[il-antlr-interest: 21572] Re: [antlr-interest] Parsing with a character that represents null

[Jim Idle]

Priolo, Scott wrote: Hello,   I’m writing a grammar based on Apache Tomcat’s Access Log format.  I’m able to parse these lines into host, timestamp, command, protocol, response, bytes, etc…   A problem occurs when the log file uses a ‘-‘ for “no data”.  I’d like to capture this as a “null” field when I walk the tree so it’s important not to treat ‘-‘ as white space.  The issue I’m having is ‘-‘ can match any of the patterns such as host, username, timestamp, bytes, etc….  When I try to use   field : HOST L_USER A_USER TIMESTAMP ‘”’ COMMAND PATH PROTOCOL ‘”’ RESPONSE_CODE BYTES;   L_USER : ‘-‘ | (‘a’..’z’|’A’..’Z’)+; BYTES : ‘-‘ | (‘0’..’9’)+;   The parser can’t distinguish if the ‘-‘ is L_USER or BYTES (see below that the second test line has a ‘-‘ for the last number because there was no data.   Actual data line 66.249.71.45 - - [25/Jan/2009:00:00:56 -0500] "GET /abc/slides/180001.1.jsp HTTP/1.1" 200 11785 67.68.5.63 - - [10/Nov/2008:16:26:12 -0500] "HEAD /abc/res/prev1.gif HTTP/1.0" 200 -   How do I manage these ‘-‘ without changing the logging pattern?   Thanks! Don't do this at the lexer level, do it at the parser: field: HOST l_user .... l_user : L_USER | DEFAULT; L_USER ('a'..'z'|'A'..'Z')+; DEFAULT: '-'; Jim --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to il-antlr-interest@googlegroups.com To unsubscribe from this group, send email to il-antlr-interest+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en -~----------~----~----~----~------~----~------~--~---

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