update slide content

resources/slides_utils.lua

 function tostr(t)
     local str = ""
     for k, v in next, t do
         if #str > 0 then
             str = str .. ", "
         end
         if type(k) == "number" then
             str = str .. "[" .. k .. "] = "
         else
             str = str .. tostring(k) .. " = "
@@ skipping 36 matching lines @@
 end
 
 function pretty_print_slides(slides)
     io.write("gSlides = {\n")
     for i = 1, #slides do
         pretty_print_slide(slides[i])
     end
     io.write("}\n")
 end
 
-function parse_transition_type(s)
-    return s:match("^<%s*transition%s*=%s*(%a+)%s*>$")
+function parse_attr(s, lvalue)
+    local ts = "^<%s*" .. lvalue .. "%s*=%s*(%a+)%s*>$"
+    return s:match(ts)
 end
 
-function parse_blockstyle_type(s)
-    return s:match("^<%s*blockstyle%s*=%s*(%a+)%s*>$")
+function flush(slides, block)
+    if #block > 0 then
+        slides[#slides + 1] = block
+        return {}
+    end
+    return block
 end
 
 function parse_file(file)
     local slides = {}
     local block = {}
 
     for line in file:lines() do
         local s = trim_ws(line)
         if #s == 0 then   -- done with a block
-            if #block > 0 then
-                slides[#slides + 1] = block
-                block = {}
-            end
+            block = flush(slides, block)
         else
-            local transition_type = parse_transition_type(s)
-            local blockstyle = parse_blockstyle_type(s)
+            local transition_type = parse_attr(s, "transition")
+            local blockstyle = parse_attr(s, "blockstyle")
             if transition_type then
                 block["transition"] = transition_type
             elseif blockstyle then
                 block["blockstyle"] = blockstyle
             else
                 if block.blockstyle == "code" then
                     block[#block + 1] = { text = line }
                 else
                     local n = count_hypens(s)
                     block[#block + 1] = {
                         indent = n,
                         text = trim_ws(s:sub(n + 1, -1))
                     }
                 end
             end
         end
     end
 --    pretty_print_slides(slides)
     return slides
 end