Package com.google.common.escape

Class 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 Summary

      Constructors 
      Modifier Constructor Description
      protected CharEscaper()
      Constructor for use by subclasses.

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      protected abstract char[] escape​(char c)
      Returns the escaped form of the given character, or null if this character does not need to be escaped.
      java.lang.String escape​(java.lang.String string)
      Returns the escaped form of a given literal string.
      protected java.lang.String escapeSlow​(java.lang.String s, int index)
      Returns the escaped form of a given literal string, starting at the given index.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • CharEscaper

        protected CharEscaper()
        Constructor for use by subclasses.

    • Method Detail

      • escape

        public java.lang.String escape​(java.lang.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:
        java.lang.NullPointerException - if string is null

      • escape

        @CheckForNull
protected abstract char[] 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 java.lang.String escapeSlow​(java.lang.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:
        java.lang.NullPointerException - if string is null