org.tomitribe.crest.help.Wrap Maven / Gradle / Ivy

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.tomitribe.crest.help;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Wrap {

    private Wrap() {
    }

    public static int length(final CharSequence cs) {
        return cs == null ? 0 : cs.length();
    }

    public static boolean isBlank(final CharSequence cs) {
        int strLen = length(cs);
        if (strLen == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(cs.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    /**
     * Wraps a single line of text, identifying words by {@code ' '}.
     *
     * New lines will be separated by the system property line separator.
     * Very long words, such as URLs will not be wrapped.
     *
     * Leading spaces on a new line are stripped.
     * Trailing spaces are not stripped.
     *
     * @param str  the String to be word wrapped, may be null
     * @param wrapLength  the column to wrap the words at, less than 1 is treated as 1
     * @return a line with newlines inserted, {@code null} if null input
     */
    public static String wrap(final String str, final int wrapLength) {
        return wrap(str, wrapLength, null, false);
    }

    /**
     * Wraps a single line of text, identifying words by {@code ' '}.
     *
     * Leading spaces on a new line are stripped. Trailing spaces are not stripped.
     *
     * @param str  the String to be word wrapped, may be null
     * @param wrapLength  the column to wrap the words at, less than 1 is treated as 1
     * @param newLineStr  the string to insert for a new line,
     *  {@code null} uses the system property line separator
     * @param wrapLongWords  true if long words (such as URLs) should be wrapped
     * @return a line with newlines inserted, {@code null} if null input
     **/
    public static String wrap(final String str, final int wrapLength, final String newLineStr, final boolean wrapLongWords) {
        return wrap(str, wrapLength, newLineStr, wrapLongWords, " ");
    }

    /**
     * Wraps a single line of text, identifying words by {@code wrapOn}.
     *
     * Leading spaces on a new line are stripped.
     * Trailing spaces are not stripped.
     *
     * @param str  the String to be word wrapped, may be null
     * @param wrapLength  the column to wrap the words at, less than 1 is treated as 1
     * @param newLineStr  the string to insert for a new line,
     *  {@code null} uses the system property line separator
     * @param wrapLongWords  true if long words (such as URLs) should be wrapped
     * @param wrapOn regex expression to be used as a breakable characters,
     *               if blank string is provided a space character will be used
     * @return a line with newlines inserted, {@code null} if null input
     */
    public static String wrap(final String str, int wrapLength, String newLineStr, final boolean wrapLongWords, String wrapOn) {
        if (str == null) {
            return null;
        }
        if (newLineStr == null) {
            newLineStr = System.lineSeparator();
        }
        if (wrapLength < 1) {
            wrapLength = 1;
        }
        if (isBlank(wrapOn)) {
            wrapOn = " ";
        }
        final Pattern patternToWrapOn = Pattern.compile(wrapOn);
        final int inputLineLength = str.length();
        int offset = 0;
        final StringBuilder wrappedLine = new StringBuilder(inputLineLength + 32);

        while (offset < inputLineLength) {
            int spaceToWrapAt = -1;
            Matcher matcher = patternToWrapOn.matcher(
                    str.substring(offset, Math.min((int) Math.min(Integer.MAX_VALUE, offset + wrapLength + 1L), inputLineLength)));
            if (matcher.find()) {
                if (matcher.start() == 0) {
                    offset += matcher.end();
                    continue;
                }
                spaceToWrapAt = matcher.start() + offset;
            }

            // only last line without leading spaces is left
            if (inputLineLength - offset <= wrapLength) {
                break;
            }

            while (matcher.find()) {
                spaceToWrapAt = matcher.start() + offset;
            }

            if (spaceToWrapAt >= offset) {
                // normal case
                wrappedLine.append(str, offset, spaceToWrapAt);
                wrappedLine.append(newLineStr);
                offset = spaceToWrapAt + 1;

            } else {
                // really long word or URL
                if (wrapLongWords) {
                    // wrap really long word one line at a time
                    wrappedLine.append(str, offset, wrapLength + offset);
                    wrappedLine.append(newLineStr);
                    offset += wrapLength;
                } else {
                    // do not wrap really long word, just extend beyond limit
                    matcher = patternToWrapOn.matcher(str.substring(offset + wrapLength));
                    if (matcher.find()) {
                        spaceToWrapAt = matcher.start() + offset + wrapLength;
                    }

                    if (spaceToWrapAt >= 0) {
                        wrappedLine.append(str, offset, spaceToWrapAt);
                        wrappedLine.append(newLineStr);
                        offset = spaceToWrapAt + 1;
                    } else {
                        wrappedLine.append(str, offset, str.length());
                        offset = inputLineLength;
                    }
                }
            }
        }

        // Whatever is left in line is short enough to just pass through
        wrappedLine.append(str, offset, str.length());

        return wrappedLine.toString();
    }
}