Add a small script for tab removal

replace_non_leading_tabs.lua

@@ -0,0 +1,87 @@
+#!/bin/env luajit
+
+-- SPDX-FileCopyrightText: 2024 DS
+--
+-- SPDX-License-Identifier: Apache-2.0
+
+local function string_width(s)
+	local w = 0
+	for i = 1, #s do
+		if s:sub(i,i) == "\t" then
+			w = w + 4
+		else
+			w = w + 1 -- (just an estimate. works well for most of ascii)
+		end
+	end
+	return w
+end
+
+local path = ...
+assert(path, "No path given")
+
+local file = assert(io.open(path, "r"))
+
+local lines_new = {}
+local in_multiline_comment = false
+
+for line in file:lines() do
+	local line_new = {}
+	local line_new_columns = 0
+	local function add_to_line_new(s)
+		table.insert(line_new, s)
+		line_new_columns = line_new_columns + string_width(s)
+	end
+
+	-- skip leading tabs
+	local i = line:find("[^\t]") or #line + 1
+	add_to_line_new(string.rep("\t", i-1))
+
+	while i <= #line do
+		if in_multiline_comment then
+			local j = line:find("*/", i, true)
+			if j then
+				add_to_line_new(line:sub(i, j+1))
+				in_multiline_comment = false
+				i = j + 2
+			else
+				add_to_line_new(line:sub(i))
+				i = #line + 1
+			end
+		else
+			local j = line:find("\t", i, true) or #line + 1
+			j = math.min(j, line:find("/*", i, true) or #line + 1)
+			j = math.min(j, line:find("//", i, true) or #line + 1)
+			if j ~= #line + 1 then
+				add_to_line_new(line:sub(i, j-1))
+				if line:sub(j, j) == "\t" then
+					add_to_line_new(string.rep(" ", 4 - (line_new_columns % 4)))
+					i = j + 1
+				elseif line:sub(j, j+1) == "/*" then
+					add_to_line_new("/*")
+					in_multiline_comment = true
+					i = j + 2
+				else -- //
+					add_to_line_new(line:sub(j))
+					i = #line + 1
+				end
+			else
+				add_to_line_new(line:sub(i))
+				i = #line + 1
+			end
+		end
+	end
+
+	line_new = table.concat(line_new)
+	table.insert(lines_new, line_new)
+end
+
+file:close()
+
+-- new line at end of file
+table.insert(lines_new, "")
+
+lines_new = table.concat(lines_new, "\n")
+
+file = assert(io.open(path, "w"))
+assert(file:write(lines_new))
+file:close()