Syntax Clusters, Including Syntax Files, and Synchronization in Vim

elements: numbers and identifiers. You define them like this: > :syntax match xFor /^for.*/ contains=xNumber,xIdent :syntax match xIf /^if.*/ contains=xNumber,xIdent :syntax match xWhile /^while.*/ contains=xNumber,xIdent You have to repeat the same "contains=" every time. If you want to add another contained item, you have to add it three times. Syntax clusters simplify these definitions by enabling you to have one cluster stand for several syntax groups. To define a cluster for the two items that the three groups contain, use the following command: > :syntax cluster xState contains=xNumber,xIdent Clusters are used inside other syntax items just like any syntax group. Their names start with @. Thus, you can define the three groups like this: > :syntax match xFor /^for.*/ contains=@xState :syntax match xIf /^if.*/ contains=@xState :syntax match xWhile /^while.*/ contains=@xState You can add new group names to this cluster with the "add" argument: > :syntax cluster xState add=xString You can remove syntax groups from this list as well: > :syntax cluster xState remove=xNumber ============================================================================== *44.9* Including another syntax file The C++ language syntax is a superset of the C language. Because you do not want to write two syntax files, you can have the C++ syntax file read in the one for C by using the following command: > :runtime! syntax/c.vim The ":runtime!" command searches 'runtimepath' for all "syntax/c.vim" files. This makes the C parts of the C++ syntax be defined like for C files. If you have replaced the c.vim syntax file, or added items with an extra file, these will be loaded as well. After loading the C syntax items the specific C++ items can be defined. For example, add keywords that are not used in C: > :syntax keyword cppStatement new delete this friend using This works just like in any other syntax file. Now consider the Perl language. A Perl script consists of two distinct parts: a documentation section in POD format, and a program written in Perl itself. The POD section starts with "=head" and ends with "=cut". You want to define the POD syntax in one file, and use it from the Perl syntax file. The ":syntax include" command reads in a syntax file and stores the elements it defined in a syntax cluster. For Perl, the statements are as follows: > :syntax include @Pod <sfile>:p:h/pod.vim :syntax region perlPOD start=/^=head/ end=/^=cut/ contains=@Pod When "=head" is found in a Perl file, the perlPOD region starts. In this region the @Pod cluster is contained. All the items defined as top-level items in the pod.vim syntax files will match here. When "=cut" is found, the region ends and we go back to the items defined in the Perl file. The ":syntax include" command is clever enough to ignore a ":syntax clear" command in the included file. And an argument such as "contains=ALL" will only contain items defined in the included file, not in the file that includes it. The "<sfile>:p:h/" part uses the name of the current file (<sfile>), expands it to a full path (:p) and then takes the head (:h). This results in the directory name of the file. This causes the pod.vim file in the same directory to be included. ============================================================================== *44.10* Synchronizing Compilers have it easy. They start at the beginning of a file and parse it straight through. Vim does not have it so easy. It must start in the middle, where the editing is being done. So how does it tell where it is? The secret is the ":syntax sync" command. This tells Vim how to figure out where it is. For example, the following command tells Vim to scan backward for the beginning or end of a C-style comment and begin syntax coloring from there: > :syntax sync ccomment You can tune this processing with some arguments. The "minlines" argument tells Vim the minimum number of lines to

This section discusses advanced syntax management in Vim. It details how to use syntax clusters to group syntax items for reusability, and how to add or remove items from these clusters. It explains how to include another syntax file using ':runtime!' for languages like C++ that extend others (like C), and ':syntax include' for incorporating syntax from separate files, demonstrated with Perl and POD. Finally, it touches on synchronization with ':syntax sync', enabling Vim to start syntax highlighting from arbitrary points in a file.