1 files changed, 125 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/page-inj.lua b/tex/context/base/mkiv/page-inj.lua
new file mode 100644
index 000000000..fd66ead08
--- /dev/null
+++ b/tex/context/base/mkiv/page-inj.lua
@@ -0,0 +1,125 @@
+if not modules then modules = { } end modules ["page-inj"] = {
+    version   = 1.000,
+    comment   = "Page injections",
+    author    = "Wolfgang Schuster & Hans Hagen",
+    copyright = "Wolfgang Schuster & Hans Hagen",
+    license   = "see context related readme files",
+}
+
+-- Adapted a bit by HH: numbered states, tracking, delayed, order, etc.
+
+local type, tonumber = type, tonumber
+
+local injections        = pagebuilders.injections or { }
+pagebuilders.injections = injections
+
+local report            = logs.reporter("pagebuilder","injections")
+local trace             = false  trackers.register("pagebuilder.injections",function(v) trace = v end)
+
+local context           = context
+local implement         = interfaces.implement
+local variables         = interfaces.variables
+
+local texsetcount       = tex.setcount
+
+local v_yes             = variables.yes
+local v_previous        = variables.previous
+local v_next            = variables.next
+
+local order             = 0
+local cache             = { }
+
+function injections.save(specification) -- maybe not public, just commands.*
+    order = order + 1
+    cache[#cache+1] = {
+        order      = order,
+        name       = specification.name,
+        state      = tonumber(specification.state) or specification.state,
+        parameters = specification.userdata,
+    }
+    texsetcount("global","c_page_boxes_flush_n",#cache)
+end
+
+function injections.flushbefore() -- maybe not public, just commands.*
+    if #cache > 0 then
+        local delayed = { }
+        context.unprotect()
+        for i=1,#cache do
+            local c = cache[i]
+            local oldstate = c.state
+            if oldstate == v_previous then
+                if trace then
+                    report("entry %a, order %a, flushing due to state %a",i,c.order,oldstate)
+                end
+                context.page_injections_flush_saved(c.name,c.parameters)
+            elseif type(oldstate) == "number" and oldstate < 0 then
+                local newstate = oldstate + 1
+                if newstate >= 0 then
+                    newstate = v_previous
+                end
+                if trace then
+                    report("entry %a, order %a, changing state from %a to %a",i,c.order,oldstate,newstate)
+                end
+                c.state = newstate
+                delayed[#delayed+1] = c
+            else
+                delayed[#delayed+1] = c
+            end
+        end
+        context.unprotect()
+        cache = delayed
+        texsetcount("global","c_page_boxes_flush_n",#cache)
+    end
+end
+
+function injections.flushafter() -- maybe not public, just commands.*
+    if #cache > 0 then
+        local delayed = { }
+        context.unprotect()
+        for i=1,#cache do
+            local c = cache[i]
+            local oldstate = c.state
+            if oldstate == v_next then
+                if trace then
+                    report("entry %a, order %a, flushing due to state %a",i,c.order,oldstate)
+                end
+                context.page_injections_flush_saved(c.name,c.parameters)
+            elseif type(oldstate) == "number" and oldstate> 0 then
+                local newstate = oldstate- 1
+                if newstate <= 0 then
+                    newstate = v_next
+                end
+                if trace then
+                    report("entry %a, order %a, changing state from %a to %a",i,c.order,oldstate,newstate)
+                end
+                c.state = newstate
+                delayed[#delayed+1] = c
+            end
+        end
+        context.protect()
+        cache = delayed
+        texsetcount("global","c_page_boxes_flush_n",#cache)
+    end
+end
+
+implement {
+    name      = "savepageinjections",
+    actions   = injections.save,
+    arguments = {
+        {
+            { "name" },
+            { "state" },
+            { "userdata" }
+        }
+    }
+}
+
+implement {
+    name    = "flushpageinjectionsbefore",
+    actions = injections.flushbefore
+}
+
+implement {
+    name    = "flushpageinjectionsafter",
+    actions = injections.flushafter
+}