Re: [Groff] calling all automake'ers ...

[Ralph Corderoy]

Hi Mike,

> I know the current code uses  diff -Dname  option which is not
> universal.

As an aside, I see POSIX has diff support -e for ed(1) output.  And -s
for running a script.  How about turning -e's output into ed that
inserts the cpp(1) commands and carrying on as before?  Have a poke at

--8<--snip--
    #! /bin/bash

    seq 10 >foo
    seq 12 | sed '3,4d; 6s/./&&/; 7p' >bar

    diff -Dfoo foo bar
    echo

    cp foo foo.new
    diff -e foo bar |
    awk -F, '
        copy {
            if ($0 == ".") {
                if (closing)
                    print closing
                copy = 0
            }
            print
            next
        }

        # 42a -> 42,a
        /[acd]$/ {
            $0 = substr($0, 1, length - 1) FS substr($0, length)
        }
        # 42,a -> 42,42,a
        NF == 2 {
            $0 = $1 FS $1 FS $2
        }

        {
            print "\t=" $0
        }

        # 42,a
        $NF == "a" {
            print $1 "a"
            print "#ifdef foo"
            closing = "#endif /* foo */"
            copy = 1
            next
        }

        # 42,314,c
        $NF == "c" {
            print $1 "i"
            print "#ifndef foo"
            print "."
            print ($2 + 1) "a"   # Bumped on by insert.
            print "#else /* foo */"
            copy = 1
            closing = "#endif /* foo */"
            next
        }

        # 42,314,d
        $NF == "d" {
            print $2 "a"
            print "#endif /* ! foo */"
            print "."
            print $1 "i"
            print "#ifndef foo"
            print "."
            next
        }

        END {
            print "w\nq"
        }
    ' >foo.ed
    cat foo.ed
    echo

    sed -i '/^\t=/d' foo.ed
    ed -s foo.new <foo.ed

    diff <(diff -Dfoo foo bar) foo.new && echo ok
--8<--snip--

It's not had much testing as I've just knocked it up, but it shows the
idea.  And you might want to ditch the cpp commands and switch to
something that's nicer to handle in the rest of the script.  Or maybe do
the .mk-up directly.

Cheers, Ralph.