ununicode

snippets/ununicode

@@ -0,0 +1,105 @@
+#!/usr/bin/env escript
+
+% Takes an input file, shows where non-ascii characters are
+%
+% Written by Peter Harpending, 2026-03-05
+%
+% Copyright (c) 2026 QPQ AG
+%
+% Permission is hereby granted, free of charge, to any person obtaining a copy
+% of this software and associated documentation files (the "Software"), to deal
+% in the Software without restriction, including without limitation the rights
+% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+% copies of the Software, and to permit persons to whom the Software is
+% furnished to do so, subject to the following conditions:
+%
+% The above copyright notice and this permission notice shall be included in
+% all copies or substantial portions of the Software.
+%
+% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+% SOFTWARE.
+
+-mode(compile).
+
+help() ->
+    io:format("USAGE: ununicode Filename~n"
+              "~n"
+              "Example:~n"
+              "     ununicode foo.md | less -RS~n",
+              []).
+
+
+main([Filename]) ->
+    case file:read_file(Filename) of
+        {ok, Bytes} ->
+            Lines = string:split(Bytes, "\n", all),
+            go(Lines, 1, []);
+        Error ->
+            io:format("ERROR reading file ~p: ~tp~n", [Filename, Error]),
+            help()
+    end;
+main(_) ->
+    help().
+
+
+go([Line | Rest], LineNum, Badnesses) ->
+    NewAcc =
+        case bad(Line) of
+            true  -> [{LineNum, Line} | Badnesses];
+            false -> Badnesses
+        end,
+    go(Rest, LineNum + 1, NewAcc);
+go([], _, Badness) ->
+    punish(Badness).
+
+
+bad(<<0:1, _:7, Rest/bytes>>) -> bad(Rest);
+bad(<<1:1, _:7, _/bytes>>)    -> true;
+bad(<<>>)                     -> false.
+
+% tabulate
+punish([]) ->
+    io:format("no badness found~n");
+punish(Bads = [{MaxLineNum, _} | _]) ->
+    punish(ndigits(MaxLineNum), lists:reverse(Bads)).
+
+
+punish(NDigits, [{Linum, Line} | Rest]) ->
+    Print = [format_digits(NDigits, Linum), "\t", highlight_bad(Line)],
+    io:format("~ts~n", [Print]),
+    punish(NDigits, Rest);
+punish(_, []) ->
+    ok.
+
+
+highlight_bad(Line) ->
+    hlb(Line, []).
+
+hlb(<<0:1, A:7, Rest/bytes>>, Acc) ->
+    hlb(Rest, [Acc, <<0:1, A:7>>]);
+hlb(<<(2#110):3, A:5, B:8, Rest/bytes>>, Acc) ->
+    hlb(Rest, [Acc, red(<<(2#110):3, A:5, B:8>>)]);
+hlb(<<(2#1110):4, A:4, B:8, C:8, Rest/bytes>>, Acc) ->
+    hlb(Rest, [Acc, red(<<(2#1110):4, A:4, B:8, C:8>>)]);
+hlb(<<(2#11110):5, A:3, B:8, C:8, D:8, Rest/bytes>>, Acc) ->
+    hlb(Rest, [Acc, red(<<(2#11110):5, A:3, B:8, C:8, D:8>>)]);
+hlb(<<>>, Acc) ->
+    Acc.
+
+red(String) ->
+    ["\e[7;31m", String, "\e[0m"].
+
+ndigits(N) ->
+    round(math:floor(math:log10(N)) + 1).
+
+format_digits(Width, N) ->
+    NSpaces = Width - ndigits(N),
+    [spaces(NSpaces), integer_to_list(N)].
+
+spaces(N) when N >= 1 -> [" " | spaces(N - 1)];
+spaces(_)             -> "".