69 lines
2.9 KiB
Plaintext
69 lines
2.9 KiB
Plaintext
# @(#)structures 5.4 (Berkeley) 10/4/95
|
|
|
|
There are three major data structures in this package, plus a single data
|
|
structure per screen type. The first is a single global structure (GS)
|
|
which contains information common to all files and screens. It hold
|
|
global things like the input key queues, and functions as a single place
|
|
to hang things. For example, interrupt routines have to be able to find
|
|
screen structures, and they can only do this if they have a starting
|
|
point. The number of globals in nvi is dependent on the screen type, but
|
|
every screen type will have at least one global, __global_list, which
|
|
references the GS structure.
|
|
|
|
The GS structure contains linked lists of screen (SCR) structures.
|
|
Each SCR structure normally references a file (EXF) structure.
|
|
|
|
The GS structure has a set of functions which update the screen and/or
|
|
return information about the screen from the underlying screen package.
|
|
The GS structure never goes away. The SCR structure persists over
|
|
instances of screens, and the EXF structure persists over references to
|
|
files.
|
|
|
|
File names have different properties than files themselves, so the name
|
|
information for a file is held in an FREF structure which is chained from
|
|
the SCR structure.
|
|
|
|
In general, functions are always passed an SCR structure, which usually
|
|
references an underlying EXF structure. The SCR structure is necessary
|
|
for any routine that wishes to talk to the screen, the EXF structure is
|
|
necessary for any routine that wants to modify the file. The relationship
|
|
between an SCR structure and its underlying EXF structure is not fixed,
|
|
and various ex commands will substitute a new EXF in place of the current
|
|
one, and there's no way to detect this.
|
|
|
|
The naming of the structures is consistent across the program. (Macros
|
|
even depend on it, so don't try and change it!) The global structure is
|
|
"gp", the screen structure is "sp", and the file structure is "ep".
|
|
|
|
A few other data structures:
|
|
|
|
TEXT In nvi/cut.h. This structure describes a portion of a line,
|
|
and is used by the input routines and as the "line" part of a
|
|
cut buffer.
|
|
|
|
CB In nvi/cut.h. A cut buffer. A cut buffer is a place to
|
|
hang a list of TEXT structures.
|
|
|
|
CL The curses screen private data structure. Everything to
|
|
do standalone curses screens.
|
|
|
|
MARK In nvi/mark.h. A cursor position, consisting of a line number
|
|
and a column number.
|
|
|
|
MSG In nvi/msg.h. A chain of messages for the user.
|
|
|
|
SEQ In nvi/seq.h. An abbreviation or a map entry.
|
|
|
|
TK The Tcl/Tk screen private data structure. Everything to
|
|
do standalone Tcl/Tk screens.
|
|
|
|
EXCMD In nvi/ex/ex.h. The structure that gets passed around to the
|
|
functions that implement the ex commands. (The main ex command
|
|
loop (see nvi/ex/ex.c) builds this up and then passes it to the
|
|
ex functions.)
|
|
|
|
VICMD In nvi/vi/vi.h. The structure that gets passed around to the
|
|
functions that implement the vi commands. (The main vi command
|
|
loop (see nvi/vi/vi.c) builds this up and then passes it to the
|
|
vi functions.)
|