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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.List;

/**
 * This {@link StringParser} can create {@link StringMatcher} instances for regular expressions. The
 * regular expressions are either presented as a list, or they are interpreted as comma-separated
 * lists, optionally prefixed with '!' negators. If an entry with a negator matches, a negative
 * match is returned, without considering any subsequent entries in the list. The creation of {@link
 * StringMatcher} instances for the entries is delegated to the given {@link StringParser}.
 *
 * For example, "*.xml,*.jpg" matches all strings with the given extensions; "!dummy" matches all
 * strings except "dummy"; "!dummy.xml,*.xml" matches all strings with .xml, except "dummy.xml";
 * "special.xml,!*.xml" matches "special.xml" and all other non-.xml strings.
 *
 * @author Eric Lafortune
 */
public class ListParser implements StringParser {
  private final StringParser stringParser;

  /**
   * Creates a new ListParser that parses individual elements in the comma-separated list with the
   * given StringParser.
   */
  public ListParser(StringParser stringParser) {
    this.stringParser = stringParser;
  }

  // Implementations for StringParser.

  public StringMatcher parse(String regularExpression) {
    // Split the regular expression to a list and parse it.
    return parse(ListUtil.commaSeparatedList(regularExpression));
  }

  /**
   * Creates a StringMatcher for the given regular expression, which can be a list of optionally
   * negated simple entries.
   *
   * An empty list results in a StringMatcher that matches any string.
   */
  public StringMatcher parse(List regularExpressions) {
    StringMatcher listMatcher = null;

    // Loop over all simple regular expressions, backward, creating a
    // linked list of matchers.
    for (int index = regularExpressions.size() - 1; index >= 0; ) {
      String regularExpression = (String) regularExpressions.get(index);

      boolean isNegated = isNegated(regularExpression);

      // Group similar expressions (all negated or all not negated) in
      // an array and an OrMatcher, to reduce the length of the linked
      // list and the resulting recursion depth when using the matchers
      // later on.
      int lastNegatedIndex = lastNegatedIndex(regularExpressions, index, isNegated);

      StringMatcher[] stringMatchers = parseEntries(regularExpressions, lastNegatedIndex, index);

      StringMatcher stringMatcher = new OrMatcher(stringMatchers);

      // Account for the negator, if any.
      if (isNegated) {
        stringMatcher = new NotMatcher(stringMatcher);
      }

      // Prepend the string matcher.
      listMatcher =
          listMatcher == null
              ? stringMatcher
              : isNegated
                  ? new AndMatcher(stringMatcher, listMatcher)
                  : new OrMatcher(stringMatcher, listMatcher);

      index -= stringMatchers.length;
    }

    return listMatcher != null ? listMatcher : new ConstantMatcher(true);
  }

  // Small utility methods.

  /** Returns the highest index that is negated or not, as specified. */
  private int lastNegatedIndex(List regularExpressions, int lastIndex, boolean isNegated) {
    for (int index = lastIndex; index > 0; index--) {
      String regularExpression = (String) regularExpressions.get(index - 1);

      if (isNegated(regularExpression) != isNegated) {
        return index;
      }
    }

    return 0;
  }

  /** Creates an array of StringMatcher instances for the specified simple regular expressions. */
  private StringMatcher[] parseEntries(List regularExpressions, int firstIndex, int lastIndex) {
    StringMatcher[] stringMatchers = new StringMatcher[lastIndex - firstIndex + 1];

    for (int index = firstIndex; index <= lastIndex; index++) {
      String regularExpression = (String) regularExpressions.get(index);

      stringMatchers[index - firstIndex] = parseEntry(regularExpression);
    }

    return stringMatchers;
  }

  /** Creates a StringMatcher for the given regular expression, stripping any negator. */
  private StringMatcher parseEntry(String regularExpression) {
    // Strip the negator, if any.
    if (isNegated(regularExpression)) {
      regularExpression = regularExpression.substring(1);
    }

    return stringParser.parse(regularExpression);
  }

  /** Returns whether the given simple regular expression is negated. */
  private boolean isNegated(String regularExpression) {
    return regularExpression.length() > 0 && regularExpression.charAt(0) == '!';
  }

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