use pseudo-enum table to track parser enclosure state

1 files changed, 19 insertions, 11 deletions

diff --git a/_extensions/ruc-play/semantic-markdown/semantic-markdown.lua b/_extensions/ruc-play/semantic-markdown/semantic-markdown.lua
index 4df6d38..f6f0579 100644
--- a/_extensions/ruc-play/semantic-markdown/semantic-markdown.lua
+++ b/_extensions/ruc-play/semantic-markdown/semantic-markdown.lua
@@ -57,6 +57,14 @@
 -- @see <https://pandoc.org/lua-filters.html#common-pitfalls>
 os.setlocale 'C'
 
+--- pseudo-enum table to track parser enclosure state
+--- @see <https://stackoverflow.com/a/70529481/18619283>
+local Enclosure = {
+  NONE = "0",
+  BRACKETED = "1",
+  BRACED = "2",
+}
+
 -- TODO: cover non-ASCII Unicode characters
 -- @see <https://www.lua.org/manual/5.4/manual.html#6.5>
 --- curie_prefix - CURIE prefix component as set of chars
@@ -201,7 +209,7 @@ function Statements (block)
 
   -- flags for enclosing stages
   -- TODO: support nested bracket enclosure
-  local bracketed, braced
+  local enclosure = Enclosure.NONE
 
   -- amount of detected statements in this block
   local statement_count = 0
@@ -216,7 +224,7 @@ function Statements (block)
     if el.t ~= 'Str' then
 
       -- TODO: support mixed-use braced enclosure
-      if not braced then
+      if enclosure ~= Enclosure.BRACED then
         table.insert(stack, el)
       end
       goto continue
@@ -224,7 +232,7 @@ function Statements (block)
 
     -- unenclosed
     -- TODO: support backslash except immediately before bracket
-    if not (bracketed or braced) then
+    if enclosure == Enclosure.NONE then
       _, x, s = el.text:find("^([^%[\\]*)")
       if x then
         a = x + 1
@@ -234,9 +242,9 @@ function Statements (block)
       if el.text:sub(a, a) == "[" then
 
         -- entering bracketed enclosure
-        bracketed = true
         pos = a + 1
         stack_next = stack_next..s
+        enclosure = Enclosure.BRACKETED
 
       -- staying unenclosed
       else
@@ -248,7 +256,7 @@ function Statements (block)
     -- in bracketed enclosure
     -- TODO: support backslash except immediately before bracket/brace
     -- TODO: support nested bracket enclosure
-    if bracketed and not braced then
+    if enclosure == Enclosure.BRACKETED then
       _, x, s = el.text:find("^([^%[%]}\\]*)", pos)
       if x then
         b = x + 1
@@ -260,14 +268,13 @@ function Statements (block)
 
         -- entering braced enclosure
         if el.text:sub(c, c) == "{" then
-          braced = true
           pos = c + 1
           stack_next = stack_next..s
+          enclosure = Enclosure.BRACED
 
         -- leaving non-annotation enclosure
         else
-          bracketed = false
-          braced = false
+          enclosure = Enclosure.NONE
 
           -- TODO: clear only back to entering this bracketed enclosure
           stack = {}
@@ -284,7 +291,7 @@ function Statements (block)
 
     -- in braced enclosure, leaving it
     -- TODO: support mixed-use enclosure
-    if braced then
+    if enclosure == Enclosure.BRACED then
       _, d1 = el.text:find("^"..curie_long.."}", pos)
       _, d2 = el.text:find("^"..curie_no_ref.."}", pos)
       _, d3 = el.text:find("^"..curie_local.."}", pos)
@@ -296,11 +303,12 @@ function Statements (block)
       end
       if d then
         statement_count = statement_count + 1
-        bracketed = false
-        braced = false
         pos = d + 1
+
         -- TODO: instead recursively call Statements() on remains of Str
         stack_next = stack_next..el.text:sub(pos)
+
+        enclosure = Enclosure.NONE
       end
     end