better grammarly prep

thesis/filters/math-omit.lua

@@ -0,0 +1,48 @@
+-- math-omit.lua
+-- Replace any math with a placeholder and ensure a space before it when appropriate.
+local PH = "[math omitted]"
+
+function Math(el)
+    -- Emit the placeholder as a Str; spacing is fixed in Para/Plain below.
+    return pandoc.Str(PH)
+end
+
+local function ensure_space_before_ph(inlines)
+    local out = {}
+    for i = 1, #inlines do
+        local cur = inlines[i]
+        if cur.t == "Str" and cur.text == PH then
+            local prev = out[#out]
+            local need_space = true
+
+            -- No space if it's the first token in the block
+            if not prev then
+                need_space = false
+            elseif prev.t == "Space" then
+                need_space = false
+            elseif prev.t == "Str" then
+                -- If previous char is an opening bracket/paren/slash/hyphen or whitespace, skip
+                local last = prev.text:sub(-1)
+                if last:match("[%(%[%{%/%-]") or last:match("%s") then
+                    need_space = false
+                end
+            end
+
+            if need_space then table.insert(out, pandoc.Space()) end
+            table.insert(out, cur)
+        else
+            table.insert(out, cur)
+        end
+    end
+    return out
+end
+
+function Para(el)
+    el.content = ensure_space_before_ph(el.content)
+    return el
+end
+
+function Plain(el)
+    el.content = ensure_space_before_ph(el.content)
+    return el
+end