[antlr-interest] anybody using dynamic scopes?

[Terence Parr]

I plan on allowing initializers this time. :)
T
On Feb 10, 2010, at 10:07 AM, Iztok Kavkler wrote:

> I use it for error reporting from a compiler: during tree parsing phase 
> I call several functions that may throw CompileError, which needs 
> information about current node's line and column. Since I don't want to 
> pass the current node as a parameter to all of these functions I have 
> created a scope
> 
> scope InfoScope {
>     CommonTree node;
> }
> 
> There is some extra work involved, since I have to say
> 
> scope InfoScope;
> $InfoScope::node = $rule.start;
> 
> at the beginning of every rule.
> 
> Then again, perhaps there is an easier way to do this?
> 
> Iztok
> 
> 
> On 10.2.2010 2:30, Terence Parr wrote:
>> Hi,
>> 
>> Is anybody using scopes?  E.g., here is the use C grammar:
>> 
>> scope Symbols {
>>         Set types; // only track types in order to get parser working
>> }
>> 
>> Every rule that declares its usage of Symbols pushes a new copy on the stack effectively creating a new symbol scope.
>> 
>> translation_unit
>> scope Symbols; // entire file is a scope
>> @init {
>>   $Symbols::types = new HashSet();
>> }
>>     : external_declaration+
>>     ;
>> 
>> 
>> Then rule declaration declares a rule scope that lets any invoked rule see isTypedef boolean.  It's much easier than passing that info down as parameters:
>> 
>> declaration
>> scope {
>>   boolean isTypedef;
>> }
>> @init {
>>   $declaration::isTypedef = false;
>> }
>>     : 'typedef' declaration_specifiers? {$declaration::isTypedef=true;}
>>       init_declarator_list ';' // special case, looking for typedef
>>     | declaration_specifiers init_declarator_list? ';'
>>     ;
>> 
>> 
>> Rule direct_declarator can then easily determine whether the IDENTIFIER
>> should be declared as a type name.
>> 
>> direct_declarator
>>     :   (   IDENTIFIER
>>             {
>>             if ($declaration.size()>0&&$declaration::isTypedef) {
>>                 $Symbols::types.add($IDENTIFIER.text);
>>                 System.out.println("define type "+$IDENTIFIER.text);
>>             }
>>             }
>>         |   '(' declarator ')'
>>         )
>>         declarator_suffix*
>>     ;
>> 
>> Trying to decide if it's worth reimplementing for v4.
>> 
>> Ter
>> 
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