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62 lines
2.6 KiB
Plaintext
62 lines
2.6 KiB
Plaintext
# @(#)structures 5.2 (Berkeley) 11/1/93
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There are three major data structures in this package. The first is a
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single global structure (named GS) which contains information common to
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all files and screens. It's really pretty tiny, and functions more as a
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single place to hang things than anything else.
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The second and third structures are the file structures (named EXF) and
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the screen structures (named SCR). They contain information theoretically
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unique to a screen or file, respectively. Each SCR structure has a set
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of functions which update the screen and/or return information about the
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screen from the underlying screen package.
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The GS structure contains linked lists SCR structures. The structures
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can also be classed by persistence. The GS structure never goes away
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and the SCR structure persists over instances of 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 and often an EXF
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structure as well. The SCR structure is necessary for any routine that
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wishes to talk to the screen, the EXF structure is necessary for any
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routine that wants to modify the file. The relationship between an SCR
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structure and its underlying EXF structure is not fixed, and although you
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can translate from an SCR to the underlying EXF, it is discouraged. If
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this becomes too onerous, I suspect I'll just stop passing around the EXF
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in the future.
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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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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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EXCMDARG
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In nvi/ex/excmd.h.stub. The structure that gets passed around
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to the functions that implement the ex commands. (The main
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ex command loop (see nvi/ex/ex.c) builds this up and then passes
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it to the ex functions.)
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VICMDARG
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In nvi/vi/vcmd.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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