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1 | /* | |
2 | * Copyright (C) 2010 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; | |
18 | ||
19 | import com.google.gson.JsonElement; | |
20 | import com.google.gson.JsonIOException; | |
21 | import com.google.gson.JsonNull; | |
22 | import com.google.gson.JsonParseException; | |
23 | import com.google.gson.JsonSyntaxException; | |
24 | import com.google.gson.internal.bind.TypeAdapters; | |
25 | import com.google.gson.stream.JsonReader; | |
26 | import com.google.gson.stream.JsonWriter; | |
27 | import com.google.gson.stream.MalformedJsonException; | |
28 | import java.io.EOFException; | |
29 | import java.io.IOException; | |
30 | import java.io.Writer; | |
31 | ||
32 | /** | |
33 | * Reads and writes GSON parse trees over streams. | |
34 | */ | |
35 | public final class Streams { | |
36 | /** | |
37 | * Takes a reader in any state and returns the next value as a JsonElement. | |
38 | */ | |
39 | public static JsonElement parse(JsonReader reader) throws JsonParseException { | |
40 | boolean isEmpty = true; | |
41 | try { | |
42 | reader.peek(); | |
43 | isEmpty = false; | |
44 | return TypeAdapters.JSON_ELEMENT.read(reader); | |
45 | } catch (EOFException e) { | |
46 | /* | |
47 | * For compatibility with JSON 1.5 and earlier, we return a JsonNull for | |
48 | * empty documents instead of throwing. | |
49 | */ | |
50 | if (isEmpty) { | |
51 | return JsonNull.INSTANCE; | |
52 | } | |
53 | // The stream ended prematurely so it is likely a syntax error. | |
54 | throw new JsonSyntaxException(e); | |
55 | } catch (MalformedJsonException e) { | |
56 | throw new JsonSyntaxException(e); | |
57 | } catch (IOException e) { | |
58 | throw new JsonIOException(e); | |
59 | } catch (NumberFormatException e) { | |
60 | throw new JsonSyntaxException(e); | |
61 | } | |
62 | } | |
63 | ||
64 | /** | |
65 | * Writes the JSON element to the writer, recursively. | |
66 | */ | |
67 | public static void write(JsonElement element, JsonWriter writer) throws IOException { | |
68 | TypeAdapters.JSON_ELEMENT.write(writer, element); | |
69 | } | |
70 | ||
71 | public static Writer writerForAppendable(Appendable appendable) { | |
72 | return appendable instanceof Writer ? (Writer) appendable : new AppendableWriter(appendable); | |
73 | } | |
74 | ||
75 | /** | |
76 | * Adapts an {@link Appendable} so it can be passed anywhere a {@link Writer} | |
77 | * is used. | |
78 | */ | |
79 | private static final class AppendableWriter extends Writer { | |
80 | private final Appendable appendable; | |
81 | private final CurrentWrite currentWrite = new CurrentWrite(); | |
82 | ||
83 | private AppendableWriter(Appendable appendable) { | |
84 | this.appendable = appendable; | |
85 | } | |
86 | ||
87 | @Override public void write(char[] chars, int offset, int length) throws IOException { | |
88 | currentWrite.chars = chars; | |
89 | appendable.append(currentWrite, offset, offset + length); | |
90 | } | |
91 | ||
92 | @Override public void write(int i) throws IOException { | |
93 | appendable.append((char) i); | |
94 | } | |
95 | ||
96 | @Override public void flush() {} | |
97 | @Override public void close() {} | |
98 | ||
99 | /** | |
100 | * A mutable char sequence pointing at a single char[]. | |
101 | */ | |
102 | static class CurrentWrite implements CharSequence { | |
103 | char[] chars; | |
104 | public int length() { | |
105 | return chars.length; | |
106 | } | |
107 | public char charAt(int i) { | |
108 | return chars[i]; | |
109 | } | |
110 | public CharSequence subSequence(int start, int end) { | |
111 | return new String(chars, start, end - start); | |
112 | } | |
113 | } | |
114 | } | |
115 | ||
116 | } |