com.opengamma.strata.report.framework.format.AsciiTable.java Source code

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Here is the source code for com.opengamma.strata.report.framework.format.AsciiTable.java

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/**
 * Copyright (C) 2016 - present by OpenGamma Inc. and the OpenGamma group of companies
 * 
 * Please see distribution for license.
 */
package com.opengamma.strata.report.framework.format;

import java.util.List;

import com.google.common.base.Strings;
import com.opengamma.strata.collect.ArgChecker;

/**
 * An ASCII table generator.
 * <p>
 * Provides the ability to generate an ASCII table, typically used on the command line.
 */
final class AsciiTable {

    /**
     * Line separator.
     */
    private static final String LINE_SEPARATOR = System.lineSeparator();

    //-------------------------------------------------------------------------
    /**
     * Restricted constructor.
     */
    private AsciiTable() {
    }

    /**
     * Generates the ASCII table.
     * 
     * @param alignments  the table alignments
     * @param headers  the table headers
     * @param cells  the table cells, outer list of rows, inner list of columns
     * @return the table
     * @throws IllegalArgumentException if the number of columns specified is inconsistent
     */
    static String generate(List<AsciiTableAlignment> alignments, List<String> headers,
            List<? extends List<String>> cells) {

        int colCount = alignments.size();
        int rowCount = cells.size();
        ArgChecker.isTrue(headers.size() == colCount, "Number of headers {} must match number of alignments {}",
                headers.size(), colCount);

        // find max length of each column
        int[] colLengths = new int[colCount];
        for (int colIdx = 0; colIdx < colCount; colIdx++) {
            colLengths[colIdx] = headers.get(colIdx).length();
        }
        for (int rowIdx = 0; rowIdx < rowCount; rowIdx++) {
            List<String> row = cells.get(rowIdx);
            ArgChecker.isTrue(row.size() == colCount, "Table of cells has incorrect number of columns {} in row {}",
                    row.size(), rowIdx);
            for (int colIdx = 0; colIdx < colCount; colIdx++) {
                colLengths[colIdx] = Math.max(colLengths[colIdx], row.get(colIdx).length());
            }
        }
        int colTotalLength = 3; // allow for last vertical separator and windows line separator
        for (int colIdx = 0; colIdx < colCount; colIdx++) {
            colTotalLength += colLengths[colIdx] + 3; // each column has two spaces and a vertical separator
        }

        // write table
        StringBuilder buf = new StringBuilder((rowCount + 3) * colTotalLength);
        writeSeparatorLine(buf, colLengths);
        writeDataLine(buf, colLengths, alignments, headers);
        writeSeparatorLine(buf, colLengths);
        for (int rowIdx = 0; rowIdx < rowCount; rowIdx++) {
            writeDataLine(buf, colLengths, alignments, cells.get(rowIdx));
        }
        writeSeparatorLine(buf, colLengths);
        return buf.toString();
    }

    // write a separator line
    private static void writeSeparatorLine(StringBuilder buf, int[] colLengths) {
        for (int colIdx = 0; colIdx < colLengths.length; colIdx++) {
            buf.append('+');
            for (int i = 0; i < colLengths[colIdx] + 2; i++) {
                buf.append('-');
            }
        }
        buf.append('+').append(LINE_SEPARATOR);
    }

    // write a data line
    private static void writeDataLine(StringBuilder buf, int[] colLengths, List<AsciiTableAlignment> alignments,
            List<String> values) {

        for (int colIdx = 0; colIdx < colLengths.length; colIdx++) {
            String value = Strings.nullToEmpty(values.get(colIdx));
            buf.append('|').append(' ').append(formatValue(buf, colLengths[colIdx], alignments.get(colIdx), value))
                    .append(' ');
        }
        buf.append('|').append(LINE_SEPARATOR);
    }

    // writes a data item
    private static String formatValue(StringBuilder buf, int colLength, AsciiTableAlignment alignment,
            String value) {

        if (alignment == AsciiTableAlignment.RIGHT) {
            return Strings.padStart(value, colLength, ' ');
        } else {
            return Strings.padEnd(value, colLength, ' ');
        }
    }

}