Re: Reclaiming dynamic memory if parse fails?

<carsonbj@gmail.com> wrote
> I'm using lex and yacc for parsing a configuration file that builds
> a dynamically allocated tree structure for runtime searching as user
> requests come in. When a parse fails, in the middle of the
> configuration file, and the tree is partially built, how can I
> reclaim all of the dynamic memory gracefully? The tree is built
> from the bottom up, the references to the pointers of the tree are
> passed between each of the grammar rules using the $$ = (some
> pointer) scheme, finally the root of the tree is set at the start
> symbol.


<snip globals idea>


The newer versions of Bison have this already. In your grammar
definition file you can specify %destructor definitions for each of
your grammar symbols. These will be called if there is a failure
during parsing for each symbol which has been created when the parser
is clearing up it's internal stack.


Here is a link to the relevant manual section:
http://www.gnu.org/software/bison/manual/html_mono/bison.html#Destructor-Decl


HTH
Mark

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