Add support for gettext message catalogs.

1 files changed, 288 insertions, 0 deletions

diff --git a/gettext.lua b/gettext.lua
new file mode 100644
index 0000000..6f3a1cb
--- /dev/null
+++ b/gettext.lua
@@ -0,0 +1,288 @@
+
+local strfind, strsub, strrep = string.find, string.sub, string.rep
+local strmatch, strgsub = string.match, string.gsub
+local floor = math.floor
+
+local function split(str, sep)
+	local pos, endp = 1, #str+1
+	return function()
+		if (not pos) or pos > endp then return end
+		local s, e = strfind(str, sep, pos, true)
+		local part = strsub(str, pos, s and s-1)
+		pos = e and e + 1
+		return part
+	end
+end
+
+local function trim(str)
+	return strmatch(str, "^%s*(.-)%s*$")
+end
+
+local escapes = { n="\n", r="\r", t="\t" }
+
+local function unescape(str)
+	return (strgsub(str, "(\\+)([nrt]?)", function(bs, c)
+		local bsl = #bs
+		local realbs = strrep("\\", bsl/2)
+		if bsl%2 == 1 then
+			c = escapes[c]
+		end
+		return realbs..c
+	end))
+end
+
+local function parse_po(str)
+	local state, msgid, msgid_plural, msgstrind
+	local texts = { }
+	local lineno = 0
+	local function perror(msg)
+		return error(msg.." at line "..lineno)
+	end
+	for line in split(str, "\n") do repeat
+		lineno = lineno + 1
+		line = trim(line)
+
+		if line == "" or strmatch(line, "^#") then
+			state, msgid, msgid_plural = nil, nil, nil
+			break -- continue
+		end
+
+		local mid = strmatch(line, "^%s*msgid%s*\"(.*)\"%s*$")
+		if mid then
+			if state == "id" then
+				return perror("unexpected msgid")
+			end
+			state, msgid = "id", unescape(mid)
+			break -- continue
+		end
+
+		mid = strmatch(line, "^%s*msgid_plural%s*\"(.*)\"%s*$")
+		if mid then
+			if state ~= "id" then
+				return perror("unexpected msgid_plural")
+			end
+			state, msgid_plural = "idp", unescape(mid)
+			break -- continue
+		end
+
+		local ind, mstr = strmatch(line,
+				"^%s*msgstr([0-9%[%]]*)%s*\"(.*)\"%s*$")
+		if ind then
+			if not msgid then
+				return perror("missing msgid")
+			elseif ind == "" then
+				msgstrind = 0
+			elseif strmatch(ind, "%[[0-9]+%]") then
+				msgstrind = tonumber(strsub(ind, 2, -2))
+			else
+				return perror("malformed msgstr")
+			end
+			texts[msgid] = texts[msgid] or { }
+			if msgid_plural then
+				texts[msgid_plural] = texts[msgid]
+			end
+			texts[msgid][msgstrind] = unescape(mstr)
+			state = "str"
+			break -- continue
+		end
+
+		mstr = strmatch(line, "^%s*\"(.*)\"%s*$")
+		if mstr then
+			if state == "id" then
+				msgid = msgid..unescape(mstr)
+				break -- continue
+			elseif state == "idp" then
+				msgid_plural = msgid_plural..unescape(mstr)
+				break -- continue
+			elseif state == "str" then
+				local text = texts[msgid][msgstrind]
+				texts[msgid][msgstrind] = text..unescape(mstr)
+				break -- continue
+			end
+		end
+
+		return perror("malformed line")
+
+	until true end -- end for
+
+	return texts
+end
+
+local M = { }
+
+local domains = { }
+local dgettext_cache = { }
+local dngettext_cache = { }
+local langs
+
+local function detect_languages()
+	if langs then return langs end
+
+	langs = { }
+
+	local function addlang(l)
+		local sep
+		langs[#langs+1] = l
+		sep = strfind(l, ".", 1, true)
+		if sep then
+			l = strsub(l, 1, sep-1)
+			langs[#langs+1] = l
+		end
+		sep = strfind(l, "_", 1, true)
+		if sep then
+			langs[#langs+1] = strsub(l, 1, sep-1)
+		end
+	end
+
+	local v
+
+	v = rawget(_G, "minetest") and minetest.setting_get("language")
+	if v and v~="" then
+		addlang(v)
+	end
+
+	v = os.getenv("LANGUAGE")
+	if v then
+		for item in split(v, ":") do
+			addlang(item)
+		end
+	end
+
+	v = os.getenv("LANG")
+	if v then
+		addlang(v)
+	end
+
+	return langs
+end
+
+local function warn(msg)
+	if rawget(_G, "minetest") then
+		minetest.log("warning", msg)
+	else
+		io.stderr:write("WARNING: ", msg, "\n")
+	end
+end
+
+-- hax!
+-- This function converts a C expression to an equivalent Lua expression.
+-- It handles enough stuff to parse the `Plural-Forms` header correctly.
+-- Note that it assumes the C expression is valid to begin with.
+local function compile_plural_forms(str)
+	local plural = strmatch(str, "plural=([^;]+);?$")
+	local function replace_ternary(str)
+		local c, t, f = strmatch(str, "^(.-)%?(.-):(.*)")
+		if c then
+			return ("__if("
+					..replace_ternary(c)
+					..","..replace_ternary(t)
+					..","..replace_ternary(f)
+					..")")
+		end
+		return str
+	end
+	plural = replace_ternary(plural)
+	plural = strgsub(plural, "&&", " and ")
+	plural = strgsub(plural, "||", " or ")
+	plural = strgsub(plural, "!=", "~=")
+	plural = strgsub(plural, "!", " not ")
+	local f, err = loadstring([[
+		local function __if(c, t, f)
+			if c and c~=0 then return t else return f end
+		end
+		local function __f(n)
+			return (]]..plural..[[)
+		end
+		return (__f(...))
+	]])
+	if not f then return nil, err end
+	local env = { }
+	env._ENV, env._G = env, env
+	setfenv(f, env)
+	return function(n)
+		local v = f(n)
+		if type(v) == "boolean" then
+			-- Handle things like a plain `n != 1`
+			v = v and 1 or 0
+		end
+		return v
+	end
+end
+
+local function parse_headers(str)
+	local headers = { }
+	for line in split(str, "\n") do
+		local k, v = strmatch(line, "^([^:]+):%s*(.*)")
+		if k then
+			headers[k] = v
+		end
+	end
+	return headers
+end
+
+local function load_catalog(filename)
+	local f, data, err
+
+	local function bail(msg)
+		warn(msg..(err and ": ")..(err or ""))
+		return nil
+	end
+
+	f, err = io.open(filename, "rb")
+	if not f then
+		return --bail("failed to open catalog")
+	end
+
+	data, err = f:read("*a")
+
+	f:close()
+
+	if not data then
+		return bail("failed to read catalog")
+	end
+
+	data, err = parse_po(data)
+	if not data then
+		return bail("failed to parse catalog")
+	end
+
+	err = nil
+	local hdrs = data[""]
+	if not (hdrs and hdrs[0]) then
+		print(dump(hdrs))
+		return bail("catalog has no headers")
+	end
+
+	hdrs = parse_headers(hdrs[0])
+
+	local pf = hdrs["Plural-Forms"]
+	if not pf then
+		return bail("failed to load catalog:"
+				.." catalog has no Plural-Forms header")
+	end
+
+	data.plural_index, err = compile_plural_forms(pf)
+	if not data.plural_index then
+		return bail("failed to compile plural forms")
+	end
+
+	--warn("loaded: "..filename)
+
+	return data
+end
+
+function M.load_catalogs(path)
+	detect_languages()
+
+	local cats = { }
+	for _, lang in ipairs(langs) do
+		local cat = load_catalog(path.."/"..lang..".po")
+		if cat then
+			cats[#cats+1] = cat
+		end
+	end
+
+	return cats
+end
+
+return M