9304060604

Committed 30 May 2024 02:07PM UTC coverage: 74.124% (-0.6%) from 74.707%

Build # 9304060604

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push

github

Committed by

alerque

Commit Message

style: Reformat Lua with stylua

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92.25

/typesetters/base.lua

--- SILE typesetter (default/base) class.
--
-- @copyright License: MIT
-- @module typesetters.base
--

-- Typesetter base class

local typesetter = pl.class()
typesetter.type = "typesetter"
typesetter._name = "base"

-- This is the default typesetter. You are, of course, welcome to create your own.
local awful_bad = 1073741823
local inf_bad = 10000
-- local eject_penalty = -inf_bad
local supereject_penalty = 2 * -inf_bad
-- local deplorable = 100000

-- Local helper class to compare pairs of margins
local _margins = pl.class({
   lskip = SILE.nodefactory.glue(),
   rskip = SILE.nodefactory.glue(),

   _init = function (self, lskip, rskip)
      self.lskip, self.rskip = lskip, rskip
   end,

   __eq = function (self, other)
      return self.lskip.width == other.lskip.width and self.rskip.width == other.rskip.width
   end,
})

local warned = false

function typesetter:init (frame)
   SU.deprecated("std.object", "pl.class", "0.13.0", "0.14.0", warned and "" or [[
  The typesetter instance inheritance system for instances has been
  refactored using a different object model. Your instance was created
  and initialized using the object copy syntax from the stdlib model.
  It has been shimmed for you using the new Penlight model, but this may
  lead to unexpected behaviour. Please update your code to use the new
  Penlight based inheritance model.]])
   warned = true
   self:_init(frame)
end

function typesetter:_init (frame)
   self:declareSettings()
   self.hooks = {}
   self.breadcrumbs = SU.breadcrumbs()

   self.frame = nil
   self.stateQueue = {}
   self:initFrame(frame)
   self:initState()
   -- In case people use stdlib prototype syntax off of the instantiated typesetter...
   getmetatable(self).__call = self.init
   return self
end

function typesetter.declareSettings (_)
   -- Settings common to any typesetter instance.
   -- These shouldn't be re-declared and overwritten/reset in the typesetter
   -- constructor (see issue https://github.com/sile-typesetter/sile/issues/1708).
   -- On the other hand, it's fairly acceptable to have them made global:
   -- Any derived typesetter, whatever its implementation, should likely provide
   -- some logic for them (= widows, orphans, spacing, etc.)

   SILE.settings:declare({
      parameter = "typesetter.widowpenalty",
      type = "integer",
      default = 3000,
      help = "Penalty to be applied to widow lines (at the start of a paragraph)",
   })

   SILE.settings:declare({
      parameter = "typesetter.parseppattern",
      type = "string or integer",
      default = "\r?\n[\r\n]+",
      help = "Lua pattern used to separate paragraphs",
   })

   SILE.settings:declare({
      parameter = "typesetter.obeyspaces",
      type = "boolean or nil",
      default = nil,
      help = "Whether to ignore paragraph initial spaces",
   })

   SILE.settings:declare({
      parameter = "typesetter.orphanpenalty",
      type = "integer",
      default = 3000,
      help = "Penalty to be applied to orphan lines (at the end of a paragraph)",
   })

   SILE.settings:declare({
      parameter = "typesetter.parfillskip",
      type = "glue",
      default = SILE.nodefactory.glue("0pt plus 10000pt"),
      help = "Glue added at the end of a paragraph",
   })

   SILE.settings:declare({
      parameter = "document.letterspaceglue",
      type = "glue or nil",
      default = nil,
      help = "Glue added between tokens",
   })

   SILE.settings:declare({
      parameter = "typesetter.underfulltolerance",
      type = "length or nil",
      default = SILE.length("1em"),
      help = "Amount a page can be underfull without warning",
   })

   SILE.settings:declare({
      parameter = "typesetter.overfulltolerance",
      type = "length or nil",
      default = SILE.length("5pt"),
      help = "Amount a page can be overfull without warning",
   })

   SILE.settings:declare({
      parameter = "typesetter.breakwidth",
      type = "measurement or nil",
      default = nil,
      help = "Width to break lines at",
   })

   SILE.settings:declare({
      parameter = "typesetter.softHyphen",
      type = "boolean",
      default = true,
      help = "When true, soft hyphens are rendered as discretionary breaks, otherwise they are ignored",
   })

   SILE.settings:declare({
      parameter = "typesetter.softHyphenWarning",
      type = "boolean",
      default = false,
      help = "When true, a warning is issued when a soft hyphen is encountered",
   })

   SILE.settings:declare({
      parameter = "typesetter.fixedSpacingAfterInitialEmdash",
      type = "boolean",
      default = true,
      help = "When true, em-dash starting a paragraph is considered as a speaker change in a dialogue",
   })
end

function typesetter:initState ()
   self.state = {
      nodes = {},
      outputQueue = {},
      lastBadness = awful_bad,
   }
end

function typesetter:initFrame (frame)
   if frame then
      self.frame = frame
      self.frame:init(self)
   end
end

function typesetter.getMargins ()
   return _margins(SILE.settings:get("document.lskip"), SILE.settings:get("document.rskip"))
end

function typesetter.setMargins (_, margins)
   SILE.settings:set("document.lskip", margins.lskip)
   SILE.settings:set("document.rskip", margins.rskip)
end

function typesetter:pushState ()
   self.stateQueue[#self.stateQueue + 1] = self.state
   self:initState()
end

function typesetter:popState (ncount)
   local offset = ncount and #self.stateQueue - ncount or nil
   self.state = table.remove(self.stateQueue, offset)
   if not self.state then
      SU.error("Typesetter state queue empty")
   end
end

function typesetter:isQueueEmpty ()
   if not self.state then
      return nil
   end
   return #self.state.nodes == 0 and #self.state.outputQueue == 0
end

function typesetter:vmode ()
   return #self.state.nodes == 0
end

function typesetter:debugState ()
   print("\n---\nI am in " .. (self:vmode() and "vertical" or "horizontal") .. " mode")
   print("Writing into " .. tostring(self.frame))
   print("Recent contributions: ")
   for i = 1, #self.state.nodes do
      io.stderr:write(self.state.nodes[i] .. " ")
   end
   print("\nVertical list: ")
   for i = 1, #self.state.outputQueue do
      print("  " .. self.state.outputQueue[i])
   end
end

-- Boxy stuff
function typesetter:pushHorizontal (node)
   self:initline()
   self.state.nodes[#self.state.nodes + 1] = node
   return node
end

function typesetter:pushVertical (vbox)
   self.state.outputQueue[#self.state.outputQueue + 1] = vbox
   return vbox
end

function typesetter:pushHbox (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushHorizontal() to pass a premade node instead of a spec") end
   local ntype = SU.type(spec)
   local node = (ntype == "hbox" or ntype == "zerohbox") and spec or SILE.nodefactory.hbox(spec)
   return self:pushHorizontal(node)
end

function typesetter:pushUnshaped (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushHorizontal() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "unshaped" and spec or SILE.nodefactory.unshaped(spec)
   return self:pushHorizontal(node)
end

function typesetter:pushGlue (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushHorizontal() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "glue" and spec or SILE.nodefactory.glue(spec)
   return self:pushHorizontal(node)
end

function typesetter:pushExplicitGlue (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushHorizontal() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "glue" and spec or SILE.nodefactory.glue(spec)
   node.explicit = true
   node.discardable = false
   return self:pushHorizontal(node)
end

function typesetter:pushPenalty (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushHorizontal() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "penalty" and spec or SILE.nodefactory.penalty(spec)
   return self:pushHorizontal(node)
end

function typesetter:pushMigratingMaterial (material)
   local node = SILE.nodefactory.migrating({ material = material })
   return self:pushHorizontal(node)
end

function typesetter:pushVbox (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushVertical() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "vbox" and spec or SILE.nodefactory.vbox(spec)
   return self:pushVertical(node)
end

function typesetter:pushVglue (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushVertical() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "vglue" and spec or SILE.nodefactory.vglue(spec)
   return self:pushVertical(node)
end

function typesetter:pushExplicitVglue (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushVertical() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "vglue" and spec or SILE.nodefactory.vglue(spec)
   node.explicit = true
   node.discardable = false
   return self:pushVertical(node)
end

function typesetter:pushVpenalty (spec)
   -- if SU.type(spec) ~= "table" then SU.warn("Please use pushVertical() to pass a premade node instead of a spec") end
   local node = SU.type(spec) == "penalty" and spec or SILE.nodefactory.penalty(spec)
   return self:pushVertical(node)
end

-- Actual typesetting functions
function typesetter:typeset (text)
   text = tostring(text)
   if text:match("^%\r?\n$") then
      return
   end
   local pId = SILE.traceStack:pushText(text)
   for token in SU.gtoke(text, SILE.settings:get("typesetter.parseppattern")) do
      if token.separator then
         self:endline()
      else
         if SILE.settings:get("typesetter.softHyphen") then
            local warnedshy = false
            for token2 in SU.gtoke(token.string, luautf8.char(0x00AD)) do
               if token2.separator then -- soft hyphen support
                  local discretionary = SILE.nodefactory.discretionary({})
                  local hbox = SILE.typesetter:makeHbox({ SILE.settings:get("font.hyphenchar") })
                  discretionary.prebreak = { hbox }
                  table.insert(SILE.typesetter.state.nodes, discretionary)
                  if not warnedshy and SILE.settings:get("typesetter.softHyphenWarning") then
                     SU.warn("Soft hyphen encountered and replaced with discretionary")
                  end
                  warnedshy = true
               else
                  self:setpar(token2.string)
               end
            end
         else
            if
               SILE.settings:get("typesetter.softHyphenWarning") and luautf8.match(token.string, luautf8.char(0x00AD))
            then
               SU.warn("Soft hyphen encountered and ignored")
            end
            text = luautf8.gsub(token.string, luautf8.char(0x00AD), "")
            self:setpar(text)
         end
      end
   end
   SILE.traceStack:pop(pId)
end

function typesetter:initline ()
   if self.state.hmodeOnly then
      return
   end -- https://github.com/sile-typesetter/sile/issues/1718
   if #self.state.nodes == 0 then
      self.state.nodes[#self.state.nodes + 1] = SILE.nodefactory.zerohbox()
      SILE.documentState.documentClass.newPar(self)
   end
end

function typesetter:endline ()
   self:leaveHmode()
   SILE.documentState.documentClass.endPar(self)
end

-- Just compute once, to avoid unicode characters in source code.
local speakerChangePattern = "^"
   .. luautf8.char(0x2014) -- emdash
   .. "[ "
   .. luautf8.char(0x00A0)
   .. luautf8.char(0x202F) -- regular space or NBSP or NNBSP
   .. "]+"
local speakerChangeReplacement = luautf8.char(0x2014) .. " "

-- Special unshaped node subclass to handle space after a speaker change in dialogues
-- introduced by an em-dash.
local speakerChangeNode = pl.class(SILE.nodefactory.unshaped)
function speakerChangeNode:shape ()
   local node = self._base.shape(self)
   local spc = node[2]
   if spc and spc.is_glue then
      -- Switch the variable space glue to a fixed kern
      node[2] = SILE.nodefactory.kern({ width = spc.width.length })
      node[2].parent = self.parent
   else
      -- Should not occur:
      -- How could it possibly be shaped differently?
      SU.warn("Speaker change logic met an unexpected case, this might be a bug.")
   end
   return node
end

-- Takes string, writes onto self.state.nodes
function typesetter:setpar (text)
   text = text:gsub("\r?\n", " "):gsub("\t", " ")
   if #self.state.nodes == 0 then
      if not SILE.settings:get("typesetter.obeyspaces") then
         text = text:gsub("^%s+", "")
      end
      self:initline()

      if
         SILE.settings:get("typesetter.fixedSpacingAfterInitialEmdash")
         and not SILE.settings:get("typesetter.obeyspaces")
      then
         local speakerChange = false
         local dialogue = luautf8.gsub(text, speakerChangePattern, function ()
            speakerChange = true
            return speakerChangeReplacement
         end)
         if speakerChange then
            local node = speakerChangeNode({ text = dialogue, options = SILE.font.loadDefaults({}) })
            self:pushHorizontal(node)
            return -- done here: speaker change space handling is done after nnode shaping
         end
      end
   end
   if #text > 0 then
      self:pushUnshaped({ text = text, options = SILE.font.loadDefaults({}) })
   end
end

function typesetter:breakIntoLines (nodelist, breakWidth)
   self:shapeAllNodes(nodelist)
   local breakpoints = SILE.linebreak:doBreak(nodelist, breakWidth)
   return self:breakpointsToLines(breakpoints)
end

function typesetter.shapeAllNodes (_, nodelist)
   local newNl = {}
   for i = 1, #nodelist do
      if nodelist[i].is_unshaped then
         pl.tablex.insertvalues(newNl, nodelist[i]:shape())
      else
         newNl[#newNl + 1] = nodelist[i]
      end
   end
   for i = 1, #newNl do
      nodelist[i] = newNl[i]
   end
   if #nodelist > #newNl then
      for i = #newNl + 1, #nodelist do
         nodelist[i] = nil
      end
   end
end

-- Empties self.state.nodes, breaks into lines, puts lines into vbox, adds vbox to
-- Turns a node list into a list of vboxes
function typesetter:boxUpNodes ()
   local nodelist = self.state.nodes
   if #nodelist == 0 then
      return {}
   end
   for j = #nodelist, 1, -1 do
      if not nodelist[j].is_migrating then
         if nodelist[j].discardable then
            table.remove(nodelist, j)
         else
            break
         end
      end
   end
   while #nodelist > 0 and nodelist[1].is_penalty do
      table.remove(nodelist, 1)
   end
   if #nodelist == 0 then
      return {}
   end
   self:shapeAllNodes(nodelist)
   local parfillskip = SILE.settings:get("typesetter.parfillskip")
   parfillskip.discardable = false
   self:pushGlue(parfillskip)
   self:pushPenalty(-inf_bad)
   SU.debug("typesetter", function ()
      return "Boxed up " .. (#nodelist > 500 and #nodelist .. " nodes" or SU.contentToString(nodelist))
   end)
   local breakWidth = SILE.settings:get("typesetter.breakwidth") or self.frame:getLineWidth()
   local lines = self:breakIntoLines(nodelist, breakWidth)
   local vboxes = {}
   for index = 1, #lines do
      local line = lines[index]
      local migrating = {}
      -- Move any migrating material
      local nodes = {}
      for i = 1, #line.nodes do
         local node = line.nodes[i]
         if node.is_migrating then
            for j = 1, #node.material do
               migrating[#migrating + 1] = node.material[j]
            end
         else
            nodes[#nodes + 1] = node
         end
      end
      local vbox = SILE.nodefactory.vbox({ nodes = nodes, ratio = line.ratio })
      local pageBreakPenalty = 0
      if #lines > 1 and index == 1 then
         pageBreakPenalty = SILE.settings:get("typesetter.widowpenalty")
      elseif #lines > 1 and index == (#lines - 1) then
         pageBreakPenalty = SILE.settings:get("typesetter.orphanpenalty")
      end
      vboxes[#vboxes + 1] = self:leadingFor(vbox, self.state.previousVbox)
      vboxes[#vboxes + 1] = vbox
      for i = 1, #migrating do
         vboxes[#vboxes + 1] = migrating[i]
      end
      self.state.previousVbox = vbox
      if pageBreakPenalty > 0 then
         SU.debug("typesetter", "adding penalty of", pageBreakPenalty, "after", vbox)
         vboxes[#vboxes + 1] = SILE.nodefactory.penalty(pageBreakPenalty)
      end
   end
   return vboxes
end

function typesetter.pageTarget (_)
   SU.deprecated("SILE.typesetter:pageTarget", "SILE.typesetter:getTargetLength", "0.13.0", "0.14.0")
end

function typesetter:getTargetLength ()
   return self.frame:getTargetLength()
end

function typesetter:registerHook (category, func)
   if not self.hooks[category] then
      self.hooks[category] = {}
   end
   table.insert(self.hooks[category], func)
end

function typesetter:runHooks (category, data)
   if not self.hooks[category] then
      return data
   end
   for _, func in ipairs(self.hooks[category]) do
      data = func(self, data)
   end
   return data
end

function typesetter:registerFrameBreakHook (func)
   self:registerHook("framebreak", func)
end

function typesetter:registerNewFrameHook (func)
   self:registerHook("newframe", func)
end

function typesetter:registerPageEndHook (func)
   self:registerHook("pageend", func)
end

function typesetter:buildPage ()
   local pageNodeList
   local res
   if self:isQueueEmpty() then
      return false
   end
   if SILE.scratch.insertions then
      SILE.scratch.insertions.thisPage = {}
   end
   pageNodeList, res = SILE.pagebuilder:findBestBreak({
      vboxlist = self.state.outputQueue,
      target = self:getTargetLength(),
      restart = self.frame.state.pageRestart,
   })
   if not pageNodeList then -- No break yet
      -- self.frame.state.pageRestart = res
      self:runHooks("noframebreak")
      return false
   end
   SU.debug("pagebuilder", "Buildding page for", self.frame.id)
   self.state.lastPenalty = res
   self.frame.state.pageRestart = nil
   pageNodeList = self:runHooks("framebreak", pageNodeList)
   self:setVerticalGlue(pageNodeList, self:getTargetLength())
   self:outputLinesToPage(pageNodeList)
   return true
end

function typesetter:setVerticalGlue (pageNodeList, target)
   local glues = {}
   local gTotal = SILE.length()
   local totalHeight = SILE.length()

   local pastTop = false
   for _, node in ipairs(pageNodeList) do
      if not pastTop and not node.discardable and not node.explicit then
         -- "Ignore discardable and explicit glues at the top of a frame."
         -- See typesetter:outputLinesToPage()
         -- Note the test here doesn't check is_vglue, so will skip other
         -- discardable nodes (e.g. penalties), but it shouldn't matter
         -- for the type of computing performed here.
         pastTop = true
      end
      if pastTop then
         if not node.is_insertion then
            totalHeight:___add(node.height)
            totalHeight:___add(node.depth)
         end
         if node.is_vglue then
            table.insert(glues, node)
            gTotal:___add(node.height)
         end
      end
   end

   if totalHeight:tonumber() == 0 then
      return SU.debug("pagebuilder", "No glue adjustment needed on empty page")
   end

   local adjustment = target - totalHeight
   if adjustment:tonumber() > 0 then
      if adjustment > gTotal.stretch then
         if
            (adjustment - gTotal.stretch):tonumber() > SILE.settings:get("typesetter.underfulltolerance"):tonumber()
         then
            SU.warn(
               "Underfull frame "
                  .. self.frame.id
                  .. ": "
                  .. adjustment
                  .. " stretchiness required to fill but only "
                  .. gTotal.stretch
                  .. " available"
            )
         end
         adjustment = gTotal.stretch
      end
      if gTotal.stretch:tonumber() > 0 then
         for i = 1, #glues do
            local g = glues[i]
            g:adjustGlue(adjustment:tonumber() * g.height.stretch:absolute() / gTotal.stretch)
         end
      end
   elseif adjustment:tonumber() < 0 then
      adjustment = 0 - adjustment
      if adjustment > gTotal.shrink then
         if (adjustment - gTotal.shrink):tonumber() > SILE.settings:get("typesetter.overfulltolerance"):tonumber() then
            SU.warn(
               "Overfull frame "
                  .. self.frame.id
                  .. ": "
                  .. adjustment
                  .. " shrinkability required to fit but only "
                  .. gTotal.shrink
                  .. " available"
            )
         end
         adjustment = gTotal.shrink
      end
      if gTotal.shrink:tonumber() > 0 then
         for i = 1, #glues do
            local g = glues[i]
            g:adjustGlue(-adjustment:tonumber() * g.height.shrink:absolute() / gTotal.shrink)
         end
      end
   end
   SU.debug("pagebuilder", "Glues for this page adjusted by", adjustment, "drawn from", gTotal)
end

function typesetter:initNextFrame ()
   local oldframe = self.frame
   self.frame:leave(self)
   if #self.state.outputQueue == 0 then
      self.state.previousVbox = nil
   end
   if self.frame.next and self.state.lastPenalty > supereject_penalty then
      self:initFrame(SILE.getFrame(self.frame.next))
   elseif not self.frame:isMainContentFrame() then
      if #self.state.outputQueue > 0 then
         SU.warn("Overfull content for frame " .. self.frame.id)
         self:chuck()
      end
   else
      self:runHooks("pageend")
      SILE.documentState.documentClass:endPage()
      self:initFrame(SILE.documentState.documentClass:newPage())
   end

   if not SU.feq(oldframe:getLineWidth(), self.frame:getLineWidth()) then
      self:pushBack()
      -- Some what of a hack below.
      -- Before calling this method, we were in vertical mode...
      -- pushback occurred, and it seems it messes up a bit...
      -- Regardless what it does, at the end, we ought to be in vertical mode
      -- again:
      self:leaveHmode()
   else
      -- If I have some things on the vertical list already, they need
      -- proper top-of-frame leading applied.
      if #self.state.outputQueue > 0 then
         local lead = self:leadingFor(self.state.outputQueue[1], nil)
         if lead then
            table.insert(self.state.outputQueue, 1, lead)
         end
      end
   end
   self:runHooks("newframe")
end

function typesetter:pushBack ()
   SU.debug("typesetter", "Pushing back", #self.state.outputQueue, "nodes")
   local oldqueue = self.state.outputQueue
   self.state.outputQueue = {}
   self.state.previousVbox = nil
   local lastMargins = self:getMargins()
   for _, vbox in ipairs(oldqueue) do
      SU.debug("pushback", "process box", vbox)
      if vbox.margins and vbox.margins ~= lastMargins then
         SU.debug("pushback", "new margins", lastMargins, vbox.margins)
         if not self.state.grid then
            self:endline()
         end
         self:setMargins(vbox.margins)
      end
      if vbox.explicit then
         SU.debug("pushback", "explicit", vbox)
         self:endline()
         self:pushExplicitVglue(vbox)
      elseif vbox.is_insertion then
         SU.debug("pushback", "pushBack", "insertion", vbox)
         SILE.typesetter:pushMigratingMaterial({ material = { vbox } })
      elseif not vbox.is_vglue and not vbox.is_penalty then
         SU.debug("pushback", "not vglue or penalty", vbox.type)
         local discardedFistInitLine = false
         if #self.state.nodes == 0 then
            -- Setup queue but avoid calling newPar
            self.state.nodes[#self.state.nodes + 1] = SILE.nodefactory.zerohbox()
         end
         for i, node in ipairs(vbox.nodes) do
            if node.is_glue and not node.discardable then
               self:pushHorizontal(node)
            elseif node.is_glue and node.value == "margin" then
               SU.debug("pushback", "discard", node.value, node)
            elseif node.is_discretionary then
               SU.debug("pushback", "re-mark discretionary as unused", node)
               node.used = false
               if i == 1 then
                  SU.debug("pushback", "keep first discretionary", node)
                  self:pushHorizontal(node)
               else
                  SU.debug("pushback", "discard all other discretionaries", node)
               end
            elseif node.is_zero then
               if discardedFistInitLine then
                  self:pushHorizontal(node)
               end
               discardedFistInitLine = true
            elseif node.is_penalty then
               if not discardedFistInitLine then
                  self:pushHorizontal(node)
               end
            else
               node.bidiDone = true
               self:pushHorizontal(node)
            end
         end
      else
         SU.debug("pushback", "discard", vbox.type)
      end
      lastMargins = vbox.margins
      -- self:debugState()
   end
   while
      self.state.nodes[#self.state.nodes]
      and (self.state.nodes[#self.state.nodes].is_penalty or self.state.nodes[#self.state.nodes].is_zero)
   do
      self.state.nodes[#self.state.nodes] = nil
   end
end

function typesetter:outputLinesToPage (lines)
   SU.debug("pagebuilder", "OUTPUTTING frame", self.frame.id)
   -- It would have been nice to avoid storing this "pastTop" into a frame
   -- state, to keep things less entangled. There are situations, though,
   -- we will have left horizontal mode (triggering output), but will later
   -- call typesetter:chuck() do deal with any remaining content, and we need
   -- to know whether some content has been output already.
   local pastTop = self.frame.state.totals.pastTop
   for _, line in ipairs(lines) do
      -- Ignore discardable and explicit glues at the top of a frame:
      -- Annoyingly, explicit glue *should* disappear at the top of a page.
      -- if you don't want that, add an empty vbox or something.
      if not pastTop and not line.discardable and not line.explicit then
         -- Note the test here doesn't check is_vglue, so will skip other
         -- discardable nodes (e.g. penalties), but it shouldn't matter
         -- for outputting.
         pastTop = true
      end
      if pastTop then
         line:outputYourself(self, line)
      end
   end
   self.frame.state.totals.pastTop = pastTop
end

function typesetter:leaveHmode (independent)
   if self.state.hmodeOnly then
      -- HACK HBOX
      -- This should likely be an error, but may break existing uses
      -- (although these are probably already defective).
      -- See also comment HACK HBOX in typesetter:makeHbox().
      SU.warn([[Building paragraphs in this context may have unpredictable results.
It will likely break in future versions]])
   end
   SU.debug("typesetter", "Leaving hmode")
   local margins = self:getMargins()
   local vboxlist = self:boxUpNodes()
   self.state.nodes = {}
   -- Push output lines into boxes and ship them to the page builder
   for _, vbox in ipairs(vboxlist) do
      vbox.margins = margins
      self:pushVertical(vbox)
   end
   if independent then
      return
   end
   if self:buildPage() then
      self:initNextFrame()
   end
end

function typesetter:inhibitLeading ()
   self.state.previousVbox = nil
end

function typesetter.leadingFor (_, vbox, previous)
   -- Insert leading
   SU.debug("typesetter", "   Considering leading between two lines:")
   SU.debug("typesetter", "   1)", previous)
   SU.debug("typesetter", "   2)", vbox)
   if not previous then
      return SILE.nodefactory.vglue()
   end
   local prevDepth = previous.depth
   SU.debug("typesetter", "   Depth of previous line was", prevDepth)
   local bls = SILE.settings:get("document.baselineskip")
   local depth = bls.height:absolute() - vbox.height:absolute() - prevDepth:absolute()
   SU.debug("typesetter", "   Leading height =", bls.height, "-", vbox.height, "-", prevDepth, "=", depth)

   -- the lineskip setting is a vglue, but we need a version absolutized at this point, see #526
   local lead = SILE.settings:get("document.lineskip").height:absolute()
   if depth > lead then
      return SILE.nodefactory.vglue(SILE.length(depth.length, bls.height.stretch, bls.height.shrink))
   else
      return SILE.nodefactory.vglue(lead)
   end
end

function typesetter:addrlskip (slice, margins, hangLeft, hangRight)
   local LTR = self.frame:writingDirection() == "LTR"
   local rskip = margins[LTR and "rskip" or "lskip"]
   if not rskip then
      rskip = SILE.nodefactory.glue(0)
   end
   if hangRight and hangRight > 0 then
      rskip = SILE.nodefactory.glue({ width = rskip.width:tonumber() + hangRight })
   end
   rskip.value = "margin"
   -- while slice[#slice].discardable do table.remove(slice, #slice) end
   table.insert(slice, rskip)
   table.insert(slice, SILE.nodefactory.zerohbox())
   local lskip = margins[LTR and "lskip" or "rskip"]
   if not lskip then
      lskip = SILE.nodefactory.glue(0)
   end
   if hangLeft and hangLeft > 0 then
      lskip = SILE.nodefactory.glue({ width = lskip.width:tonumber() + hangLeft })
   end
   lskip.value = "margin"
   while slice[1].discardable do
      table.remove(slice, 1)
   end
   table.insert(slice, 1, lskip)
   table.insert(slice, 1, SILE.nodefactory.zerohbox())
end

function typesetter:breakpointsToLines (breakpoints)
   local linestart = 1
   local lines = {}
   local nodes = self.state.nodes

   for i = 1, #breakpoints do
      local point = breakpoints[i]
      if point.position ~= 0 then
         local slice = {}
         local seenNonDiscardable = false
         for j = linestart, point.position do
            slice[#slice + 1] = nodes[j]
            if nodes[j] then
               if not nodes[j].discardable then
                  seenNonDiscardable = true
               end
            end
         end
         if not seenNonDiscardable then
            -- Slip lines containing only discardable nodes (e.g. glues).
            SU.debug("typesetter", "Skipping a line containing only discardable nodes")
            linestart = point.position + 1
         else
            -- If the line ends with a discretionary, repeat it on the next line,
            -- so as to account for a potential postbreak.
            if slice[#slice].is_discretionary then
               linestart = point.position
            else
               linestart = point.position + 1
            end

            -- Then only we can add some extra margin glue...
            local mrg = self:getMargins()
            self:addrlskip(slice, mrg, point.left, point.right)

            -- And compute the line...
            local ratio = self:computeLineRatio(point.width, slice)
            local thisLine = { ratio = ratio, nodes = slice }
            lines[#lines + 1] = thisLine
         end
      end
   end
   if linestart < #nodes then
      -- Abnormal, but warn so that one has a chance to check which bits
      -- are missing at output.
      SU.warn("Internal typesetter error " .. (#nodes - linestart) .. " skipped nodes")
   end
   return lines
end

function typesetter.computeLineRatio (_, breakwidth, slice)
   -- This somewhat wrong, see #1362 and #1528
   -- This is a somewhat partial workaround, at least made consistent with
   -- the nnode and discretionary outputYourself routines
   -- (which are somewhat wrong too, or to put it otherwise, the whole
   -- logic here, marking nodes without removing/replacing them, likely makes
   -- things more complex than they should).
   -- TODO Possibly consider a full rewrite/refactor.
   local naturalTotals = SILE.length()

   -- From the line end, check if the line is hyphenated (to account for a prebreak)
   -- or contains extraneous glues (e.g. to account for spaces to ignore).
   local n = #slice
   while n > 1 do
      if slice[n].is_glue or slice[n].is_zero then
         -- Skip margin glues (they'll be accounted for in the loop below) and
         -- zero boxes, so as to reach actual content...
         if slice[n].value ~= "margin" then
            -- ... but any other glue than a margin, at the end of a line, is actually
            -- extraneous. It will however also be accounted for below, so subtract
            -- them to cancel their width. Typically, if a line break occurred at
            -- a space, the latter is then at the end of the line now, and must be
            -- ignored.
            naturalTotals:___sub(slice[n].width)
         end
      elseif slice[n].is_discretionary then
         -- Stop as we reached an hyphenation, and account for the prebreak.
         slice[n].used = true
         if slice[n].parent then
            slice[n].parent.hyphenated = true
         end
         naturalTotals:___add(slice[n]:prebreakWidth())
         slice[n].height = slice[n]:prebreakHeight()
         break
      else
         -- Stop as we reached actual content.
         break
      end
      n = n - 1
   end

   local seenNodes = {}
   local skipping = true
   for i, node in ipairs(slice) do
      if node.is_box then
         skipping = false
         if node.parent and not node.parent.hyphenated then
            if not seenNodes[node.parent] then
               naturalTotals:___add(node.parent:lineContribution())
            end
            seenNodes[node.parent] = true
         else
            naturalTotals:___add(node:lineContribution())
         end
      elseif node.is_penalty and node.penalty == -inf_bad then
         skipping = false
      elseif node.is_discretionary then
         skipping = false
         local seen = node.parent and seenNodes[node.parent]
         if not seen and not node.used then
            naturalTotals:___add(node:replacementWidth():absolute())
            slice[i].height = slice[i]:replacementHeight():absolute()
         end
      elseif not skipping then
         naturalTotals:___add(node.width)
      end
   end

   -- From the line start, skip glues and margins, and check if it then starts
   -- with a used discretionary. If so, account for a postbreak.
   n = 1
   while n < #slice do
      if slice[n].is_discretionary and slice[n].used then
         naturalTotals:___add(slice[n]:postbreakWidth())
         slice[n].height = slice[n]:postbreakHeight()
         break
      elseif not (slice[n].is_glue or slice[n].is_zero) then
         break
      end
      n = n + 1
   end

   local _left = breakwidth:tonumber() - naturalTotals:tonumber()
   local ratio = _left / naturalTotals[_left < 0 and "shrink" or "stretch"]:tonumber()
   ratio = math.max(ratio, -1)
   return ratio, naturalTotals
end

function typesetter:chuck () -- emergency shipout everything
   self:leaveHmode(true)
   if #self.state.outputQueue > 0 then
      SU.debug("typesetter", "Emergency shipout", #self.state.outputQueue, "lines in frame", self.frame.id)
      self:outputLinesToPage(self.state.outputQueue)
      self.state.outputQueue = {}
   end
end

-- Logic for building an hbox from content.
-- It returns the hbox and an horizontal list of (migrating) elements
-- extracted outside of it.
-- None of these are pushed to the typesetter node queue. The caller
-- is responsible of doing it, if the hbox is built for anything
-- else than e.g. measuring it. Likewise, the call has to decide
-- what to do with the migrating content.
local _rtl_pre_post = function (box, atypesetter, line)
   local advance = function ()
      atypesetter.frame:advanceWritingDirection(box:scaledWidth(line))
   end
   if atypesetter.frame:writingDirection() == "RTL" then
      advance()
      return function () end
   else
      return advance
   end
end
function typesetter:makeHbox (content)
   local recentContribution = {}
   local migratingNodes = {}

   -- HACK HBOX
   -- This is from the original implementation.
   -- It would be somewhat cleaner to use a temporary typesetter state
   -- (pushState/popState) rather than using the current one, removing
   -- the processed nodes from it afterwards. However, as long
   -- as leaving horizontal mode is not strictly forbidden here, it would
   -- lead to a possibly different result (the output queue being skipped).
   -- See also HACK HBOX comment in typesetter:leaveHmode().
   local index = #self.state.nodes + 1
   self.state.hmodeOnly = true
   SILE.process(content)
   self.state.hmodeOnly = false -- Wouldn't be needed in a temporary state

   local l = SILE.length()
   local h, d = SILE.length(), SILE.length()
   for i = index, #self.state.nodes do
      local node = self.state.nodes[i]
      if node.is_migrating then
         migratingNodes[#migratingNodes + 1] = node
      elseif node.is_unshaped then
         local shape = node:shape()
         for _, attr in ipairs(shape) do
            recentContribution[#recentContribution + 1] = attr
            h = attr.height > h and attr.height or h
            d = attr.depth > d and attr.depth or d
            l = l + attr:lineContribution():absolute()
         end
      elseif node.is_discretionary then
         -- HACK https://github.com/sile-typesetter/sile/issues/583
         -- Discretionary nodes have a null line contribution...
         -- But if discretionary nodes occur inside an hbox, since the latter
         -- is not line-broken, they will never be marked as 'used' and will
         -- evaluate to the replacement content (if any)...
         recentContribution[#recentContribution + 1] = node
         l = l + node:replacementWidth():absolute()
         -- The replacement content may have ascenders and descenders...
         local hdisc = node:replacementHeight():absolute()
         local ddisc = node:replacementDepth():absolute()
         h = hdisc > h and hdisc or h
         d = ddisc > d and ddisc or d
      -- By the way it's unclear how this is expected to work in TTB
      -- writing direction. For other type of nodes, the line contribution
      -- evaluates to the height rather than the width in TTB, but the
      -- whole logic might then be dubious there too...
      else
         recentContribution[#recentContribution + 1] = node
         l = l + node:lineContribution():absolute()
         h = node.height > h and node.height or h
         d = node.depth > d and node.depth or d
      end
      self.state.nodes[i] = nil -- wouldn't be needed in a temporary state
   end

   local hbox = SILE.nodefactory.hbox({
      height = h,
      width = l,
      depth = d,
      value = recentContribution,
      outputYourself = function (box, atypesetter, line)
         local _post = _rtl_pre_post(box, atypesetter, line)
         local ox = atypesetter.frame.state.cursorX
         local oy = atypesetter.frame.state.cursorY
         SILE.outputter:setCursor(atypesetter.frame.state.cursorX, atypesetter.frame.state.cursorY)
         for _, node in ipairs(box.value) do
            node:outputYourself(atypesetter, line)
         end
         atypesetter.frame.state.cursorX = ox
         atypesetter.frame.state.cursorY = oy
         _post()
         SU.debug("hboxes", function ()
            SILE.outputter:debugHbox(box, box:scaledWidth(line))
            return "Drew debug outline around hbox"
         end)
      end,
   })
   return hbox, migratingNodes
end

function typesetter:pushHlist (hlist)
   for _, h in ipairs(hlist) do
      self:pushHorizontal(h)
   end
end

return typesetter

sile-typesetter / sile / 9304060604

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