close #28: when author is an array of length > 1, write each author in a separate <h2> (for LaTeX output, join authors by \and)

Author: yihui

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: litedown
 Type: Package
 Title: A Lightweight Version of R Markdown
-Version: 0.2.7
+Version: 0.2.8
 Authors@R: c(
    person("Yihui", "Xie", role = c("aut", "cre"), email = "[email protected]", comment = c(ORCID = "0000-0003-0645-5666")),
    person()

NEWS.md

@@ -10,6 +10,8 @@
 
 - Added a new vignette engine `litedown::book` to make it possible to build multiple vignettes into a book. To use this engine, declare `\VignetteEngine{litedown::book}` only in the book index file (e.g., `index.Rmd`) but not in other book chapter files.
 
+- Added support for an array of multiple authors in the YAML metadata (thanks, @AlbertLei, #28). If the `author` field in YAML is an array of length > 1, each author will be written to a separate `<h2>` in HTML output, or concatenated by `\and` in LaTeX output. Note that you can also write multiple authors in a single string (e.g., `author: "Jane X and John Y"`) instead of using an array (`author: ["Jane X", "John Y"]`), in which case the string will be treated as a single author (they will be put inside a single `<h2>` in HTML output).
+
 # CHANGES IN litedown VERSION 0.2
 
 - A data frame (or matrix/tibble) wrapped in `I()` is fully printed to a table now by default. Without `I()`, data objects are truncated to 10 rows by default when printing to tables.

R/mark.R

@@ -309,18 +309,22 @@ mark = function(input, output = NULL, text = NULL, options = NULL, meta = list()
 
   meta$body = ret
   # convert some meta variables in case they use Markdown syntax
-  for (i in top_meta) if (length(meta[[i]])) {
-    meta[[i]] = render(meta[[i]], clean = i != 'abstract')
+  for (i in top_meta) if (meta_len <- length(meta[[i]])) {
+    # if author is of length > 1, render them individually
+    m_author = i == 'author' && meta_len > 1
+    meta[[i]] = if (m_author) uapply(meta[[i]], render) else {
+      render(meta[[i]], clean = i != 'abstract')
+    }
     # also provide *_ version of top-level meta variables, containing tags/commands
     meta[[paste0(i, '_')]] = I(if (format == 'html') {
       tag = tag_meta[i]
       sprintf(
-        '<div class="%s">%s</div>', i, if (tag == '') meta[[i]] else sprintf(
-          '<%s>%s</%s>', tag, meta[[i]], tag
-        )
+        '<div class="%s">%s</div>', i, if (tag == '') meta[[i]] else {
+          one_string(sprintf('<%s>%s</%s>', tag, meta[[i]], tag))
+        }
       )
     } else if (format == 'latex') {
-      sprintf(cmd_meta[i], meta[[i]])
+      sprintf(cmd_meta[i], if (m_author) one_string(meta[[i]], ' \\and ') else meta[[i]])
     })
   }
   # use the template (if provided) to create a standalone document