proguard.util.MatchedStringMatcher Maven / Gradle / Ivy

/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2021 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;

/**
 * This {@link StringMatcher} tests whether strings start with a specified variable
 * string and then match another optional given {@link StringMatcher}.
 *
 * @see VariableStringMatcher
 * @author Eric Lafortune
 */
public class MatchedStringMatcher extends StringMatcher
{
    private final VariableStringMatcher variableStringMatcher;
    private final StringMatcher         nextMatcher;


    /**
     * Creates a new MatchedStringMatcher
     *
     * @param variableStringMatcher the variable string matcher that can
     *                              provide the string to match.
     * @param nextMatcher           an optional string matcher to match the
     *                              remainder of the string.
     */
    public MatchedStringMatcher(VariableStringMatcher variableStringMatcher,
                                StringMatcher         nextMatcher)
    {
        this.variableStringMatcher = variableStringMatcher;
        this.nextMatcher           = nextMatcher;
    }


    // Implementation for StringMatcher.

    @Override
    public String prefix()
    {
        String prefix = variableStringMatcher.getMatchingString();
        // Append the next matcher's prefix if applicable
        if (nextMatcher != null)
        {
            String nextPrefix = nextMatcher.prefix();
            if (nextPrefix == null)
            {
                return null;
            }
            prefix += nextMatcher.prefix();
        }
        return prefix;
    }

    @Override
    protected boolean matches(String string, int beginOffset, int endOffset)
    {
        String matchingString = variableStringMatcher.getMatchingString();
        if (matchingString == null)
        {
            return false;
        }

        int stringLength        = endOffset - beginOffset;
        int matchingStringLength = matchingString.length();
        return stringLength >= matchingStringLength &&
               string.startsWith(matchingString, beginOffset) &&
               ((nextMatcher == null && stringLength == matchingStringLength) ||
                (nextMatcher != null && nextMatcher.matches(string,
                                    beginOffset + matchingStringLength,
                                    endOffset)));
    }
}