Better errors and new whatsit handling

The whatsit handling is actually much more similar to the old whatsit
handling then the previous new one, so that part could be seen as a
partial revert of the new whatsit handling... Anyway, whatsits work
different than in the previous commit now.

luametalatex-back-pdf.lua

@@ -8,6 +8,7 @@ local fontdirs = setmetatable({}, {__index=function(t, k)t[k] = pfile:getobj() r
 local usedglyphs = {}
 local dests = {}
 local cur_page
+local declare_whatsit = require'luametalatex-whatsits'.new
 local whatsit_id = node.id'whatsit'
 local whatsits = node.whatsits()
 local colorstacks = {{
@@ -264,9 +265,16 @@ local function linkcontext_set(linkcontext, p, x, y, list, level, kind)
   end end
 end
 
-function do_start_link(prop, p, n, x, y, outer, _, level)
+local start_link_whatsit = declare_whatsit('pdf_start_link', function(prop, p, n, x, y, outer, _, level)
+  if not prop then
+    tex.error('Invalid pdf_start_link whatsit', {"A pdf_start_link whatsit did not contain all necessary \z
+        parameters. Maybe your code hasn't been adapted to LuaMetaLaTeX yet?"})
+    return
+  end
   if not p.is_page then
-    error[[No link allowed here]]
+    tex.error('pdf_start_link outside of page', {"PDF links are not allowed in Type3 charstrings or Form XObjects. \z
+        The link will be ignored"})
+    return
   end
   local links = p.linkcontext
   if not links then
@@ -276,29 +284,45 @@ function do_start_link(prop, p, n, x, y, outer, _, level)
   local link = {quads = {}, attr = prop.link_attr, action = prop.action, level = level, force_separate = false} -- force_separate should become an option
   links[#links+1] = link
   addlinkpoint(p, link, x, y, outer, 'start')
-end
-function do_end_link(prop, p, n, x, y, outer, _, level)
+end)
+local end_link_whatsit = declare_whatsit('pdf_end_link', function(prop, p, n, x, y, outer, _, level)
   if not p.is_page then
-    error[[No link allowed here]]
+    tex.error('pdf_start_link outside of page', {"PDF links are not allowed in Type3 charstrings or Form XObjects. \z
+        The link will be ignored"})
+    return
   end
   local links = p.linkcontext
-  if not links then error"No link here to end" end
+  if not links then
+    tex.error('No link here to end', {"You asked me to end a link, but currently there is no link active. \z
+        Maybe you forgot to run \\pdfextension startlink first?"})
+    return
+  end
   local link = links[#links]
+  if link.level ~= level then
+    tex.error('Inconsistent link level', {"You asked me to end a link, but the most recent link had been started at another level. \z
+        I will continue with the link for now."})
+    return
+  end
   links[#links] = nil
   if not links[1] then p.linkcontext = nil end
-  if link.level ~= level then error"Wrong link level" end
   addlinkpoint(p, link, x, y, outer, 'final')
-end
+end)
 
-local do_setmatrix do
+local setmatrix_whatsit do
   local numberpattern = (lpeg.P'-'^-1 * lpeg.R'09'^0 * ('.' * lpeg.R'09'^0)^-1)/tonumber
   local matrixpattern = numberpattern * ' ' * numberpattern * ' ' * numberpattern * ' ' * numberpattern
-  function do_setmatrix(prop, p, n, x, y, outer)
+  setmatrix_whatsit = declare_whatsit('pdf_setmatrix', function(prop, p, n, x, y, outer)
+    if not prop then
+      tex.error('Invalid pdf_setmatrix whatsit', {"A pdf_setmatrix whatsit did not contain a matrix value. \z
+          Maybe your code hasn't been adapted to LuaMetaLaTeX yet?"})
+      return
+    end
     local m = p.matrix
     local a, b, c, d = matrixpattern:match(prop.data)
     if not a then
-      print(prop.data)
-      error[[No valid matrix found]]
+      tex.error('Invalid matrix', {"The matrix in this pdf_setmatrix whatsit does not have the expected structure and could not be parsed. \z
+          Did you provide enough parameters? The matrix needs exactly four decimal entries."})
+      return
     end
     local e, f = (1-a)*x-c*y, (1-d)*y-b*x -- Emulate that the origin is at x, y for this transformation
                                           -- (We could also first translate by (-x, -y), then apply the matrix
@@ -308,19 +332,23 @@ local do_setmatrix do
     c, d = projected(m, c, d, 0)
     e, f = projected(m, e, f, 1)
     m[1], m[2], m[3], m[4], m[5], m[6] = a, b, c, d, e, f
+  end)
 end
-end
-local function do_save(prop, p, n, x, y, outer)
+local save_whatsit = declare_whatsit('pdf_save', function(prop, p, n, x, y, outer)
   pdf.write('page', 'q', x, y, p)
   local lastmatrix = p.matrix
   p.matrix = {[0] = lastmatrix, table.unpack(lastmatrix)}
-end
-local function do_restore(prop, p, n, x, y, outer)
+end)
+local restore_whatsit = declare_whatsit('pdf_restore', function(prop, p, n, x, y, outer)
   -- TODO: Check x, y
   pdf.write('page', 'Q', x, y, p)
   p.matrix = p.matrix[0]
+end)
+local dest_whatsit = declare_whatsit('pdf_dest', function(prop, p, n, x, y)
+  if not prop then
+    tex.error('Invalid pdf_dest whatsit', {"A pdf_dest whatsit did not contain all necessary \z
+        parameters. Maybe your code hasn't been adapted to LuaMetaLaTeX yet?"})
   end
-local function do_dest(prop, p, n, x, y)
   assert(cur_page, "Destinations can not appear outside of a page")
   local id = prop.dest_id
   local dest_type = prop.dest_type
@@ -365,14 +393,29 @@ local function do_dest(prop, p, n, x, y)
   else
     dests[id] = pfile:indirect(dests[id], data)
   end
+end)
+local refobj_whatsit = declare_whatsit('pdf_refobj', function(prop, p, n, x, y)
+  if not prop then
+    tex.error('Invalid pdf_refobj whatsit', {"A pdf_refobj whatsit did not reference any object. \z
+        Maybe your code hasn't been adapted to LuaMetaLaTeX yet?"})
+    return
   end
-local function do_refobj(prop, p, n, x, y)
   pfile:reference(prop.obj)
+end)
+local literal_whatsit = declare_whatsit('pdf_literal', function(prop, p, n, x, y)
+  if not prop then
+    tex.error('Invalid pdf_literal whatsit', {"A pdf_literal whatsit did not contain a literal to be inserted. \z
+        Maybe your code hasn't been adapted to LuaMetaLaTeX yet?"})
+    return
   end
-local function do_literal(prop, p, n, x, y)
   pdf.write(prop.mode, prop.data, x, y, p)
+end)
+local colorstack_whatsit = declare_whatsit('pdf_colorstack', function(prop, p, n, x, y)
+  if not prop then
+    tex.error('Invalid pdf_colorstack whatsit', {"A pdf_colorstack whatsit did not contain all necessary \z
+        parameters. Maybe your code hasn't been adapted to LuaMetaLaTeX yet?"})
+    return
   end
-local function do_colorstack(prop, p, n, x, y)
   local colorstack = prop.colorstack
   local stack
   if p.is_page then
@@ -393,28 +436,33 @@ local function do_colorstack(prop, p, n, x, y)
     stack[#stack] = prop.data
   end
   pdf.write(colorstack.mode, stack[#stack], x, y, p)
-end
+end)
 local function write_colorstack()
   local idx = token.scan_int()
   local colorstack = colorstacks[idx + 1]
   if not colorstack then
-    error[[Undefined colorstack]]
+    tex.error('Undefined colorstack', {"The requested colorstack is not initialized. \z
+        This probably means that you forgot to run \\pdffeedback colorstackinit or \z
+        that you specified the wrong index. I will continue with colorstack 0."})
+    colorstack = colorstacks[1]
   end
   local action = token.scan_keyword'pop' and 'pop'
               or token.scan_keyword'set' and 'set'
               or token.scan_keyword'current' and 'current'
               or token.scan_keyword'push' and 'push'
   if not action then
-    error[[Missing action specifier for colorstack command]]
+    tex.error('Missing action specifier for colorstack', {
+        "I don't know what you want to do with this colorstack. I would have expected pop/set/current or push here. \z
+        I will ignore this command."})
+    return
   end
   local text
   if action == "push" or "set" then
     text = token.scan_string()
     -- text = token.to_string(token.scan_tokenlist()) -- Attention! This should never be executed in an expand-only context
   end
-  local whatsit = node.new(whatsit_id, whatsits.pdf_colorstack)
+  local whatsit = node.new(whatsit_id, colorstack_whatsit)
   node.setproperty(whatsit, {
-      handle = do_colorstack,
       colorstack = colorstack,
       action = action,
       data = text,
@@ -498,52 +546,40 @@ token.luacmd("pdfextension", function(_, imm)
   elseif token.scan_keyword"literal" then
     local mode = scan_literal_mode()
     local literal = token.scan_string()
-    local whatsit = node.new(whatsit_id, whatsits.pdf_literal)
+    local whatsit = node.new(whatsit_id, literal_whatsit)
     node.setproperty(whatsit, {
-        handle = do_literal,
         mode = mode,
         data = literal,
       })
     node.write(whatsit)
   elseif token.scan_keyword"startlink" then
     local pfile = get_pfile()
-    local whatsit = node.new(whatsit_id, whatsits.pdf_start_link)
+    local whatsit = node.new(whatsit_id, start_link_whatsit)
     local attr = token.scan_keyword'attr' and token.scan_string() or ''
     local action = scan_action()
     local objnum = pfile:getobj()
     lastannot = num
     node.setproperty(whatsit, {
-        handle = do_start_link,
         link_attr = attr,
         action = action,
         objnum = objnum,
       })
     node.write(whatsit)
   elseif token.scan_keyword"endlink" then
-    local whatsit = node.new(whatsit_id, whatsits.pdf_end_link)
-    node.setproperty(whatsit, {
-        handle = do_end_link,
-      })
+    local whatsit = node.new(whatsit_id, end_link_whatsit)
     node.write(whatsit)
   elseif token.scan_keyword"save" then
-    local whatsit = node.new(whatsit_id, whatsits.pdf_save)
-    node.setproperty(whatsit, {
-        handle = do_save,
-      })
+    local whatsit = node.new(whatsit_id, save_whatsit)
     node.write(whatsit)
   elseif token.scan_keyword"setmatrix" then
     local matrix = token.scan_string()
-    local whatsit = node.new(whatsit_id, whatsits.pdf_setmatrix)
+    local whatsit = node.new(whatsit_id, setmatrix_whatsit)
     node.setproperty(whatsit, {
-        handle = do_setmatrix,
         data = matrix,
       })
     node.write(whatsit)
   elseif token.scan_keyword"restore" then
-    local whatsit = node.new(whatsit_id, whatsits.pdf_restore)
-    node.setproperty(whatsit, {
-        handle = do_restore,
-      })
+    local whatsit = node.new(whatsit_id, restore_whatsit)
     node.write(whatsit)
   elseif token.scan_keyword"info" then
     infodir = infodir .. token.scan_string()
@@ -577,10 +613,9 @@ token.luacmd("pdfextension", function(_, imm)
     end
   elseif token.scan_keyword"refobj" then
     local num = token.scan_int()
-    local whatsit = node.new(whatsit_id, whatsits.pdf_refobj)
+    local whatsit = node.new(whatsit_id, refobj_whatsit)
     node.setproperty(whatsit, {
         obj = num,
-        handle = do_refobj,
       })
     node.write(whatsit)
   elseif token.scan_keyword"outline" then
@@ -616,10 +651,9 @@ token.luacmd("pdfextension", function(_, imm)
     else
       error[[Unsupported id type]]
     end
-    local whatsit = node.new(whatsit_id, whatsits.pdf_dest)
+    local whatsit = node.new(whatsit_id, dest_whatsit)
     local prop = {
       dest_id = id,
-      handle = do_dest,
     }
     node.setproperty(whatsit, prop)
     if token.scan_keyword'xyz' then

luametalatex-firstcode.lua

@@ -63,50 +63,8 @@ end
 --     end
 --   })
 
+local new_whatsit = require'luametalatex-whatsits'.new
 local whatsit_id = node.id'whatsit'
-local whatsits = {
-  [0] = "open",
-        "write",
-        "close",
-        "special",
-        nil,
-        nil,
-        "save_pos",
-        "late_lua",
-        "user_defined",
-        nil,
-        nil,
-        nil,
-        nil,
-        nil,
-        nil,
-        nil,
-        "pdf_literal",
-        "pdf_refobj",
-        "pdf_annot",
-        "pdf_start_link",
-        "pdf_end_link",
-        "pdf_dest",
-        "pdf_action",
-        "pdf_thread",
-        "pdf_start_thread",
-        "pdf_end_thread",
-        "pdf_thread_data",
-        "pdf_link_data",
-        "pdf_colorstack",
-        "pdf_setmatrix",
-        "pdf_save",
-        "pdf_restore",
-}
-whatsits[whatsits[0]] = 0
-for i = 0,#whatsits do
-  local v = whatsits[i]
-  if v then
-    whatsits[v] = i
-  end
-end
-function node.whatsits() return whatsits end
-function node.subtype(s) return type(s) == "string" and whatsits[s] or nil end
 local spacer_cmd, relax_cmd = token.command_id'spacer', token.command_id'relax'
 local function scan_filename()
   local name = {}
@@ -141,15 +99,16 @@ local function do_openout(p)
     end
   end
 end
+local open_whatsit = new_whatsit('open', do_openout)
 token.luacmd("openout", function(_, immediate) -- \openout
   local file = token.scan_int()
   token.scan_keyword'='
   local name = scan_filename()
-  local props = {file = file, name = name, handle = do_openout}
+  local props = {file = file, name = name}
   if immediate == "immediate" then
     do_openout(props)
   else
-    local whatsit = node.direct.new(whatsit_id, whatsits.open)
+    local whatsit = node.direct.new(whatsit_id, open_whatsit)
     properties[whatsit] = props
     node.direct.write(whatsit)
   end
@@ -160,13 +119,14 @@ local function do_closeout(p)
     ofiles[p.file] = nil
   end
 end
+local close_whatsit = new_whatsit('close', do_closeout)
 token.luacmd("closeout", function(_, immediate) -- \closeout
   local file = token.scan_int()
-  local props = {file = file, handle = do_closeout}
+  local props = {file = file}
   if immediate == "immediate" then
     do_closeout(props)
   else
-    local whatsit = node.direct.new(whatsit_id, whatsits.close)
+    local whatsit = node.direct.new(whatsit_id, close_whatsit)
     properties[whatsit] = props
     node.direct.write(whatsit)
   end
@@ -180,14 +140,15 @@ local function do_write(p)
     texio.write_nl(p.file < 0 and "log" or "term and log", content)
   end
 end
+local write_whatsit = new_whatsit('write', do_write)
 token.luacmd("write", function(_, immediate) -- \write
   local file = token.scan_int()
   local content = token.scan_tokenlist()
-  local props = {file = file, data = content, handle = do_write}
+  local props = {file = file, data = content}
   if immediate == "immediate" then
     do_write(props)
   else
-    local whatsit = node.direct.new(whatsit_id, whatsits.write)
+    local whatsit = node.direct.new(whatsit_id, write_whatsit)
     properties[whatsit] = props
     node.direct.write(whatsit)
   end
@@ -199,7 +160,7 @@ token.luacmd("immediate", function() -- \immediate
     return token.put_next(next_tok)
   end
   local function_id = next_tok.mode
-  functions[function_id](function_id, 'immediate')
+  return functions[function_id](function_id, 'immediate')
 end, "protected")
 -- functions[43] = function() -- \pdfvariable
 --   local name = token.scan_string()

luametalatex-init.lua

@@ -98,7 +98,8 @@ callback_register('handle_error_hook', function()
     if line == "" then return 3 end
     local first = line:sub(1,1):upper()
     if first == 'H' then
-      texio.write(tex.gethelptext())
+      texio.write(tex.gethelptext() or "Sorry, I don't know how to help in this situation.\n\z
+        Maybe you should try asking a human?")
     elseif first == 'I' then
       line = line:sub(2)
       tex.runtoks(function()

luametalatex-nodewriter.lua

@@ -31,6 +31,8 @@ local rangedimensions = direct.rangedimensions
 local traverse_id = direct.traverse_id
 local getdata = direct.getdata
 
+local get_whatsit_handler = require'luametalatex-whatsits'.handler
+
 local dir_id = node.id'dir'
 
 local function doublekeyed(t, id2name, name2id, index)
@@ -470,9 +472,9 @@ function nodehandler.glyph(p, n, x, y, ...)
   p.pos.x = p.pos.x + math.floor(getwidth(n)*(1+getexpansion(n)/1000000)+.5)
 end
 function nodehandler.whatsit(p, n, ...) -- Whatsit?
-  local prop = properties[n]-- or node.getproperty(n)
-  if prop and prop.handle then
-    prop:handle(p, n, ...)
+  local handler, prop = get_whatsit_handler(n)
+  if handler then
+    handler(prop, p, n, ...)
   else
     write("Invalid whatsit found (missing handler).")
   end

luametalatex-whatsits.lua

@@ -0,0 +1,96 @@
+local whatsit_id = node.id'whatsit'
+local whatsits = {
+  [0] = "open",
+        "write",
+        "close",
+        "special",
+        nil,
+        nil,
+        "save_pos",
+        "late_lua",
+        "user_defined",
+        nil,
+        nil,
+        nil,
+        nil,
+        nil,
+        nil,
+        nil,
+        "pdf_literal",
+        "pdf_refobj",
+        "pdf_annot",
+        "pdf_start_link",
+        "pdf_end_link",
+        "pdf_dest",
+        "pdf_action",
+        "pdf_thread",
+        "pdf_start_thread",
+        "pdf_end_thread",
+        "pdf_thread_data",
+        "pdf_link_data",
+        "pdf_colorstack",
+        "pdf_setmatrix",
+        "pdf_save",
+        "pdf_restore",
+}
+local whatsithandler = {}
+-- for i = 0,#whatsits do -- #whatsits isn't guaranteed to work because of the nil entries
+for i = 0,31 do
+  local v = whatsits[i]
+  if v then
+    whatsits[v] = i
+  end
+end
+function node.whatsits() return whatsits end
+function node.subtype(s) return type(s) == "string" and whatsits[s] or nil end
+
+local direct = node.direct
+local getsubtype = direct.getsubtype
+local properties = direct.get_properties_table()
+local tonode, todirect = direct.tonode, direct.todirect
+
+local function get_handler(n, subtype)
+  local props = properties[n]
+  return props and props.handle or whatsithandler[subtype or getsubtype(n)], props
+end
+local function new(name, handler)
+  assert(type(name) == 'string')
+  local subtype = whatsits[name]
+  if subtype then
+    if whatsithandler[subtype] then
+      texio.write_nl'WARNING: Overwriting default whatsit handler'
+    end
+  else
+    subtype = #whatsits + 1
+    whatsits[subtype] = name
+    whatsits[name] = subtype
+  end
+  whatsithandler[subtype] = handler
+  return subtype
+end
+
+-- TODO: Some fields might expect different values
+local function setwhatsitfield(n, name, value)
+  local props = properties[n]
+  if not props then
+    props = {}
+    properties[n] = props
+  end
+  props[name] = value
+end
+direct.setwhatsitfield = setwhatsitfield
+
+local function getwhatsitfield(n, name)
+  local props = properties[n]
+  return props and props[name]
+end
+direct.getwhatsitfield = getwhatsitfield
+
+-- TODO: Some fields might be nodes and therefore have to be converted
+function node.setwhatsitfield(n, ...) return setwhatsitfield(todirect(n), ...) end
+function node.getwhatsitfield(n, ...) return getwhatsitfield(todirect(n), ...) end
+
+return {
+  handler = get_handler,
+  new = new,
+}