content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you 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 org.apache.calcite.util;
  
  import org.apache.calcite.linq4j.Enumerator;
  import org.apache.calcite.linq4j.Linq4j;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.AbstractSet;
  import java.util.Iterator;
  import java.util.Set;
  
  import static java.lang.Integer.parseInt;
  
  /**
   * A set of non-negative integers defined by a sequence of points, intervals,
   * and exclusions.
   */
  public class IntegerIntervalSet extends AbstractSet<Integer> {
    private final String s;
  
    private IntegerIntervalSet(String s) {
      this.s = s;
    }
  
    private static void visit(String s, Handler handler) {
      final String[] split = s.split(",");
      for (String s1 : split) {
        if (s1.isEmpty()) {
          continue;
        }
        boolean exclude = false;
        if (s1.startsWith("-")) {
          s1 = s1.substring(1);
          exclude = true;
        }
        final String[] split1 = s1.split("-");
        if (split1.length == 1) {
          final int n = parseInt(split1[0]);
          handler.range(n, n, exclude);
        } else {
          final int n0 = parseInt(split1[0]);
          final int n1 = parseInt(split1[1]);
          handler.range(n0, n1, exclude);
        }
      }
    }
  
    /**
     * Parses a range of integers expressed as a string. The string can contain
     * non-negative integers separated by commas, ranges (represented by a
     * hyphen between two integers), and exclusions (represented by a preceding
     * hyphen). For example, "1,2,3-20,-7,-10-15,12".
     *
     * <p>Inclusions and exclusions are performed in the order that they are
     * seen. For example, "1-10,-2-9,3-7,-4-6" does contain 3, because it is
     * included by "1-10", excluded by "-2-9" and last included by "3-7". But it
     * does not include 4.
     *
     * @param s Range set
     */
    public static Set<Integer> of(String s) {
      return new IntegerIntervalSet(s);
    }
  
    @SuppressWarnings("NullableProblems")
    @Override public Iterator<Integer> iterator() {
      return Linq4j.enumeratorIterator(enumerator());
    }
  
    @Override public int size() {
      int n = 0;
      Enumerator<Integer> e = enumerator();
      while (e.moveNext()) {
        ++n;
      }
      return n;
    }
  
    private Enumerator<Integer> enumerator() {
      final int[] bounds = {Integer.MAX_VALUE, Integer.MIN_VALUE};
      visit(
          s, (start, end, exclude) -> {
            if (!exclude) {
              bounds[0] = Math.min(bounds[0], start);
              bounds[1] = Math.max(bounds[1], end);
            }
          });
      return new Enumerator<Integer>() {
        int i = bounds[0] - 1;
  
        @Override public Integer current() {
          return i;
        }
  
        @Override public boolean moveNext() {
          for (;;) {
            if (++i > bounds[1]) {
              return false;
            }
            if (contains(i)) {
              return true;
            }
          }
        }
  
        @Override public void reset() {
          i = bounds[0] - 1;
        }
  
        @Override public void close() {
          // no resources
        }
      };
    }
  
    @Override public boolean contains(@Nullable Object o) {
      return o instanceof Number
          && contains(((Number) o).intValue());
    }
  
    public boolean contains(final int n) {
      final boolean[] bs = {false};
      visit(
          s, (start, end, exclude) -> {
            if (start <= n && n <= end) {
              bs[0] = !exclude;
            }
          });
      return bs[0];
    }
  
    /** A callback. */
    private interface Handler {
      void range(int start, int end, boolean exclude);
    }
  }
  