/usr/share/texlive/texmf-dist/tex/luatex/lualibs/lualibs-dimen.lua is in texlive-luatex 2012.20120611-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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version = 1.001,
comment = "support for dimensions",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
--[[ldx--
<p>Internally <l n='luatex'/> work with scaled point, which are
represented by integers. However, in practice, at east at the
<l n='tex'/> end we work with more generic units like points (pt). Going
from scaled points (numbers) to one of those units can be
done by using the conversion factors collected in the following
table.</p>
--ldx]]--
local format, match, gsub, type, setmetatable = string.format, string.match, string.gsub, type, setmetatable
local P, S, R, Cc, lpegmatch = lpeg.P, lpeg.S, lpeg.R, lpeg.Cc, lpeg.match
number = number or { }
number.tonumberf = function(n) return match(format("%.20f",n),"(.-0?)0*$") end -- one zero too much but alas
number.tonumberg = function(n) return format("%.20g",n) end
local dimenfactors = {
["pt"] = 1/65536,
["in"] = ( 100/ 7227)/65536,
["cm"] = ( 254/ 7227)/65536,
["mm"] = ( 2540/ 7227)/65536,
["sp"] = 1, -- 65536 sp in 1pt
["bp"] = ( 7200/ 7227)/65536,
["pc"] = ( 1/ 12)/65536,
["dd"] = ( 1157/ 1238)/65536,
["cc"] = ( 1157/14856)/65536,
["nd"] = (20320/21681)/65536,
["nc"] = ( 5080/65043)/65536
}
--~ print(table.serialize(dimenfactors))
--~
--~ %.99g:
--~
--~ t={
--~ ["bp"]=1.5201782378580324e-005,
--~ ["cc"]=1.1883696112892098e-006,
--~ ["cm"]=5.3628510057769479e-007,
--~ ["dd"]=1.4260435335470516e-005,
--~ ["em"]=0.000152587890625,
--~ ["ex"]=6.103515625e-005,
--~ ["in"]=2.1113586636917117e-007,
--~ ["mm"]=5.3628510057769473e-008,
--~ ["nc"]=1.1917446679504327e-006,
--~ ["nd"]=1.4300936015405194e-005,
--~ ["pc"]=1.2715657552083333e-006,
--~ ["pt"]=1.52587890625e-005,
--~ ["sp"]=1,
--~ }
--~
--~ patched %s and tonumber
--~
--~ t={
--~ ["bp"]=0.00001520178238,
--~ ["cc"]=0.00000118836961,
--~ ["cm"]=0.0000005362851,
--~ ["dd"]=0.00001426043534,
--~ ["em"]=0.00015258789063,
--~ ["ex"]=0.00006103515625,
--~ ["in"]=0.00000021113587,
--~ ["mm"]=0.00000005362851,
--~ ["nc"]=0.00000119174467,
--~ ["nd"]=0.00001430093602,
--~ ["pc"]=0.00000127156576,
--~ ["pt"]=0.00001525878906,
--~ ["sp"]=1,
--~ }
--[[ldx--
<p>A conversion function that takes a number, unit (string) and optional
format (string) is implemented using this table.</p>
--ldx]]--
-- was:
local function todimen(n,unit,fmt)
if type(n) == 'string' then
return n
else
unit = unit or 'pt'
return format(fmt or "%s%s",n*dimenfactors[unit],unit)
-- if fmt then
-- return format(fmt,n*dimenfactors[unit],unit)
-- else
-- return match(format("%.20f",n*dimenfactors[unit]),"(.-0?)0*$") .. unit
-- end
end
end
--[[ldx--
<p>We collect a bunch of converters in the <type>number</type> namespace.</p>
--ldx]]--
number.maxdimen = 1073741823
number.todimen = todimen
number.dimenfactors = dimenfactors
function number.topoints (n) return todimen(n,"pt") end
function number.toinches (n) return todimen(n,"in") end
function number.tocentimeters (n) return todimen(n,"cm") end
function number.tomillimeters (n) return todimen(n,"mm") end
function number.toscaledpoints(n) return todimen(n,"sp") end
function number.toscaledpoints(n) return n .. "sp" end
function number.tobasepoints (n) return todimen(n,"bp") end
function number.topicas (n) return todimen(n "pc") end
function number.todidots (n) return todimen(n,"dd") end
function number.tociceros (n) return todimen(n,"cc") end
function number.tonewdidots (n) return todimen(n,"nd") end
function number.tonewciceros (n) return todimen(n,"nc") end
--[[ldx--
<p>More interesting it to implement a (sort of) dimen datatype, one
that permits calculations too. First we define a function that
converts a string to scaledpoints. We use <l n='lpeg'/>. We capture
a number and optionally a unit. When no unit is given a constant
capture takes place.</p>
--ldx]]--
local amount = (S("+-")^0 * R("09")^0 * P(".")^0 * R("09")^0) + Cc("0")
local unit = R("az")^1
local dimenpair = amount/tonumber * (unit^1/dimenfactors + Cc(1)) -- tonumber is new
lpeg.patterns.dimenpair = dimenpair
--[[ldx--
<p>We use a metatable to intercept errors. When no key is found in
the table with factors, the metatable will be consulted for an
alternative index function.</p>
--ldx]]--
local mt = { } setmetatable(dimenfactors,mt)
mt.__index = function(t,s)
-- error("wrong dimension: " .. (s or "?")) -- better a message
return false
end
function string:todimen()
if type(self) == "number" then
return self
else
local value, unit = lpegmatch(dimenpair,self)
return value/unit
end
end
local amount = S("+-")^0 * R("09")^0 * S(".,")^0 * R("09")^0
local unit = P("pt") + P("cm") + P("mm") + P("sp") + P("bp") + P("in") +
P("pc") + P("dd") + P("cc") + P("nd") + P("nc")
local validdimen = amount * unit
lpeg.patterns.validdimen = pattern
--[[ldx--
<p>This converter accepts calls like:</p>
<typing>
string.todimen("10")
string.todimen(".10")
string.todimen("10.0")
string.todimen("10.0pt")
string.todimen("10pt")
string.todimen("10.0pt")
</typing>
<p>And of course the often more efficient:</p>
<typing>
somestring:todimen("12.3cm")
</typing>
<p>With this in place, we can now implement a proper datatype for dimensions, one
that permits us to do this:</p>
<typing>
s = dimen "10pt" + dimen "20pt" + dimen "200pt"
- dimen "100sp" / 10 + "20pt" + "0pt"
</typing>
<p>We create a local metatable for this new type:</p>
--ldx]]--
local dimensions = { }
--[[ldx--
<p>The main (and globally) visible representation of a dimen is defined next: it is
a one-element table. The unit that is returned from the match is normally a number
(one of the previously defined factors) but we also accept functions. Later we will
see why.</p>
--ldx]]--
function dimen(a)
if a then
local ta= type(a)
if ta == "string" then
local value, unit = lpegmatch(pattern,a)
if type(unit) == "function" then
k = value/unit()
else
k = value/unit
end
a = k
elseif ta == "table" then
a = a[1]
end
return setmetatable({ a }, dimensions)
else
return setmetatable({ 0 }, dimensions)
end
end
--[[ldx--
<p>This function return a small hash with a metatable attached. It is
through this metatable that we can do the calculations. We could have
shared some of the code but for reasons of speed we don't.</p>
--ldx]]--
function dimensions.__add(a, b)
local ta, tb = type(a), type(b)
if ta == "string" then a = a:todimen() elseif ta == "table" then a = a[1] end
if tb == "string" then b = b:todimen() elseif tb == "table" then b = b[1] end
return setmetatable({ a + b }, dimensions)
end
function dimensions.__sub(a, b)
local ta, tb = type(a), type(b)
if ta == "string" then a = a:todimen() elseif ta == "table" then a = a[1] end
if tb == "string" then b = b:todimen() elseif tb == "table" then b = b[1] end
return setmetatable({ a - b }, dimensions)
end
function dimensions.__mul(a, b)
local ta, tb = type(a), type(b)
if ta == "string" then a = a:todimen() elseif ta == "table" then a = a[1] end
if tb == "string" then b = b:todimen() elseif tb == "table" then b = b[1] end
return setmetatable({ a * b }, dimensions)
end
function dimensions.__div(a, b)
local ta, tb = type(a), type(b)
if ta == "string" then a = a:todimen() elseif ta == "table" then a = a[1] end
if tb == "string" then b = b:todimen() elseif tb == "table" then b = b[1] end
return setmetatable({ a / b }, dimensions)
end
function dimensions.__unm(a)
local ta = type(a)
if ta == "string" then a = a:todimen() elseif ta == "table" then a = a[1] end
return setmetatable({ - a }, dimensions)
end
--[[ldx--
<p>It makes no sense to implement the power and modulo function but
the next two do make sense because they permits is code like:</p>
<typing>
local a, b = dimen "10pt", dimen "11pt"
...
if a > b then
...
end
</typing>
--ldx]]--
-- makes no sense: dimensions.__pow and dimensions.__mod
function dimensions.__lt(a, b)
return a[1] < b[1]
end
function dimensions.__eq(a, b)
return a[1] == b[1]
end
--[[ldx--
<p>We also need to provide a function for conversion to string (so that
we can print dimensions). We print them as points, just like <l n='tex'/>.</p>
--ldx]]--
function dimensions.__tostring(a)
return a[1]/65536 .. "pt" -- instead of todimen(a[1])
end
--[[ldx--
<p>Since it does not take much code, we also provide a way to access
a few accessors</p>
<typing>
print(dimen().pt)
print(dimen().sp)
</typing>
--ldx]]--
function dimensions.__index(tab,key)
local d = dimenfactors[key]
if not d then
error("illegal property of dimen: " .. key)
d = 1
end
return 1/d
end
--[[ldx--
<p>In the converter from string to dimension we support functions as
factors. This is because in <l n='tex'/> we have a few more units:
<type>ex</type> and <type>em</type>. These are not constant factors but
depend on the current font. They are not defined by default, but need
an explicit function call. This is because at the moment that this code
is loaded, the relevant tables that hold the functions needed may not
yet be available.</p>
--ldx]]--
function dimensions.texify() -- todo: %
local fti, fc = fonts and fonts.ids and fonts.ids, font and font.current
if fti and fc then
dimenfactors["ex"] = function() return fti[fc()].ex_height end
dimenfactors["em"] = function() return fti[fc()].quad end
else
dimenfactors["ex"] = 1/65536* 4 -- 4pt
dimenfactors["em"] = 1/65536*10 -- 10pt
end
end
--[[ldx--
<p>In order to set the defaults we call this function now. At some point
the macro package needs to make sure the function is called again.</p>
--ldx]]--
dimensions.texify()
--[[ldx--
<p>The previous code is rather efficient (also thanks to <l n='lpeg'/>) but we
can speed it up by caching converted dimensions. On my machine (2008) the following
loop takes about 25.5 seconds.</p>
<typing>
for i=1,1000000 do
local s = dimen "10pt" + dimen "20pt" + dimen "200pt"
- dimen "100sp" / 10 + "20pt" + "0pt"
end
</typing>
<p>When we cache converted strings this becomes 16.3 seconds. In order not
to waste too much memory on it, we tag the values of the cache as being
week which mean that the garbage collector will collect them in a next
sweep. This means that in most cases the speed up is mostly affecting the
current couple of calculations and as such the speed penalty is small.</p>
<p>We redefine two previous defined functions that can benefit from
this:</p>
--ldx]]--
local known = { } setmetatable(known, { __mode = "v" })
function dimen(a)
if a then
local ta= type(a)
if ta == "string" then
local k = known[a]
if k then
a = k
else
local value, unit = lpegmatch(dimenpair,a)
if type(unit) == "function" then
k = value/unit()
else
k = value/unit
end
known[a] = k
a = k
end
elseif ta == "table" then
a = a[1]
end
return setmetatable({ a }, dimensions)
else
return setmetatable({ 0 }, dimensions)
end
end
function string:todimen()
if type(self) == "number" then
return self
else
local k = known[self]
if not k then
local value, unit = lpegmatch(dimenpair,self)
if value and unit then
k = value/unit
else
k = 0
end
-- print(self,value,unit)
known[self] = k
end
return k
end
end
function number.toscaled(d)
return format("0.5f",d/2^16)
end
--[[ldx--
<p>In a similar fashion we can define a glue datatype. In that case we
probably use a hash instead of a one-element table.</p>
--ldx]]--
--[[ldx--
<p>Goodie:s</p>
--ldx]]--
function number.percent(n) -- will be cleaned up once luatex 0.30 is out
local hsize = tex.hsize
if type(hsize) == "string" then
hsize = hsize:todimen()
end
return (n/100) * hsize
end
number["%"] = number.percent
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