Import support about packcc

[arithy]

PackCC does not have a functionality like "import".
Thanks for the suggestion.

I understand its usability, but currently I'm reluctant to realize it since it brings some complexity in PackCC's simpleness.
Let me only add this issue to the want list for the time being.
If there are strong requests by several users, I'll begin to implement it.

[dolik-rce]

I believe import functionality should be quite easily implemented by custom PCC_GETCHAR. It would just have to check if the next few characers is an import statement and start to read another file. At the same time, it would have to keep track of the "stack" in *auxil structure, so it knows to which file to return when the current one is parsed.

I don't think support for this should be directly in PackCC, as it only works with stream of characters. It doesn't know anything about files. At best, there could be some function to help with the stack keeping and/or some examples how to implement this.

[ccleve]

@dolik-rce This isn't a suggestion to import data being parsed. It's a suggestion to import specs into the parser itself while the parser is being generated. For example, imagine that we're parsing a query language that must handle standard keywords like AND, OR, and NOT, but must also have special handling for different languages like French or Arabic. In that case it would be really helpful to create a separate .peg file for every language, but then import a standard, common .peg file that recognizes keywords. It would save a lot of copying and pasting.

[dolik-rce]

@ccleve Oh, I see. My bad, I guess I wasn't paying enough attention when I read the issue 🙄