At 2024-02-19T22:12:53-0500, Douglas McIlroy wrote: > > The question is whether or not man macros can be expanded > > to their groff equivalents. > > If you'd consider a preprocessor based on groff, there's a > notionally simple way to get a copy of the input with macros > and strings expanded: Provide a groff option that has the > side effect of sending post-expansion input to a file, but > otherwise behaves exactly like groff. > > This scheme may have trouble with diversions and groff-only > requests. However some of the latter may be approximated > by appropriate macro definitions.
This sounds to me approximately as hard what I mused about in response to Alex in the first place. By the time the formatter is done processing an input line, what it has to work with is a series of "nodes". These are each converted to one or more device-independent output commands. At this point what we have doesn't look much like *roff anymore. One of my introspectability notions is to add yet another debugging request (I've added a few other less ambitious ones lately).[1] The name I have in mind for it is `pout`, for `print (to stderr) the pending output`. To do this usefully will require adding a self-describing member function to every node class in the formatter, and there are a few dozen. That's the main reason I haven't done it yet. But once I've done it, I can implement what I have in mind for expanded function of the `pm` request, such that it will dump you the contents of a macro, string, or diversion named in its argument. Since a diversion can contain nodes, the work done above will be useful. Straw man follows. .ds s1 \" empty .ds s2 foobar .de xx .sp 1 .ft B .. .box dd .ft B blah .ft .br .box .pm s1 .pm s2 foobar .pm xx .sp 1 newline .ft B newline .pm dd node glyph character="f" font=3 node glyph character="o" font=3 node glyph character="o" font=3 node glyph character="b" font=3 node glyph character="a" font=3 node glyph character="r" font=3 node break I have some confidence in my expectations for string and macro dumping, but my ideas about dumped diversions are pretty inchoate. As far as I know, no *roff has ever documented this aspect of its implementation-- not in detail, at any rate. I reckon `pout` output would look similar to that for `pm` of a diversion. To tie this in with other recent discussions (and commits), dumping a diversion or the pending output could also show things like this. node device-control content="ps:exec [/Dest /pdf:bm1 /Title (Attack...) /Level 1 /OUT pdfmark" As one might infer from the syntax I'm proposing on the back of this napkin, I would like this output to be relatively easy to split into words and parse. Regards, Branden [1] NEWS: o A new request, `pcolor`, reports to the standard error stream the current list of defined colors. (A device's default stroke and/or fill colors, "default", are not listed since they are immutable and their details unknown to the formatter.) o A new request, `pcomposite`, reports to the standard error stream the current list of defined composite characters. o A new request, `phw`, reports to the standard error stream the current list of hyphenation exceptions.
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