rename-identifier

#!/bin/bash

# This came from Gary Bernhardt's dotfiles:
#
#   https://github.com/garybernhardt/dotfiles


# This script efficiently bulk-renames identifiers, with confirmation of each
# change. For example, to rename the User class to Person in all files in app
# and lib, do:
#
#   rename-identifier User Person {app,lib}/**/*.rb
#
# The arguments are:
#
#   1) The old (current) identifier
#   2) The new identifier (to rename the old one to)
#   3) The files to look in (in the example above, a standard shell glob is
#   used).
#
# The script will collect all of the given files that contain the old
# identifier, then open them all in a vim instance. Vim will have two new keys
# mapped:
#
#   <leader>j to do a global search and replace from the old to the new
#   identifier. This uses :s///c, so it will individually confirm each change.
#
#   <leader>k to write the current file and delete the buffer (going to the
#   next file). This is for when you're doing renaming in the current file.
#
# For both file searching and vim replacing, word boundaries are used. So, if
# you're replacing "User", and you have a file with the string "Users" but not
# "User", that file won't be matched. If a file containing "Users" also matches
# "User", the vim search/replace still won't hit the "Users" token.
#
# A typical session will look like this (assuming <leader> is ","):
#
#       # Run script
#   ,j  # Trigger rename process in first file
#   y   # Replace first identifier found
#   n   # Don't replace second identifier
#       # No more matches are found, so Vim drops us back in normal mode
#   ,k  # Write file and go to the next one
#   ,j  # Trigger rename process in second file
#       # Etc.
#
# This is much more efficient than clumsily typing the ack, then the ":%s",
# then repeatedly saying ":w" to write, ":bd" to close the buffer, ":<up>" to
# recall the search and replace command, etc.
#
# Notes:
#
#   Sometimes you need to manually adjust something (e.g., things don't line up
#   after an identifier change). That's easy, though: just cancel the
#   search/replace with <esc>, make your change, and hit <leader>j to start the
#   search/replace over again. This is why there are two maps instead of one.
#
#   Despite its name, this isn't limited to single-identifier renames. It will
#   happily rename "Day::Range" to "DayRange", behaving as you'd expect, since
#   it's simply adding word boundaries to both sides of the string.

set -e

if [ $# -lt 3 ]; then
    echo "usage: $(basename $0) old_identifier new_identifier paths ..." >&2
    echo "example: rename-identifier User Person {app,lib}/**/*.rb" >&2
    exit 1
fi

old=$1
new=$2
shift; shift
files=$*

files=$(ack -l '\b'$old'\b' $files)
leader_j='nnoremap <leader>j :%s/\<'$old'\>/'$new'/gc<cr>'
leader_k='nnoremap <leader>k :update\|:bd<cr>'
vim -c "$leader_j" -c "$leader_k" $files