Re: [Fwd: question about error handling]

[Tim Van Holder]

On Fri, 2002-10-04 at 14:33, Latha G wrote:
> Hi,
>    I am also struggling with the same problem as Ashish. I had gone through 
> the set of responses for this problem. But still I have not got the 
> solution. Could anybody help me to solve the memory leak problem in C?

> ------- Original Message --------
> Subject: question about error handling
> Date: Thu, 07 Jun 2001 11:12:34 -0400
> From: ashish sehgal <<EMAIL: PROTECTED>>
> To: <EMAIL: PROTECTED>
> 
> HI,
> 
> I have the following question about bison:--
> 
> When the bison generated parser encounters an error in the input
> expression and there is no error recovery grammar then the forrest of
> linked up structures that may have been created as part of parsing need to 
> be cleaned up else every wrong input stream causes this memory to be 
> allocated and not get deleted at all when the parser is working as part of 
> another thread.
> 
> Is there some standard functionality available to do some cleanup
> associated with the values associated with bison's internal stack ?? for 
> instance something that lets you iterate over all the values in the stack 
> and delete them.
> 
> thanks for the help


One common way (not built into bison though), is to keep all nodes of a
parse tree in a list of 'dangling' nodes until they have been assigned a
parent.  This fits in nicely with the bottom-up tree construction that
is natural for a bison-generated grammar.
After a parse, you can then clean up that list to get rid of structures
that were 'killed' by a (recovered) parse error.