[SOLVED] Replace a string, but only when it is the last occurance of that string before a specific line

Issue

I am converting a custom markup language to TeX.

I have a file like this:

\macro{stuff}
{more stuff}
{yet other stuff}
{some stuff}
these are extra lines
another extra line
there can be any number of extra lines
e

\macro{yet more stuff stuff}
{even more stuff}
{yet other stuff}
{some stuff}
this is extra
this is extra too
e

I need the result to be this:

\macro{stuff}
{more stuff}
{yet other stuff}
{some stuff}{
these are extra lines
another extra line
there can be any number of extra lines
}

\macro{yet more stuff stuff}
{even more stuff}
{yet other stuff}
{some stuff}{
this is extra
this is extra too
}

Notice e is by itself on a line, indicating the end of a set of data, it simply gets replaced with a closing bracket.

I could simply use this:

sed -i 's/^e$/}/g' file.tex

Resulting in this:

\macro{stuff}
{more stuff}
{yet other stuff}
{some stuff}
these are extra lines
another extra line
there can be any number of extra lines
}

\macro{yet more stuff stuff}
{even more stuff}
{yet other stuff}
{some stuff}
this is extra
this is extra too
}

The problem is, I also need a matching starting bracket to surround this extra text before the e.

One way to think of it is:

1. Replace every occurrence of }.
2. But only if that occurrence is at the end of the line.
3. And only if that it is the last occurrence appearing before an e appearing completely by itself.

This is the closest I can figure, not sure how to match across any number of lines not containing more matches of }$:

sed -i 's/}$\n.*\n.*\n.*\n^e$/}{&}/g' file.tex

How can I wrap that final extra text inside { and }?

Solution

It is easier to do this using awk using an empty RS. Here is a gnu-awk solution:

awk -v RS= '{sub(/.*}/, "&{"); sub(/\ne$/, "\n}"); ORS=RT} 1' file

\macro{stuff}
{more stuff}
{yet other stuff}
{some stuff}{
these are extra lines
another extra line
there can be any number of extra lines
}

\macro{yet more stuff stuff}
{even more stuff}
{yet other stuff}
{some stuff}{
this is extra
this is extra too
}

Or in any version of awk:

awk -v RS= '{sub(/.*}/, "&{"); sub(/\ne$/, "\n}\n")} 1' file

Answered By - anubhava

Answer Checked By - Marie Seifert (WPSolving Admin)