R Markdown to Markdown on Jekyll

jekyll_it.R

# Copied from <http://jason.bryer.org/posts/2012-12-10/Markdown_Jekyll_R_for_Blogging.html>

jekyll_it <- function(dir=getwd(), images.dir=dir, images.url='../',  out_ext='.md', in_ext='.rmd', recursive=FALSE) {
  require(knitr, quietly=TRUE, warn.conflicts=FALSE)
  files <- list.files(path=dir, pattern=in_ext, ignore.case=TRUE, recursive=recursive)
  for(f in files) {
    message(paste("Processing ", f, sep=''))
    content <- readLines(f)
    frontMatter <- which(substr(content, 1, 3) == '---')
    if(length(frontMatter) >= 2 & 1 %in% frontMatter) {
      statusLine <- which(substr(content, 1, 10) == 'published:')
      if(statusLine > frontMatter[1] & statusLine < frontMatter[2]) {
        status <- unlist(strsplit(content[statusLine], ':'))[2]
        status <- sub('[[:space:]]+$', '', status)
        status <- sub('^[[:space:]]+', '', status)
        if(tolower(status) == 'true') {
          message(paste('Processing ', f, sep=''))
          #Write 'published: false' to original files to prevent overwrite 
          #converted files in next time we run this script.
          content[statusLine] <- 'published: false'
          writeLines( content, f)
          #Generate content to new files
          content[nchar(content) == 0] <- ' '
          content[statusLine] <- paste('converted:',format(Sys.time(), "%d/%m/%Y %H:%M:%S"))
          outFile <- paste0("../_posts/",substr(f, 1, (nchar(f)-(nchar(in_ext)))), out_ext, sep='')
          render_markdown(strict=TRUE)
          render_jekyll(highlight='pygments')
          opts_knit$set(out.format='markdown')
          opts_knit$set(base.dir=images.dir)
          opts_knit$set(base.url=images.url)
          opts_chunk$set(fig.path='../figures/')
          try(knit(text=content, output=outFile), silent=FALSE)
        } else {
          warning(paste("Not processing ", f, ", status is '", status, 
                        "'. Set status to 'true' to convert.", sep=''))
        }
      } else {
        warning("'published:' status not found in front matter.")
      }
    } else {
      warning("No front matter found. Will not process this file.")
    }
  }
  invisible()
}
jekyll_it()