Parsing for structural editors

We present techniques that enable the construction of an algorithm capable of re-parsing a string after another string has been inserted into it. Let M be the minimal, under certain restrictions, number of changes which must be made to the parse tree to reflect the insertions. Then the algorithm we present should work in no more time than M times a log factor of the height of the parse tree. The grammars we allow include all LR(1) grammars.