Automatically Update Copyright Notice in Files

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created October 9, 2007 · complexity advanced · author Fritzophrenic · version 7.0

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Especially when editing source code, there is often a copyright notice embedded in the file. Insert one of the following in a vimrc file to automatically update this copyright notice in ALL FILES when writing them.

Simple Copyright Notices

" Automatically update copyright notice with current year
autocmd BufWritePre *
  \ if &modified |
  \   exe "g#\\cCOPYRIGHT \\(".strftime("%Y")."\\)\\@![0-9]\\{4\\}\\(-".strftime("%Y")."\\)\\@!#s#\\([0-9]\\{4\\}\\)\\(-[0-9]\\{4\\}\\)\\?#\\1-".strftime("%Y") |
  \ endif

This replaces yyyy or yyyy-yyyy with yyyy-<current year> on any line in the file containing an outdated "COPYRIGHT yyyy" notice (case-insensitive). It only does this if the file has been modified.

An explanation of the command string follows:

• g# - search and replace only on a line matching copyright notice patten. '#' is used rather than the customary '/' to avoid confusion with all the '\' characters.

• \\cCOPYRIGHT - match on text COPYRIGHT followed by a space (case-insensitive)
• \\(".strftime("%Y")."\\)\\@! - only match when the entire match does not consist of the current year (i.e. don't update a notice containing only the current year, like "Copyright 2007").
• [0-9]\\{4\\} - matches a 4-digit number for the first year in the notice
• \\(-".strftime("%Y")."\\)\\@! - don't match on up-to-date notices

• #s# - search and replace the outdated year

• \\([0-9]\\{4\\}\\) - match a 4-digit year and give it a backreference
• \\(-[0-9]\\{4\\}\\)\\? - optionally match an ending year, e.g. the "-2006" in "copyright 2000-2006".
• #\\1-".strftime("%Y") - replace the found text with the first year in the copyright, a hyphen, and the current year

This script will "jump" to the copyright notice whenever it gets updated. If this is not desired, you can put in a command before the g#s# to create a mark and a command after it to jump back to the mark.

References

• :help :g
• :help :s
• :help strftime()
• :help /\@!
• :help m
• :help `

More Complex Notices

The above works great for simple copyrights with just a range of years, but if you need more precise/correct ones (that skip years something was not worked on, e.g. "copyright 2004, 2006-2008") it will fail miserably. Here's what to replace the guts with, instead of the g#s## command above:

          \   exe '%s:'.
          \       '\cCOPYRIGHT\s*\%((c)\|©\|©\)\?\s*'.
          \         '\%([0-9]\{4}\(-[0-9]\{4\}\)\?,\s*\)*\zs'.
          \         '\('.
          \           '\%('.strftime("%Y").'\)\@![0-9]\{4\}'.
          \           '\%(-'.strftime("%Y").'\)\@!\%(-[0-9]\{4\}\)\?'.
          \         '\&'.
          \           '\%([0-9]\{4\}-\)\?'.
          \           '\%('.(strftime("%Y")-1).'\)\@!'.
          \           '\%([0-9]\)\{4\}'.
          \         '\)'.
          \         '\ze\%(\%([0-9]\{4\}\)\@!.\)*$:'.
          \       '&, '.strftime("%Y").':e' |
          \   exe '%s:'.
          \       '\cCOPYRIGHT\s*\%((c)\|©\|©\)\?\s*'.
          \         '\%([0-9]\{4}\%(-[0-9]\{4\}\)\?,\s*\)*\zs'.
          \           '\%('.strftime("%Y").'\)\@!\([0-9]\{4\}\)'.
          \           '\%(-'.strftime("%Y").'\)\@!\%(-[0-9]\{4\}\)\?'.
          \         '\ze\%(\%([0-9]\{4\}\)\@!.\)*$:'.
          \       '\1-'.strftime("%Y").':e' |

This makes two passes, one to update years that it needs a comma for, the next to update years it can use a hyphen for.

First Pass (needs a comma)

Summary: Replace all lines with a copyright notice, that do NOT end in the previous or current year, with a comma and the current year.

• %s: - start a "replace in all lines" search, using ':' rather than the customary '/' for clarity.
• \cCOPYRIGHT\s*\%((c)\|©\|©\)\?\s* - find lines containing the copyright flag (copyright {optional symbol}) as in the simple method.
• \%({below}\)* - match any number of year ranges followed by commas, but DO NOT use them for backreferences.

• [0-9]\{4}\(-[0-9]\{4\}\)\?,\s* - match a year or year range, followed by a comma and whitespace.

• \zs - Place the "start of match" at this point. This means that any matched text previous to this point (i.e. the copyright flag, and any year-ranges followed by commas) will NOT be replaced with the replacement text.
• \({below}\&{below}\) - The parentheses group two "concats" separated by the \&. All concats must match at the same place for the pattern to match. When it matches, it matches the final concat.

• \%('.strftime("%Y").'\)\@![0-9]\{4\} - match any year that is not the current year.
• \%(-'.strftime("%Y").'\)\@!\%(-[0-9]\{4\}\)\? - optionally match any year range ending ("-{year}") to complete the first concat
• \%([0-9]\{4\}-\)\? - optionally match a year range beginning ("-{year}")
• \%('.(strftime("%Y")-1).'\)\@!\%([0-9]\)\{4\} - match any year except for the previous year (note, current year already known NOT to match) to complete the final concat

• \ze - place the end of the match at this point, so that any text following this point is NOT affected by the replacement.
• \%(\%([0-9]\{4\}\)\@!.\)*$ - match any text that does not contain a year, until the end of the line. This ensures that we captured only the very last year in the line with our final concat, above.
• :&, '.strftime("%Y") - replace with the entire match (i.e. the last concat above) followed by a comma and the current year. Recall that the match start and end were defined carefully so that only the desired text is replaced.
• :e - suppress error when no match is found so you don't see error messages when your copyright is up-to-date, and to allow the mapping to continue on to the second pass...

Second Pass (can use a hyphen)

Summary: Replace all remaining lines with a copyright notice, that do NOT end in the current year (i.e. they end in the previous year), with a hyphen and the current year.

• %s: - start a "replace in all lines" search, using ':' rather than the customary '/' for clarity.
• \cCOPYRIGHT\s*\%((c)\|©\|©\)\?\s* - find lines containing the copyright flag (copyright {optional symbol}) as in the simple method.
• \%({below}\)* - match any number of year ranges followed by commas, but DO NOT use them for backreferences.

• [0-9]\{4}\(-[0-9]\{4\}\)\?,\s* - match a year or year range, followed by a comma and whitespace.

• \zs - Place the "start of match" at this point. This means that any matched text previous to this point (i.e. the copyright flag, and any year-ranges followed by commas) will NOT be replaced with the replacement text.
• \%('.strftime("%Y").'\)\@!\([0-9]\{4\}\) - match any year except for the current year, and place it in the first backreference (note the use of \%(\) in every previous grouping)
• \%(-'.strftime("%Y").'\)\@!\%(-[0-9]\{4\}\)\? - optionally match a year range ending that does NOT include the current year.
• \ze - place the end of the match at this point, so that any text following this point is NOT affected by the replacement.
• \%(\%([0-9]\{4\}\)\@!.\)*$ - match any text that does not contain a year, until the end of the line. This ensures that we captured only the very last year in the line.
• \1-'.strftime("%Y") - replace with the first backreference (i.e. the first year in the final year range of the line), followed by a hyphen and the current year.
• :e - suppress error when no match is found so you don't see error messages whenever your copyright notice is up-to-date.

References

• :help /branch
• :help /\zs
• :help /\ze
• :help /\%(\)
• :help /\@!

Take-Away Lessons

• Use the 'g' command or \zs and \ze atoms to carefully limit your 's' commands to certain lines, and to simplify your replacement text for 's' commands.
• Use \%(\) for grouping whenever you don't need the group for a back-reference to simplify things and provide some speedup.
• Zero-width matches such as \@! are very powerful - familiarize yourself with them.
• Complicated regular expressions can be made far less complex by splitting them into sections and working on each section independently.
• Familiarize yourself with the definition of a pattern (:help /pattern) and its constituent components (like branches - :help /branch). Using these components fully can simplify your patterns or even make possible things that are not possible otherwise.

See also

• Tip 97 Insert current date or time