[antlr-interest] Trying to resolve mutual left-recursion

[向秦贤]

I try it:)
At first let me rewrite by math-like style
query=join | noj    1)
noj = nojterm | query others 2)
let we replace noj of 1) by use 2), so get
query = join | (nojterm | query others)    3)
so (soooorry for my english), get
query = join | nojterm | query others 4)
query = join | nojterm | (join | nojterm | query others) others 4)
and so concludise join and nojterm times, maybe like
query = (join | nojterm)+ others
:)
Could you give some grammar target details?

2007/9/27, Jeremy Sheldon <Jeremy.Sheldon at 90degreesoftware.com>:
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> Hi everyone,
>
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> I'm new to Antlr and have come up against mutual left-recursion for the
> first time.  Despite doing some googling, I'm still struggling to try and
> remove it.  Would anyone be kind enough to give me some pointers?
>
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> Here are the culprits:
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> query_expression
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>                 : joined_table
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>                 |  non_join_query_expression;
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> non_join_query_expression
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>                 :  non_join_query_term
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>                 |  query_expression (UNION ALL | EXCEPT ALL)?
> corresponding_spec? query_term;
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> Thanks in advance for your help,
>
> Jeremy


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