NAME

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

SYNOPSIS

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

DESCRIPTION

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

KINDS

       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

                                        ┌─────────────┬───────────┐
                                        │Constructor  │ kind      │
                                        ├─────────────┼───────────┤
                                        │function()   │ function  │
                                        ├─────────────┼───────────┤
                                        │c()          │ vector    │
                                        ├─────────────┼───────────┤
                                        │list()       │ list      │
                                        ├─────────────┼───────────┤
                                        │data.frame() │ dataframe │
                                        └─────────────┴───────────┘

       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"

          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
          }

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

          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

SEE ALSO

       ctags(1)