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authorPřemysl Eric Janouch <p@janouch.name>2020-10-10 17:55:14 +0200
committerPřemysl Eric Janouch <p@janouch.name>2020-10-10 17:55:14 +0200
commitee5cac4f217f811070c532fe53c4ff8ae7590b99 (patch)
tree0481559b19316d5b78b0a2b4d32b22cc2ad2fedb
parent59ac02d91f83521e31fbc56745496f8754765965 (diff)
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degesch: add a plugin to highlight prime numbers
-rw-r--r--plugins/degesch/prime.lua50
1 files changed, 50 insertions, 0 deletions
diff --git a/plugins/degesch/prime.lua b/plugins/degesch/prime.lua
new file mode 100644
index 0000000..bffc0e1
--- /dev/null
+++ b/plugins/degesch/prime.lua
@@ -0,0 +1,50 @@
+--
+-- prime.lua: highlight prime numbers in messages
+--
+-- Copyright (c) 2020, Přemysl Eric Janouch <p@janouch.name>
+--
+-- Permission to use, copy, modify, and/or distribute this software for any
+-- purpose with or without fee is hereby granted.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+--
+
+-- The prime test is actually very fast, so there is no DoS concern
+local is_prime = function (n)
+ if tonumber (n) < 2 then return false end
+ for i = 2, n ^ (1 / 2) do if (n % i) == 0 then return false end end
+ return true
+end
+
+local do_interlink = function (run)
+ -- Let's not cripple formatting, colours especially
+ -- TODO: we can just employ the same approach as in do_text and skip over
+ if run:find ('%c') then return run end
+
+ return run:gsub ("%f[%w_]%d+%f[^%w_]", function (number)
+ if is_prime (number) then return "\x1f" .. number .. "\x1f" end
+ return number
+ end)
+end
+
+local do_text = function (text)
+ local rebuilt, last = {""}, 1
+ for run, link, endpos in text:gmatch ('(.-)(%f[%g]https?://%g+)()') do
+ last = endpos
+ table.insert (rebuilt, do_interlink (run) .. link)
+ end
+ return table.concat (rebuilt, "") .. do_interlink (text:sub (last))
+end
+
+-- XXX: sadly it won't typically highlight primes in our own messages,
+-- unless IRCv3 echo-message is on
+degesch.hook_irc (function (hook, server, line)
+ local start, message = line:match ("^(.- PRIVMSG .- :)(.*)$")
+ return message and start .. do_text (message) or line
+end)