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DIR:/usr/share/doc/pinfo-0.6.10/
Current File : //usr/share/doc/pinfo-0.6.10/TECHSTUFF
How does this program work. (for hackers ;)

1. Info file format

Info files always contain a tag_table, which contains offsets to all nodes.
If the info is splitted up into several subinfo files, there is a indirect
table, which indicates, which offsets are in which file. Every node starts
from an INFO_TAG, and ends at the EOF, or at another INFO_TAG.

Menus are recognized as lines of format 

*Tag Table Node Name::comment

and also as

* comment: [spaces] Tag Table Node Name.

Notes are recognized as lines of format

blabla*note Tag Table Node Name::blabla

and also as

blabla*note comment: [spaces] Tag Table Node Name.

Notes may be split up across lines.

The offsets in tag_table in an indirect split are counted as follows:

tag_table_offset-indirect_offset+tag_table[1]_offset

In nonindirect splits it's normal.

2. How are man pages handled?

All of this is handled in manual.c. It is called man program there to
produce output, which is then parsed by pinfo.

3. A scheme of working when viewing info

a) opening file (pinfo.c, filehandling_functions.c)
b) seeking to the indirect table, and reading it
	- important function here is read_item, which reads an info
	  node; that is a block of text starting with INFOTAG, and ending
	  with it, or with another INFOTAG
c) doing the same for tag_table
d) running 'work' function (mainfunction.c), which handles keyboard actions
	- when this function is called, before it gets to the main loop,
	  it sets up some standard variables, like position in viewed node,
 	  position of selected line with node (it is line oriented selection
	  here).
		* it handles also here situations like 'aftersearch',
		  where the function recognizes, that it's called after
		  a search across infofiles, and that it must set the
		  position to a value determined by previous search
		* besides aftersearch it must also handle the history
		  -backward move; it uses then the npos and ncursor vars.
		* it also initializes caches for isnote and ismenu functions
		  which check if given line contains a menu or note.
	- after that there follows a normal loop with quite clear cases.
e) from the 'work' function there is called a function showscreen, which
   paints the screen (in quite simple way).

The scheme of work when viewing manual is quite similar.

4. Additional notes
- the regexp search via all info files is probably one of the most
  complicated functions
For regexp search I've adapted a procedure from midnight commander, and
put it into the file regexp_search.c

For list of global variables, see datatypes.h

For list of global vars for the manual code, see manual.c