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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
There is a newer version: 9.1.6
/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * 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.
 */
package proguard.util;

import java.util.*;

/**
 * This {@link StringParser} can create {@link StringMatcher} instances for regular expressions
 * matching names. The regular expressions are interpreted as comma-separated
 * lists of names, optionally prefixed with '!' negators.
 * If a name with a negator matches, a negative match is returned, without
 * considering any subsequent entries in the list.
 * The regular expressions can contain the following wildcards:
 * '?'   for a single character,
 * '*'   for any number of characters, and
 * '' for a reference to an earlier wildcard (n = 1, 2, ...)
 *
 * @author Eric Lafortune
 */
public class NameParser implements StringParser
{
    private final WildcardManager wildcardManager;


    /**
     * Creates a new NameParser.
     */
    public NameParser()
    {
        this(null);
    }


    /**
     * Creates a new NameParser that supports references to earlier
     * wildcards.
     *
     * @param wildcardManager an optional scope for StringMatcher instances
     *                        that match wildcards.
     */
    public NameParser(WildcardManager wildcardManager)
    {
        this.wildcardManager = wildcardManager;
    }


    // Implementations for StringParser.

    public StringMatcher parse(String regularExpression)
    {
        int           index;
        StringMatcher nextMatcher = new EmptyStringMatcher();

        // Look for wildcards.
        for (index = 0; index < regularExpression.length(); index++)
        {
            // Is there a '*' wildcard?
            if (regularExpression.charAt(index) == '*')
            {
                SettableMatcher settableMatcher = new SettableMatcher();

                // Create a matcher for the wildcard.
                VariableStringMatcher variableStringMatcher =
                    new VariableStringMatcher(null,
                                              null,
                                              0,
                                              Integer.MAX_VALUE,
                                              settableMatcher);

                // Remember it so it can be referenced back.
                if (wildcardManager != null)
                {
                    wildcardManager.rememberVariableStringMatcher(variableStringMatcher);
                }

                // Recursively create a matcher for the rest of the string.
                settableMatcher.setMatcher(parse(regularExpression.substring(index + 1)));

                nextMatcher = variableStringMatcher;
                break;
            }

            // Is there a '?' wildcard?
            else if (regularExpression.charAt(index) == '?')
            {
                SettableMatcher settableMatcher = new SettableMatcher();

                // Create a matcher for the wildcard.
                VariableStringMatcher variableStringMatcher =
                    new VariableStringMatcher(null,
                                              null,
                                              1,
                                              1,
                                              settableMatcher);

                // Remember it so it can be referenced back.
                if (wildcardManager != null)
                {
                    wildcardManager.rememberVariableStringMatcher(variableStringMatcher);
                }

                // Recursively create a matcher for the rest of the string.
                settableMatcher.setMatcher(parse(regularExpression.substring(index + 1)));

                nextMatcher = variableStringMatcher;
                break;
            }

            // Is there a '' wildcard?
            else if (wildcardManager != null)
            {
                int wildCardIndex = wildcardManager.wildCardIndex(regularExpression, index);
                if (wildCardIndex >= 0)
                {
                    // Find the index of the closing bracket again.
                    int closingIndex = regularExpression.indexOf('>', index + 1);

                    // Retrieve the specified variable string matcher and
                    // recursively create a matcher for the rest of the string.
                    nextMatcher = wildcardManager.createMatchedStringMatcher(
                        wildCardIndex,
                        parse(regularExpression.substring(closingIndex + 1)));

                    break;
                }
            }
        }

        // Return a matcher for the fixed first part of the regular expression,
        // if any, and the remainder.
        return index != 0 ?
            new FixedStringMatcher(regularExpression.substring(0, index), nextMatcher) :
            nextMatcher;
    }


    /**
     * A main method for testing name matching.
     */
    public static void main(String[] args)
    {
        try
        {
            System.out.println("Regular expression ["+args[0]+"]");
            NameParser parser  = new NameParser();
            StringMatcher  matcher = parser.parse(args[0]);
            for (int index = 1; index < args.length; index++)
            {
                String string = args[index];
                System.out.print("String             ["+string+"]");
                System.out.println(" -> match = "+matcher.matches(args[index]));
            }
        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }
    }
}