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 * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package com.sun.tools.javac.parser;

import java.util.HashSet;
import java.util.Set;

Methods used to support text blocks lint.
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/**
 * Methods used to support text blocks lint.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
class TextBlockSupport {
     enum WhitespaceChecks {
        INCONSISTENT,
        TRAILING
    };

    
Check that the use of white space in content is not problematic.
/** Check that the use of white space in content is not problematic.
     */
    static Set<WhitespaceChecks> checkWhitespace(String string) {
        // Start with empty result set.
        Set<WhitespaceChecks> checks = new HashSet<>();
        // No need to check empty strings.
        if (string.isEmpty()) {
            return checks;
        }
        // Maximum common indentation.
        int outdent = 0;
        // No need to check indentation if opting out (last line is empty.)
        char lastChar = string.charAt(string.length() - 1);
        boolean optOut = lastChar == '\n' || lastChar == '\r';
        // Split string based at line terminators.
        String[] lines = string.split("\\R");
        int length = lines.length;
        // Extract last line.
        String lastLine = length == 0 ? "" : lines[length - 1];
         if (!optOut) {
            // Prime with the last line indentation (may be blank.)
            outdent = indexOfNonWhitespace(lastLine);
            for (String line : lines) {
                // Blanks lines have no influence (last line accounted for.)
                if (!line.isBlank()) {
                    outdent = Integer.min(outdent, indexOfNonWhitespace(line));
                    if (outdent == 0) {
                        break;
                    }
                }
            }
        }
        // Last line is representative.
        String start = lastLine.substring(0, outdent);
        for (String line : lines) {
            // Fail if a line does not have the same indentation.
            if (!line.isBlank() && !line.startsWith(start)) {
                // Mix of different white space
                checks.add(WhitespaceChecks.INCONSISTENT);
            }
            // Line has content even after indent is removed.
            if (outdent < line.length()) {
                // Is the last character a white space.
                lastChar = line.charAt(line.length() - 1);
                if (Character.isWhitespace(lastChar)) {
                    // Has trailing white space.
                    checks.add(WhitespaceChecks.TRAILING);
                }
            }
        }
        return checks;
    }

   private static int indexOfNonWhitespace(String string) {
        return string.length() - string.stripLeading().length();
    }
}