* @param cp the Unicode code point to escape
   */
  public static void assertEscaping(UnicodeEscaper escaper, String expected, int cp) {

    String escaped = computeReplacement(escaper, cp);
    Assert.assertNotNull(escaped);
    Assert.assertEquals(expected, escaped);
  }

  /**
   * Asserts that an escaper does not escape the given character.
   *
   * @param escaper the non-null escaper to test

   * @param cp the Unicode code point to escape
   */
  public static void assertEscaping(UnicodeEscaper escaper, String expected, int cp) {

    String escaped = computeReplacement(escaper, cp);
    Assert.assertNotNull(escaped);
    Assert.assertEquals(expected, escaped);
  }

  /**
   * Asserts that an escaper does not escape the given character.
   *
   * @param escaper the non-null escaper to test

  }

  private static final Escaper XML_ESCAPER;
  private static final Escaper XML_CONTENT_ESCAPER;
  private static final Escaper XML_ATTRIBUTE_ESCAPER;

  static {
    Escapers.Builder builder = Escapers.builder();
    // The char values \uFFFE and \uFFFF are explicitly not allowed in XML
    // (Unicode code points above \uFFFF are represented via surrogate pairs
    // which means they are treated as pairs of safe characters).

  /**
   * Returns an {@link Escaper} instance that escapes strings so they can be safely included in <a
   * href="https://url.spec.whatwg.org/#syntax-url-path-segment">URL path segments</a>. The returned
   * escaper escapes all non-ASCII characters, even though <a
   * href="https://url.spec.whatwg.org/#url-code-points">many of these are accepted in modern
   * URLs</a>. (<a href="https://url.spec.whatwg.org/#path-state">If the escaper were to leave these

 * the License.
 */

package com.google.common.html;

import com.google.common.annotations.GwtCompatible;
import com.google.common.escape.Escaper;
import com.google.common.escape.Escapers;

/**
 * {@code Escaper} instances suitable for strings to be included in HTML attribute values and
 * most elements' text contents. When possible, avoid manual escaping by using templating

  /**
   * Returns an {@link Escaper} instance that escapes strings so they can be safely included in <a
   * href="https://url.spec.whatwg.org/#syntax-url-path-segment">URL path segments</a>. The returned
   * escaper escapes all non-ASCII characters, even though <a
   * href="https://url.spec.whatwg.org/#url-code-points">many of these are accepted in modern
   * URLs</a>. (<a href="https://url.spec.whatwg.org/#path-state">If the escaper were to leave these

public abstract class CharEscaper extends Escaper {
  /** Constructor for use by subclasses. */
  protected CharEscaper() {}

  /**
   * Returns the escaped form of a given literal string.
   *
   * @param string the literal string to be escaped
   * @return the escaped form of {@code string}
   * @throws NullPointerException if {@code string} is null
   */
  @Override
  public String escape(String string) {

public abstract class CharEscaper extends Escaper {
  /** Constructor for use by subclasses. */
  protected CharEscaper() {}

  /**
   * Returns the escaped form of a given literal string.
   *
   * @param string the literal string to be escaped
   * @return the escaped form of {@code string}
   * @throws NullPointerException if {@code string} is null
   */
  @Override
  public String escape(String string) {

    assertUnicodeEscaping(e, "%F4%8F%BF%BF", '\uDBFF', '\uDFFF');

    assertEquals("", e.escape(""));
    assertEquals("safestring", e.escape("safestring"));
    assertEquals("embedded%00null", e.escape("embedded\0null"));
    assertEquals("max%EF%BF%BFchar", e.escape("max\uffffchar"));
  }

  // Helper to assert common expected behaviour of uri escapers.
  static void assertBasicUrlEscaper(UnicodeEscaper e) {

    // Test quotes are escaped.
    assertEquals(""test"", xmlAttributeEscaper.escape("\"test\""));
    assertEquals("'test'", xmlAttributeEscaper.escape("\'test'"));
    // Test all escapes
    assertEquals(
        "a&quot;b&lt;c&gt;d&amp;e&quot;f&apos;", xmlAttributeEscaper.escape("a\"b<c>d&e\"f'"));
    // Test '\t', '\n' and '\r' are escaped.