Proof of concept: readme_document format

DESCRIPTION

@@ -27,6 +27,7 @@ Suggests:
     rmarkdown,
     jsonlite,
     MASS,
+    rmarkdown,
     testthat,
     covr,
     pkgload,

NAMESPACE

@@ -21,4 +21,5 @@ export(evaluate_and_highlight)
 export(highlight)
 export(href_article)
 export(href_topic)
+export(readme_document)
 import(rlang)

R/highlight.R

@@ -60,7 +60,7 @@ highlight <- function(text, classes = classes_chroma(), pre_class = NULL) {
 
   paste0(
     "<pre class='", paste0(pre_class, collapse = " "), "'>\n",
-    out, "\n",
+    out,
     "</pre>"
   )
 }

R/metadata.R

@@ -44,6 +44,13 @@ remote_metadata_slow <- function(package) {
       if (has_name(yaml, "articles")) {
         yaml$articles <- unlist(yaml$articles)
       }
+      if (!has_name(yaml, "urls")) {
+        base_url <- dirname(url)
+        yaml$urls <- list(
+          reference = paste0(base_url, "/reference"),
+          article = paste0(base_url, "/articles")
+        )
+      }
       return(yaml)
     }
   }
@@ -78,7 +85,6 @@ package_urls <- function(package) {
 parse_urls <- function(x) {
   urls <- trimws(strsplit(trimws(x), "[,\\s]+", perl = TRUE)[[1]])
   urls <- urls[grepl("^http", urls)]
-  urls <- sub("/$", "", urls)
 
   sub_special_cases(urls)
 }

R/readme-document.R

@@ -0,0 +1,61 @@
+#' Auto-linking for README files
+#'
+#' A drop-in replacement for [rmarkdown::github_document] that applies
+#' highlighting and auto-linking to the resulting Markdown file.
+#' GitHub strips the highlighting when displaying the README file,
+#' it is still available when the site is displayed in pkgdown.
+#'
+#' @param ... Passed on to [rmarkdown::github_document]
+#' @examples
+#'
+#' # Include this into the front matter of your README.Rmd:
+#' #
+#' # output: downlit::readme_document
+#' @export
+readme_document <- function(...) {
+  check_packages()
+
+  format <- rmarkdown::github_document(...)
+
+  format_pre_knit <- format$pre_knit
+  format_post_knit <- format$post_knit
+
+  format_post_processor <- format$post_processor
+
+  old_options <- NULL
+
+  format$pre_knit <- function(...) {
+    old_options <<- options(crayon.enabled = TRUE)
+
+    # Run preknit at end
+    if (!is.null(format_pre_knit)) {
+      format_pre_knit(...)
+    }
+  }
+
+  format$post_knit <- function(...) {
+    if (!is.null(format_post_knit)) {
+      out <- format_post_knit(...)
+    } else {
+      out <- NULL
+    }
+    options(old_options)
+    out
+  }
+
+  format$post_processor <- function(front_matter, utf8_input, output_file, clean, quiet) {
+    if (!quiet) {
+      message("Auto-linking code")
+    }
+    downlit_md_path(output_file, output_file)
+
+    # Run postprocessor at end, on downlit file
+    if (!is.null(format_post_processor)) {
+      output_file <- format_post_processor(front_matter, utf8_input, output_file, clean, quiet)
+    }
+
+    output_file
+  }
+
+  format
+}

tests/testthat/test-highlight.txt

@@ -10,7 +10,7 @@
 
 > # implicit package
 > cat(highlight("library(MASS)"))
-<span class='nf'><a href='https://rdrr.io/r/base/library.html'>library</a></span>(<span class='k'><a href='http://www.stats.ox.ac.uk/pub/MASS4'>MASS</a></span>)
+<span class='nf'><a href='https://rdrr.io/r/base/library.html'>library</a></span>(<span class='k'><a href='http://www.stats.ox.ac.uk/pub/MASS4/'>MASS</a></span>)
 
 > cat(highlight("addterm()"))
 <span class='nf'><a href='https://rdrr.io/pkg/MASS/man/addterm.html'>addterm</a></span>()

tests/testthat/test-link.R

@@ -124,7 +124,7 @@ test_that("library() linked to package reference", {
 
   expect_equal(href_expr_(library()), NA_character_)
   expect_equal(href_expr_(library(rlang)), "http://rlang.r-lib.org")
-  expect_equal(href_expr_(library(MASS)), "http://www.stats.ox.ac.uk/pub/MASS4")
+  expect_equal(href_expr_(library(MASS)), "http://www.stats.ox.ac.uk/pub/MASS4/")
 })
 
 # vignette ----------------------------------------------------------------

tests/testthat/test-metadata.R

@@ -4,7 +4,7 @@ test_that("can extract urls for package", {
 
   expect_equal(package_urls("base"), character())
   expect_equal(package_urls("packagethatdoesn'texist"), character())
-  expect_equal(package_urls("MASS"), "http://www.stats.ox.ac.uk/pub/MASS4")
+  expect_equal(package_urls("MASS"), "http://www.stats.ox.ac.uk/pub/MASS4/")
 })
 
 test_that("handle common url formats", {