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