koreader/frontend/util.lua

--[[--
Miscellaneous helper functions for KOReader frontend.
  ]]

local util = {}

function util.stripePunctuations(word)
    if not word then return end
    -- strip ASCII punctuation characters around word
    -- and strip any generic punctuation (U+2000 - U+206F) in the word
    return word: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
---- @return 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

return util