The principle of Vimscript segment movement

If you haven't used Vim's ]] segment [] move commands [[ , . ][ Also read by the :help section

Still don't understand? I t's not a problem, it's the same when I first read this. Before we write the code, let's go and learn how these movements work, and then in the next chapter we'll make our Potion plug-ins support them.

Nroff file

The four "segment move" commands, as they literally mean, can be used to move between "segments" of a file.

These commands are designed by default for the nroff file. Nroff is similar to LaTex or Markdown -- it's used to write tag text (and eventually generates a UNIX man page).

Nroff files use a set of "macros" to define "segment headers." For example, here's awk man page:

.SH NAME                                                     ***
awk \- pattern-directed scanning and processing language
.SH SYNOPSIS                                                 ***
.B awk
[
.BI \-F
.I fs
]
[
.BI \-v
.I var=value
]
[
.I 'prog'
|
.BI \-f
.I progfile
]
[
.I file ...
]
.SH DESCRIPTION                                              ***
.I Awk
scans each input
.I file
for lines that match ...

To .SH the beginning of the SH is the segment header. *** out with a . . . The four-segment move command moves your cursor between the first lines of the segment.

Vim . And nroff's segment header starts with any line as a segment header, even if you're not editing the nroff file!

You can sections to change the segment header, but Vim still needs to have a point at the beginning of the line, and the segment header must be a pair of characters, so this change to the Potion file won't be flexible enough.

Brackets

The segment move command also sees another thing: an open or closed brace { ) } the first character of the line.

[[ and ]] open brackets, ][ and view closed parentheses. []

This extra "behavior" allows you to easily move between segments of the C-style language. However, these rules still don't take into account the type of file you're editing!

Add the following to a buffer:

Test           A B
Test

.SH Hello      A B

Test

{              A
Test
}                B

Test

.H World       A B

Test
Test           A B

Now execute :set filetype=basic tell Vim that this is a BASIC file and try the segment move command.

[[ The ]] will move A ][ marked A, and the lines marked B will move between rows marked B []

This tells us that Vim always uses the same two rules to handle segment movements, even if none of them work (as in the case of BASIC)!

Practice

Read :help section and now you should be able to understand segment movement.

Also read by the :help sections