Re: Interactive parsing with Bison

[Hans Aberg]

On 23 Jun 2006, at 16:20, Satya wrote:

> I am considering the possibility of building a free IDE for Bison

A few years ago, I made plugins (DLL's) of Bison and Flex for a  
commercial IDE (CodeWarrior for MAC OS 9). It was not difficult to  
make these plugins and get them work, but I encountered the following  
problems:

* Bison, at least then, leaked memory, and when run as a DLL, the  
memory was not released, as when run as a program. So, after a couple  
of runs, memory of the IDE (which was fixed for programs under Mac OS  
9) ran out. An IDE would have to cope with this problem - the  
simplest would be to run Bison and Flex not as DLL's, but as programs.

* The IDE was not smart enough to compute the file dependencies, so  
although one could set the .y and .l files to compile before the C/C+ 
+ source code files, the IDE would not recompute file dependencies  
after Bison and Flex had been run, causing the output C/C++ parser/ 
lexer that these produce to not be compiled.

* I wanted to go ahead to put Bison/Flex info into the debugger, but  
then it turned out that the format was proprietary. So finding a  
public such debugging format seems to be an important issue.

> with
> at least the following abilities :
>
> 1. Single step through a test input file and obtain a trace (like the
> one produced by a %debug directive. But now it will break after each
> step and wait for user input)
>
> 2. Alter input before proceeding to the next step.
>
> 3. Set breakpoints in the input and parse until break point is  
> reached.
>
> 4. Watch the stack, current state, look-aheads at each state.

Otherwise, I think that these thing might not be so difficult to  
achieve with an already existing IDE, as it already can do such  
equivalents for ordinary programming language source code. - Though  
one must try, to find out.

  Hans Aberg