1 files changed, 89 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/math-spa.lua b/tex/context/base/mkiv/math-spa.lua
new file mode 100644
index 000000000..92ee662b9
--- /dev/null
+++ b/tex/context/base/mkiv/math-spa.lua
@@ -0,0 +1,89 @@
+if not modules then modules = { } end modules ['math-spa'] = {
+    version   = 1.001,
+    comment   = "companion to math-ini.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+-- for the moment (when testing) we use a penalty 1
+
+local penalty_code = nodes.nodecodes.penalty
+local glue_code    = nodes.nodecodes.glue
+
+local nuts         = nodes.nuts
+local tonut        = nodes.tonut
+local tonode       = nodes.tonode
+local getid        = nuts.getid
+local getnext      = nuts.getnext
+local getwidth     = nuts.getwidth
+local setglue      = nuts.setglue
+local getpenalty   = nuts.getpenalty
+local setpenalty   = nuts.setpenalty
+
+local traverse_id    = nuts.traverse_id
+local get_dimensions = nuts.dimensions
+
+
+local texsetdimen    = tex.setdimen
+
+local v_none = interfaces.variables.none
+local v_auto = interfaces.variables.auto
+
+local method   = v_none
+local distance = 0
+
+function noads.handlers.align(l)
+    if method ~= v_none then
+        local h = tonut(l)
+        if method == v_auto then
+            local s = h
+            while s do
+                local id = getid(s)
+                local n  = getnext(s)
+                if id == penalty_code and getpenalty(s) == 1 then
+                    setpenalty(s,0)
+                    if n and getid(n) == glue_code then
+                        s = n
+                        n = getnext(s)
+                    end
+                    local w = get_dimensions(h,n) + distance
+                    texsetdimen("global","d_strc_math_indent",w)
+                    break
+                end
+                s = n
+            end
+        else
+            texsetdimen("global","d_strc_math_indent",distance)
+        end
+        for n in traverse_id(glue_code,h) do
+            setglue(n,getwidth(n),0,0)
+        end
+    else
+     -- texsetdimen("global","d_strc_math_indent",0)
+    end
+    return l, true
+end
+
+interfaces.implement {
+    name      = "setmathhang",
+    arguments = {
+        {
+            { "method", "string" },
+            { "distance", "dimension" },
+        }
+    },
+    actions   = function(t)
+        method   = t.method or v_none
+        distance = t.distance or 0
+    end
+}
+
+interfaces.implement {
+    name      = "resetmathhang",
+    actions   = function(t)
+        method   = v_none
+        distance = 0
+    end
+}
+