syntax: fix conflicts introduced with #896

* mainly the language_md got affected which has some exotic rules
* some other languages are also using spaces at start of pattern
  and even if not affected this change tackles that

data/core/syntax.lua

@@ -7,11 +7,49 @@ local plain_text_syntax = { name = "Plain Text", patterns = {}, symbols = {} }
 
 
 function syntax.add(t)
-  -- this rule gives us a performance gain for the tokenizer in lines with
-  -- long amounts of consecutive spaces without affecting other patterns
+  -- the rule %s+ gives us a performance gain for the tokenizer in lines with
+  -- long amounts of consecutive spaces, to not affect other patterns we
+  -- insert it after any rule that starts with spaces to prevent conflicts
   if t.patterns then
-    table.insert(t.patterns, 1, { pattern = "%s+", type = "normal" })
+    local temp_patterns = {}
+    ::pattern_remove_loop::
+    for pos, pattern in ipairs(t.patterns) do
+      local pattern_str = ""
+      local ptype = pattern.pattern
+        and "pattern" or (pattern.regex and "regex" or nil)
+      if ptype then
+        if type(pattern[ptype]) == "table" then
+          pattern_str = pattern[ptype][1]
+        else
+          pattern_str = pattern[ptype]
+        end
+        if (ptype == "pattern" and(
+            pattern_str:find("^%^?%%s")
+            or
+            pattern_str:find("^%^?%s")
+          ))
+          or
+          (ptype == "regex" and (
+            pattern_str:find("^%^?\\s")
+            or
+            pattern_str:find("^%^?%s")
+          ))
+        then
+          table.insert(temp_patterns, table.remove(t.patterns, pos))
+          -- since we are removing from iterated table we need to start
+          -- from the beginning again to prevent any issues
+          goto pattern_remove_loop
+        end
+      end
+    end
+    for pos, pattern in ipairs(temp_patterns) do
+      table.insert(t.patterns, pos, pattern)
+    end
+    local pos = 1
+    if #temp_patterns > 0 then pos = #temp_patterns+1 end
+    table.insert(t.patterns, pos, { pattern = "%s+", type = "normal" })
   end
+
   table.insert(syntax.items, t)
 end