review.lua (29a3ed5) - memoire

review.lua

--[[
    stuff to help with the review mechanics
]]

--[[
    manipulates `Prompt` `prompt` in-place as it should be
    when reviewed at timestamp `revtime` with review success `revsucc`
]]
local function update(prompt, revtime, revsucc)
    if revsucc and revsucc > 0 then
        local ad = revtime - prompt.time
        prompt.delay = 2.5 ^ revsucc * ad + math.max(40000 - 0.5 * ad, 0)
        prompt.succ = prompt.succ + 1
    else
        prompt.delay = 30
        prompt.fail = prompt.fail + 1
    end
    prompt.time = revtime
end

--[[
    checks (returns boolean) if `Prompt` `prompt` should be reviewed now
]]
local function should(prompt)
    return os.time() - prompt.time >= prompt.delay
end

--[[
    returns a shuffled version of the table,
    destroying the table in-place
    adapted from
    https://stackoverflow.com/q/55192727
]]
local function shuffle(t)
    local ret = {}
    local ci = 1
    while #t > 0 do
        local ri = math.random(1, #t)
        ret[ci] = t[ri]
        table.remove(t, ri)
        ci = ci + 1
    end
    return ret
end

--[[
    returns a table of pairs of integers to index the deck
    to get prompts to be reviewed now;
    prompts are shuffled in order
]]
local function toreviewlist(deck)
    local ctrt = {}
    for i, cg in ipairs(deck) do
        for j, pr in ipairs(cg) do
            if should(pr) then
                table.insert(ctrt, { i, j })
            end
        end
    end
    ctrt = shuffle(ctrt)
    return ctrt
end

return { update = update, should = should, list = toreviewlist }

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