2016-01-12 16:26:00

1 files changed, 452 insertions, 0 deletions

diff --git a/tex/context/base/mkiv/util-dim.lua b/tex/context/base/mkiv/util-dim.lua
new file mode 100644
index 000000000..2bdb870e7
--- /dev/null
+++ b/tex/context/base/mkiv/util-dim.lua
@@ -0,0 +1,452 @@
+if not modules then modules = { } end modules ['util-dim'] = {
+    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, C, lpegmatch = lpeg.P, lpeg.S, lpeg.R, lpeg.Cc, lpeg.C, lpeg.match
+
+local allocate          = utilities.storage.allocate
+local setmetatableindex = table.setmetatableindex
+local formatters        = string.formatters
+
+local texget            = tex and tex.get or function() return 65536*10*100 end
+
+local p_stripzeros      = lpeg.patterns.stripzeros
+
+--this might become another namespace
+
+number = number or { }
+local number = number
+
+number.tonumberf = function(n) return lpegmatch(p_stripzeros,format("%.20f",n)) end
+number.tonumberg = function(n) return format("%.20g",n) end
+
+local dimenfactors = allocate {
+    ["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]]--
+
+local f_none = formatters["%s%s"]
+local f_true = formatters["%0.5F%s"]
+
+local function numbertodimen(n,unit,fmt) -- will be redefined later !
+    if type(n) == 'string' then
+        return n
+    else
+        unit = unit or 'pt'
+        n = n * dimenfactors[unit]
+        if not fmt then
+            fmt = f_none(n,unit)
+        elseif fmt == true then
+            fmt = f_true(n,unit)
+        else
+            return formatters[fmt](n,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      = numbertodimen
+number.dimenfactors = dimenfactors
+
+function number.topoints      (n,fmt) return numbertodimen(n,"pt",fmt) end
+function number.toinches      (n,fmt) return numbertodimen(n,"in",fmt) end
+function number.tocentimeters (n,fmt) return numbertodimen(n,"cm",fmt) end
+function number.tomillimeters (n,fmt) return numbertodimen(n,"mm",fmt) end
+function number.toscaledpoints(n,fmt) return numbertodimen(n,"sp",fmt) end
+function number.toscaledpoints(n)     return            n .. "sp"      end
+function number.tobasepoints  (n,fmt) return numbertodimen(n,"bp",fmt) end
+function number.topicas       (n,fmt) return numbertodimen(n "pc",fmt) end
+function number.todidots      (n,fmt) return numbertodimen(n,"dd",fmt) end
+function number.tociceros     (n,fmt) return numbertodimen(n,"cc",fmt) end
+function number.tonewdidots   (n,fmt) return numbertodimen(n,"nd",fmt) end
+function number.tonewciceros  (n,fmt) return numbertodimen(n,"nc",fmt) 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 + P("%")
+
+local dimenpair = amount/tonumber * (unit^1/dimenfactors + Cc(1)) -- tonumber is new
+
+lpeg.patterns.dimenpair = dimenpair
+
+local splitter = amount/tonumber * C(unit^1)
+
+function number.splitdimen(str)
+    return lpegmatch(splitter,str)
+end
+
+--[[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]]--
+
+setmetatableindex(dimenfactors, function(t,s)
+ -- error("wrong dimension: " .. (s or "?")) -- better a message
+    return false
+end)
+
+--[[ldx--
+<p>We redefine the following function later on, so we comment it
+here (which saves us bytecodes.</p>
+--ldx]]--
+
+-- function string.todimen(str)
+--     if type(str) == "number" then
+--         return str
+--     else
+--         local value, unit = lpegmatch(dimenpair,str)
+--         return value/unit
+--     end
+-- end
+--
+-- local stringtodimen = string.todimen
+
+local stringtodimen -- assigned later (commenting saves bytecode)
+
+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 = validdimen
+
+--[[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>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. This function is redefined later.</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 = stringtodimen(a) elseif ta == "table" then a = a[1] end
+    if tb == "string" then b = stringtodimen(b) 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 = stringtodimen(a) elseif ta == "table" then a = a[1] end
+    if tb == "string" then b = stringtodimen(b) 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 = stringtodimen(a) elseif ta == "table" then a = a[1] end
+    if tb == "string" then b = stringtodimen(b) 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 = stringtodimen(a) elseif ta == "table" then a = a[1] end
+    if tb == "string" then b = stringtodimen(b) 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 = stringtodimen(a) 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]]--
+
+   dimenfactors["ex"] =  4 * 1/65536 --   4pt
+   dimenfactors["em"] = 10 * 1/65536 --  10pt
+-- dimenfactors["%"]  =  4 * 1/65536 -- 400pt/100
+
+--[[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 value and unit then
+                    k = value/unit -- to be considered: round
+                else
+                    k = 0
+                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(str) -- maybe use tex.sp when available
+    if type(str) == "number" then
+        return str
+    else
+        local k = known[str]
+        if not k then
+            local value, unit = lpegmatch(dimenpair,str)
+            if value and unit then
+                k = value/unit -- to be considered: round
+            else
+                k = 0
+            end
+            -- print(str,value,unit)
+            known[str] = k
+        end
+        return k
+    end
+end
+
+-- local known = { }
+--
+-- function string.todimen(str) -- maybe use tex.sp
+--     local k = known[str]
+--     if not k then
+--         k = tex.sp(str)
+--         known[str] = k
+--     end
+--     return k
+-- end
+
+stringtodimen = string.todimen -- local variable defined earlier
+
+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,d) -- will be cleaned up once luatex 0.30 is out
+    d = d or texget("hsize")
+    if type(d) == "string" then
+        d = stringtodimen(d)
+    end
+    return (n/100) * d
+end
+
+number["%"] = number.percent