Module:Iterator

Documentation for this module may be created at Module:Iterator/doc

-- [[Category:Todo]]:
-- more generic interface and compositions (filtering, grouping, mapping, sorting, etc.)
-- prevent clients from infinite loops

local Iterator = {}

-- legacy, not a proper iterator
function Iterator.array(arr, i, n)
    i = i or 0
    n = n and math.min(#arr, n) or #arr
    function step(n, i)
        if i < n then
            i = i + 1
            return i, arr[i]
        end
    end
    return function()
        return step, n, i
    end
end

function stringKey(name, context, n, default)
    return context and context[name .. (n and tostring(n) or '')] or default
end

function numberKey(name, context, n, default)
    return context and tonumber(context[name .. (n and tostring(n) or '')]) or default
end

function Iterator.equipmentBy(context, n, pred)
    local predKey = stringKey('pred', context, n)
    if predKey then
        pred = function(e)
            local EquipmentData = require('Module:EquipmentData')
            local obj = EquipmentData(e)
            return obj[predKey](obj)
        end
    end
    local collection = require('Module:Collection/Equipment')
    local sortKey = stringKey('sort', context, n)
    if sortKey then
        table.sort(collection, function(a, b) return a[sortKey] < b[sortKey] end)
    end
    local i = 1
    local current = nil
    return {
        next = function()
            for _ = i, #collection do
                local e = collection[i]
                if pred(e, i) then
                    current = e._name
                    i = i + 1
                    return true
                end
                i = i + 1
            end
            current = nil
            return false
        end,
        current = function()
            return current
        end,
    }
end

function Iterator.equipmentById(context, n)
    local from = numberKey('from', context, n, 1)
    local to = numberKey('to', context, n, 500)
    return Iterator.equipmentBy(context, n, function(_, i)
        -- use _id?
        return i >= from and i <= to
    end)
end

function Iterator.equipmentByType(context, n)
    local type = numberKey('type', context, n)
    return Iterator.equipmentBy(context, n, function(e)
        return e._type == type
    end)
end

function Iterator.equipmentByTypeAndIcon(context, n)
    local type = numberKey('type', context, n)
    local icon = numberKey('icon', context, n)
    return Iterator.equipmentBy(context, n, function(e)
        return e._type == type and e._icon == icon
    end)
end

function Iterator.test()
    function testIterator(name, args)
        local iterator = Iterator[name](args)
        mw.log(name)
        while iterator.next() do
            mw.log('  ' .. iterator.current())
        end
        mw.log()
    end
    testIterator('equipmentById', { from = '11', to = '20' })
    testIterator('equipmentByType', { type = '2' })
    testIterator('equipmentByTypeAndIcon', { type = '1', icon = '16' })
    testIterator('equipmentBy', { pred = 'is_large_caliber_main_gun', sort = '_type' })
end
-- p.test()

return Iterator