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1 | /* |
2 | * Copyright (C) 2011 Google Inc. | |
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.google.gson.internal.bind; | |
18 | ||
19 | import com.google.gson.JsonArray; | |
20 | import com.google.gson.JsonElement; | |
21 | import com.google.gson.JsonNull; | |
22 | import com.google.gson.JsonObject; | |
23 | import com.google.gson.JsonPrimitive; | |
24 | import com.google.gson.stream.JsonReader; | |
25 | import com.google.gson.stream.JsonToken; | |
26 | import java.io.IOException; | |
27 | import java.io.Reader; | |
28 | import java.util.ArrayList; | |
29 | import java.util.Iterator; | |
30 | import java.util.List; | |
31 | import java.util.Map; | |
32 | ||
33 | /** | |
34 | * This reader walks the elements of a JsonElement as if it was coming from a | |
35 | * character stream. | |
36 | * | |
37 | * @author Jesse Wilson | |
38 | */ | |
39 | public final class JsonTreeReader extends JsonReader { | |
40 | private static final Reader UNREADABLE_READER = new Reader() { | |
41 | @Override public int read(char[] buffer, int offset, int count) throws IOException { | |
42 | throw new AssertionError(); | |
43 | } | |
44 | @Override public void close() throws IOException { | |
45 | throw new AssertionError(); | |
46 | } | |
47 | }; | |
48 | private static final Object SENTINEL_CLOSED = new Object(); | |
49 | ||
50 | private final List<Object> stack = new ArrayList<Object>(); | |
51 | ||
52 | public JsonTreeReader(JsonElement element) { | |
53 | super(UNREADABLE_READER); | |
54 | stack.add(element); | |
55 | } | |
56 | ||
57 | @Override public void beginArray() throws IOException { | |
58 | expect(JsonToken.BEGIN_ARRAY); | |
59 | JsonArray array = (JsonArray) peekStack(); | |
60 | stack.add(array.iterator()); | |
61 | } | |
62 | ||
63 | @Override public void endArray() throws IOException { | |
64 | expect(JsonToken.END_ARRAY); | |
65 | popStack(); // empty iterator | |
66 | popStack(); // array | |
67 | } | |
68 | ||
69 | @Override public void beginObject() throws IOException { | |
70 | expect(JsonToken.BEGIN_OBJECT); | |
71 | JsonObject object = (JsonObject) peekStack(); | |
72 | stack.add(object.entrySet().iterator()); | |
73 | } | |
74 | ||
75 | @Override public void endObject() throws IOException { | |
76 | expect(JsonToken.END_OBJECT); | |
77 | popStack(); // empty iterator | |
78 | popStack(); // object | |
79 | } | |
80 | ||
81 | @Override public boolean hasNext() throws IOException { | |
82 | JsonToken token = peek(); | |
83 | return token != JsonToken.END_OBJECT && token != JsonToken.END_ARRAY; | |
84 | } | |
85 | ||
86 | @Override public JsonToken peek() throws IOException { | |
87 | if (stack.isEmpty()) { | |
88 | return JsonToken.END_DOCUMENT; | |
89 | } | |
90 | ||
91 | Object o = peekStack(); | |
92 | if (o instanceof Iterator) { | |
93 | boolean isObject = stack.get(stack.size() - 2) instanceof JsonObject; | |
94 | Iterator<?> iterator = (Iterator<?>) o; | |
95 | if (iterator.hasNext()) { | |
96 | if (isObject) { | |
97 | return JsonToken.NAME; | |
98 | } else { | |
99 | stack.add(iterator.next()); | |
100 | return peek(); | |
101 | } | |
102 | } else { | |
103 | return isObject ? JsonToken.END_OBJECT : JsonToken.END_ARRAY; | |
104 | } | |
105 | } else if (o instanceof JsonObject) { | |
106 | return JsonToken.BEGIN_OBJECT; | |
107 | } else if (o instanceof JsonArray) { | |
108 | return JsonToken.BEGIN_ARRAY; | |
109 | } else if (o instanceof JsonPrimitive) { | |
110 | JsonPrimitive primitive = (JsonPrimitive) o; | |
111 | if (primitive.isString()) { | |
112 | return JsonToken.STRING; | |
113 | } else if (primitive.isBoolean()) { | |
114 | return JsonToken.BOOLEAN; | |
115 | } else if (primitive.isNumber()) { | |
116 | return JsonToken.NUMBER; | |
117 | } else { | |
118 | throw new AssertionError(); | |
119 | } | |
120 | } else if (o instanceof JsonNull) { | |
121 | return JsonToken.NULL; | |
122 | } else if (o == SENTINEL_CLOSED) { | |
123 | throw new IllegalStateException("JsonReader is closed"); | |
124 | } else { | |
125 | throw new AssertionError(); | |
126 | } | |
127 | } | |
128 | ||
129 | private Object peekStack() { | |
130 | return stack.get(stack.size() - 1); | |
131 | } | |
132 | ||
133 | private Object popStack() { | |
134 | return stack.remove(stack.size() - 1); | |
135 | } | |
136 | ||
137 | private void expect(JsonToken expected) throws IOException { | |
138 | if (peek() != expected) { | |
139 | throw new IllegalStateException("Expected " + expected + " but was " + peek()); | |
140 | } | |
141 | } | |
142 | ||
143 | @Override public String nextName() throws IOException { | |
144 | expect(JsonToken.NAME); | |
145 | Iterator<?> i = (Iterator<?>) peekStack(); | |
146 | Map.Entry<?, ?> entry = (Map.Entry<?, ?>) i.next(); | |
147 | stack.add(entry.getValue()); | |
148 | return (String) entry.getKey(); | |
149 | } | |
150 | ||
151 | @Override public String nextString() throws IOException { | |
152 | JsonToken token = peek(); | |
153 | if (token != JsonToken.STRING && token != JsonToken.NUMBER) { | |
154 | throw new IllegalStateException("Expected " + JsonToken.STRING + " but was " + token); | |
155 | } | |
156 | return ((JsonPrimitive) popStack()).getAsString(); | |
157 | } | |
158 | ||
159 | @Override public boolean nextBoolean() throws IOException { | |
160 | expect(JsonToken.BOOLEAN); | |
161 | return ((JsonPrimitive) popStack()).getAsBoolean(); | |
162 | } | |
163 | ||
164 | @Override public void nextNull() throws IOException { | |
165 | expect(JsonToken.NULL); | |
166 | popStack(); | |
167 | } | |
168 | ||
169 | @Override public double nextDouble() throws IOException { | |
170 | JsonToken token = peek(); | |
171 | if (token != JsonToken.NUMBER && token != JsonToken.STRING) { | |
172 | throw new IllegalStateException("Expected " + JsonToken.NUMBER + " but was " + token); | |
173 | } | |
174 | double result = ((JsonPrimitive) peekStack()).getAsDouble(); | |
175 | if (!isLenient() && (Double.isNaN(result) || Double.isInfinite(result))) { | |
176 | throw new NumberFormatException("JSON forbids NaN and infinities: " + result); | |
177 | } | |
178 | popStack(); | |
179 | return result; | |
180 | } | |
181 | ||
182 | @Override public long nextLong() throws IOException { | |
183 | JsonToken token = peek(); | |
184 | if (token != JsonToken.NUMBER && token != JsonToken.STRING) { | |
185 | throw new IllegalStateException("Expected " + JsonToken.NUMBER + " but was " + token); | |
186 | } | |
187 | long result = ((JsonPrimitive) peekStack()).getAsLong(); | |
188 | popStack(); | |
189 | return result; | |
190 | } | |
191 | ||
192 | @Override public int nextInt() throws IOException { | |
193 | JsonToken token = peek(); | |
194 | if (token != JsonToken.NUMBER && token != JsonToken.STRING) { | |
195 | throw new IllegalStateException("Expected " + JsonToken.NUMBER + " but was " + token); | |
196 | } | |
197 | int result = ((JsonPrimitive) peekStack()).getAsInt(); | |
198 | popStack(); | |
199 | return result; | |
200 | } | |
201 | ||
202 | @Override public void close() throws IOException { | |
203 | stack.clear(); | |
204 | stack.add(SENTINEL_CLOSED); | |
205 | } | |
206 | ||
207 | @Override public void skipValue() throws IOException { | |
208 | if (peek() == JsonToken.NAME) { | |
209 | nextName(); | |
210 | } else { | |
211 | popStack(); | |
212 | } | |
213 | } | |
214 | ||
215 | @Override public String toString() { | |
216 | return getClass().getSimpleName(); | |
217 | } | |
218 | ||
219 | public void promoteNameToValue() throws IOException { | |
220 | expect(JsonToken.NAME); | |
221 | Iterator<?> i = (Iterator<?>) peekStack(); | |
222 | Map.Entry<?, ?> entry = (Map.Entry<?, ?>) i.next(); | |
223 | stack.add(entry.getValue()); | |
224 | stack.add(new JsonPrimitive((String)entry.getKey())); | |
225 | } | |
226 | } |