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Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
SPDX-License-Identifier: MIT-0
"""
from collections import deque
from typing import Any
from cfnlint.jsonschema import ValidationError, ValidationResult
from cfnlint.jsonschema.protocols import Validator
from cfnlint.rules import CloudFormationLintRule
class SubNotJoin(CloudFormationLintRule):
"""Check if Join is being used with no join characters"""
id = "I1022"
shortdesc = "Use Sub instead of Join"
description = (
"Prefer a sub instead of Join when using a join delimiter that is empty"
)
source_url = "https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-sub.html"
tags = ["functions", "sub", "join"]
def _check_element(self, element):
if isinstance(element, dict):
if len(element) == 1:
for key, value in element.items():
if key in ["Fn::Sub"]:
if not isinstance(value, str):
return False
elif key not in ["Ref", "Fn::GetAtt"]:
return False
return True
def _check_elements(self, elements):
for element in elements:
if not self._check_element(element):
return False
return True
def validate(
self, validator: Validator, s: Any, instance: Any, schema: Any
) -> ValidationResult:
if validator.cfn.is_cdk_template():
return
key = list(instance.keys())[0]
value = instance.get(key)
if value[0] != "":
return
if self._check_elements(value[1]):
yield ValidationError(
("Prefer using Fn::Sub over Fn::Join with an" " empty delimiter"),
path=deque([key, 0]),
rule=self,
)
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