Support JsonReader API on DOM objects.
This still needs test coverage & documentation but it appears to work!
This commit is contained in:
Jesse Wilson
parent
423d18feb5
commit
bd2a0ac466
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@ -0,0 +1,192 @@
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/*
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* Copyright (C) 2011 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.internal.bind;
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import com.google.gson.JsonArray;
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import com.google.gson.JsonElement;
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import com.google.gson.JsonNull;
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import com.google.gson.JsonObject;
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import com.google.gson.JsonPrimitive;
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import com.google.gson.stream.JsonReader;
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import com.google.gson.stream.JsonToken;
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import java.io.IOException;
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import java.io.Reader;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map;
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/**
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*
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*/
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public final class JsonElementReader extends JsonReader {
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private static final Reader UNREADABLE_READER = new Reader() {
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@Override public int read(char[] buffer, int offset, int count) throws IOException {
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throw new AssertionError();
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}
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@Override public void close() throws IOException {
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throw new AssertionError();
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}
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};
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private final List<Object> stack = new ArrayList<Object>();
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/**
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* Creates a new instance that reads a JSON-encoded stream from {@code in}.
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*/
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public JsonElementReader(JsonElement element) {
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super(UNREADABLE_READER);
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stack.add(element);
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}
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@Override public void beginArray() throws IOException {
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expect(JsonToken.BEGIN_ARRAY);
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JsonArray array = (JsonArray) peekStack();
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stack.add(array.iterator());
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}
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@Override public void endArray() throws IOException {
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expect(JsonToken.END_ARRAY);
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popStack(); // empty iterator
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popStack(); // array
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}
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@Override public void beginObject() throws IOException {
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expect(JsonToken.BEGIN_OBJECT);
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JsonObject object = (JsonObject) peekStack();
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stack.add(object.entrySet().iterator());
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}
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@Override public void endObject() throws IOException {
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expect(JsonToken.END_OBJECT);
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popStack(); // empty iterator
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popStack(); // object
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}
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@Override public boolean hasNext() throws IOException {
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JsonToken token = peek();
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return token != JsonToken.END_OBJECT && token != JsonToken.END_ARRAY;
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}
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@Override public JsonToken peek() throws IOException {
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if (stack.isEmpty()) {
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return JsonToken.END_DOCUMENT;
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}
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Object o = peekStack();
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if (o instanceof Iterator) {
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boolean isObject = stack.get(stack.size() - 2) instanceof JsonObject;
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Iterator<?> iterator = (Iterator<?>) o;
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if (iterator.hasNext()) {
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if (isObject) {
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return JsonToken.NAME;
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} else {
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stack.add(iterator.next());
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return peek();
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}
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} else {
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return isObject ? JsonToken.END_OBJECT : JsonToken.END_ARRAY;
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}
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} else if (o instanceof JsonObject) {
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return JsonToken.BEGIN_OBJECT;
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} else if (o instanceof JsonArray) {
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return JsonToken.BEGIN_ARRAY;
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} else if (o instanceof JsonPrimitive) {
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JsonPrimitive primitive = (JsonPrimitive) o;
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if (primitive.isString()) {
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return JsonToken.STRING;
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} else if (primitive.isBoolean()) {
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return JsonToken.BOOLEAN;
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} else if (primitive.isNumber()) {
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return JsonToken.NUMBER;
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} else {
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throw new AssertionError();
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}
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} else if (o instanceof JsonNull) {
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return JsonToken.NULL;
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} else {
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throw new AssertionError();
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}
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}
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private Object peekStack() {
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return stack.get(stack.size() - 1);
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}
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private Object popStack() {
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return stack.remove(stack.size() - 1);
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}
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private void expect(JsonToken expected) throws IOException {
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if (peek() != expected) {
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throw new IllegalStateException("Expected " + expected + " but was " + peek());
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}
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}
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@Override public String nextName() throws IOException {
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expect(JsonToken.NAME);
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Iterator<?> i = (Iterator) peekStack();
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Map.Entry<?, ?> entry = (Map.Entry<?, ?>) i.next();
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stack.add(entry.getValue());
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return (String) entry.getKey();
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}
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@Override public String nextString() throws IOException {
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expect(JsonToken.STRING);
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return ((JsonPrimitive) popStack()).getAsString();
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}
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@Override public boolean nextBoolean() throws IOException {
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expect(JsonToken.BOOLEAN);
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return ((JsonPrimitive) popStack()).getAsBoolean();
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}
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@Override public void nextNull() throws IOException {
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expect(JsonToken.NULL);
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popStack();
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}
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@Override public double nextDouble() throws IOException {
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expect(JsonToken.NUMBER);
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return ((JsonPrimitive) popStack()).getAsDouble();
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}
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@Override public long nextLong() throws IOException {
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expect(JsonToken.NUMBER);
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return ((JsonPrimitive) popStack()).getAsLong();
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}
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@Override public int nextInt() throws IOException {
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expect(JsonToken.NUMBER);
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return ((JsonPrimitive) popStack()).getAsInt();
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}
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@Override public void close() throws IOException {
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}
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@Override public void skipValue() throws IOException {
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if (peek() == JsonToken.NAME) {
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nextName();
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} else {
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popStack();
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}
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}
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@Override public String toString() {
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return getClass().getSimpleName();
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}
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}
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@ -183,7 +183,7 @@ import java.util.List;
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* @author Jesse Wilson
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* @since 1.6
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*/
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public final class JsonReader implements Closeable {
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public class JsonReader implements Closeable {
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/** The only non-execute prefix this parser permits */
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private static final char[] NON_EXECUTE_PREFIX = ")]}'\n".toCharArray();
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@ -279,14 +279,14 @@ public final class JsonReader implements Closeable {
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* <li>Name/value pairs separated by {@code ;} instead of {@code ,}.
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* </ul>
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*/
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public void setLenient(boolean lenient) {
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public final void setLenient(boolean lenient) {
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this.lenient = lenient;
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}
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/**
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* Returns true if this parser is liberal in what it accepts.
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*/
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public boolean isLenient() {
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public final boolean isLenient() {
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return lenient;
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}
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@ -0,0 +1,76 @@
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/*
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* Copyright (C) 2011 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.internal.bind;
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import com.google.gson.JsonElement;
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import com.google.gson.JsonParser;
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import com.google.gson.stream.JsonToken;
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import java.io.IOException;
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import junit.framework.TestCase;
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public final class JsonElementReaderTest extends TestCase {
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public void testArray() throws IOException {
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JsonElement array = new JsonParser().parse("[1, 2, 3]");
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JsonElementReader reader = new JsonElementReader(array);
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assertEquals(JsonToken.BEGIN_ARRAY, reader.peek());
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reader.beginArray();
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assertEquals(JsonToken.NUMBER, reader.peek());
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assertEquals(1, reader.nextInt());
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assertEquals(JsonToken.NUMBER, reader.peek());
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assertEquals(2, reader.nextInt());
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assertEquals(JsonToken.NUMBER, reader.peek());
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assertEquals(3, reader.nextInt());
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assertEquals(JsonToken.END_ARRAY, reader.peek());
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reader.endArray();
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assertEquals(JsonToken.END_DOCUMENT, reader.peek());
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}
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public void testObject() throws IOException {
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JsonElement array = new JsonParser().parse("{\"A\": 1, \"B\": 2}");
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JsonElementReader reader = new JsonElementReader(array);
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assertEquals(JsonToken.BEGIN_OBJECT, reader.peek());
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reader.beginObject();
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assertEquals(JsonToken.NAME, reader.peek());
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assertEquals("A", reader.nextName());
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assertEquals(JsonToken.NUMBER, reader.peek());
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assertEquals(1, reader.nextInt());
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assertEquals(JsonToken.NAME, reader.peek());
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assertEquals("B", reader.nextName());
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assertEquals(JsonToken.NUMBER, reader.peek());
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assertEquals(2, reader.nextInt());
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assertEquals(JsonToken.END_OBJECT, reader.peek());
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reader.endObject();
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assertEquals(JsonToken.END_DOCUMENT, reader.peek());
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}
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public void testEmptyArray() throws IOException {
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JsonElement array = new JsonParser().parse("[]");
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JsonElementReader reader = new JsonElementReader(array);
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reader.beginArray();
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reader.endArray();
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}
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public void testEmptyObject() throws IOException {
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JsonElement array = new JsonParser().parse("{}");
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JsonElementReader reader = new JsonElementReader(array);
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reader.beginObject();
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reader.endObject();
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}
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// TODO: more test coverage
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}
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