com.oracle.truffle.regex.tregex.buffer.CharArrayBuffer Maven / Gradle / Ivy

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/*
 * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The Universal Permissive License (UPL), Version 1.0
 *
 * Subject to the condition set forth below, permission is hereby granted to any
 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
 * freely licensable by each licensor hereunder covering either (i) the
 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
 *
 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
 * is contributed by such licensors),
 *
 * without restriction, including without limitation the rights to copy, create
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
 *
 * This license is subject to the following condition:
 *
 * The above copyright notice and either this complete permission notice or at a
 * minimum a reference to the UPL must be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 * SOFTWARE.
 */

package com.oracle.truffle.regex.tregex.buffer;

import java.util.Arrays;

/**
 * This class is designed as a "scratchpad" for generating many char arrays of unknown size. It will
 * never shrink its internal buffer, so it should be disposed as soon as it is no longer needed.
 * 
 * Usage Example:
 * 
 *
 *  * CharArrayBuffer buf = new CharArrayBuffer();
 * List results = new ArrayList<>();
 * for (Object obj : listOfThingsToProcess) {
 *     for (Object x : obj.thingsThatShouldBecomeChars()) {
 *         buf.add(someCalculation(x));
 *     }
 *     results.add(buf.toArray());
 *     buf.clear();
 * }
 * 
 */
public class CharArrayBuffer extends AbstractArrayBuffer {

    private static final char[] EMPTY = {};
    protected char[] buf;

    public CharArrayBuffer() {
        this(16);
    }

    public CharArrayBuffer(int initialSize) {
        buf = new char[initialSize];
    }

    @Override
    int getBufferLength() {
        return buf.length;
    }

    @Override
    void grow(int newSize) {
        buf = Arrays.copyOf(buf, newSize);
    }

    public char[] getBuffer() {
        return buf;
    }

    public char get(int i) {
        return buf[i];
    }

    public void set(int i, char c) {
        buf[i] = c;
    }

    public void add(char c) {
        if (length == buf.length) {
            grow(length * 2);
        }
        buf[length++] = c;
    }

    public char[] toArray() {
        return isEmpty() ? EMPTY : Arrays.copyOf(buf, length);
    }
}