【高级技巧】迭代器模式：闭包实现自定义遍历

local function filterIter(t, pred)
    local i = 0
    return function()
        i = i + 1
        while i <= #t do
            if pred(t[i]) then
                return t[i]
            end
            i = i + 1
        end
        return nil
    end
end
local players = {
    { name = "甲", red = 0 },
    { name = "乙", red = 220 },
    { name = "丙", red = 0 },
    { name = "丁", red = 95 },
}
for p in filterIter(players, function(p)
    return p.red > 0
end
) do
    sendmsg(nil, 1, "红名玩家：" .. p.name .. " 值 " .. p.red)
end

local function pageIter(t, size)
    local page = 0
    return function()
        page = page + 1
        local from = (page - 1) * size + 1
        if from > #t then
            return nil
        end
        local slice = {}
        for i = from, math.min(from + size - 1, #t) do
            slice[#slice + 1] = t[i]
        end
        return slice
    end
end