Hi--

I'm working on a grammar to parse SQL, and here's some of what I've so far... 

my $grammar = q {
    
    select          : /SELECT/i select_list /FROM/i table_source

    
    select_list     : column(s /,/)
                      
    
    column          : identifier /=/ col_name
                    | col_name /AS/i alias
                    | col_name alias(?)
                    | string
                    | number
    
    
    table_source    : table alias(?) with_hint(?) table_join(s?)
                    | table alias(?) table_join(s)
                    | table alias(?) /,/ table_list
                    | table alias(?)

yada...yada...

[download]

And something simple to parse: 

select colA, colB, colC from customer x

[download]

The problem I'm having is that when RecDescent gets to colC, it matches "from" as an **alias** instead of being a token on the **start** production. ColA and ColB work fine, as the comma effective terminates a column. If I add a column alias to ColC, everything works fine. So it seems that "from" is sent down to select_list->column and matching there...and not where I had intended.

Any ideas as to how I can fix this? Do I explicitly look for "col_name /from/i" in the column production and then reject it if it matches (and if so what would that syntax be?), or should my grammar structured differently?

Let me know if you want the entire script and not just the snippet I've posted.

Thanks!

In reply to Parse::RecDescent greedy matches by zuma53

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