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How to resolve terminal conflict [message #1806143]

Fri, 03 May 2019 14:39

Balz Guenat

Messages: 23
Registered: January 2018

Junior Member

My DSL extends from Xbase, which uses the '|' token for named lambda parameters.

In my DSL, I want to parse input such as

|foo|   |123|anything could be here~

that is, table columns with more-or-less-arbitrary content, separated by bars '|' and terminated by a tilde '~'.

The terminal rule for this input currently looks like this:

terminal LINE:
  '|' !('|' | '~') (!'~')* '~';

This shadows the '|' terminal used in the aforementioned Xbase definition, which means that lambda parameters renaming doesn't work anymore.

Since such input doesn't appear in the same context as lambdas, I considered rewriting the terminal rule as a data type rule. Something like

Line:
  '|' LINE_CONTENT '~';
terminal LINE_CONTENT:
  !('|' | '~') (!'~')*;

The problem here of course is, that now LINE_CONTENT shadows basically everything! No good at all.

Is there a way to write my grammar so it parses both these inputs as well as the Xbase lambdas?

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