mirror of
https://github.com/moparisthebest/mailiverse
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261 lines
8.6 KiB
Java
261 lines
8.6 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package java.io;
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/**
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* A specialized {@link Reader} that reads characters from a {@code String} in
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* a sequential manner.
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*
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* @see StringWriter
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*/
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public class StringReader extends Reader {
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private String str;
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private int markpos = -1;
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private int pos;
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private int count;
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/**
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* Construct a new {@code StringReader} with {@code str} as source. The size
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* of the reader is set to the {@code length()} of the string and the Object
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* to synchronize access through is set to {@code str}.
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*
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* @param str
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* the source string for this reader.
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*/
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public StringReader(String str) {
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super();
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this.str = str;
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this.count = str.length();
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}
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/**
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* Closes this reader. Once it is closed, read operations on this reader
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* will throw an {@code IOException}. Only the first invocation of this
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* method has any effect.
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*/
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@Override
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public void close() {
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str = null;
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}
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/**
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* Returns a boolean indicating whether this reader is closed.
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*
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* @return {@code true} if closed, otherwise {@code false}.
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*/
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private boolean isClosed() {
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return str == null;
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}
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/**
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* Sets a mark position in this reader. The parameter {@code readLimit} is
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* ignored for this class. Calling {@code reset()} will reposition the
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* reader back to the marked position.
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*
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* @param readLimit
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* ignored for {@code StringReader} instances.
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* @throws IllegalArgumentException
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* if {@code readLimit < 0}.
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* @throws IOException
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* if this reader is closed.
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* @see #markSupported()
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* @see #reset()
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*/
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@Override
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public void mark(int readLimit) throws IOException {
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if (readLimit < 0) {
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throw new IllegalArgumentException();
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}
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synchronized (lock) {
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if (isClosed()) {
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throw new IOException(Msg.getString("K0083")); //$NON-NLS-1$
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}
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markpos = pos;
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}
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}
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/**
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* Indicates whether this reader supports the {@code mark()} and {@code
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* reset()} methods. This implementation returns {@code true}.
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*
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* @return always {@code true}.
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*/
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@Override
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public boolean markSupported() {
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return true;
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}
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/**
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* Reads a single character from the source string and returns it as an
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* integer with the two higher-order bytes set to 0. Returns -1 if the end
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* of the source string has been reached.
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*
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* @return the character read or -1 if the end of the source string has been
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* reached.
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* @throws IOException
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* if this reader is closed.
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*/
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@Override
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public int read() throws IOException {
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synchronized (lock) {
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if (isClosed()) {
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throw new IOException(Msg.getString("K0083")); //$NON-NLS-1$
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}
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if (pos != count) {
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return str.charAt(pos++);
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}
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return -1;
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}
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}
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/**
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* Reads at most {@code len} characters from the source string and stores
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* them at {@code offset} in the character array {@code buf}. Returns the
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* number of characters actually read or -1 if the end of the source string
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* has been reached.
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*
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* @param buf
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* the character array to store the characters read.
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* @param offset
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* the initial position in {@code buffer} to store the characters
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* read from this reader.
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* @param len
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* the maximum number of characters to read.
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* @return the number of characters read or -1 if the end of the reader has
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* been reached.
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* @throws IndexOutOfBoundsException
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* if {@code offset < 0} or {@code len < 0}, or if
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* {@code offset + len} is greater than the size of {@code buf}.
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* @throws IOException
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* if this reader is closed.
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*/
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@Override
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public int read(char buf[], int offset, int len) throws IOException {
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synchronized (lock) {
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if (isClosed()) {
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// K0083=StringReader is closed.
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throw new IOException(Msg.getString("K0083")); //$NON-NLS-1$
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}
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if (offset < 0 || offset > buf.length) {
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// K002e=Offset out of bounds \: {0}
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throw new ArrayIndexOutOfBoundsException(Msg.getString("K002e", offset)); //$NON-NLS-1$
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}
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if (len < 0 || len > buf.length - offset) {
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// K0031=Length out of bounds \: {0}
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throw new ArrayIndexOutOfBoundsException(Msg.getString("K0031", len)); //$NON-NLS-1$
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}
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if (len == 0) {
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return 0;
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}
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if (pos == this.count) {
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return -1;
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}
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int end = pos + len > this.count ? this.count : pos + len;
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str.getChars(pos, end, buf, offset);
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int read = end - pos;
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pos = end;
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return read;
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}
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}
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/**
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* Indicates whether this reader is ready to be read without blocking. This
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* implementation always returns {@code true}.
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*
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* @return always {@code true}.
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* @throws IOException
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* if this reader is closed.
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* @see #read()
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* @see #read(char[], int, int)
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*/
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@Override
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public boolean ready() throws IOException {
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synchronized (lock) {
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if (isClosed()) {
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throw new IOException(Msg.getString("K0083")); //$NON-NLS-1$
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}
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return true;
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}
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}
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/**
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* Resets this reader's position to the last {@code mark()} location.
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* Invocations of {@code read()} and {@code skip()} will occur from this new
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* location. If this reader has not been marked, it is reset to the
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* beginning of the source string.
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*
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* @throws IOException
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* if this reader is closed.
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* @see #mark(int)
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* @see #markSupported()
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*/
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@Override
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public void reset() throws IOException {
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synchronized (lock) {
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if (isClosed()) {
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throw new IOException(Msg.getString("K0083")); //$NON-NLS-1$
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}
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pos = markpos != -1 ? markpos : 0;
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}
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}
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/**
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* Moves {@code ns} characters in the source string. Unlike the {@link
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* Reader#skip(long) overridden method}, this method may skip negative skip
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* distances: this rewinds the input so that characters may be read again.
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* When the end of the source string has been reached, the input cannot be
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* rewound.
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*
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* @param ns
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* the maximum number of characters to skip. Positive values skip
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* forward; negative values skip backward.
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* @return the number of characters actually skipped. This is bounded below
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* by the number of characters already read and above by the
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* number of characters remaining:<br> {@code -(num chars already
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* read) <= distance skipped <= num chars remaining}.
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* @throws IOException
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* if this reader is closed.
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* @see #mark(int)
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* @see #markSupported()
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* @see #reset()
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*/
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@Override
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public long skip(long ns) throws IOException {
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synchronized (lock) {
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if (isClosed()) {
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throw new IOException(Msg.getString("K0083")); //$NON-NLS-1$
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}
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int minSkip = -pos;
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int maxSkip = count - pos;
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if (maxSkip == 0 || ns > maxSkip) {
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ns = maxSkip; // no rewinding if we're at the end
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} else if (ns < minSkip) {
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ns = minSkip;
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}
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pos += ns;
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return ns;
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}
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}
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} |