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koreader/frontend/util.lua

180 lines
5.8 KiB
Lua

--[[--
This module contains miscellaneous helper functions for the KOReader frontend.
]]
local BaseUtil = require("ffi/util")
local util = {}
--- Strips all punctuation and spaces from a string.
---- @string text the string to be stripped
---- @treturn string stripped text
function util.stripePunctuations(text)
if not text then return end
-- strip ASCII punctuation characters around text
-- and strip any generic punctuation (U+2000 - U+206F) in the text
return text:gsub("\226[\128-\131][\128-\191]", ''):gsub("^%p+", ''):gsub("%p+$", '')
end
--[[
Lua doesn't have a string.split() function and most of the time
you don't really need it because string.gmatch() is enough.
However string.gmatch() has one significant disadvantage for me:
You can't split a string while matching both the delimited
strings and the delimiters themselves without tracking positions
and substrings. The gsplit function below takes care of
this problem.
Author: Peter Odding
License: MIT/X11
Source: http://snippets.luacode.org/snippets/String_splitting_130
--]]
function util.gsplit(str, pattern, capture)
pattern = pattern and tostring(pattern) or '%s+'
if (''):find(pattern) then
error('pattern matches empty string!', 2)
end
return coroutine.wrap(function()
local index = 1
repeat
local first, last = str:find(pattern, index)
if first and last then
if index < first then
coroutine.yield(str:sub(index, first - 1))
end
if capture then
coroutine.yield(str:sub(first, last))
end
index = last + 1
else
if index <= #str then
coroutine.yield(str:sub(index))
end
break
end
until index > #str
end)
end
-- https://gist.github.com/jesseadams/791673
function util.secondsToClock(seconds, withoutSeconds)
seconds = tonumber(seconds)
if seconds == 0 or seconds ~= seconds then
if withoutSeconds then
return "00:00";
else
return "00:00:00";
end
else
local hours = string.format("%02.f", math.floor(seconds / 3600));
local mins = string.format("%02.f", math.floor(seconds / 60 - (hours * 60)));
if withoutSeconds then
return hours .. ":" .. mins
end
local secs = string.format("%02.f", math.floor(seconds - hours * 3600 - mins * 60));
return hours .. ":" .. mins .. ":" .. secs
end
end
--- Returns number of keys in a table.
---- @param T Lua table
---- @treturn int number of keys in table T
function util.tableSize(T)
local count = 0
for _ in pairs(T) do count = count + 1 end
return count
end
-- append all elements from t2 into t1
function util.arrayAppend(t1, t2)
for _, v in ipairs(t2) do
table.insert(t1, v)
end
end
-- Returns the index within this string of the last occurrence of the specified character
-- or -1 if the character does not occur.
-- To find . you need to escape it.
function util.lastIndexOf(string, ch)
local i = string:match(".*" .. ch .. "()")
if i == nil then return -1 else return i - 1 end
end
--- Splits string into a list of UTF-8 characters.
---- @string text the string to be split.
---- @treturn table list of UTF-8 chars
function util.splitToChars(text)
local tab = {}
if text ~= nil then
local prevcharcode, charcode = 0
for uchar in string.gfind(text, "([%z\1-\127\194-\244][\128-\191]*)") do
charcode = BaseUtil.utf8charcode(uchar)
if prevcharcode then -- utf8
table.insert(tab, uchar)
end
prevcharcode = charcode
end
end
return tab
end
-- Tests whether c is a CJK character
function util.isCJKChar(c)
return string.match(c, "[\228-\234][\128-\191].") == c
end
-- Test whether str contains CJK characters
function util.hasCJKChar(str)
return string.match(str, "[\228-\234][\128-\191].") ~= nil
end
--- Split texts into a list of words, spaces and punctuation.
---- @string text text to split
---- @treturn table list of words, spaces and punctuation
function util.splitToWords(text)
local wlist = {}
for word in util.gsplit(text, "[%s%p]+", true) do
-- if space splitted word contains CJK characters
if util.hasCJKChar(word) then
-- split with CJK characters
for char in util.gsplit(word, "[\228-\234\192-\255][\128-\191]+", true) do
table.insert(wlist, char)
end
else
table.insert(wlist, word)
end
end
return wlist
end
-- We don't want to split on a space if it is followed by some
-- specific punctuation : e.g. "word :" or "word )"
-- (In french, there is a space before a colon, and it better
-- not be wrapped there.)
-- Includes U+00BB >> (right double angle quotation mark) and
-- U+201D '' (right double quotation mark)
local non_splitable_space_tailers = ":;,.!?)]}$%-=/<>»”"
-- Test whether a string could be separated by this char for multi-line rendering
-- Optional next char may be provided to help make the decision
function util.isSplitable(c, next_c)
if util.isCJKChar(c) then
-- a CJKChar is a word in itself, and so is splitable
return true
elseif c == " " then
-- we only split on a space (so punctuation sticks to prev word)
-- if next_c is provided, we can make a better decision
if next_c and non_splitable_space_tailers:find(next_c, 1, true) then
-- this space is followed by some punctuation that is better
-- kept with us along previous word
return false
else
-- we can split on this space
return true
end
end
-- otherwise, non splitable
return false
end
return util