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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;

/**
 * This {@link StringFunctionParser} creates {@link StringFunction} instances for regular
 * expressions with optional "->" transformations. It parses the first part with a given {@link
 * StringParser} and the second part with an optional {@link WildcardManager}.
 *
 * @author Eric Lafortune
 */
public class SingleFunctionParser implements StringFunctionParser {
  private final StringParser stringParser;
  private final WildcardManager wildcardManager;

  /** Creates a new SingleFunctionParser. */
  public SingleFunctionParser(StringParser stringParser, WildcardManager wildcardManager) {
    this.stringParser = stringParser;
    this.wildcardManager = wildcardManager;
  }

  // Implementations for StringFunctionParser.

  public StringFunction parse(String regularExpression) {
    // Reset the string matchers, since all wildcards have to be local
    // inside this regular expression.
    if (wildcardManager != null) {
      wildcardManager.reset();
    }

    // Does the regular expression specify a transformation?
    int arrowIndex = regularExpression.indexOf("->");
    if (arrowIndex < 0) {
      // Otherwise just pass any matched strings.
      return new MatchingStringFunction(stringParser.parse(regularExpression));
    }

    // Split the regular expression into its two parts.
    String patternExpression = regularExpression.substring(0, arrowIndex);
    String replacementExpression = regularExpression.substring(arrowIndex + 2);

    // First parse the pattern, possibly with wildcards.
    StringFunction patternStringFunction =
        new MatchingStringFunction(stringParser.parse(patternExpression));

    // Then parse the replacement, possibly with references to
    // these wildcards.
    StringFunction replacementStringFunction =
        wildcardManager == null
            ? new ConstantStringFunction(replacementExpression)
            : wildcardManager.createMatchedStringFunction(replacementExpression);

    // Finally combine the two.
    return new AndStringFunction(patternStringFunction, replacementStringFunction);
  }

  /** A main method for testing name matching and replacement. */
  public static void main(String[] args) {
    try {
      System.out.println("Regular expression [" + args[0] + "]");

      WildcardManager wildcardManager = new WildcardManager();

      NameParser stringParser = new NameParser(wildcardManager);

      StringFunctionParser stringFunctionParser =
          new SingleFunctionParser(stringParser, wildcardManager);

      StringFunction function = stringFunctionParser.parse(args[0]);

      for (int index = 1; index < args.length; index++) {
        String string = args[index];
        System.out.print("String              [" + string + "]");
        System.out.println(" -> transformed = " + function.transform(args[index]));
      }
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}