Install hyphen-* packages when babel can't define the language

NEWS.md

@@ -1,5 +1,6 @@
 # CHANGES IN tinytex VERSION 0.62
 
+- `latexmk()` can automatically install missing `hyphen-*` packages when the missing hyphenation patterns lead to the babel error `You haven't defined the language 'xxx' yet` instead of a warning, e.g., for the babel option `nswissgerman` (from `lang: de-CH` in R Markdown or Quarto), which needs the patterns of `ngerman` from **hyphen-german** (thanks, @stibu81, #515). Language names found in the log are now only used if they look like valid package names, and more of them are mapped to the package that provides them, e.g., `hindi` and the other Indic languages to **hyphen-indic**, and `slovene` to **hyphen-slovenian**.
 
 # CHANGES IN tinytex VERSION 0.61
 

R/latex.R

@@ -426,11 +426,51 @@ check_extra = function(file) {
 
 check_babel = function(text) {
   r = "^(\\(babel\\).* |Package babel Warning: No hyphenation patterns were preloaded for the )language [`']([^']+)'.*$"
-  if (length(m <- grep_sub(r, 'hyphen-\\2', text)) == 0) return(FALSE)
+  if (length(m <- grep_sub(r, '\\2', text)) == 0) return(FALSE)
+  length(pkgs <- hyphen_pkgs(m)) > 0 && tlmgr_install(pkgs) == 0
+}
+
+# map language names in babel/polyglossia messages to TeX Live hyphen-* packages
+hyphen_pkgs = function(x) {
+  x = tolower(gsub("[`']", '', x))
   # (babel) the language `German (new orthography)' into the format
-  m = gsub('\\s.*', '', m)
-  m[m == 'hyphen-pinyin'] = 'hyphen-chinese'
-  tlmgr_install(tolower(m)) == 0
+  x = gsub('\\s.*', '', x)
+  # hyphenation pattern names (in language.dat) that differ from the package
+  # names, according to `execute AddHyphen` in texlive.tlpdb
+  m = c(
+    ngerman = 'german', swissgerman = 'german', pinyin = 'chinese',
+    ukenglish = 'english', british = 'english', usenglishmax = 'english',
+    bokmal = 'norwegian', norsk = 'norwegian', nynorsk = 'norwegian',
+    schoolfinnish = 'finnish', monogreek = 'greek', ibycus = 'ancientgreek',
+    classiclatin = 'latin', liturgicallatin = 'latin',
+    mongolianlmc = 'mongolian', serbianc = 'serbian',
+    # older names (synonyms in texlive.tlpdb)
+    amharic = 'ethiopic', geez = 'ethiopic', persian = 'farsi',
+    patois = 'french', francais = 'french', polygreek = 'greek',
+    portuges = 'portuguese', slovene = 'slovenian', espanol = 'spanish',
+    # all of these are in the hyphen-indic package
+    assamese = 'indic', bengali = 'indic', gujarati = 'indic', hindi = 'indic',
+    kannada = 'indic', malayalam = 'indic', marathi = 'indic', oriya = 'indic',
+    pali = 'indic', panjabi = 'indic', tamil = 'indic', telugu = 'indic'
+  )
+  i = x %in% names(m)
+  x[i] = m[x[i]]
+  x = unique(paste0('hyphen-', x))
+  # names come from a log file, so only keep what looks like a package name
+  # (all names in language.dat/texlive.tlpdb are lowercase letters, digits, and
+  # hyphens), since package names are passed to tlmgr via system2()
+  x[grepl('^hyphen-[a-z0-9-]+$', x)]
+}
+
+# missing hyphenation patterns may also lead to babel errors (instead of
+# warnings), e.g., with the babel option nswissgerman (#515):
+# ! Package babel Error: You haven't defined the language 'ngerman' yet.
+# (babel)                Perhaps you misspelled it or your installation
+# (babel)                is not complete.
+detect_hyphen = function(text) {
+  r = ".*Package babel Error: You haven't defined the language [`']([^'`]+)' yet.*"
+  if (length(m <- grep_sub(r, '\\1', text)) == 0) return(character())
+  hyphen_pkgs(m)
 }
 
 # Package glossaries Warning: No language module detected for `english'.
@@ -448,9 +488,7 @@ check_glossaries = function(text) {
 check_polyglossia = function(text) {
   r = "^Package polyglossia Warning: No hyphenation patterns were loaded for ([`'][^']+'|British English).*"
   if (length(m <- grep_sub(r, '\\1', text)) == 0) return(FALSE)
-  m[m == 'British English'] = 'english'
-  m = gsub("[`']", '', m)
-  tlmgr_install(paste0('hyphen-', m)) == 0
+  length(pkgs <- hyphen_pkgs(m)) > 0 && tlmgr_install(pkgs) == 0
 }
 
 # Package datetime2 Warning: Date-Time Language Module `english' not installed on
@@ -505,9 +543,13 @@ exist_files = function(files) {
 parse_packages = function(
   log, text = read_lines(log), files = detect_files(text), quiet = rep(FALSE, 3)
 ) {
-  pkgs = character(); quiet = rep_len(quiet, length.out = 3)
+  quiet = rep_len(quiet, length.out = 3)
+  # hyphen-* packages are inferred from language names instead of file names
+  # (`text` may be unavailable, e.g., parse_packages(files = 'bibtex'))
+  pkgs = if (missing(log) && missing(text)) character() else detect_hyphen(text)
   x = unique(c(files, miss_font()))
   if (length(x) == 0) {
+    if (length(pkgs)) return(pkgs)
     if (!quiet[1]) message(
       'I was unable to find any missing LaTeX packages from the error log',
       if (missing(log)) '.' else c(' ', log, '.')
@@ -520,7 +562,7 @@ parse_packages = function(
     # Known packages where tlmgr search returns results but no file path ends
     # with the exact package name (e.g., no file ends with "/latex-lab").
     # These packages are returned directly without further tlmgr search parsing.
-    if (x[j] %in% c('fandol', 'latex-lab')) return(x[j])
+    if (x[j] %in% c('fandol', 'latex-lab')) return(unique(c(pkgs, x[j])))
     # why $? e.g. searching for mf returns a list like this
     # metafont.x86_64-darwin:
     #     bin/x86_64-darwin/mf       <- what we want

tests/test-cran/test-latex.R

@@ -36,6 +36,61 @@ assert('detect_files() can detect filenames from LaTeX log', {
   (detect_files("(pdf backend): cannot open file for embedding") %==% 'colorprofiles.sty')
 })
 
+assert('hyphen_pkgs() maps babel/polyglossia language names to hyphen-* packages', {
+  (hyphen_pkgs('french') %==% 'hyphen-french')
+  (hyphen_pkgs("`hungarian'") %==% 'hyphen-hungarian')
+  (hyphen_pkgs('German (new orthography)') %==% 'hyphen-german')
+  (hyphen_pkgs('British English') %==% 'hyphen-english')
+  (hyphen_pkgs('pinyin') %==% 'hyphen-chinese')
+  (hyphen_pkgs(c('ngerman', 'swissgerman', 'german')) %==% 'hyphen-german')
+  (hyphen_pkgs('nynorsk') %==% 'hyphen-norwegian')
+  # all Indic languages are in a single package
+  (hyphen_pkgs(c('hindi', 'tamil', 'bengali', 'Panjabi')) %==% 'hyphen-indic')
+  (hyphen_pkgs(c(
+    'assamese', 'bengali', 'gujarati', 'hindi', 'kannada', 'malayalam',
+    'marathi', 'oriya', 'pali', 'panjabi', 'tamil', 'telugu'
+  )) %==% 'hyphen-indic')
+  # older names that are synonyms of other languages
+  (hyphen_pkgs(c('amharic', 'geez')) %==% 'hyphen-ethiopic')
+  (hyphen_pkgs('persian') %==% 'hyphen-farsi')
+  (hyphen_pkgs(c('patois', 'francais', 'french')) %==% 'hyphen-french')
+  (hyphen_pkgs(c('polygreek', 'monogreek', 'greek')) %==% 'hyphen-greek')
+  (hyphen_pkgs('portuges') %==% 'hyphen-portuguese')
+  (hyphen_pkgs('slovene') %==% 'hyphen-slovenian')
+  (hyphen_pkgs('espanol') %==% 'hyphen-spanish')
+  # names in language.dat may be in mixed case
+  (hyphen_pkgs('UKenglish') %==% 'hyphen-english')
+})
+
+assert('hyphen_pkgs() drops names that are not valid package names', {
+  # names come from the log, and they must not be interpreted by the shell
+  (hyphen_pkgs('ngerman;id') %==% character())
+  (hyphen_pkgs('$(id)') %==% character())
+  (hyphen_pkgs('a|b') %==% character())
+  (hyphen_pkgs('a&b') %==% character())
+  (hyphen_pkgs('--repository=x') %==% character())
+  (hyphen_pkgs(character()) %==% character())
+  # valid names are kept
+  (hyphen_pkgs(c('french', 'x;id', 'swissgerman')) %==% c('hyphen-french', 'hyphen-german'))
+  # nothing to install, so tlmgr must not be called (and no rerun is needed)
+  (detect_hyphen("! Package babel Error: You haven't defined the language 'x;id' yet.") %==% character())
+  (!check_babel("Package babel Warning: No hyphenation patterns were preloaded for the language `x;id'."))
+  (!check_polyglossia("Package polyglossia Warning: No hyphenation patterns were loaded for `x;id'"))
+})
+
+assert('missing hyphenation patterns are detected from babel errors (#515)', {
+  x = c(
+    "! Package babel Error: You haven't defined the language 'ngerman' yet.",
+    "(babel)                Perhaps you misspelled it or your installation",
+    "(babel)                is not complete."
+  )
+  (detect_hyphen(x) %==% 'hyphen-german')
+  (detect_hyphen("! Package babel Error: You haven't defined the language `french' yet.") %==% 'hyphen-french')
+  (detect_hyphen("! Package babel Error: Unknown option 'ngerman'.") %==% character())
+  # the error is not about a missing file, so no tlmgr search is needed
+  (length(detect_files(x)) == 0)
+  (parse_packages(text = x, quiet = rep(TRUE, 3)) %==% 'hyphen-german')
+})
 
 assert('rerun are correctly detected', {
   (needs_rerun(text = "Package biblatex Warning: Please rerun LaTeX."))