LimitedLineWriter.java

package org.rascalmpl.repl;

import java.io.IOException;
import java.io.Writer;

import org.rascalmpl.interpreter.utils.LimitedResultWriter.IOLimitReachedException;


public class LimitedLineWriter extends NonClosingFilterWriter {

    private final long limit;
    private int written;

    public LimitedLineWriter(Writer out, long limit) {
        super(out);
        this.limit = limit;
        written = 0;
    }
    @Override
    public void write(int c) throws IOException {
        if (written == limit) {
            throw new IOLimitReachedException();
        }
        out.write(c);
        if (c == '\n' || c == '\r') {
            written++;
            if (written == limit) {
                out.write("...");
            }
        }
    }
    @Override
    public void write(char[] cbuf, int off, int len) throws IOException {
        if (written == limit) {
            throw new IOLimitReachedException();
        }
        len = calculateNewLength(cbuf, off, len);
        out.write(cbuf, off, len);
        if (written == limit) {
            out.write("...");
        }
    }

    private int calculateNewLength(char[] cbuf, int off, int len) {
        for (int i = off; i < off + len; i++) {
            if (cbuf[i] == '\n' || cbuf[i]  == '\r') {
                written++;
                if (written == limit) {
                    // we have to change the length to just after the last newline
                    return Math.min((i + 1) - off, len);
                }
            }
        }
        return len;
    }

    private int calculateNewLength(String str, int off, int len) {
        for (int i = off; i < off + len; i++) {
            if (str.charAt(i) == '\n' || str.charAt(i)  == '\r') {
                written++;
                if (written == limit) {
                    // we have to change the length to just after the last newline
                    return Math.min((i + 1) - off, len);
                }
            }
        }
        return len;
    }

    @Override
    public void write(String str, int off, int len) throws IOException {
        if (written == limit) {
            throw new IOLimitReachedException();
        }
        len = calculateNewLength(str, off, len);
        out.write(str, off, len);
        if (written == limit) {
            out.write("...");
        }
    }

}