src/java.base/share/classes/java/io/CharArrayReader.java
changeset 47216 71c04702a3d5
parent 40263 6d435de7abbc
child 58242 94bb65cb37d3
child 58678 9cf78a70fa4f
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/io/CharArrayReader.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,240 @@
+/*
+ * Copyright (c) 1996, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.io;
+
+/**
+ * This class implements a character buffer that can be used as a
+ * character-input stream.
+ *
+ * @author      Herb Jellinek
+ * @since       1.1
+ */
+public class CharArrayReader extends Reader {
+    /** The character buffer. */
+    protected char buf[];
+
+    /** The current buffer position. */
+    protected int pos;
+
+    /** The position of mark in buffer. */
+    protected int markedPos = 0;
+
+    /**
+     *  The index of the end of this buffer.  There is not valid
+     *  data at or beyond this index.
+     */
+    protected int count;
+
+    /**
+     * Creates a CharArrayReader from the specified array of chars.
+     * @param buf       Input buffer (not copied)
+     */
+    public CharArrayReader(char buf[]) {
+        this.buf = buf;
+        this.pos = 0;
+        this.count = buf.length;
+    }
+
+    /**
+     * Creates a CharArrayReader from the specified array of chars.
+     *
+     * <p> The resulting reader will start reading at the given
+     * {@code offset}.  The total number of {@code char} values that can be
+     * read from this reader will be either {@code length} or
+     * {@code buf.length-offset}, whichever is smaller.
+     *
+     * @throws IllegalArgumentException
+     *         If {@code offset} is negative or greater than
+     *         {@code buf.length}, or if {@code length} is negative, or if
+     *         the sum of these two values is negative.
+     *
+     * @param buf       Input buffer (not copied)
+     * @param offset    Offset of the first char to read
+     * @param length    Number of chars to read
+     */
+    public CharArrayReader(char buf[], int offset, int length) {
+        if ((offset < 0) || (offset > buf.length) || (length < 0) ||
+            ((offset + length) < 0)) {
+            throw new IllegalArgumentException();
+        }
+        this.buf = buf;
+        this.pos = offset;
+        this.count = Math.min(offset + length, buf.length);
+        this.markedPos = offset;
+    }
+
+    /** Checks to make sure that the stream has not been closed */
+    private void ensureOpen() throws IOException {
+        if (buf == null)
+            throw new IOException("Stream closed");
+    }
+
+    /**
+     * Reads a single character.
+     *
+     * @exception   IOException  If an I/O error occurs
+     */
+    public int read() throws IOException {
+        synchronized (lock) {
+            ensureOpen();
+            if (pos >= count)
+                return -1;
+            else
+                return buf[pos++];
+        }
+    }
+
+    /**
+     * Reads characters into a portion of an array.
+     * @param b  Destination buffer
+     * @param off  Offset at which to start storing characters
+     * @param len   Maximum number of characters to read
+     * @return  The actual number of characters read, or -1 if
+     *          the end of the stream has been reached
+     *
+     * @exception   IOException  If an I/O error occurs
+     * @exception   IndexOutOfBoundsException {@inheritDoc}
+     */
+    public int read(char b[], int off, int len) throws IOException {
+        synchronized (lock) {
+            ensureOpen();
+            if ((off < 0) || (off > b.length) || (len < 0) ||
+                ((off + len) > b.length) || ((off + len) < 0)) {
+                throw new IndexOutOfBoundsException();
+            } else if (len == 0) {
+                return 0;
+            }
+
+            if (pos >= count) {
+                return -1;
+            }
+
+            int avail = count - pos;
+            if (len > avail) {
+                len = avail;
+            }
+            if (len <= 0) {
+                return 0;
+            }
+            System.arraycopy(buf, pos, b, off, len);
+            pos += len;
+            return len;
+        }
+    }
+
+    /**
+     * Skips characters.  Returns the number of characters that were skipped.
+     *
+     * <p>The <code>n</code> parameter may be negative, even though the
+     * <code>skip</code> method of the {@link Reader} superclass throws
+     * an exception in this case. If <code>n</code> is negative, then
+     * this method does nothing and returns <code>0</code>.
+     *
+     * @param n The number of characters to skip
+     * @return       The number of characters actually skipped
+     * @exception  IOException If the stream is closed, or an I/O error occurs
+     */
+    public long skip(long n) throws IOException {
+        synchronized (lock) {
+            ensureOpen();
+
+            long avail = count - pos;
+            if (n > avail) {
+                n = avail;
+            }
+            if (n < 0) {
+                return 0;
+            }
+            pos += n;
+            return n;
+        }
+    }
+
+    /**
+     * Tells whether this stream is ready to be read.  Character-array readers
+     * are always ready to be read.
+     *
+     * @exception  IOException  If an I/O error occurs
+     */
+    public boolean ready() throws IOException {
+        synchronized (lock) {
+            ensureOpen();
+            return (count - pos) > 0;
+        }
+    }
+
+    /**
+     * Tells whether this stream supports the mark() operation, which it does.
+     */
+    public boolean markSupported() {
+        return true;
+    }
+
+    /**
+     * Marks the present position in the stream.  Subsequent calls to reset()
+     * will reposition the stream to this point.
+     *
+     * @param  readAheadLimit  Limit on the number of characters that may be
+     *                         read while still preserving the mark.  Because
+     *                         the stream's input comes from a character array,
+     *                         there is no actual limit; hence this argument is
+     *                         ignored.
+     *
+     * @exception  IOException  If an I/O error occurs
+     */
+    public void mark(int readAheadLimit) throws IOException {
+        synchronized (lock) {
+            ensureOpen();
+            markedPos = pos;
+        }
+    }
+
+    /**
+     * Resets the stream to the most recent mark, or to the beginning if it has
+     * never been marked.
+     *
+     * @exception  IOException  If an I/O error occurs
+     */
+    public void reset() throws IOException {
+        synchronized (lock) {
+            ensureOpen();
+            pos = markedPos;
+        }
+    }
+
+    /**
+     * Closes the stream and releases any system resources associated with
+     * it.  Once the stream has been closed, further read(), ready(),
+     * mark(), reset(), or skip() invocations will throw an IOException.
+     * Closing a previously closed stream has no effect. This method will block
+     * while there is another thread blocking on the reader.
+     */
+    public void close() {
+        synchronized (lock) {
+            buf = null;
+        }
+    }
+}