112 lines
3.6 KiB
Java
112 lines
3.6 KiB
Java
/*
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* Copyright (C) 2008 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson;
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/**
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* A simple implementation of the {@link JsonElementVisitor} that simply delegates the method
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* invocation onto a {@code delegate} instance of the {@link JsonElementVisitor}. This object
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* can be used to build a chain of visitors such that each Visitor instance can perform some
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* operation on the {@link JsonElement} and then pass on the input to the delegate. This kind
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* of pattern is sometimes referred as a "Chain of Responsibility".
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*
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* <p>The following is an example use case:
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*
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* <pre>
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* class JsonEscapingVisitor extends DelegatingJsonElementVisitor {
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* public JsonEscapingVisitor(JsonElementVisitor) {
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* super(visitor);
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* }
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*
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* public void visitPrimitive(JsonPrimitive primitive) {
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* JsonPrimitive escapedPrimitive = escapePrimitiveObject(primitive);
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* super.visitPrimitive(escapedPrimitive);
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* }
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* }
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*
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* JsonElementVisitor visitor = new JsonEscapingVisitor(new FormattingVisitor());
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* </pre></p>
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*
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* @author Joel Leitch
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*/
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class DelegatingJsonElementVisitor implements JsonElementVisitor {
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private final JsonElementVisitor delegate;
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protected DelegatingJsonElementVisitor(JsonElementVisitor delegate) {
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Preconditions.checkNotNull(delegate);
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this.delegate = delegate;
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}
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public void endArray(JsonArray array) {
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delegate.endArray(array);
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}
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public void endObject(JsonObject object) {
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delegate.endObject(object);
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}
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public void startArray(JsonArray array) {
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delegate.startArray(array);
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}
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public void startObject(JsonObject object) {
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delegate.startObject(object);
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}
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public void visitArrayMember(JsonArray parent, JsonPrimitive member, boolean isFirst) {
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delegate.visitArrayMember(parent, member, isFirst);
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}
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public void visitArrayMember(JsonArray parent, JsonArray member, boolean isFirst) {
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delegate.visitArrayMember(parent, member, isFirst);
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}
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public void visitArrayMember(JsonArray parent, JsonObject member, boolean isFirst) {
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delegate.visitArrayMember(parent, member, isFirst);
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}
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public void visitObjectMember(
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JsonObject parent, String memberName, JsonPrimitive member, boolean isFirst) {
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delegate.visitObjectMember(parent, memberName, member, isFirst);
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}
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public void visitObjectMember(
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JsonObject parent, String memberName, JsonArray member, boolean isFirst) {
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delegate.visitObjectMember(parent, memberName, member, isFirst);
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}
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public void visitObjectMember(
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JsonObject parent, String memberName, JsonObject member, boolean isFirst) {
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delegate.visitObjectMember(parent, memberName, member, isFirst);
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}
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public void visitNullObjectMember(JsonObject parent, String memberName, boolean isFirst) {
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delegate.visitNullObjectMember(parent, memberName, isFirst);
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}
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public void visitPrimitive(JsonPrimitive primitive) {
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delegate.visitPrimitive(primitive);
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}
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public void visitNull() {
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delegate.visitNull();
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}
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public void visitNullArrayMember(JsonArray parent, boolean isFirst) {
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delegate.visitNullArrayMember(parent, isFirst);
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}
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}
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