Starting at the given offset, the matcher chooses a character close to this offset. The matcher then searches for the matching peer character of the chosen character and if it finds one, returns the minimal region of the document that contains both characters.
Since version 3.8 the recommended way for finding matching peers is to use {@link org.eclipse.jface.text.source.ICharacterPairMatcherExtension#match(IDocument,int,int)}.
@param document the document to work on
@param offset the start offset
@return the minimal region containing the peer characters or
null
if there is nopeer character.