Class CharEscaper

java.lang.Object
com.google.common.escape.Escaper
com.google.common.escape.CharEscaper
Direct Known Subclasses:
ArrayBasedCharEscaper
@GwtCompatible public abstract class CharEscaper extends Escaper
An object that converts literal text into a format safe for inclusion in a particular context (such as an XML document). Typically (but not always), the inverse process of "unescaping" the text is performed automatically by the relevant parser.

For example, an XML escaper would convert the literal string "Foo<Bar>" into "Foo&lt;Bar&gt;" to prevent "<Bar>" from being confused with an XML tag. When the resulting XML document is parsed, the parser API will return this text as the original literal string "Foo<Bar>".

A CharEscaper instance is required to be stateless, and safe when used concurrently by multiple threads.

Popular escapers are defined as constants in classes like HtmlEscapers and XmlEscapers. To create your own escapers extend this class and implement the escape(char) method.

Since:
15.0
Author:
Sven Mawson

  • Constructor Details

    • CharEscaper

      protected CharEscaper()
      Constructor for use by subclasses.

  • Method Details

    • escape

      public String escape(String string)
      Returns the escaped form of a given literal string.
      Specified by:
      escape in class Escaper
      Parameters:
      string - the literal string to be escaped
      Returns:
      the escaped form of string
      Throws:
      NullPointerException - if string is null

    • escape

      protected abstract char @Nullable [] escape(char c)
      Returns the escaped form of the given character, or null if this character does not need to be escaped. If an empty array is returned, this effectively strips the input character from the resulting text.

      If the character does not need to be escaped, this method should return null, rather than a one-character array containing the character itself. This enables the escaping algorithm to perform more efficiently.

      An escaper is expected to be able to deal with any char value, so this method should not throw any exceptions.

      Parameters:
      c - the character to escape if necessary
      Returns:
      the replacement characters, or null if no escaping was needed

    • escapeSlow

      protected final String escapeSlow(String s, int index)
      Returns the escaped form of a given literal string, starting at the given index. This method is called by the escape(String) method when it discovers that escaping is required. It is protected to allow subclasses to override the fastpath escaping function to inline their escaping test. See CharEscaperBuilder for an example usage.
      Parameters:
      s - the literal string to be escaped
      index - the index to start escaping from
      Returns:
      the escaped form of string
      Throws:
      NullPointerException - if string is null