"fromstart" is equivalent to using "minlines" with a very large number.
Second syncing method: *:syn-sync-second* *:syn-sync-ccomment*
For the second method, only the "ccomment" argument needs to be given.
Example: >
:syntax sync ccomment
When Vim finds that the line where displaying starts is inside a C-style
comment, the last region syntax item with the group-name "Comment" will be
used. This requires that there is a region with the group-name "Comment"!
An alternate group name can be specified, for example: >
:syntax sync ccomment javaComment
This means that the last item specified with "syn region javaComment" will be
used for the detected C comment region. This only works properly if that
region does have a start pattern "\/*" and an end pattern "*\/".
The "maxlines" argument can be used to restrict the search to a number of
lines. The "minlines" argument can be used to at least start a number of
lines back (e.g., for when there is some construct that only takes a few
lines, but it hard to sync on).
Note: Syncing on a C comment doesn't work properly when strings are used
that cross a line and contain a "*/". Since letting strings cross a line
is a bad programming habit (many compilers give a warning message), and the
chance of a "*/" appearing inside a comment is very small, this restriction
is hardly ever noticed.
Third syncing method: *:syn-sync-third*
For the third method, only the "minlines={N}" argument needs to be given.
Vim will subtract {N} from the line number and start parsing there. This
means {N} extra lines need to be parsed, which makes this method a bit slower.
Example: >
:syntax sync minlines=50
"lines" is equivalent to "minlines" (used by older versions).
Fourth syncing method: *:syn-sync-fourth*
The idea is to synchronize on the end of a few specific regions, called a
sync pattern. Only regions can cross lines, so when we find the end of some
region, we might be able to know in which syntax item we are. The search
starts in the line just above the one where redrawing starts. From there
the search continues backwards in the file.
This works just like the non-syncing syntax items. You can use contained
matches, nextgroup, etc. But there are a few differences:
- Keywords cannot be used.
- The syntax items with the "sync" keyword form a completely separated group
of syntax items. You can't mix syncing groups and non-syncing groups.
- The matching works backwards in the buffer (line by line), instead of
forwards.
- A line continuation pattern can be given. It is used to decide which group
of lines need to be searched like they were one line. This means that the
search for a match with the specified items starts in the first of the
consecutive lines that contain the continuation pattern.
- When using "nextgroup" or "contains", this only works within one line (or
group of continued lines).
- When using a region, it must start and end in the same line (or group of
continued lines). Otherwise the end is assumed to be at the end of the
line (or group of continued lines).
- When a match with a sync pattern is found, the rest of the line (or group of
continued lines) is searched for another match. The last match is used.
This is used when a line can contain both the start and the end of a region
(e.g., in a C-comment like `/* this */`, the last "*/" is used).
There are two ways how a match with a sync pattern can be used:
1. Parsing for highlighting starts where redrawing starts (and where the
search for the sync pattern started). The syntax group that is expected
to be valid there must be specified. This works well when the regions
that cross lines cannot contain other regions.
2. Parsing for highlighting continues just after the match. The syntax group
that is expected to be present just after the match must be specified.
This can be used when the previous method doesn't work well. It's much
slower, because more text needs to