lower().startswith("bower"),
                        h.requirements.keys())
    else:
        groups = [text_type.strip(group) for group in groups.split(",")]

    if output_yaml:
        for requirements in h.requirements.values():
            for requirement in requirements:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
        click.echo(h.requirements.yaml)
    else:
        for group in groups:
            if not h.requirements[group]:
                continue
            click.echo("# {}".format(group))
            for requirement in h.requirements[group]:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
                click.echo(str(requirement))
def _regex(kind, pat, globsuffix):
    """Convert a (normalized) pattern of any kind into a regular expression.
    globsuffix is appended to the regexp of globs."""
    if not pat and kind in ("glob", "relpath"):
        return ""
    if kind == "re":
        return pat
    if kind in ("path", "relpath"):
        if pat == ".":
            return ""
        return util.re.escape(pat) + "(?:/|$)"
    if kind == "rootfilesin":
        if pat == ".":
            escaped = ""
        else:
            # Pattern is a directory name.
            escaped = util.re.escape(pat) + "/"
        # Anything after the pattern must be a non-directory.
        return escaped + "[^/]+$"
    if kind == "relglob":
        return "(?:|.*/)" + _globre(pat) + globsuffix
    if kind == "relre":
        if pat.startswith("^"):
            return pat
        return ".*" + pat
    return _globre(pat) + globsuffix