sile 0.15.11

SILE.settings:declare({
   parameter = "linebreak.parShape",
   type = "boolean",
   default = false,
   help = "If set to true, the paragraph shaping method is activated.",
})
SILE.settings:declare({ parameter = "linebreak.tolerance", type = "integer or nil", default = 500 })
SILE.settings:declare({ parameter = "linebreak.pretolerance", type = "integer or nil", default = 100 })
SILE.settings:declare({ parameter = "linebreak.hangIndent", type = "measurement", default = 0 })
SILE.settings:declare({ parameter = "linebreak.hangAfter", type = "integer or nil", default = nil })
SILE.settings:declare({
   parameter = "linebreak.adjdemerits",
   type = "integer",
   default = 10000,
   help = "Additional demerits which are accumulated in the course of paragraph building when two consecutive lines are visually incompatible. In these cases, one line is built with much space for justification, and the other one with little space.",
})
SILE.settings:declare({ parameter = "linebreak.looseness", type = "integer", default = 0 })
SILE.settings:declare({ parameter = "linebreak.prevGraf", type = "integer", default = 0 })
SILE.settings:declare({ parameter = "linebreak.emergencyStretch", type = "measurement", default = 0 })
SILE.settings:declare({ parameter = "linebreak.doLastLineFit", type = "boolean", default = false }) -- unimplemented
SILE.settings:declare({ parameter = "linebreak.linePenalty", type = "integer", default = 10 })
SILE.settings:declare({ parameter = "linebreak.hyphenPenalty", type = "integer", default = 50 })
SILE.settings:declare({ parameter = "linebreak.doubleHyphenDemerits", type = "integer", default = 10000 })
SILE.settings:declare({ parameter = "linebreak.finalHyphenDemerits", type = "integer", default = 5000 })

-- doubleHyphenDemerits
-- hyphenPenalty

local classes = { "tight", "decent", "loose", "veryLoose" }
local passSerial = 0
local awful_bad = 1073741823
local inf_bad = 10000
local ejectPenalty = -inf_bad
local lineBreak = {}

--[[
  Basic control flow:
  doBreak:
    init
    for each node:
      checkForLegalBreak
        tryBreak
          createNewActiveNodes
          considerDemerits
            deactivateR (or) recordFeasible
    tryFinalBreak
    postLineBreak
]]

local param = function (key)
   local value = SILE.settings:get("linebreak." .. key)
   return type(value) == "table" and value:absolute() or value
end

-- Routines here will be called thousands of times; we micro-optimize
-- to avoid debugging and concat calls.
local debugging = false

function lineBreak:init ()
   self:trimGlue() -- 842
   -- 849
   self.activeWidth = SILE.types.length()
   self.curActiveWidth = SILE.types.length()
   self.breakWidth = SILE.types.length()
   -- 853
   local rskip = (SILE.settings:get("document.rskip") or SILE.types.node.glue()).width:absolute()
   local lskip = (SILE.settings:get("document.lskip") or SILE.types.node.glue()).width:absolute()
   self.background = rskip + lskip
   -- 860
   self.bestInClass = {}
   for i = 1, #classes do
      self.bestInClass[classes[i]] = {
         minimalDemerits = awful_bad,
      }
   end
   self.minimumDemerits = awful_bad
   self:setupLineLengths()
end

function lineBreak:trimGlue () -- 842
   local nodes = self.nodes
   if nodes[#nodes].is_glue then
      nodes[#nodes] = nil
   end
   nodes[#nodes + 1] = SILE.types.node.penalty(inf_bad)
end

-- NOTE FOR DEVELOPERS: this method is called when the linebreak.parShape
-- setting is true. The arguments passed are self (the linebreaker instance)
-- and a counter representing the current line number.
--
-- The default implementation does nothing but waste a function call, resulting
-- in normal paragraph shapes. Extended paragraph shapes are intended to be
-- provided by overriding this method.
--
-- The expected return is three values, any of which may be nil to use default
-- values or a measurement to override the defaults. The values are considered
-- as left, width, and right respectively.
--
-- Since self.hsize holds the current line width, these three values should add
-- up to the that total. Returning values that don't add up may produce
-- unexpected results.
--
-- TeX wizards shall also note that this is slightly different from
-- Knuth's definition "nline l1 i1 l2 i2 ... lN iN".
function lineBreak:parShape (_)
   return 0, self.hsize, 0
end

local parShapeCache = {}

local grantLeftoverWidth = function (hsize, l, w, r)
   local width = SILE.types.measurement(w or hsize)
   if not w and l then
      width = width - SILE.types.measurement(l)
   end
   if not w and r then
      width = width - SILE.types.measurement(r)
   end
   local remaining = hsize:tonumber() - width:tonumber()
   local left = SU.cast("number", l or (r and (remaining - SU.cast("number", r))) or 0)
   local right = SU.cast("number", r or (l and (remaining - SU.cast("number", l))) or remaining)
   return left, width, right
end

-- Wrap linebreak:parShape in a memoized table for fast access
function lineBreak:parShapeCache (n)
   local cache = parShapeCache[n]
   if not cache then
      local l, w, r = self:parShape(n)
      local left, width, right = grantLeftoverWidth(self.hsize, l, w, r)
      cache = { left, width, right }
   end
   return cache[1], cache[2], cache[3]
end

function lineBreak:parShapeCacheClear ()
   pl.tablex.clear(parShapeCache)
end

function lineBreak:setupLineLengths () -- 874
   self.parShaping = param("parShape") or false
   if self.parShaping then
      self.lastSpecialLine = nil
      self.easy_line = nil
   else
      self.hangAfter = param("hangAfter") or 0
      self.hangIndent = param("hangIndent"):tonumber()
      if self.hangIndent == 0 then
         self.lastSpecialLine = 0
         self.secondWidth = self.hsize or SU.error("No hsize")
      else -- 875
         self.lastSpecialLine = math.abs(self.hangAfter)
         if self.hangAfter < 0 then
            self.secondWidth = self.hsize or SU.error("No hsize")
            self.firstWidth = self.hsize - math.abs(self.hangIndent)
         else
            self.firstWidth = self.hsize or SU.error("No hsize")
            self.secondWidth = self.hsize - math.abs(self.hangIndent)
         end
      end
      if param("looseness") == 0 then
         self.easy_line = self.lastSpecialLine
      else
         self.easy_line = awful_bad
      end
      -- self.easy_line = awful_bad
   end
end

function lineBreak:tryBreak () -- 855
   local pi, breakType
   local node = self.nodes[self.place]
   if not node then
      pi = ejectPenalty
      breakType = "hyphenated"
   elseif node.is_discretionary then
      breakType = "hyphenated"
      pi = param("hyphenPenalty")
   else
      breakType = "unhyphenated"
      pi = node.penalty or 0
   end
   if debugging then
      SU.debug("break", "Trying a", breakType, "break p =", pi)
   end
   self.no_break_yet = true -- We have to store all this state crap in the object, or it's global variables all the way
   self.prev_prev_r = nil
   self.prev_r = self.activeListHead
   self.old_l = 0
   self.r = nil
   self.curActiveWidth = SILE.types.length(self.activeWidth)
   while true do
      while true do -- allows "break" to function as "continue"
         self.r = self.prev_r.next
         if debugging then
            SU.debug(
               "break",
               "We have moved the link  forward, ln is now",
               self.r.type == "delta" and "XX" or self.r.lineNumber
            )
         end
         if self.r.type == "delta" then -- 858
            if debugging then
               SU.debug("break", " Adding delta node width of", self.r.width)
            end
            self.curActiveWidth:___add(self.r.width)
            self.prev_prev_r = self.prev_r
            self.prev_r = self.r
            break
         end
         -- 861
         if self.r.lineNumber > self.old_l then
            if debugging then
               SU.debug("break", "Minimum demerits =", self.minimumDemerits)
            end
            if self.minimumDemerits < awful_bad and (self.old_l ~= self.easy_line or self.r == self.activeListHead) then
               self:createNewActiveNodes(breakType)
            end
            if self.r == self.activeListHead then
               if debugging then
                  SU.debug("break", "<- tryBreak")
               end
               return
            end
            -- 876
            if self.easy_line and self.r.lineNumber > self.easy_line then
               self.lineWidth = self.secondWidth
               self.old_l = awful_bad - 1
            else
               self.old_l = self.r.lineNumber
               if self.lastSpecialLine and self.r.lineNumber > self.lastSpecialLine then
                  self.lineWidth = self.secondWidth
               elseif self.parShaping then
                  local _
                  _, self.lineWidth, _ = self:parShapeCache(self.r.lineNumber)
               else
                  self.lineWidth = self.firstWidth
               end
            end
            if debugging then
               SU.debug("break", "line width =", self.lineWidth)
            end
         end
         if debugging then
            SU.debug("break", " ---> (2) cuaw is", self.curActiveWidth)
            SU.debug("break", " ---> aw is", self.activeWidth)
         end
         self:considerDemerits(pi, breakType)
         if debugging then
            SU.debug("break", " <--- cuaw is", self.curActiveWidth)
            SU.debug("break", " <--- aw is ", self.activeWidth)
         end
      end
   end
end

-- Note: This function gets called a lot and to optimize it we're assuming that
-- the lengths being passed are already absolutized. This is not a safe
-- assumption to make universally.
local function fitclass (self, shortfall)
   shortfall = shortfall.amount
   local badness, class
   local stretch = self.curActiveWidth.stretch.amount
   local shrink = self.curActiveWidth.shrink.amount
   if shortfall > 0 then
      if shortfall > 110 and stretch < 25 then
         badness = inf_bad
      else
         badness = SU.rateBadness(inf_bad, shortfall, stretch)
      end
      if badness > 99 then
         class = "veryLoose"
      elseif badness > 12 then
         class = "loose"
      else
         class = "decent"
      end
   else
      shortfall = -shortfall
      if shortfall > shrink then
         badness = inf_bad + 1
      else
         badness = SU.rateBadness(inf_bad, shortfall, shrink)
      end
      if badness > 12 then
         class = "tight"
      else
         class = "decent"
      end
   end
   return badness, class
end

function lineBreak:tryAlternatives (from, to)
   local altSizes = {}
   local alternates = {}
   for i = from, to do
      if self.nodes[i] and self.nodes[i].is_alternative then
         alternates[#alternates + 1] = self.nodes[i]
         altSizes[#altSizes + 1] = #self.nodes[i].options
      end
   end
   if #alternates == 0 then
      return
   end
   local localMinimum = awful_bad
   -- local selectedShortfall
   local shortfall = self.lineWidth - self.curActiveWidth
   if debugging then
      SU.debug("break", "Shortfall was ", shortfall)
   end
   for combination in SU.allCombinations(altSizes) do
      local addWidth = 0
      for i = 1, #alternates do
         local alternative = alternates[i]
         addWidth = (addWidth + alternative.options[combination[i]].width - alternative:minWidth())
         if debugging then
            SU.debug("break", alternative.options[combination[i]], " width", addWidth)
         end
      end
      local ss = shortfall - addWidth
      -- Warning, assumes abosolute
      local badness =
         SU.rateBadness(inf_bad, ss.length.amount, self.curActiveWidth[ss > 0 and "stretch" or "shrink"].length.amount)
      if debugging then
         SU.debug("break", "  badness of", ss, "(", self.curActiveWidth, ") is", badness)
      end
      if badness < localMinimum then
         self.r.alternates = alternates
         self.r.altSelections = combination
         -- selectedShortfall = addWidth
         localMinimum = badness
      end
   end
   if debugging then
      SU.debug("break", "Choosing ", alternates[1].options[self.r.altSelections[1]])
   end
   -- self.curActiveWidth:___add(selectedShortfall)
   shortfall = self.lineWidth - self.curActiveWidth
   if debugging then
      SU.debug("break", "Is now ", shortfall)
   end
end

function lineBreak:considerDemerits (pi, breakType) -- 877
   self.artificialDemerits = false
   local nodeStaysActive = false
   -- self:dumpActiveRing()
   if self.seenAlternatives then
      self:tryAlternatives(
         self.r.prevBreak and self.r.prevBreak.curBreak or 1,
         self.r.curBreak and self.r.curBreak or 1
      )
   end
   local shortfall = self.lineWidth - self.curActiveWidth
   self.badness, self.fitClass = fitclass(self, shortfall)
   if debugging then
      SU.debug("break", self.badness, self.fitClass)
   end
   if self.badness > inf_bad or pi == ejectPenalty then
      if
         self.finalpass
         and self.minimumDemerits == awful_bad
         and self.r.next == self.activeListHead
         and self.prev_r == self.activeListHead
      then
         self.artificialDemerits = true
      else
         if self.badness > self.threshold then
            self:deactivateR()
            return
         end
      end
   else
      self.prev_r = self.r
      if self.badness > self.threshold then
         return
      end
      nodeStaysActive = true
   end

   local _shortfall = shortfall:tonumber()
   local function shortfallratio (metric)
      local prop = self.curActiveWidth[metric]:tonumber()
      local factor = prop ~= 0 and prop or awful_bad
      return _shortfall / factor
   end
   self.lastRatio = shortfallratio(_shortfall > 0 and "stretch" or "shrink")
   self:recordFeasible(pi, breakType)
   if not nodeStaysActive then
      self:deactivateR()
   end
end

function lineBreak:deactivateR () -- 886
   if debugging then
      SU.debug("break", " Deactivating r (" .. self.r.type .. ")")
   end
   self.prev_r.next = self.r.next
   if self.prev_r == self.activeListHead then
      -- 887
      self.r = self.activeListHead.next
      if self.r.type == "delta" then
         self.activeWidth:___add(self.r.width)
         self.curActiveWidth = SILE.types.length(self.activeWidth)
         self.activeListHead.next = self.r.next
      end
      if debugging then
         SU.debug("break", "  Deactivate, branch 1")
      end
   else
      if self.prev_r.type == "delta" then
         self.r = self.prev_r.next
         if self.r == self.activeListHead then
            self.curActiveWidth:___sub(self.prev_r.width)
            -- FIXME It was crashing here, so changed from:
            -- self.curActiveWidth:___sub(self.r.width)
            -- But I'm not so sure reading Knuth here...
            self.prev_prev_r.next = self.activeListHead
            self.prev_r = self.prev_prev_r
         elseif self.r.type == "delta" then
            self.curActiveWidth:___add(self.r.width)
            self.prev_r.width:___add(self.r.width)
            self.prev_r.next = self.r.next
         end
      end
      if debugging then
         SU.debug("break", "  Deactivate, branch 2")
      end
   end
end

function lineBreak:computeDemerits (pi, breakType)
   if self.artificialDemerits then
      return 0
   end
   local demerit = param("linePenalty") + self.badness
   if math.abs(demerit) >= 10000 then
      demerit = 100000000
   else
      demerit = demerit * demerit
   end
   if pi > 0 then
      demerit = demerit + pi * pi
   -- elseif pi == 0 then
   --   -- do nothing
   elseif pi > ejectPenalty then
      demerit = demerit - pi * pi
   end
   if breakType == "hyphenated" and self.r.type == "hyphenated" then
      if self.nodes[self.place] then
         demerit = demerit + param("doubleHyphenDemerits")
      else
         demerit = demerit + param("finalHyphenDemerits")
      end
   end
   -- XXX adjDemerits not added here
   return demerit
end

function lineBreak:recordFeasible (pi, breakType) -- 881
   local demerit = lineBreak:computeDemerits(pi, breakType)
   if debugging then
      if self.nodes[self.place] then
         SU.debug(
            "break",
            "@",
            self.nodes[self.place],
            "via @@",
            (self.r.serial or "0"),
            "badness =",
            self.badness,
            "demerit =",
            demerit
         ) -- 882
      else
         SU.debug("break", "@ \\par via @@")
      end
      SU.debug("break", " fit class =", self.fitClass)
   end
   demerit = demerit + self.r.totalDemerits
   if demerit <= self.bestInClass[self.fitClass].minimalDemerits then
      self.bestInClass[self.fitClass] = {
         minimalDemerits = demerit,
         node = self.r.serial and self.r,
         line = self.r.lineNumber,
      }
      -- XXX do last line fit
      if demerit < self.minimumDemerits then
         self.minimumDemerits = demerit
      end
   end
end

function lineBreak:createNewActiveNodes (breakType) -- 862
   if self.no_break_yet then
      -- 863
      self.no_break_yet = false
      self.breakWidth = SILE.types.length(self.background)
      local place = self.place
      local node = self.nodes[place]
      if node and node.is_discretionary then -- 866
         self.breakWidth:___add(node:prebreakWidth())
         self.breakWidth:___add(node:postbreakWidth())
         self.breakWidth:___sub(node:replacementWidth())
      end
      while self.nodes[place] and not self.nodes[place].is_box do
         if self.sideways and self.nodes[place].height then
            self.breakWidth:___sub(self.nodes[place].height)
            self.breakWidth:___sub(self.nodes[place].depth)
         elseif self.nodes[place].width then -- We use the fact that (a) nodes know if they have width and (b) width subtraction is polymorphic
            self.breakWidth:___sub(self.nodes[place]:lineContribution())
         end
         place = place + 1
      end
      if debugging then
         SU.debug("break", "Value of breakWidth =", self.breakWidth)
      end
   end
   -- 869 (Add a new delta node)
   if self.prev_r.type == "delta" then
      self.prev_r.width:___sub(self.curActiveWidth)
      self.prev_r.width:___add(self.breakWidth)
   elseif self.prev_r == self.activeListHead then
      self.activeWidth = SILE.types.length(self.breakWidth)
   else
      local newDelta = { next = self.r, type = "delta", width = self.breakWidth - self.curActiveWidth }
      if debugging then
         SU.debug("break", "Added new delta node =", newDelta.width)
      end
      self.prev_r.next = newDelta
      self.prev_prev_r = self.prev_r
      self.prev_r = newDelta
   end
   if math.abs(self.adjdemerits) >= (awful_bad - self.minimumDemerits) then
      self.minimumDemerits = awful_bad - 1
   else
      self.minimumDemerits = self.minimumDemerits + math.abs(self.adjdemerits)
   end

   for i = 1, #classes do
      local class = classes[i]
      local best = self.bestInClass[class]
      local value = best.minimalDemerits
      if debugging then
         SU.debug("break", "Class is", class, "Best value here is", value)
      end

      if value <= self.minimumDemerits then
         -- 871: this is what creates new active notes
         passSerial = passSerial + 1

         local newActive = {
            type = breakType,
            next = self.r,
            curBreak = self.place,
            prevBreak = best.node,
            serial = passSerial,
            ratio = self.lastRatio,
            lineNumber = best.line + 1,
            fitness = class,
            totalDemerits = value,
         }
         -- DoLastLineFit? 1636 XXX
         self.prev_r.next = newActive
         self.prev_r = newActive
         self:dumpBreakNode(newActive)
      end
      self.bestInClass[class] = { minimalDemerits = awful_bad }
   end

   self.minimumDemerits = awful_bad
   -- 870
   if self.r ~= self.activeListHead then
      local newDelta = { next = self.r, type = "delta", width = self.curActiveWidth - self.breakWidth }
      self.prev_r.next = newDelta
      self.prev_prev_r = self.prev_r
      self.prev_r = newDelta
   end
end

function lineBreak:dumpBreakNode (node)
   if not SU.debugging("break") then
      return
   end
   SU.debug("break", lineBreak:describeBreakNode(node))
end

function lineBreak:describeBreakNode (node)
   --SU.debug("break", "@@", b.serial, ": line", b.lineNumber - 1, ".", b.fitness, b.type, "t=", b.totalDemerits, "-> @@", b.prevBreak and b.prevBreak.serial or "0")
   if node.sentinel then
      return node.sentinel
   end
   if node.type == "delta" then
      return "delta " .. node.width .. "pt"
   end
   local before = self.nodes[node.curBreak - 1]
   local after = self.nodes[node.curBreak + 1]
   local from = node.prevBreak and node.prevBreak.curBreak or 1
   local to = node.curBreak
   return ('b %s-%s "%s | %s" [%s, %s]'):format(
      from,
      to,
      before and before:toText() or "",
      after and after:toText() or "",
      node.totalDemerits,
      node.fitness
   )
end

-- NOTE: this function is called many thousands of times even in single
-- page documents. Speed is more important than pretty code here.
function lineBreak:checkForLegalBreak (node) -- 892
   if debugging then
      SU.debug("break", "considering node " .. node)
   end
   local previous = self.nodes[self.place - 1]
   if node.is_alternative then
      self.seenAlternatives = true
   end
   if self.sideways and node.is_box then
      self.activeWidth:___add(node.height)
      self.activeWidth:___add(node.depth)
   elseif self.sideways and node.is_vglue then
      if previous and previous.is_box then
         self:tryBreak()
      end
      self.activeWidth:___add(node.height)
      self.activeWidth:___add(node.depth)
   elseif node.is_alternative then
      self.activeWidth:___add(node:minWidth())
   elseif node.is_box then
      self.activeWidth:___add(node:lineContribution())
   elseif node.is_glue then
      -- 894 (We removed the auto_breaking parameter)
      if previous and previous.is_box then
         self:tryBreak()
      end
      self.activeWidth:___add(node.width)
   elseif node.is_kern then
      self.activeWidth:___add(node.width)
   elseif node.is_discretionary then -- 895
      self.activeWidth:___add(node:prebreakWidth())
      self:tryBreak()
      self.activeWidth:___sub(node:prebreakWidth())
      self.activeWidth:___add(node:replacementWidth())
   elseif node.is_penalty then
      self:tryBreak()
   end
end

function lineBreak:tryFinalBreak () -- 899
   -- XXX TeX has self:tryBreak() here. But this doesn't seem to work
   -- for us. If we call tryBreak(), we end up demoting all break points
   -- to veryLoose (possibly because the active width gets reset - why?).
   -- This means we end up doing unnecessary passes.
   -- However, there doesn't seem to be any downside to not calling it
   -- (how scary is that?) so I have removed it for now. With this
   -- "fix", we only perform hyphenation and emergency passes when necessary
   -- instead of every single time. If things go strange with the break
   -- algorithm in the future, this should be the first place to look!
   -- self:tryBreak()
   if self.activeListHead.next == self.activeListHead then
      return
   end
   self.r = self.activeListHead.next
   local fewestDemerits = awful_bad
   repeat
      if self.r.type ~= "delta" and self.r.totalDemerits < fewestDemerits then
         fewestDemerits = self.r.totalDemerits
         self.bestBet = self.r
      end
      self.r = self.r.next
   until self.r == self.activeListHead
   if param("looseness") == 0 then
      return true
   end
   -- XXX node 901 not implemented
   if self.actualLooseness == param("looseness") or self.finalpass then
      return true
   end
end

function lineBreak:doBreak (nodes, hsize, sideways)
   passSerial = 1
   debugging = SILE.debugFlags["break"]
   self.seenAlternatives = false
   self.nodes = nodes
   self.hsize = hsize
   self.sideways = sideways
   self:init()
   self.adjdemerits = param("adjdemerits")
   self.threshold = param("pretolerance")
   if self.threshold >= 0 then
      self.pass = "first"
      self.finalpass = false
   else
      self.threshold = param("tolerance")
      self.pass = "second"
      self.finalpass = param("emergencyStretch") <= 0
   end
   -- 889
   while 1 do
      if debugging then
         SU.debug("break", "@", self.pass, "pass")
      end
      if self.threshold > inf_bad then
         self.threshold = inf_bad
      end
      if self.pass == "second" then
         self.nodes = SILE.hyphenate(self.nodes)
         SILE.typesetter.state.nodes = self.nodes -- Horrible breaking of separation of concerns here. :-(
      end
      -- 890
      self.activeListHead = {
         sentinel = "START",
         type = "hyphenated",
         lineNumber = awful_bad,
         subtype = 0,
      } -- 846
      self.activeListHead.next = {
         sentinel = "END",
         type = "unhyphenated",
         fitness = "decent",
         next = self.activeListHead,
         lineNumber = param("prevGraf") + 1,
         totalDemerits = 0,
      }

      -- Not doing 1630
      self.activeWidth = SILE.types.length(self.background)

      self.place = 1
      while self.nodes[self.place] and self.activeListHead.next ~= self.activeListHead do
         self:checkForLegalBreak(self.nodes[self.place])
         self.place = self.place + 1
      end
      if self.place > #self.nodes then
         if self:tryFinalBreak() then
            break
         end
      end
      -- (Not doing 891)
      if self.pass ~= "second" then
         self.pass = "second"
         self.threshold = param("tolerance")
      else
         self.pass = "emergency"
         self.background.stretch:___add(param("emergencyStretch"))
         self.finalpass = true
      end
   end
   -- Not doing 1638
   return self:postLineBreak()
end

function lineBreak:postLineBreak () -- 903
   local p = self.bestBet
   local breaks = {}
   local line = 1

   local nbLines = 0
   local p2 = p
   repeat
      nbLines = nbLines + 1
      p2 = p2.prevBreak
   until not p2

   repeat
      local left, _, right
      -- SILE handles the actual line width differently than TeX,
      -- so below always return a width of self.hsize. Would they
      -- be needed at some point, the exact width are commented out
      -- below.
      if self.parShaping then
         left, _, right = self:parShapeCache(nbLines + 1 - line)
      else
         if self.hangAfter == 0 then
            -- width = self.hsize
            left = 0
            right = 0
         else
            local indent
            if self.hangAfter > 0 then
               -- width = line > nbLines - self.hangAfter and self.firstWidth or self.secondWidth
               indent = line > nbLines - self.hangAfter and 0 or self.hangIndent
            else
               -- width = line > nbLines + self.hangAfter and self.firstWidth or self.secondWidth
               indent = line > nbLines + self.hangAfter and self.hangIndent or 0
            end
            if indent > 0 then
               left = indent
               right = 0
            else
               left = 0
               right = -indent
            end
         end
      end

      table.insert(breaks, 1, {
         position = p.curBreak,
         width = self.hsize,
         left = left,
         right = right,
      })
      if p.alternates then
         for i = 1, #p.alternates do
            p.alternates[i].selected = p.altSelections[i]
            p.alternates[i].width = p.alternates[i].options[p.altSelections[i]].width
         end
      end
      p = p.prevBreak
      line = line + 1
   until not p
   self:parShapeCacheClear()
   return breaks
end

function lineBreak:dumpActiveRing ()
   local p = self.activeListHead
   if not SILE.quiet then
      io.stderr:write("\n")
   end
   repeat
      if not SILE.quiet then
         if p == self.r then
            io.stderr:write("-> ")
         else
            io.stderr:write("   ")
         end
      end
      SU.debug("break", lineBreak:describeBreakNode(p))
      p = p.next
   until p == self.activeListHead
end

return lineBreak