/*
    * 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
    *
    *      https://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.commons.lang3;
  
  import java.util.concurrent.ThreadLocalRandom;
  import java.util.concurrent.TimeUnit;
  
  import org.openjdk.jmh.annotations.Benchmark;
  import org.openjdk.jmh.annotations.BenchmarkMode;
  import org.openjdk.jmh.annotations.Level;
  import org.openjdk.jmh.annotations.Mode;
  import org.openjdk.jmh.annotations.OutputTimeUnit;
  import org.openjdk.jmh.annotations.Param;
  import org.openjdk.jmh.annotations.Scope;
  import org.openjdk.jmh.annotations.Setup;
  import org.openjdk.jmh.annotations.State;
  
  @BenchmarkMode(Mode.AverageTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  @State(Scope.Thread)
  public class StringUtilsGetDigitsBenchmark {
  
      public static String getDigitsManually(final String str) {
          if (StringUtils.isEmpty(str)) {
              return str;
          }
          final int len = str.length();
          final char[] buffer = new char[len];
          int count = 0;
          for (int i = 0; i < len; i++) {
              final char tempChar = str.charAt(i);
              if (Character.isDigit(tempChar)) {
                  buffer[count++] = tempChar;
              }
          }
          return new String(buffer, 0, count);
      }
      public static String getDigitsWithBuilder(final String str) {
          if (StringUtils.isEmpty(str)) {
              return str;
          }
          final int sz = str.length();
          final StringBuilder strDigits = new StringBuilder(sz);
          for (int i = 0; i < sz; i++) {
              final char tempChar = str.charAt(i);
              if (Character.isDigit(tempChar)) {
                  strDigits.append(tempChar);
              }
          }
          return strDigits.toString();
      }
  
      @Param({ "10", "100", "1000", "10000" })
      public int length;
  
      private String testStr;
  
      @Setup(Level.Invocation)
      public void setup() {
          final StringBuilder sb = new StringBuilder(length);
          for (int i = 0; i < length; i++) {
              final int code = ThreadLocalRandom.current().nextInt(33, 127);
              sb.append((char) code);
          }
          testStr = sb.toString();
      }
  
      @Benchmark
      public String testGetDigitsManually() {
          return getDigitsManually(testStr);
      }
  
      @Benchmark
      public String testGetDigitsWithBuilder() {
          return getDigitsWithBuilder(testStr);
      }
  }