sile 0.14.8

Simon’s Improved Layout Engine
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local function charclass(u)
  if (u >= 0x1000 and u <= 0x102A) or u == 0x104E or u == 0x25CC or u == 0x2d then return "CI" end
  if u == 0x1039 then return "VI" end
  if u >= 0x103B and u <= 0x103E then return "ME" end
  if u == 0x1031 then return "EV" end
  if u == 0x102F or u == 0x1030 then return "LV" end
  if u == 0x102D or u == 0x102E or u == 0x1032 then return "UV" end
  if u == 0x102C or u == 0x102B then -- 0x102b added by SC because it was splitting visargas
    return "AV"
  end
  if u == 0x1036 then return "AN" end
  if u == 0x103A then return "KI" end
  if u == 0x1037 then return "LD" end
  if u == 0x1038 then return "VG" end
  if u >= 0x1040 and u <= 0x1049 then return "MD" end
  if u == 0x104A or u == 0x104B or u == 0x2c or u == 0x2e or u == 0x3a or u == 0x3b then
    return "SE"
  end
  if u == 0x104C or u == 0x104D or u == 0x104F then return "VS" end
  if u >= 0x1050 and u <= 0x1055 then return "PL" end
  if u >= 0x1056 and u <= 0x1059 then return "PV" end
  if u == 0x20 or (u >= 0x2000 and u <= 0x200b) then return "SP" end
  if u == 0x28 or u == 0x5b or u == 0x7b or u == 0xab or u== 0x2018 or u == 0x201C or u == 0x2039 then
    return "LQ"
  end
  if u == 0x29 or u == 0x5d or u == 0x7d or u == 0xbb or u== 0x2019 or u == 0x201d or u == 0x203a then
    return "RQ"
  end
  if u == 0x200c then return "NJ" end
  if u == 0x2060 or u == 0x200d then return "WJ" end
  return "OT"
end

-- "Syllable Based Dual Weight Algorithm for Line Breaking in Myanmar Unicode"
-- Keith Stribley, http://thanlwinsoft.github.io/www.thanlwinsoft.org/ThanLwinSoft/MyanmarUnicode/Parsing/my2weightLineBreakAlg1_1.pdf
local p2 = SILE.nodefactory.penalty({ penalty = -25 })
local p1 = SILE.nodefactory.penalty({ penalty = -50 })

local penaltyFor = function (ca, cb)
  if ca == "WJ" or ca == "LQ" then return end
  if cb == "RQ" or cb == "WJ" then return end
  if ca == "OT" then return p1 end
  if ca == "RQ" then return p2 end
  if cb == "LQ" then return p2 end

  if cb == "CI" then
    if ca == "AN" or ca == "KI" or ca == "LD" or ca == "VG" or ca == "PL" or ca == "PV" or ca == "RQ" then
      return p2
    end
    if ca == "MD" or ca == "SE" or ca == "VS" or ca == "SP" then
      return p1
    end
    return
  end
  if ca == "MD" and not (cb == "VI" or cb == "MD") then return p1 end
  if cb == "PL" then
    if ca == "VI" then return end
    if ca == "SE" or ca == "VB" then return p1 end
    return p2
  end
end

SILE.tokenizers.my = function(string)
  return coroutine.wrap(function()
    local lastclass = ""
    local collection = ""
    for uchar in string.gmatch(string, "([%z\1-\127\194-\244][\128-\191]*)") do
      local thiscp = SU.codepoint(uchar)
      local thisclass = charclass(thiscp)
      if thisclass == "SP" then
        coroutine.yield({ separator = uchar })
      else
        local pen = penaltyFor(lastclass, thisclass)
        if pen then
          coroutine.yield({ node = pen })
          coroutine.yield({ string = collection})
          collection = ""
        end
        collection = collection .. uchar
      end
      lastclass = thisclass
    end
    coroutine.yield({ string = collection })
  end)
end