Conversion between `my.function`, `my_function`, `myFunction` to find which variant actually exists in the R search path

fun.r

split_dot <- function(x)
  strsplit(x, "\\.")[[1]]

is_dot <- function(x)
  length(split_dot(x)) == 2L

split_underscore <- function(x)
  strsplit(x, "_")[[1]]

is_underscore <- function(x)
  length(split_underscore(x)) == 2L

split_camel <- function(x){
  strsplit(x, "[A-Z]")[[1]]
}

is_camel <- function(x)
  length(split_camel(x)) == 2L

uncamel <- function(x){
  sub("([A-Z])", "_\\L\\1", x, perl=TRUE)
}

camel <- function(x){ #function for camel case
  gsub('\\.(\\w?)', '\\U\\1', x, perl=T)
}

dot <- function(x){
  gsub('_', '\\.', x, perl=T)
}

run_fun <- run.fun <- runFun <- function(fun){
  
  fun_str <- deparse(substitute(fun))
  ofun <- fun.str <- funStr <- fun_str
  
  # test the input type
  if(is_underscore(fun_str)){
    fun.str <- dot(fun_str)
    funStr <- camel(fun.str)
  }
  if(is_camel(fun_str)){
    funStr <- fun_str
    fun_str <- uncamel(funStr)
    fun.str <- dot(fun_str)
  }
  if(is_dot(fun_str)){
    fun.str <- fun_str
    funStr <- camel(fun.str)
    fun_str <- uncamel(funStr)
  }

  if(fun_str == "run_fun")
    message("there's indeed no limit to the fun we can have")

  possibilities <- c(fun_str, funStr, fun.str)
  # message(possibilities)
  test <- FALSE
  for( testfun_str in possibilities){
    test <- exists(testfun_str) && is.function(get(testfun_str))
  if(test){
    print(testfun_str)
    return(get(testfun_str))
   }
  }
  message(ofun, " wasn't found, nor any of its variants")
  return(NULL)
}