entities.lua

-- convert numeric html entities to utf8
-- converts from stdin to stdout
-- example:  €    ->   €
-- from http://www.hpelbers.org/lua/utf8

--- Functions for dealing with HTML/XML entities.

local M = {}


local char = string.char

local function tail(n, k)
  local u, r=''
  for i=1,k do
    n,r = math.floor(n/0x40), n%0x40
    u = char(r+0x80) .. u
  end
  return u, n
end

local function to_utf8(a)
	if not a then return nil end
	local n, r, u = tonumber(a)
	if n<0x80 then												-- 1 byte
		return char(n)
	elseif n<0x800 then										-- 2 byte
		u, n = tail(n, 1)
		return char(n+0xc0) .. u
	elseif n<0x10000 then									-- 3 byte
		u, n = tail(n, 2)
		return char(n+0xe0) .. u
	elseif n<0x200000 then								-- 4 byte
		u, n = tail(n, 3)
		return char(n+0xf0) .. u
	elseif n<0x4000000 then								-- 5 byte
		u, n = tail(n, 4)
		return char(n+0xf8) .. u
	else																	-- 6 byte
		u, n = tail(n, 5)
		return char(n+0xfc) .. u
	end
end


local character_entities = {
  ["quot"] = 0x0022,
  ["amp"] = 0x0026,
  ["apos"] = 0x0027,
  ["lt"] = 0x003C,
  ["gt"] = 0x003E,
  ["nbsp"] = 160,
  ["iexcl"] = 0x00A1,
  ["cent"] = 0x00A2,
  ["pound"] = 0x00A3,
  ["curren"] = 0x00A4,
  ["yen"] = 0x00A5,
  ["brvbar"] = 0x00A6,
  ["sect"] = 0x00A7,
  ["uml"] = 0x00A8,
  ["copy"] = 0x00A9,
  ["ordf"] = 0x00AA,
  ["laquo"] = 0x00AB,
  ["not"] = 0x00AC,
  ["shy"] = 173,
  ["reg"] = 0x00AE,
  ["macr"] = 0x00AF,
  ["deg"] = 0x00B0,
  ["plusmn"] = 0x00B1,
  ["sup2"] = 0x00B2,
  ["sup3"] = 0x00B3,
  ["acute"] = 0x00B4,
  ["micro"] = 0x00B5,
  ["para"] = 0x00B6,
  ["middot"] = 0x00B7,
  ["cedil"] = 0x00B8,
  ["sup1"] = 0x00B9,
  ["ordm"] = 0x00BA,
  ["raquo"] = 0x00BB,
  ["frac14"] = 0x00BC,
  ["frac12"] = 0x00BD,
  ["frac34"] = 0x00BE,
  ["iquest"] = 0x00BF,
  ["Agrave"] = 0x00C0,
  ["Aacute"] = 0x00C1,
  ["Acirc"] = 0x00C2,
  ["Atilde"] = 0x00C3,
  ["Auml"] = 0x00C4,
  ["Aring"] = 0x00C5,
  ["AElig"] = 0x00C6,
  ["Ccedil"] = 0x00C7,
  ["Egrave"] = 0x00C8,
  ["Eacute"] = 0x00C9,
  ["Ecirc"] = 0x00CA,
  ["Euml"] = 0x00CB,
  ["Igrave"] = 0x00CC,
  ["Iacute"] = 0x00CD,
  ["Icirc"] = 0x00CE,
  ["Iuml"] = 0x00CF,
  ["ETH"] = 0x00D0,
  ["Ntilde"] = 0x00D1,
  ["Ograve"] = 0x00D2,
  ["Oacute"] = 0x00D3,
  ["Ocirc"] = 0x00D4,
  ["Otilde"] = 0x00D5,
  ["Ouml"] = 0x00D6,
  ["times"] = 0x00D7,
  ["Oslash"] = 0x00D8,
  ["Ugrave"] = 0x00D9,
  ["Uacute"] = 0x00DA,
  ["Ucirc"] = 0x00DB,
  ["Uuml"] = 0x00DC,
  ["Yacute"] = 0x00DD,
  ["THORN"] = 0x00DE,
  ["szlig"] = 0x00DF,
  ["agrave"] = 0x00E0,
  ["aacute"] = 0x00E1,
  ["acirc"] = 0x00E2,
  ["atilde"] = 0x00E3,
  ["auml"] = 0x00E4,
  ["aring"] = 0x00E5,
  ["aelig"] = 0x00E6,
  ["ccedil"] = 0x00E7,
  ["egrave"] = 0x00E8,
  ["eacute"] = 0x00E9,
  ["ecirc"] = 0x00EA,
  ["euml"] = 0x00EB,
  ["igrave"] = 0x00EC,
  ["iacute"] = 0x00ED,
  ["icirc"] = 0x00EE,
  ["iuml"] = 0x00EF,
  ["eth"] = 0x00F0,
  ["ntilde"] = 0x00F1,
  ["ograve"] = 0x00F2,
  ["oacute"] = 0x00F3,
  ["ocirc"] = 0x00F4,
  ["otilde"] = 0x00F5,
  ["ouml"] = 0x00F6,
  ["divide"] = 0x00F7,
  ["oslash"] = 0x00F8,
  ["ugrave"] = 0x00F9,
  ["uacute"] = 0x00FA,
  ["ucirc"] = 0x00FB,
  ["uuml"] = 0x00FC,
  ["yacute"] = 0x00FD,
  ["thorn"] = 0x00FE,
  ["yuml"] = 0x00FF,
  ["OElig"] = 0x0152,
  ["oelig"] = 0x0153,
  ["Scaron"] = 0x0160,
  ["scaron"] = 0x0161,
  ["Yuml"] = 0x0178,
  ["fnof"] = 0x0192,
  ["circ"] = 0x02C6,
  ["tilde"] = 0x02DC,
  ["Alpha"] = 0x0391,
  ["Beta"] = 0x0392,
  ["Gamma"] = 0x0393,
  ["Delta"] = 0x0394,
  ["Epsilon"] = 0x0395,
  ["Zeta"] = 0x0396,
  ["Eta"] = 0x0397,
  ["Theta"] = 0x0398,
  ["Iota"] = 0x0399,
  ["Kappa"] = 0x039A,
  ["Lambda"] = 0x039B,
  ["Mu"] = 0x039C,
  ["Nu"] = 0x039D,
  ["Xi"] = 0x039E,
  ["Omicron"] = 0x039F,
  ["Pi"] = 0x03A0,
  ["Rho"] = 0x03A1,
  ["Sigma"] = 0x03A3,
  ["Tau"] = 0x03A4,
  ["Upsilon"] = 0x03A5,
  ["Phi"] = 0x03A6,
  ["Chi"] = 0x03A7,
  ["Psi"] = 0x03A8,
  ["Omega"] = 0x03A9,
  ["alpha"] = 0x03B1,
  ["beta"] = 0x03B2,
  ["gamma"] = 0x03B3,
  ["delta"] = 0x03B4,
  ["epsilon"] = 0x03B5,
  ["zeta"] = 0x03B6,
  ["eta"] = 0x03B7,
  ["theta"] = 0x03B8,
  ["iota"] = 0x03B9,
  ["kappa"] = 0x03BA,
  ["lambda"] = 0x03BB,
  ["mu"] = 0x03BC,
  ["nu"] = 0x03BD,
  ["xi"] = 0x03BE,
  ["omicron"] = 0x03BF,
  ["pi"] = 0x03C0,
  ["rho"] = 0x03C1,
  ["sigmaf"] = 0x03C2,
  ["sigma"] = 0x03C3,
  ["tau"] = 0x03C4,
  ["upsilon"] = 0x03C5,
  ["phi"] = 0x03C6,
  ["chi"] = 0x03C7,
  ["psi"] = 0x03C8,
  ["omega"] = 0x03C9,
  ["thetasym"] = 0x03D1,
  ["upsih"] = 0x03D2,
  ["piv"] = 0x03D6,
  ["ensp"] = 0x2002,
  ["emsp"] = 0x2003,
  ["thinsp"] = 0x2009,
  ["ndash"] = 0x2013,
  ["mdash"] = 0x2014,
  ["lsquo"] = 0x2018,
  ["rsquo"] = 0x2019,
  ["sbquo"] = 0x201A,
  ["ldquo"] = 0x201C,
  ["rdquo"] = 0x201D,
  ["bdquo"] = 0x201E,
  ["dagger"] = 0x2020,
  ["Dagger"] = 0x2021,
  ["bull"] = 0x2022,
  ["hellip"] = 0x2026,
  ["permil"] = 0x2030,
  ["prime"] = 0x2032,
  ["Prime"] = 0x2033,
  ["lsaquo"] = 0x2039,
  ["rsaquo"] = 0x203A,
  ["oline"] = 0x203E,
  ["frasl"] = 0x2044,
  ["euro"] = 0x20AC,
  ["image"] = 0x2111,
  ["weierp"] = 0x2118,
  ["real"] = 0x211C,
  ["trade"] = 0x2122,
  ["alefsym"] = 0x2135,
  ["larr"] = 0x2190,
  ["uarr"] = 0x2191,
  ["rarr"] = 0x2192,
  ["darr"] = 0x2193,
  ["harr"] = 0x2194,
  ["crarr"] = 0x21B5,
  ["lArr"] = 0x21D0,
  ["uArr"] = 0x21D1,
  ["rArr"] = 0x21D2,
  ["dArr"] = 0x21D3,
  ["hArr"] = 0x21D4,
  ["forall"] = 0x2200,
  ["part"] = 0x2202,
  ["exist"] = 0x2203,
  ["empty"] = 0x2205,
  ["nabla"] = 0x2207,
  ["isin"] = 0x2208,
  ["notin"] = 0x2209,
  ["ni"] = 0x220B,
  ["prod"] = 0x220F,
  ["sum"] = 0x2211,
  ["minus"] = 0x2212,
  ["lowast"] = 0x2217,
  ["radic"] = 0x221A,
  ["prop"] = 0x221D,
  ["infin"] = 0x221E,
  ["ang"] = 0x2220,
  ["and"] = 0x2227,
  ["or"] = 0x2228,
  ["cap"] = 0x2229,
  ["cup"] = 0x222A,
  ["int"] = 0x222B,
  ["there4"] = 0x2234,
  ["sim"] = 0x223C,
  ["cong"] = 0x2245,
  ["asymp"] = 0x2248,
  ["ne"] = 0x2260,
  ["equiv"] = 0x2261,
  ["le"] = 0x2264,
  ["ge"] = 0x2265,
  ["sub"] = 0x2282,
  ["sup"] = 0x2283,
  ["nsub"] = 0x2284,
  ["sube"] = 0x2286,
  ["supe"] = 0x2287,
  ["oplus"] = 0x2295,
  ["otimes"] = 0x2297,
  ["perp"] = 0x22A5,
  ["sdot"] = 0x22C5,
  ["lceil"] = 0x2308,
  ["rceil"] = 0x2309,
  ["lfloor"] = 0x230A,
  ["rfloor"] = 0x230B,
  ["lang"] = 0x27E8,
  ["rang"] = 0x27E9,
  ["loz"] = 0x25CA,
  ["spades"] = 0x2660,
  ["clubs"] = 0x2663,
  ["hearts"] = 0x2665,
  ["diams"] = 0x2666,
}

--- Given a string of decimal digits, returns a UTF-8 encoded
-- string encoding a unicode character.
function M.dec_entity(s)
	local out =  string.gsub(s, '&#(%d+);', to_utf8)
	return out
end

--- Given a character entity name (like `ouml`), returns a UTF-8 encoded
-- string encoding a unicode character.
-- NOT WORKING: REQUIRES UNICODE.
--[[function M.char_entity(s)
	local i = s:match('&(%a+);')
	local n = character_entities[i]
	local s
	if (n) then
		s = char(n)
	end
	return s
end
--]]

function M.convert(s)
	if (s) then
		return M.dec_entity(s)
	else
		return s
	end
end

-- UNUSED
-- Find the entity, get the character, OR return NIL
--[[
local function get_character_entity(s)
	local c = character_entities[s]
	print ("C",c)
	if ( c ) then
		return char(c)
	end
	return nil
end
--]]

local gsub, char = string.gsub, string.char
local entitySwap = function(orig,n,s)
	local ss = to_utf8(tonumber(character_entities[s]))
	--print ("entitySwap: orig,n,s,ss",orig,ss,n,s)
	return ss or n=="#" and to_utf8(s) or orig
end
function M.unescape(str)
	return gsub( str, '(&(#?)([%d%a]+);)', entitySwap )
end

--&amp;#039;

return M