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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.apache.commons.lang3;

/**
 * Operations on {@link CharSequence} that are
 * {@code null} safe.
 *
 * @see CharSequence
 * @since 3.0
 */
public class CharSequenceUtils {

    private static final int NOT_FOUND = -1;

    static final int TO_STRING_LIMIT = 16;

    private static boolean checkLaterThan1(final CharSequence cs, final CharSequence searchChar, final int len2, final int start1) {
        for (int i = 1, j = len2 - 1; i <= j; i++, j--) {
            if (cs.charAt(start1 + i) != searchChar.charAt(i) || cs.charAt(start1 + j) != searchChar.charAt(j)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Used by the indexOf(CharSequence methods) as a green implementation of indexOf.
     *
     * @param cs the {@link CharSequence} to be processed
     * @param searchChar the {@link CharSequence} to be searched for
     * @param start the start index
     * @return the index where the search sequence was found
     */
    static int indexOf(final CharSequence cs, final CharSequence searchChar, final int start) {
        if (cs instanceof String) {
            return ((String) cs).indexOf(searchChar.toString(), start);
        }
        if (cs instanceof StringBuilder) {
            return ((StringBuilder) cs).indexOf(searchChar.toString(), start);
        }
        if (cs instanceof StringBuffer) {
            return ((StringBuffer) cs).indexOf(searchChar.toString(), start);
        }
        return cs.toString().indexOf(searchChar.toString(), start);
//        if (cs instanceof String && searchChar instanceof String) {
//            // TODO: Do we assume searchChar is usually relatively small;
//            //       If so then calling toString() on it is better than reverting to
//            //       the green implementation in the else block
//            return ((String) cs).indexOf((String) searchChar, start);
//        } else {
//            // TODO: Implement rather than convert to String
//            return cs.toString().indexOf(searchChar.toString(), start);
//        }
    }

    /**
     * Returns the index within {@code cs} of the first occurrence of the
     * specified character, starting the search at the specified index.
     * 

* If a character with value {@code searchChar} occurs in the * character sequence represented by the {@code cs} * object at an index no smaller than {@code start}, then * the index of the first such occurrence is returned. For values * of {@code searchChar} in the range from 0 to 0xFFFF (inclusive), * this is the smallest value k such that: *

*
     * (this.charAt(k) == searchChar) && (k >= start)
     * 
* is true. For other values of {@code searchChar}, it is the * smallest value k such that: *
     * (this.codePointAt(k) == searchChar) && (k >= start)
     * 
*

* is true. In either case, if no such character occurs inm {@code cs} * at or after position {@code start}, then * {@code -1} is returned. *

*

* There is no restriction on the value of {@code start}. If it * is negative, it has the same effect as if it were zero: the entire * {@link CharSequence} may be searched. If it is greater than * the length of {@code cs}, it has the same effect as if it were * equal to the length of {@code cs}: {@code -1} is returned. *

*

All indices are specified in {@code char} values * (Unicode code units). *

* * @param cs the {@link CharSequence} to be processed, not null * @param searchChar the char to be searched for * @param start the start index, negative starts at the string start * @return the index where the search char was found, -1 if not found * @since 3.6 updated to behave more like {@link String} */ static int indexOf(final CharSequence cs, final int searchChar, int start) { if (cs instanceof String) { return ((String) cs).indexOf(searchChar, start); } final int sz = cs.length(); if (start < 0) { start = 0; } if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) { for (int i = start; i < sz; i++) { if (cs.charAt(i) == searchChar) { return i; } } return NOT_FOUND; } //supplementary characters (LANG1300) if (searchChar <= Character.MAX_CODE_POINT) { final char[] chars = Character.toChars(searchChar); for (int i = start; i < sz - 1; i++) { final char high = cs.charAt(i); final char low = cs.charAt(i + 1); if (high == chars[0] && low == chars[1]) { return i; } } } return NOT_FOUND; } /** * Used by the lastIndexOf(CharSequence methods) as a green implementation of lastIndexOf * * @param cs the {@link CharSequence} to be processed * @param searchChar the {@link CharSequence} to find * @param start the start index * @return the index where the search sequence was found */ static int lastIndexOf(final CharSequence cs, final CharSequence searchChar, int start) { if (searchChar == null || cs == null) { return NOT_FOUND; } if (searchChar instanceof String) { if (cs instanceof String) { return ((String) cs).lastIndexOf((String) searchChar, start); } if (cs instanceof StringBuilder) { return ((StringBuilder) cs).lastIndexOf((String) searchChar, start); } if (cs instanceof StringBuffer) { return ((StringBuffer) cs).lastIndexOf((String) searchChar, start); } } final int len1 = cs.length(); final int len2 = searchChar.length(); if (start > len1) { start = len1; } if (start < 0 || len2 > len1) { return NOT_FOUND; } if (len2 == 0) { return start; } if (len2 <= TO_STRING_LIMIT) { if (cs instanceof String) { return ((String) cs).lastIndexOf(searchChar.toString(), start); } if (cs instanceof StringBuilder) { return ((StringBuilder) cs).lastIndexOf(searchChar.toString(), start); } if (cs instanceof StringBuffer) { return ((StringBuffer) cs).lastIndexOf(searchChar.toString(), start); } } if (start + len2 > len1) { start = len1 - len2; } final char char0 = searchChar.charAt(0); int i = start; while (true) { while (cs.charAt(i) != char0) { i--; if (i < 0) { return NOT_FOUND; } } if (checkLaterThan1(cs, searchChar, len2, i)) { return i; } i--; if (i < 0) { return NOT_FOUND; } } } /** * Returns the index within {@code cs} of the last occurrence of * the specified character, searching backward starting at the * specified index. For values of {@code searchChar} in the range * from 0 to 0xFFFF (inclusive), the index returned is the largest * value k such that: *
     * (this.charAt(k) == searchChar) && (k <= start)
     * 
* is true. For other values of {@code searchChar}, it is the * largest value k such that: *
     * (this.codePointAt(k) == searchChar) && (k <= start)
     * 
* is true. In either case, if no such character occurs in {@code cs} * at or before position {@code start}, then {@code -1} is returned. * *

* All indices are specified in {@code char} values * (Unicode code units). *

* * @param cs the {@link CharSequence} to be processed * @param searchChar the char to be searched for * @param start the start index, negative returns -1, beyond length starts at end * @return the index where the search char was found, -1 if not found * @since 3.6 updated to behave more like {@link String} */ static int lastIndexOf(final CharSequence cs, final int searchChar, int start) { if (cs instanceof String) { return ((String) cs).lastIndexOf(searchChar, start); } final int sz = cs.length(); if (start < 0) { return NOT_FOUND; } if (start >= sz) { start = sz - 1; } if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) { for (int i = start; i >= 0; --i) { if (cs.charAt(i) == searchChar) { return i; } } return NOT_FOUND; } //supplementary characters (LANG1300) //NOTE - we must do a forward traversal for this to avoid duplicating code points if (searchChar <= Character.MAX_CODE_POINT) { final char[] chars = Character.toChars(searchChar); //make sure it's not the last index if (start == sz - 1) { return NOT_FOUND; } for (int i = start; i >= 0; i--) { final char high = cs.charAt(i); final char low = cs.charAt(i + 1); if (chars[0] == high && chars[1] == low) { return i; } } } return NOT_FOUND; } /** * 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 */ 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(): 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; } /** * Returns a new {@link CharSequence} that is a subsequence of this * sequence starting with the {@code char} value at the specified index. * *

This provides the {@link CharSequence} equivalent to {@link String#substring(int)}. * The length (in {@code char}) of the returned sequence is {@code length() - start}, * so if {@code start == end} then an empty sequence is returned.

* * @param cs the specified subsequence, null returns null * @param start the start index, inclusive, valid * @return a new subsequence, may be null * @throws IndexOutOfBoundsException if {@code start} is negative or if * {@code start} is greater than {@code length()} */ public static CharSequence subSequence(final CharSequence cs, final int start) { return cs == null ? null : cs.subSequence(start, cs.length()); } /** * Converts the given CharSequence to a char[]. * * @param source the {@link CharSequence} to be processed. * @return the resulting char array, never null. * @since 3.11 */ public static char[] toCharArray(final CharSequence source) { final int len = StringUtils.length(source); if (len == 0) { return ArrayUtils.EMPTY_CHAR_ARRAY; } if (source instanceof String) { return ((String) source).toCharArray(); } final char[] array = new char[len]; for (int i = 0; i < len; i++) { array[i] = source.charAt(i); } return array; } /** * {@link CharSequenceUtils} instances should NOT be constructed in * standard programming. * *

This constructor is public to permit tools that require a JavaBean * instance to operate.

*/ public CharSequenceUtils() { } }




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