#!/usr/bin/env icon
#
#	palval.icn -- validate palindrome pages.
#	26-Nov-2018 / gmt
#
#	Prints those lines of palinwrd.htm and palinsen.htm that are not
#	palindromic.  Should only print headers if the files are correct.

link html

procedure main()
	dofile("palinwrd.htm")
	dofile("palinsen.htm")
end

procedure dofile(fname)	#: process one input file
	local f, s
	f := open(fname) | stop("cannot open ", fname)
	write("\n", fname, ":")
	while s := htchunks(f) do if *s > 0 & s[1] ~== '<' then {
		s := clean(s)
		if not ispal(s) then
			write(s)
	}
	close(f)
end

procedure clean(s)	#: remove HTML entities like &amp; and &quot;
	local t
	t := ""
	s ? {
		while t ||:= tab(upto('&')) do
			tab(upto(';')+1)
		t ||:= tab(0)
	}
	return t
end

procedure ispal(s)	#: succeed if s is a palindrome
	local t
	s := map(s, &ucase, &lcase)
	t := ""
	s ? while tab(upto(&lcase)) do
		t ||:= tab(many(&lcase))
	return t == reverse(t)
end