roc.r

roc_title <- roccer("@title", 
  parse_tag = parse_string(),
  output_tag = output_rd("title"),
)
roc_description <- roccer("@description", 
  parse_tag = parse_string(),
  output_tag = output_rd("description"),
)
roc_details <- roccer("@details", 
  parse_tag = parse_string(),
  output_tag = output_rd("details"),
)

roc_intro <- roccer("@_intro", 
  parse_after = c("title", "description", "details")
  parse_roc = function(roc, obj) {
    if (!is.null(roc$`_intro`)) {
      paragraphs <- str_trim(str_split(intro, fixed('\n\n'))[[1]])
    } else {
      paragraphs <- NULL
    }

    # 1st paragraph = title (unless has @title)
    if (!is.null(roc$title)) {
      title <- roc$title
    } else if (length(paragraphs) > 0) {
      title <- paragraphs[1]
      paragraphs <- paragraphs[-1]
    } else {
      title <- NULL
    }

    # 2nd paragraph = description (unless has @description)
    if (!is.null(roc$description)) {
      description <- roc$description
    } else if (length(paragraphs) > 0) {
      description <- paragraphs[1]
      paragraphs <- paragraphs[-1]
    } else {
      # Description is required, so if missing description, repeat title.
      description <- title
    }

    # Every thing else = details, combined with @details.
    details <- c(paragraphs, roc$details)
    if (length(details) > 0) {
      details <- paste(details, collapse = "\n\n")
    } else {
      details <- NULL
    }
    
    list(
      `_intro` = NULL, 
      title = title, 
      description = description, 
      details = details
    )
  }
)