Manpages - ctags-lang-r.7

ctags-lang-r - Random notes about tagging R source code with Universal Ctags

  ctags ... --languages=+R ...
  ctags ... --language-force=R ...
  ctags ... --map-Python=+.r ...

This man page gathers random notes about tagging R source code with Universal Ctags.

If a variable gets a value returned from a well-known constructor and the variable appears for the first time in the current input file, the R parser makes a tag for the variable and attaches a kind associated with the constructor to the tag regardless of whether the variable appears in the top-level context or a function.

Well-known constructor and kind mapping

#+begin_quote

_
Constructor	kind
_
function()	function
_
c()	vector
_
list()	list
_
data.frame()	dataframe
_

#+end_quote

If a variable doesn’t get a value returned from one of well-known constructors, the R parser attaches globalVar or functionVar kind to the tag for the variable depending on the context.

Here is an example demonstrating the usage of the kinds:

“input.r”

#+begin_quote

      G <- 1
      v <- c(1, 2)
      l <- list(3, 4)
      d <- data.frame(n = v)
      f <- function(a) {
              g <- function (b) a + b
              w <- c(1, 2)
              m <- list (3, 4)
              e <- data.frame(n = w)
              L <- 2
      }

#+end_quote

“output.tags” with “–options=NONE –sort=no –fields=+KZ -o - input.r”

#+begin_quote

      G       input.r /^G <- 1$/;"    globalVar
      v       input.r /^v <- c(1, 2)$/;"      vector
      l       input.r /^l <- list(3, 4)$/;"   list
      d       input.r /^d <- data.frame(n = v)$/;"    dataframe
      n       input.r /^d <- data.frame(n = v)$/;"    nameattr        scope:dataframe:d
      f       input.r /^f <- function(a) {$/;"        function
      g       input.r /^      g <- function (b) a + b$/;"     function        scope:function:f
      w       input.r /^      w <- c(1, 2)$/;"        vector  scope:function:f
      m       input.r /^      m <- list (3, 4)$/;"    list    scope:function:f
      e       input.r /^      e <- data.frame(n = w)$/;"      dataframe       scope:function:f
      n       input.r /^      e <- data.frame(n = w)$/;"      nameattr        scope:dataframe:f.e
      L       input.r /^      L <- 2$/;"      functionVar     scope:function:f

#+end_quote

ctags(1)