Replace capitalized letters in matching lines

Question

I have multiple lines with the key "booktitle":

  booktitle={Advances in Cryptology - CRYPTO' 89 Proceedings},
  volume={435},
  series={Lecture Notes in Computer Science},

I would like to replace the uppercase letters of each value with {LETTER}, i.e.

  booktitle={{A}dvances in {C}ryptology - {CRYPTO}' 89 {P}roceedings},
  volume={435},
  series={Lecture Notes in Computer Science},

Could you help me please?

Answer 1

To obtain this result you could use :substitute, for example with the cursor on the first line:

:s/\u\+/{\0}/g

• \u\+ one or more uppercase character: equivalent to [A-Z]\+, see:h \u
• \0 whole matched pattern, see :h sub-replace-special
• g is a flag needed to replace all occurrences in the line unless gdefault is on

To affect more than one line, you can specify a range, e.g. :%s for the entire file.

In order to execute this substitution multiple times but only on lines starting with a defined pattern (/^ booktitle=/ in this case), :global is probably what you want:

:g/^  booktitle=/s/\u\+/{\0}/g