Import, document and add checks

Import knitr, markdown and RWordPress. Some small documentation
improvements. Add checks for the imported packages at beggining of the
function.

R/knit2wpCrayon.R

@@ -2,8 +2,9 @@
 #'
 #' @name knit2wpCrayon
 #'
-#' @description This function improves the \code{RWordPress::knit2wp} to
-#'     allow properly render code when using Crayon Sintax Highlighter.
+#' @description This function improves \code{RWordPress::knit2wp} to
+#'     allow properly render code when using Crayon Sintax Highlighter
+#'     in Wordpress.
 #'
 #' @param input a markdown or Rmarkdown file.
 #' @param title title for the post.
@@ -16,15 +17,15 @@
 #' @param upload logical, if the file is to be updated to the blog.
 #' @param publish logical, if the post is to be published or stay in
 #'     draft mode.
-#' @param write logical, is the result of knit be written to a html
-#'     file. This is useful to copy from this file and paste inside the
-#'     wordpress post editor (on text mode, not visual mode).
+#' @param write logical, if the result of knit should be written to a
+#'     html file. This is useful to copy from this file and paste inside
+#'     the Wordpress editor (on text mode, not visual mode).
 #'
-#' @return None is returned by the function.
+#' @return Nothing is returned by the function.
 #'
 #' @author Walmes Zeviani, \email{walmes@@ufpr.br}
 #'
-#' @import knitr
+#' @import knitr markdown RWordPress
 #' @export
 #' @examples
 #' \donttest{
@@ -53,19 +54,35 @@ knit2wpCrayon <- function(input, title="A post from knitr", ...,
                           action=c("newPost", "editPost", "newPage"),
                           postid, encoding=getOption("encoding"),
                           upload=FALSE, publish=FALSE, write=TRUE){
+    ##
+    ##-------------------------------------------
+    ## Loading required packages.
+    ##
+    if (!requireNamespace("knitr", quietly=TRUE)){
+        stop("`knitr` needed for this function to work. Please install it.",
+             call.=FALSE)
+    }
+    if (!requireNamespace("markdown", quietly=TRUE)){
+        stop("`markdown` needed for this function to work. Please install it.",
+             call.=FALSE)
+    }
+        if (!requireNamespace("RWordPress", quietly=TRUE)){
+        stop("`RWordPress` needed for this function to work. Please install it.",
+             call.=FALSE)
+    }
     out <- knit(input, encoding=encoding)
     on.exit(unlink(out))
     con <- file(out, encoding=encoding)
     on.exit(close(con), add=TRUE)
-    content <- knitr:::native_encode(readLines(con, warn=FALSE))
+    content <- native_encode(readLines(con, warn=FALSE))
     content <- paste(content, collapse="\n")
-    content <- markdown::markdownToHTML(text=content, fragment.only=TRUE)
+    content <- markdownToHTML(text=content, fragment.only=TRUE)
     content <- gsub(
         pattern="<pre><code class=\"([[:alpha:]]+)\">(.+?)</code></pre>",
         replacement="<pre class=\"lang:\\1 decode:true\">\\2</pre>",
         x=content)
-    content=knitr:::native_encode(content, "UTF-8")
-    title=knitr:::native_encode(title, "UTF-8")
+    content=native_encode(content, "UTF-8")
+    title=native_encode(title, "UTF-8")
     if (write){
         writeLines(text=content,
                    con=gsub(x=out, pattern="\\.md$", replacement=".html"))