template_format.py 文件源码

def parse(tmpl_str):
    """Takes a string and returns a dict containing the parsed structure.

    This includes determination of whether the string is using the
    JSON or YAML format.
    """
    # strip any whitespace before the check
    tmpl_str = tmpl_str.strip()
    if tmpl_str.startswith('{'):
        tpl = json.loads(tmpl_str)
    else:
        try:
            tpl = yaml.load(tmpl_str, Loader=yaml_loader)
        except yaml.YAMLError:
            # NOTE(prazumovsky): we need to return more informative error for
            # user, so use SafeLoader, which return error message with template
            # snippet where error has been occurred.
            try:
                tpl = yaml.load(tmpl_str, Loader=yaml.SafeLoader)
            except yaml.YAMLError as yea:
                raise ValueError(yea)
        else:
            if tpl is None:
                tpl = {}
    # Looking for supported version keys in the loaded template
    if not ('HeatTemplateFormatVersion' in tpl
            or 'heat_template_version' in tpl
            or 'AWSTemplateFormatVersion' in tpl):
        raise ValueError(_("Template format version not found."))
    return tpl