How to highlight keywords in a syntax region?

Question

I'm trying to improve the cmake-syntax-highlighting for vim.

I'm unable to have vim highlight a keyword which is inside a text which is already matching a region. I'm talking about variables:

For example CMAKE_SOURCE_DIR is a built-in variable which is listed in a syn keyword cmakeVariable-list.

When accessing values of a variable in cmake you use ${...}. Highlighting this is done with a region:

syn region cmakeVariableValue start=/\${/ end=/}/
        \ contained oneline contains=CONTAINED,cmakeTodo,cmakeVariable

Both highlightings work, except when mixed together. Keywords listed in cmakeVariable are not highlighted specially when being in a ${}-region.

How can I tell vim to apply special highlighting in a region when a keyword is used?

Answer 1

You need to use the contained argument in your keyword definition. Here's a random snippet that works for me:

syntax keyword toBeContained contained foo bar
syntax region fooRegion start="{" end="}" contains=toBeContained

hi toBeContained ctermfg=51 guifg=cyan
hi fooRegion ctermfg=30 guifg=darkcyan

Note: This will make keyword toBeContained not work when it's not in a region that contains it. So you might need to make two definitions, one with contained and one without.

I recommend this great tutorial on creating syntax files, as well as :help :syn-keyword for more information.