From e1946776a33eeea9ac9c2a4460a1a221fccd0817 Mon Sep 17 00:00:00 2001
From: Dohyun Kim <nomosnomos@gmail.com>
Date: Sun, 29 Dec 2013 12:04:14 +0900
Subject: use table instead of string for transparency

---
 luaotfload-colors.lua | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/luaotfload-colors.lua b/luaotfload-colors.lua
index d8fb77a..3b430f3 100644
--- a/luaotfload-colors.lua
+++ b/luaotfload-colors.lua
@@ -126,18 +126,12 @@ registerotffeature {
 --- something is carried around in ``res``
 --- for later use by color_handler() --- but what?
 
-local res --- <- state of what?
+local res = {}
 
 --- float -> unit
 local function pageresources(alpha)
-    local tpr = tex.pdfpageresources
-    local newtrans = stringformat("/TransGs%s<</ca %s/CA %s>>",
-                                  alpha, alpha, alpha)
-    res = res or ""
-    if stringfind(tpr,newtrans) or stringfind(res,newtrans) then
-    else
-        res = res..newtrans
-    end
+    res[#res+1] = stringformat("/TransGs%s<</ca %s/CA %s>>",
+                               alpha, alpha, alpha)
 end
 
 --- we store results of below color handler as tuples of
@@ -281,19 +275,23 @@ end
 local color_handler = function (head)
     local new_head = node_colorize(head, nil, nil)
     -- now append our page resources
-    if res and stringfind(res, "%S") then -- test for non-empty string
-        local tpr = tex.pdfpageresources
-        local endtrans = "/TransGs1<</ca 1/CA 1>>"
-        if stringfind(tpr,endtrans) or stringfind(res,endtrans) then
-        else
-            res = res..endtrans
+    if res and #res > 0 then
+        local tpr, t = tex.pdfpageresources, ""
+        res[#res+1] = "/TransGs1<</ca 1/CA 1>>"
+        for i = 1,#res do
+            if stringfind(tpr,res[i]) or stringfind(t,res[i]) then
+            else
+                t = t .. res[i]
+            end
         end
-        if not stringfind(tpr,"/ExtGState<<.*>>") then
-            tpr = tpr.."/ExtGState<<>>"
+        if t ~= "" then
+            if not stringfind(tpr,"/ExtGState<<.*>>") then
+                tpr = tpr.."/ExtGState<<>>"
+            end
+            tpr = stringgsub(tpr,"/ExtGState<<","%1"..t)
+            tex.pdfpageresources = tpr
         end
-        tpr = stringgsub(tpr,"/ExtGState<<","%1"..res)
-        tex.pdfpageresources = tpr
-        res = nil -- reset res
+        res = {} -- reset res
     end
     return new_head
 end
-- 
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