neovim/runtime/queries/vim/injections.scm

((lua_statement (script (body) @injection.content))
 (#set! injection.language "lua"))

((lua_statement (chunk) @injection.content)
 (#set! injection.language "lua"))

((ruby_statement (script (body) @injection.content))
 (#set! injection.language "ruby"))

((ruby_statement (chunk) @injection.content)
 (#set! injection.language "ruby"))

((python_statement (script (body) @injection.content))
 (#set! injection.language "python"))

((python_statement (chunk) @injection.content)
 (#set! injection.language "python"))

;; If we support perl at some point...
;; ((perl_statement (script (body) @injection.content))
;;  (#set! injection.language "perl"))
;; ((perl_statement (chunk) @injection.content)
;;  (#set! injection.language "perl"))

((autocmd_statement (pattern) @injection.content)
 (#set! injection.language "regex"))

((set_item
   option: (option_name) @_option
   value: (set_value) @injection.content)
  (#any-of? @_option
    "includeexpr" "inex"
    "printexpr" "pexpr"
    "formatexpr" "fex"
    "indentexpr" "inde"
    "foldtext" "fdt"
    "foldexpr" "fde"
    "diffexpr" "dex"
    "patchexpr" "pex"
    "charconvert" "ccv")
  (#set! injection.language "vim"))


; ((comment) @injection.content
;  (#set! injection.language "comment"))

; ((line_continuation_comment) @injection.content
;  (#set! injection.language "comment"))