LuaDoc. Conversion functions and better readability. Fixed condition check.

Author: TIMONz1535

script/parser/luadoc.lua

@@ -1691,6 +1691,18 @@ local function convertTokens(doc)
     return docSwitch(text, doc)
 end
 
+local function convertLinePosToCommentPos(comment, linePos)
+    -- line pos is 0-based relative to original line of text before `--` prefix is removed
+    -- while comment pos is 1-based and with `--` prefix removed
+    -- but even if we subtracted 1-based line poses, we would get 0-based "length", so convert #3028
+    return linePos - comment.start + 1 - 2
+end
+
+local function convertCommentPosToLinePos(comment, commentPos)
+    -- the reverse of convertLinePosToCommentPos()
+    return commentPos + 2 - 1 + comment.start
+end
+
 local function trimTailComment(text)
     local comment = text
     if text:sub(1, 1) == '@' then
@@ -1743,15 +1755,11 @@ local function buildLuaDoc(comment)
                 finish = rest.firstFinish or result.finish
             end
         end
-        -- the subtraction is the length of the skipped string, so the start position is `+ 1`
-        local cpos = finish - comment.start + 1
-        -- actual text start is `comment.start + 2` because of `--` for some reason
-        local textOffset = 2
-        local cstart = text:find('%S', cpos - textOffset)
-        if cstart and cstart < comment.finish - textOffset then
+        local cstart = text:find('%S', convertLinePosToCommentPos(comment, finish))
+        if cstart and convertCommentPosToLinePos(comment, cstart) < comment.finish then
             result.comment = {
                 type   = 'doc.tailcomment',
-                start  = comment.start + cstart - 1 + textOffset,
+                start  = convertCommentPosToLinePos(comment, cstart),
                 finish = comment.finish,
                 parent = result,
                 text   = trimTailComment(text:sub(cstart)),