[antlr-interest] Interesting Problem

Hensley, Richard richard.hensley at mckesson.com
Thu Sep 12 13:16:17 PDT 2002

I have an interesting parsing problem. I want dig certain context free
constructs out of a file, while ignoring all the other constructs in the
file. My specific case is that I have a file with a bunch of SQL in it,
but all I really care about are the create table statements. The create
table statements I'm concerned with can be parsed with the following

    :   "create" (ID)* "table" ID LPAREN columns RPAREN 
    :   column (COMMA column)* 
    :   name datatype (ID)* 
    :   (   "varchar" (size)* 
        |   "varchar2" (size)* 
        |   "number" (size)* 
        |   "date" 
        |   "integer" 
        |   "long" ("raw")* 

To solve this problem, I'm thinking of using token stream filters, but I
can't look ahead in a token stream filter so that I could recognize when
I'm in a create table statement.

My basic design would be to use a filter that turns on output of tokens
when in a create table statement, and the parser grammar would have a
semantic rule that would turn off token output when the create table
statement has been fully recognized.

Does anybody have any experience with such a thing? 

Richard Hensley 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.antlr.org/pipermail/antlr-interest/attachments/20020912/0d7bfcf9/attachment.html

More information about the antlr-interest mailing list