1 /*
2 * Copyright (C) 2012 Atlassian
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package com.atlassian.jira.rest.client.api.domain.input;
18
19 import com.google.common.base.Function;
20 import com.google.common.collect.ImmutableList;
21 import com.google.common.collect.Iterables;
22 import com.google.common.collect.Lists;
23
24 import javax.annotation.Nullable;
25 import java.util.List;
26
27 /**
28 * This class allows to register {@link ValueTransformer} objects and then perform value transformation using
29 * registered transformers by invoking {@link ValueTransformerManager#apply(Object)}.
30 *
31 * @since v1.0
32 */
33 public class ValueTransformerManager implements Function<Object, Object> {
34 public final List<ValueTransformer> valueTransformers = Lists.newArrayList();
35
36 public ValueTransformerManager() {
37 }
38
39 /**
40 * Registers new transformer at the end of list so it will be processed after existing transformers.
41 *
42 * @param transformer Transformer to register
43 * @return this
44 */
45 public ValueTransformerManager registerTransformer(final ValueTransformer transformer) {
46 valueTransformers.add(transformer);
47 return this;
48 }
49
50 /**
51 * Registers new transformer at the beginning of list so it will be processed before existing transformers.
52 *
53 * @param transformer Transformer to register
54 * @return this
55 */
56 @SuppressWarnings("unused")
57 public ValueTransformerManager registerTransformerAsFirst(final ValueTransformer transformer) {
58 valueTransformers.add(0, transformer);
59 return this;
60 }
61
62 /**
63 * Use registered transformers to transform given value.
64 *
65 * @param rawInput Value to transform
66 * @return transformed value
67 * @throws CannotTransformValueException when any of available transformers was able to transform given value
68 */
69 public Object apply(@Nullable Object rawInput) {
70 if (rawInput instanceof Iterable) {
71 @SuppressWarnings("unchecked") final Iterable<Object> rawInputObjects = (Iterable<Object>) rawInput;
72 return ImmutableList.copyOf(Iterables.transform(rawInputObjects, this));
73 }
74
75 for (ValueTransformer valueTransformer : valueTransformers) {
76 final Object transformedValue = valueTransformer.apply(rawInput);
77 if (!ValueTransformer.CANNOT_HANDLE.equals(transformedValue)) {
78 return transformedValue;
79 }
80 }
81
82 throw new CannotTransformValueException("Any of available transformers was able to transform given value. Value is: "
83 + (rawInput == null ? "NULL" : rawInput.getClass().getName() + ": " + rawInput.toString()));
84 }
85 }