CyclicCharacterBuffer.java

package com.github.ruediste1.btrbck;

public class CyclicCharacterBuffer {

    boolean filled;
    private int pos;
    private char[] buffer;

    public CyclicCharacterBuffer(int size) {
        buffer = new char[size];
    }

    public String getTail() {
        StringBuilder sb = new StringBuilder();
        if (filled) {
            sb.append(buffer, pos, buffer.length - pos);
        }
        sb.append(buffer, 0, pos);
        return sb.toString();
    }

    public void append(char[] chars, int charsLength) {
        int countToAdd = charsLength;
        if (countToAdd > buffer.length) {
            countToAdd = buffer.length;
        }
        int charsOffset = charsLength - countToAdd;

        // add the part from the current position to the end of the buffer
        int firstCount = countToAdd;
        int remaining = buffer.length - pos;
        if (firstCount > remaining) {
            firstCount = buffer.length - pos;
        }
        System.arraycopy(chars, charsOffset, buffer, pos, firstCount);
        pos += firstCount;

        // add the remaining characters
        if (countToAdd > firstCount) {
            remaining = countToAdd - firstCount;
            System.arraycopy(chars, charsOffset + firstCount, buffer, 0,
                    remaining);
            pos = remaining;
            filled = true;
        }
    }

    public void append(String string) {
        append(string.toCharArray());
    }

    public void append(char[] buf) {
        append(buf, buf.length);
    }
}