me.snowdrop.istio.util.StructHelper Maven / Gradle / Ivy
Show all versions of istio-common Show documentation
/**
* Copyright 2020 Red Hat, Inc. and/or its affiliates.
*
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*/
package me.snowdrop.istio.util;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
/**
* @author Christophe Laprun
*/
public class StructHelper {
public static T get(Map struct, String dotSeparatedPath, Class expectedType) {
final String[] parts = dotSeparatedPath.split("\\.");
return get(struct, parts, expectedType, new LinkedList<>(), dotSeparatedPath);
}
private static T get(Map struct, String[] parts, Class expectedType, List processed,
String dotSeparatedPath) {
switch (parts.length) {
case 0:
return null;
case 1:
return expectedType.cast(handleNullOrEmptyPath(struct, parts, processed));
default:
final Object o = handleNullOrEmptyPath(struct, parts, processed);
if (o instanceof Map) {
Map map = (Map) o;
final String[] newParts = new String[parts.length - 1];
System.arraycopy(parts, 1, newParts, 0, parts.length - 1);
return get(map, newParts, expectedType, processed, dotSeparatedPath);
} else {
throw new IllegalArgumentException("'" + dotSeparatedPath + "' is interrupted at '"
+ String.join(".", processed) + "' because '" + parts[0] + "' is a terminal element");
}
}
}
private static Object handleNullOrEmptyPath(Map struct, String[] parts, List processed) {
final String part = parts[0];
if (part.trim().isEmpty()) {
return struct;
}
// only add part to processed if we're not looking for the last element of our path
if (parts.length > 1) {
processed.add(part);
}
final Object o = struct.get(part);
if (o == null) {
throw new IllegalArgumentException("'" + part + "' is not a child of '"
+ String.join(".", processed)
+ "'. Known children: "
+ struct.keySet().stream()
.map(k -> "'" + k + "'")
.collect(Collectors.joining(", ")));
}
return o;
}
}