if not modules then modules = { } end modules ['anch-pos'] = {
    version   = 1.001,
    comment   = "companion to anch-pos.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

--[[ldx--
<p>We save positional information in the main utility table. Not only
can we store much more information in <l n='lua'/> but it's also
more efficient.</p>
--ldx]]--

local concat, format = table.concat, string.format
local lpegmatch = lpeg.match
local allocate, mark = utilities.storage.allocate, utilities.storage.mark

local collected, tobesaved = allocate(), allocate()

local jobpositions = {
    collected = collected,
    tobesaved = tobesaved,
}

job.positions = jobpositions

_ptbs_, _pcol_ = tobesaved, collected -- global

local dx, dy = "0pt", "0pt"

local function initializer()
    tobesaved = mark(jobpositions.tobesaved)
    collected = mark(jobpositions.collected)
    _ptbs_, _pcol_ = tobesaved, collected -- global
    local p = collected["page:0"] -- page:1
    if p then
-- to be checked !
--~ dx, dy = p[2] or "0pt", p[3] or "0pt"
    end
end

job.register('job.positions.collected', tobesaved, initializer)

function jobpositions.copy(target,source)
    collected[target] = collected[source] or tobesaved[source]
end

function jobpositions.replace(name,...)
    collected[name] = {...}
end

function jobpositions.page(id)
    local jpi = collected[id] or tobesaved[id]
    context(jpi and jpi[1] or '0')
end

function jobpositions.width(id)
    local jpi = collected[id] or tobesaved[id]
    context(jpi and jpi[4] or '0pt')
end

function jobpositions.height(id)
    local jpi = collected[id] or tobesaved[id]
    context(jpi and jpi[5] or '0pt')
end

function jobpositions.depth(id)
    local jpi = collected[id] or tobesaved[id]
    context(jpi and jpi[6] or '0pt')
end

function jobpositions.x(id)
    local jpi = collected[id] or tobesaved[id]
    local x = jpi and jpi[2]
    if x then
        context('\\the\\dimexpr%s-%s\\relax',x,dx)
    else
        context('0pt')
    end
end

function jobpositions.y(id)
    local jpi = collected[id] or tobesaved[id]
    local y = jpi and jpi[3]
    if y then
        context('\\the\\dimexpr%s-%s\\relax',y,dy)
    else
        context('0pt')
    end
end

-- the following are only for MP so there we can leave out the pt

-- can be writes and no format needed any more

function jobpositions.xy(id)
    local jpi = collected[id] or tobesaved[id]
    if jpi then
        context('(%s-%s,%s-%s)',jpi[2],dx,jpi[3],dy)
    else
        context('(0,0)')
    end
end

function jobpositions.lowerleft(id)
    local jpi = collected[id] or tobesaved[id]
    if jpi then
        context('(%s-%s,%s-%s-%s)',jpi[2],dx,jpi[3],jpi[6],dy)
    else
        context('(0,0)')
    end
end

function jobpositions.lowerright(id)
    local jpi = collected[id] or tobesaved[id]
    if jpi then
        context('(%s+%s-%s,%s-%s-%s)',jpi[2],jpi[4],dx,jpi[3],jpi[6],dy)
    else
        context('(0,0)')
    end
end

function jobpositions.upperright(id)
    local jpi = collected[id] or tobesaved[id]
    if jpi then
        context('(%s+%s-%s,%s+%s-%s)',jpi[2],jpi[4],dx,jpi[3],jpi[5],dy)
    else
        context('(0,0)')
    end
end

function jobpositions.upperleft(id)
    local jpi = collected[id] or tobesaved[id]
    if jpi then
        context('(%s-%s,%s+%s-%s)',jpi[2],dx,jpi[3],jpi[5],dy)
    else
        context('(0,0)')
    end
end

function jobpositions.position(id)
    local jpi = collected[id] or tobesaved[id]
    if jpi then
        context(concat(jpi,',',1,6))
    else
        context('0,0,0,0,0,0')
    end
end

local splitter = lpeg.Ct(lpeg.splitat(","))

function jobpositions.pardata(id,n,default)
    local jpi = collected[id] or tobesaved[id]
    if not jpi then
        context(default)
    else
        local split = jpi[0]
        if not split then
            split = lpegmatch(splitter,jpi[7])
            jpi[0] = split
        end
        context(split[n] or default)
    end
end

function jobpositions.extradata(id,default)
    local jpi = collected[id] or tobesaved[id]
    context(jpi and jpi[7] or default)
end

-- interface

commands.replacepospxywhd = jobpositions.replace
commands.copyposition     = jobpositions.copy
commands.MPp              = jobpositions.page
commands.MPx              = jobpositions.x
commands.MPy              = jobpositions.y
commands.MPw              = jobpositions.width
commands.MPh              = jobpositions.height
commands.MPd              = jobpositions.depth
commands.MPxy             = jobpositions.xy
commands.MPll             = jobpositions.lowerleft
commands.MPlr             = jobpositions.lowerright
commands.MPur             = jobpositions.upperright
commands.MPul             = jobpositions.upperleft
commands.MPpos            = jobpositions.position
commands.MPplus           = jobpositions.pardata
commands.MPrest           = jobpositions.extradata

function commands.doifelse(name)
    commands.testcase(collected[name] or tobesaved[name])
end