/**
* Copyright (c) 2013, impossibl.com
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of impossibl.com nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (C) 2007 The Guava Authors
*
* 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.impossibl.postgres.utils.guava;
import static com.impossibl.postgres.utils.guava.Preconditions.checkArgument;
import static com.impossibl.postgres.utils.guava.Preconditions.checkNotNull;
import java.io.EOFException;
import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import java.nio.CharBuffer;
/**
* Provides utility methods for working with character streams.
*
* <p>All method parameters must be non-null unless documented otherwise.
*
* <p>Some of the methods in this class take arguments with a generic type of
* {@code Readable & Closeable}. A {@link java.io.Reader} implements both of
* those interfaces. Similarly for {@code Appendable & Closeable} and
* {@link java.io.Writer}.
*
* @author Chris Nokleberg
* @author Bin Zhu
* @author Colin Decker
* @since 1.0
*/
public final class CharStreams {
private static final int BUF_SIZE = 0x800; // 2K chars (4K bytes)
private CharStreams() {
}
/**
* Copies all characters between the {@link Readable} and {@link Appendable}
* objects. Does not close or flush either object.
*
* @param from the object to read from
* @param to the object to write to
* @return the number of characters copied
* @throws IOException if an I/O error occurs
*/
public static long copy(Readable from, Appendable to) throws IOException {
checkNotNull(from);
checkNotNull(to);
CharBuffer buf = CharBuffer.allocate(BUF_SIZE);
long total = 0;
while (from.read(buf) != -1) {
buf.flip();
to.append(buf);
total += buf.remaining();
buf.clear();
}
return total;
}
/**
* Reads all characters from a {@link Readable} object into a {@link String}.
* Does not close the {@code Readable}.
*
* @param r the object to read from
* @return a string containing all the characters
* @throws IOException if an I/O error occurs
*/
public static String toString(Readable r) throws IOException {
return toStringBuilder(r).toString();
}
/**
* Reads all characters from a {@link Readable} object into a new
* {@link StringBuilder} instance. Does not close the {@code Readable}.
*
* @param r the object to read from
* @return a {@link StringBuilder} containing all the characters
* @throws IOException if an I/O error occurs
*/
private static StringBuilder toStringBuilder(Readable r) throws IOException {
StringBuilder sb = new StringBuilder();
copy(r, sb);
return sb;
}
/**
* Discards {@code n} characters of data from the reader. This method
* will block until the full amount has been skipped. Does not close the
* reader.
*
* @param reader the reader to read from
* @param n the number of characters to skip
* @throws EOFException if this stream reaches the end before skipping all
* the bytes
* @throws IOException if an I/O error occurs
*/
public static void skipFully(Reader reader, long n) throws IOException {
checkNotNull(reader);
while (n > 0) {
long amt = reader.skip(n);
if (amt == 0) {
// force a blocking read
if (reader.read() == -1) {
throw new EOFException();
}
n--;
}
else {
n -= amt;
}
}
}
public static Reader limit(Reader in, long n) {
return new LimitedReader(in, n);
}
public static final class LimitedReader extends FilterReader {
private long limit;
private long left;
private long mark = -1;
LimitedReader(Reader in, long limit) {
super(in);
checkNotNull(in);
checkArgument(limit >= 0, "limit must be non-negative");
this.left = limit;
this.limit = limit;
}
public long limit() {
return limit;
}
// it's okay to mark even if mark isn't supported, as reset won't work
@Override
public synchronized void mark(int readLimit) throws IOException {
in.mark(readLimit);
mark = left;
}
@Override
public int read() throws IOException {
if (left == 0) {
return -1;
}
int result = in.read();
if (result != -1) {
--left;
}
return result;
}
@Override
public int read(char[] b, int off, int len) throws IOException {
if (left == 0) {
return -1;
}
len = (int) Math.min(len, left);
int result = in.read(b, off, len);
if (result != -1) {
left -= result;
}
return result;
}
@Override
public synchronized void reset() throws IOException {
if (!in.markSupported()) {
throw new IOException("Mark not supported");
}
if (mark == -1) {
throw new IOException("Mark not set");
}
in.reset();
left = mark;
}
@Override
public long skip(long n) throws IOException {
n = Math.min(n, left);
long skipped = in.skip(n);
left -= skipped;
return skipped;
}
}
}