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/*
* Copyright (C) 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.gson.internal;
import com.google.gson.JsonElement;
import com.google.gson.JsonIOException;
import com.google.gson.JsonNull;
import com.google.gson.JsonParseException;
import com.google.gson.JsonSyntaxException;
import com.google.gson.internal.bind.TypeAdapters;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import com.google.gson.stream.MalformedJsonException;
import java.io.EOFException;
import java.io.IOException;
import java.io.Writer;
/**
* Reads and writes GSON parse trees over streams.
*/
public final class Streams {
private Streams() {
throw new UnsupportedOperationException();
}
/**
* Takes a reader in any state and returns the next value as a JsonElement.
*/
public static JsonElement parse(JsonReader reader) throws JsonParseException {
boolean isEmpty = true;
try {
reader.peek();
isEmpty = false;
return TypeAdapters.JSON_ELEMENT.read(reader);
} catch (EOFException e) {
/*
* For compatibility with JSON 1.5 and earlier, we return a JsonNull for
* empty documents instead of throwing.
*/
if (isEmpty) {
return JsonNull.INSTANCE;
}
// The stream ended prematurely so it is likely a syntax error.
throw new JsonSyntaxException(e);
} catch (MalformedJsonException e) {
throw new JsonSyntaxException(e);
} catch (IOException e) {
throw new JsonIOException(e);
} catch (NumberFormatException e) {
throw new JsonSyntaxException(e);
}
}
/**
* Writes the JSON element to the writer, recursively.
*/
public static void write(JsonElement element, JsonWriter writer) throws IOException {
TypeAdapters.JSON_ELEMENT.write(writer, element);
}
@SuppressWarnings("resource")
public static Writer writerForAppendable(Appendable appendable) {
return appendable instanceof Writer ? (Writer) appendable : new AppendableWriter(appendable);
}
/**
* Adapts an {@link Appendable} so it can be passed anywhere a {@link Writer}
* is used.
*/
private static final class AppendableWriter extends Writer {
private final Appendable appendable;
private final CurrentWrite currentWrite = new CurrentWrite();
private AppendableWriter(Appendable appendable) {
this.appendable = appendable;
}
@Override public void write(char[] chars, int offset, int length) throws IOException {
currentWrite.chars = chars;
appendable.append(currentWrite, offset, offset + length);
}
@Override public void write(int i) throws IOException {
appendable.append((char) i);
}
@Override public void flush() {}
@Override public void close() {}
/**
* A mutable char sequence pointing at a single char[].
*/
static class CurrentWrite implements CharSequence {
char[] chars;
public int length() {
return chars.length;
}
public char charAt(int i) {
return chars[i];
}
public CharSequence subSequence(int start, int end) {
return new String(chars, start, end - start);
}
}
}
}
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