Generate R pkg NAMESPACE from roxygen tags, to avoid issue r-lib/roxygen2#372

generate-namespace.R

# Workaround for roxygen2 issue. See:
# https://github.com/klutometis/roxygen/issues/372
# https://stat.ethz.ch/pipermail/r-package-devel/2015q3/000456.html

library(magrittr)
library(stringi)
library(assertive.properties)
library(assertive.code)

r_files <- dir("R", full.names = TRUE)
lines_by_file <- r_files %>% 
  setNames(basename(r_files)) %>% 
  lapply(readLines) 
     
# Search files for lines like "#' @importFrom pkg fn" 
namespace_importFrom <- lines_by_file %>% 
  lapply(
    function(lines)
    {
      importFrom_lines <- lines[stri_detect_regex(lines, "^#' *@importFrom")]
      if(is_empty(importFrom_lines))
      {
        return(character())
      }
      matches <- stri_match_first_regex(
        importFrom_lines, 
        "^#' *@importFrom +([[:alnum:]._]+) +([[:graph:]]+)"
      )
      pkgs <- matches[, 2]
      fns <- matches[, 3]
      # non-standard names like mutators need enquoting
      ok <- is_valid_variable_name(fns)
      fns[!ok] <- shQuote(fns[!ok])
      
      paste0("importFrom(", pkgs, ",", fns, ")")
    }
  )

# Search files for lines like "#' @export", then 
# find the next line that doesn't start "#'", then
# see if that contains "function(", then 
# extract the function name
namespace_export <- lines_by_file %>% 
  lapply(
    function(lines)
    {
      export_indicies <- stri_detect_regex(lines, "^#' *@export") %>% 
        which
      if(is_empty(export_indicies))
      {
        return(character())
      }
      
      not_roxygen_indicies <- stri_detect_regex(lines, "^#'") %>% 
        not %>% 
        which
      
      object_indicies <- vapply(
        export_indicies,
        function(i)
        {
          min(not_roxygen_indicies[not_roxygen_indicies > i])
        },
        integer(1)
      )
      object_lines <- lines[object_indicies]
      function_lines <- object_lines[stri_detect_fixed(object_lines, "function(")]
      matches <- stri_match_first_regex(
        function_lines, 
        " *([[:graph:]]+) *(?:<-|=) *function"
      )
      paste0("export(", matches[, 2], ")")
    }
  )

# Combine importFroms and exports
# TODO: For more general case, should also find whole package imports
namespace <- c(namespace_importFrom, namespace_export) %>% 
  unlist(use.names = FALSE) %>% 
  unique

# Write the NAMESPACE file
writeLines(namespace, "NAMESPACE")