conditional.py 文件源码

def _check_conditional(self, conditional, templar, all_vars):
        '''
        This method does the low-level evaluation of each conditional
        set on this object, using jinja2 to wrap the conditionals for
        evaluation.
        '''

        original = conditional
        if conditional is None or conditional == '':
            return True

        if conditional in all_vars and '-' not in text_type(all_vars[conditional]):
            conditional = all_vars[conditional]

        # make sure the templar is using the variables specified with this method
        templar.set_available_variables(variables=all_vars)

        try:
            conditional = templar.template(conditional)
            if not isinstance(conditional, text_type) or conditional == "":
                return conditional

            # a Jinja2 evaluation that results in something Python can eval!
            presented = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % conditional
            conditional = templar.template(presented)
            val = conditional.strip()
            if val == "True":
                return True
            elif val == "False":
                return False
            else:
                raise AnsibleError("unable to evaluate conditional: %s" % original)
        except (AnsibleUndefinedVariable, UndefinedError) as e:
            # the templating failed, meaning most likely a
            # variable was undefined. If we happened to be
            # looking for an undefined variable, return True,
            # otherwise fail
            if "is undefined" in original:
                return True
            elif "is defined" in original:
                return False
            else:
                raise AnsibleError("error while evaluating conditional (%s): %s" % (original, e))