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 *
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 */

package org.jf.util;

import javax.annotation.Nonnull;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

Class that takes a combined output destination and provides two
output writers, one of which ends up writing to the left column and
one which goes on the right.
/**
 * Class that takes a combined output destination and provides two
 * output writers, one of which ends up writing to the left column and
 * one which goes on the right.
 */
public final class TwoColumnOutput {
    
non-null; underlying writer for final output /** non-null; underlying writer for final output */
    private final Writer out;

    
> 0; the left column width /** > 0; the left column width */
    private final int leftWidth;

    private final int rightWidth;

    private final String spacer;

    
Constructs an instance.
Params:
out – non-null; writer to send final output to
leftWidth – > 0; width of the left column, in characters
rightWidth – > 0; width of the right column, in characters
spacer – non-null; spacer string to sit between the two columns/**
     * Constructs an instance.
     *
     * @param out non-null; writer to send final output to
     * @param leftWidth > 0; width of the left column, in characters
     * @param rightWidth > 0; width of the right column, in characters
     * @param spacer non-null; spacer string to sit between the two columns
     */
    public TwoColumnOutput(@Nonnull Writer out, int leftWidth, int rightWidth,
                           @Nonnull String spacer) {

        if (leftWidth < 1) {
            throw new IllegalArgumentException("leftWidth < 1");
        }

        if (rightWidth < 1) {
            throw new IllegalArgumentException("rightWidth < 1");
        }

        this.out = out;
        this.leftWidth = leftWidth;
        this.rightWidth = rightWidth;
        this.spacer = spacer;
    }

    
Constructs an instance.
Params:
out – non-null; stream to send final output to
leftWidth – >= 1; width of the left column, in characters
rightWidth – >= 1; width of the right column, in characters
spacer – non-null; spacer string to sit between the two columns/**
     * Constructs an instance.
     *
     * @param out non-null; stream to send final output to
     * @param leftWidth &gt;= 1; width of the left column, in characters
     * @param rightWidth &gt;= 1; width of the right column, in characters
     * @param spacer non-null; spacer string to sit between the two columns
     */
    public TwoColumnOutput(OutputStream out, int leftWidth, int rightWidth,
                           String spacer) {
        this(new OutputStreamWriter(out), leftWidth, rightWidth, spacer);
    }

    private String[] leftLines = null;
    private String[] rightLines = null;
    public void write(String left, String right) throws IOException {
        leftLines = StringWrapper.wrapString(left, leftWidth, leftLines);
        rightLines = StringWrapper.wrapString(right, rightWidth, rightLines);
        int leftCount = leftLines.length;
        int rightCount = rightLines.length;

        for (int i=0; i<leftCount || i <rightCount; i++) {
            String leftLine = null;
            String rightLine = null;

            if (i < leftCount) {
                leftLine = leftLines[i];
                if (leftLine == null) {
                    leftCount = i;
                }
            }

            if (i < rightCount) {
                rightLine = rightLines[i];
                if (rightLine == null) {
                    rightCount = i;
                }
            }

            if (leftLine != null || rightLine != null) {
                int written = 0;
                if (leftLine != null) {
                    out.write(leftLine);
                    written = leftLine.length();
                }

                int remaining = leftWidth - written;
                if (remaining > 0) {
                    writeSpaces(out, remaining);
                }

                out.write(spacer);

                if (rightLine != null) {
                    out.write(rightLine);
                }

                out.write('\n');
            }
        }
    }

    
Writes the given number of spaces to the given writer.
Params:
out – non-null; where to write
amt – >= 0; the number of spaces to write/**
     * Writes the given number of spaces to the given writer.
     *
     * @param out non-null; where to write
     * @param amt &gt;= 0; the number of spaces to write
     */
    private static void writeSpaces(Writer out, int amt) throws IOException {
        while (amt > 0) {
            out.write(' ');
            amt--;
        }
    }
}