CharSequenceUtils.java

/*-
 * #%L
 * TwinColGrid add-on
 * %%
 * Copyright (C) 2017 - 2025 Flowing Code
 * %%
 * Licensed 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.
 * #L%
 */
package com.flowingcode.vaadin.addons.twincolgrid;
/*
 * 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
 *
 *      https://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.
 */

import lombok.experimental.UtilityClass;

@UtilityClass
class CharSequenceUtils {

  /**
   * Green implementation of regionMatches.
   *
   * @param cs the {@link CharSequence} to be processed
   * @param ignoreCase whether or not to be case-insensitive
   * @param thisStart the index to start on the {@code cs} CharSequence
   * @param substring the {@link CharSequence} to be looked for
   * @param start the index to start on the {@code substring} CharSequence
   * @param length character length of the region
   * @return whether the region matched
   * @see String#regionMatches(boolean, int, String, int, int)
   */
    static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
            final CharSequence substring, final int start, final int length)    {
        if (cs instanceof String && substring instanceof String) {
            return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
        }
        int index1 = thisStart;
        int index2 = start;
        int tmpLen = length;

        // Extract these first so we detect NPEs the same as the java.lang.String version
        final int srcLen = cs.length() - thisStart;
        final int otherLen = substring.length() - start;

        // Check for invalid parameters
        if (thisStart < 0 || start < 0 || length < 0) {
            return false;
        }

        // Check that the regions are long enough
        if (srcLen < length || otherLen < length) {
            return false;
        }

        while (tmpLen-- > 0) {
            final char c1 = cs.charAt(index1++);
            final char c2 = substring.charAt(index2++);

            if (c1 == c2) {
                continue;
            }

            if (!ignoreCase) {
                return false;
            }

            // The real same check as in String#regionMatches(boolean, int, String, int, int):
            final char u1 = Character.toUpperCase(c1);
            final char u2 = Character.toUpperCase(c2);
            if (u1 != u2 && Character.toLowerCase(u1) != Character.toLowerCase(u2)) {
                return false;
            }
        }

        return true;
    }

}