utils.R

# not elegant, given a part of a header,
# transform it into the row of a tibble
transform_params <- function(params) {
  params_string <- try(eval(parse(text = paste("alist(", quote_label(params), ")"))),
               silent = TRUE)

  if (inherits(params_string, "try-error")) {
    params <- sub(" ", ", ", params)
    params_string <- eval(parse(text = paste("alist(", quote_label(params), ")")))
  }

  label <- parse_label(params_string[[1]])

  tibble::tibble(language = label$language,
                 name = label$name,
                 options = sub(params_string[[1]], "", params))
}

parse_label <- function(label) {
  language_name <- sub(" ", "\\/", label)
  language_name <- unlist(strsplit(language_name, "\\/"))

  if (length(language_name) == 1) {
    tibble::tibble(language = trimws(language_name[1]),
                   name = NA)
  } else {
    tibble::tibble(language = trimws(language_name[1]),
                   name = trimws(language_name[2]))
  }
}

# from a chunk header
# to a tibble with language, name, option, option values
parse_chunk_header <- function(chunk_header) {
  # remove boundaries
  chunk_header <- gsub("```\\{", "", chunk_header)
  chunk_header <- gsub("\\}", "", chunk_header)

  # parse each part
  transform_params(chunk_header)

}

digest_chunk_header <- function(chunk_header_index,
                                lines) {
  # parse the chunk header
  chunk_info <- parse_chunk_header(
    lines[chunk_header_index])


  # keep index
  chunk_info$index <- chunk_header_index

  chunk_info
}

# helper to go from tibble with chunk info
# to header to write in R Markdown
re_write_headers <- function(info_df) {
  info_df %>%
    dplyr::group_by(.data$index) %>%
    dplyr::summarise(line = glue::glue("```{(language[1]) (name[1])(options)}",
                                       .open = "(",
                                       .close = ")"),
                     # for when no name
                     line = gsub(" \\,", ",", .data$line),
                     line = gsub(" NA", "", .data$line))
}

# helper to create a data.frame of chunk info
get_chunk_info = function(lines) {
  # find which lines are chunk starts
  chunk_header_indices = which(grepl("^```\\{[a-zA-Z0-9]", lines))

  # null if no chunks
  if (length(chunk_header_indices) == 0L) {
    return(NULL)
  }
  # parse these chunk headers
  purrr::map_df(chunk_header_indices,
                digest_chunk_header,
                lines)
}

# from knitr
# https://github.com/yihui/knitr/blob/2b3e617a700f6d236e22873cfff6cbc3568df568/R/parser.R#L148
# quote the chunk label if necessary
quote_label = function(x) {
  x = gsub("^\\s*,?", "", x)
  if (grepl('^\\s*[^\'"](,|\\s*$)', x)) {
    # <<a,b=1>>= ---> <<'a',b=1>>=
    x = gsub('^\\s*([^\'"])(,|\\s*$)', "'\\1'\\2", x)
  } else if (grepl('^\\s*[^\'"](,|[^=]*(,|\\s*$))', x)) {
    # <<abc,b=1>>= ---> <<'abc',b=1>>=
    x = gsub('^\\s*([^\'"][^=]*)(,|\\s*$)', "'\\1'\\2", x)
  }
  x
}

# from knitr:::escape_latex()
clean_latex_special_characters <- function(x, newlines = FALSE, spaces = FALSE) {
  x <- gsub("\\\\", "-", x)
  x <- gsub("([#$%&_{}])", "-", x)
  x <- gsub("\\\\textbackslash", "-", x)
  x <- gsub("~", "-", x)
  x <- gsub("\\^", "-", x)
  x <- gsub("(?<!\n)\n(?!\n)", "-", x, perl = TRUE)
  x <- gsub("  ", "-", x)
  x <- gsub("\\s", "-", x)
  x <- gsub("[-]{2,}", "-", x)
  x
}



globalVariables(".data")