On Wed, 2006-05-24 at 12:02 -0400, Manuel M T Chakravarty wrote:
I think this is still an outstanding issue.
I've got a patch to c2hs to make it do something with C style line pragmas in .chs files, eg:
# 1 "gtk/Graphics/UI/Gtk/TreeList/TreeStore.chs.pp"
Ok, I see how this would be useful. Please push your patch.
Ok, will do.
The only thing that's wrong is that c2hs doesn't recognise cpp directives as the first line in a .chs file. You can see why this is so from the code below:
cpp :: CHSLexer cpp = directive where directive = string "\n#" +> alt ('\t':inlineSet)`star` epsilon `lexmeta` \(_:_:dir) pos s -> -- strip off the "\n#" case dir of
... etc
It's requires a cpp directive to start with a newline followed by a '#' character.
I'm not sufficiently familiar with the style of c2hs's chs lexer to figure out how to fix this. Perhaps it can be done by checking if we're at the beginning of a line in a different way. Perhaps it can be done by checking the current column rather than looking for a '\n' character.
Yes, that's an awkward bit in the code that has bothered me before. The lexer combinators have not neat way to check for characters appearing in a particular column. I see only two ways to proceed:
* We could match on # alone and then check in the action what column we are in and do different things in dependence on this. I don't like this, as it messes up the longest match rule and might be fragile. * We can prepend a '\n' character to the source file before starting the lexing process by changing the triple passed to execLexer in the function lexCHS (and we must then also adjust the initial value of `pos' to still get accurate line numbers). This is a bit of a kludge, but it seems to be the more robust solution to me.
Ok, I'll push my current patch and then we can look at one of these potential solutions. Duncan