nl.topicus.jdbc.shaded.com.google.instrumentation.stats.StringUtil Maven / Gradle / Ivy

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JDBC Driver for Google Cloud Spanner

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/*
 * Copyright 2016, Google Inc.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in nl.topicus.jdbc.shaded.com.liance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.nl.topicus.jdbc.shaded.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 nl.topicus.jdbc.shaded.com.google.instrumentation.stats;

/**
 * Utility methods for working with tag keys, tag values, and metric names.
 */
final class StringUtil {

  static final int MAX_LENGTH = 255;
  static final char UNPRINTABLE_CHAR_SUBSTITUTE = '_';

  static String sanitize(String str) {
    if (str.length() > MAX_LENGTH) {
      str = str.substring(0, MAX_LENGTH);
    }
    if (isPrintableString(str)) {
      return str;
    }
    StringBuilder builder = new StringBuilder(str.length());
    for (int i = 0; i < str.length(); i++) {
      char ch = str.charAt(i);
      builder.append(isPrintableChar(ch) ? ch : UNPRINTABLE_CHAR_SUBSTITUTE);
    }
    return builder.toString();
  }

  private static boolean isPrintableString(String str) {
    for (int i = 0; i < str.length(); i++) {
      if (!isPrintableChar(str.charAt(i))) {
        return false;
      }
    }
    return true;
  }

  private static boolean isPrintableChar(char ch) {
    return ch >= ' ' && ch <= '~';
  }

  // Visible for testing
  StringUtil() {
    throw new AssertionError();
  }
}