[antlr-interest] Re: SQL grammar tree construction problem

[Joshua Davis]

My example is even simpler.  It's *supposed* to generate a node for 
every rule if the buildAST is set to true isn't it?  I was under the 
impression that explicitly creating nodes is not necessary if 
buildAST is enabled.

--- In antlr-interest at yahoogroups.com, Gustav Boström <i93gusbo at h...> 
wrote:
> Hi!
> 
> Thanks for the help!
> 
> I think I'm trying the same thing as you, but also without luck.
> I try to do:
> sql_stmt : 
> 	  sql_data_stmt  { #sql_stmt = #([SQL_STMT,"sql_stmt"], 
> #sql_stmt); }
> 
> , but I never find this node in the tree. The code seems to be 
> generated, but has no effect. Could it be that no root node is ever 
> created?
> 
> I also tried this:
> sql_script : 
> 	 (sql_stmt)? { #sql_script = #
> ([Token.MIN_USER_TYPE,"sql_script"], #sql_script); } ( SEMICOLON 
> (sql_stmt)? )*
> 
> "sql_script" is the first rule and now a node is in fact created, 
but 
> it has no children. I thought that all the subsequent nodes would 
be 
> added as children automatically.
> 
> Qoute from doc:
> "Setting the return tree is very useful in combination with normal 
> tree construction because you can have ANTLR do all the work of 
> building a tree and then add an imaginary root node such as: 
>   
> decl : ( TYPE ID )+
>        { #decl = #([DECL,"decl"], #decl); }
>      ;
> ANTLR allows you to assign to #rule anywhere within an alternative 
of 
> the rule. ANTLR ensures that references of and assignments to #rule 
> within an action force the parser's internal AST construction 
> variables into a stable state. After you assign to #rule, the state 
> of the parser's automatic AST construction variables will be set as 
> if ANTLR had generated the tree rooted at #rule. For example, any 
> children nodes added after the action will be added to the children 
> of #rule." 
>  
> This is exactly what I want, but I must be doing something wrong.
> 
> 
> 
> /Gustav
> 
> 
> 
> --- In antlr-interest at yahoogroups.com, "Joshua Davis" 
> <joshua.davis at k...> wrote:
> > ANTLR newbie question:
> > 
> > I've been having a similar problem I think.  I made a very simple 
> > grammar based on L. V.'s grammar.   It seems to be always 
producing 
> > only one root node, with no children.  What steps should I take 
to 
> > debug this?  I have tried adding actions to the rules, and it 
looks 
> > like the rules are being triggered correctly, but no AST is 
> produced.
> > 
> > --- In antlr-interest at yahoogroups.com, "lgcraymer" <lgc at m...> 
wrote:
> > > Gustav--
> > > 
> > > You cannot make a rule a root--that's what ANTLR is complaining 
> > about. 
> > >  Rules may represent subtrees, so only nodes with token ids 
(TEXT 
> > or 
> > > STRING, for example) can be followed with ^.
> > > 
> > > --Loring
> > > 
> > > 
> > > --- In antlr-interest at yahoogroups.com, Gustav Boström 
> > <i93gusbo at h...> 
> > > wrote:
> > > > Hello!
> > > > 
> > > > I'm trying to use Lubos Vnuk's (Thanks for doing all the 
work!) 
> > SQL-
> > > > grammar in order to do some 
> > > > processing on SQL-statments. I would for example like to find 
> out 
> > > > which columns are affected by a DML-statement and which 
> > parameters 
> > > > correspond to which columns.
> > > > 
> > > > I'm doing this is in Java , so I've changed the grammar 
> slightly.
> > > > I've removed the C++ actions or replaced them with Java 
> versions.
> > > > 
> > > > My thought was to add AST-construction and then navigate the 
> tree 
> > to 
> > > > find out the stuff I need. This is where I run into problems.
> > > > I tried to annotate the rules with ^ to construct my tree, 
but 
> it 
> > > > keeps giving me "unexpected token:^" when I try to dothis for 
> > > example:
> > > > sql_stmt : 
> > > > 	  sql_data_stmt^ 
> > > > ;
> > > > 
> > > > I've set the options to buildAST=true;
> > > > I'm using version 2.7.2.
> > > > 
> > > > Any ideas on what can be wrong?
> > > > 
> > > > Cheers,
> > > > 
> > > > Gustav Boström


 

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