| 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 | } |