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koreader/frontend/ui/translator.lua
Frans de Jonge c847d628e1 Docs: cosmetic updates and additions
* Content from wiki had some cosmetic leftover glitches
* Added/adapted some docs for other modules
2017-04-12 11:27:22 -07:00

107 lines
2.9 KiB
Lua

--[[--
This module translates text using Google Translate.
<http://translate.google.com/translate_a/t?client=z&ie=UTF-8&oe=UTF-8&hl=en&tl=en&text=hello>
--]]
local JSON = require("json")
local logger = require("logger")
local Translator = {
trans_servers = {
"http://translate.google.cn",
"http://translate.google.com",
},
trans_path = "/translate_a/t",
trans_params = {
client = "z", -- client z returns normal JSON result
ie = "UTF-8",
oe = "UTF-8",
hl = "en",
tl = "en",
sl = nil, -- we don't specify source languagae to detect language
},
default_lang = "en",
}
function Translator:getTransServer()
return G_reader_settings:readSetting("trans_server") or self.trans_servers[1]
end
--[[--
Returns decoded JSON table from translate server.
@string target_lang
@string source_lang
@string text
@treturn string result, or nil
--]]
function Translator:loadPage(target_lang, source_lang, text)
local socket = require('socket')
local url = require('socket.url')
local http = require('socket.http')
local https = require('ssl.https')
local ltn12 = require('ltn12')
local request, sink = {}, {}
local query = ""
self.trans_params.tl = target_lang
self.trans_params.sl = source_lang
for k,v in pairs(self.trans_params) do
query = query .. k .. '=' .. v .. '&'
end
local parsed = url.parse(self:getTransServer())
parsed.path = self.trans_path
parsed.query = query .. "text=" .. url.escape(text)
-- HTTP request
request['url'] = url.build(parsed)
request['method'] = 'GET'
request['sink'] = ltn12.sink.table(sink)
http.TIMEOUT, https.TIMEOUT = 10, 10
local httpRequest = parsed.scheme == 'http' and http.request or https.request
-- first argument returned by skip is code
local _, headers, status = socket.skip(1, httpRequest(request))
-- raise error message when network is unavailable
if headers == nil then
error("Network is unreachable")
end
if status ~= "HTTP/1.1 200 OK" then
logger.warn("translator HTTP status not okay:", status)
return
end
local content = table.concat(sink)
if content ~= "" and string.sub(content, 1,1) == "{" then
local ok, result = pcall(JSON.decode, content)
if ok and result then
return result
else
logger.warn("translator error:", result)
end
else
logger.warn("not JSON in translator response:", content)
end
end
--[[--
Tries to automatically detect language of `text`.
@string text
@treturn string lang (`"en"`, `"fr"`, `…`)
--]]
function Translator:detect(text)
local result = self:loadPage("en", nil, text)
if result then
local src_lang = result.src
logger.dbg("detected language:", src_lang)
return src_lang
else
return self.default_lang
end
end
return Translator