goja-core/src/main/java/goja/core/kits/stream/FastCharBuffer.java
public FastCharBuffer append(char[] array, int off, int len) {
        int end = off + len;
        if ((off < 0)
                || (len < 0)
                || (end > array.length)) {
            throw new IndexOutOfBoundsException();
        }
        if (len == 0) {
            return this;
        }
        int newSize = size + len;
        int remaining = len;

        if (currentBuffer != null) {
            // first try to fill current buffer
            int part = Math.min(remaining, currentBuffer.length - offset);
            System.arraycopy(array, end - remaining, currentBuffer, offset, part);
            remaining -= part;
            offset += part;
            size += part;
        }

        if (remaining > 0) {
            // still some data left
            // ask for new buffer
            needNewBuffer(newSize);

            // then copy remaining
            // but this time we are sure that it will fit
            int part = Math.min(remaining, currentBuffer.length - offset);
            System.arraycopy(array, end - remaining, currentBuffer, offset, part);
            offset += part;
            size += part;
        }

        return this;
    }
public FastCharBuffer append(char[] array, int off, int len) {
        int end = off + len;
        if ((off < 0)
                || (len < 0)
                || (end > array.length)) {
            throw new IndexOutOfBoundsException();
        }
        if (len == 0) {
            return this;
        }
        int newSize = size + len;
        int remaining = len;

        if (currentBuffer != null) {
            // first try to fill current buffer
            int part = Math.min(remaining, currentBuffer.length - offset);
            System.arraycopy(array, end - remaining, currentBuffer, offset, part);
            remaining -= part;
            offset += part;
            size += part;
        }

        if (remaining > 0) {
            // still some data left
            // ask for new buffer
            needNewBuffer(newSize);

            // then copy remaining
            // but this time we are sure that it will fit
            int part = Math.min(remaining, currentBuffer.length - offset);
            System.arraycopy(array, end - remaining, currentBuffer, offset, part);
            offset += part;
            size += part;
        }

        return this;
    }
Appends <code>char</code> array to buffer.