dot-files/scripts/localrc
Bruno BELANYI 2e927c89e7 [UPDATE][SCRIPT] Use expansion for PROMPT_COMMAND
It seems like the idiomatic way to update $PROMPT_COMMAND is to use
variable expansion to add a semi-colon and a space before the command
we're adding.

I also switched from prepending my commands to appending them, which
allows overriding behaviour, such as terminal titles which could be set
from system files.
2020-12-12 14:12:41 +01:00

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# This script applies local configuration changes from the start of your
# file hierarchy tree down to your current working directory.
#
# When you change dirctories it automatically undoes those changes by using
# the command contained in the associative array `__undo_commands` starting by
# the ones furthest down until the common ancestor with your current
#
# The '.localrc' files should add an undo command to __undo_commands which is
# keyed with the '__UNDO_DIR' variable (i.e: __undo_commands[$__UNDO_DIR]='...')
# This variable will be eval-ed to undo your local changes.
#
# Example 1: a project that needs to have the PATH pre-pended
#
# # Taking advantage of PATH being expanded when sourcing the file
# __undo_commands[$__UNDO_DIR]="export PATH='$PATH'"
# export PATH="$__UNDO_DIR/bin:$PATH"
#
# Example 2: a project that needs to activate a virtualenv
#
# __undo_commands[$__UNDO_DIR]='deactivate'
# source env/bin/activate
# Contains the commands to undo the changes made in a directory
declare -A __undo_commands
# Contains the PWD of the previous command (and not $OLDPWD)
__LAST_PWD='/'
# Declare this variable to print some debug information
#DEBUG_LOCALRC=toto
# Source localrc files from "$1" and its parents unless we find "$2" and stop
function __source_localrc_files_rec() {
# "$1" and "$2" should not have any trailing slashes unless they are '/'
if [ "$1" != "$2" ]; then
# FIXME: condition should be unnecessary, but is there to avoid loops
[ "$1" != '/' ] && __source_localrc_files_rec "$(dirname "$1")" "$2"
# Export the special '__UNDO_DIR' variable to key into '__undo_commands'
export __UNDO_DIR="$1"
local localrc="$1/.localrc"
# The post-fix traversal sourced the parent before the child
if [ -r "$localrc" ]; then
source "$localrc"
if [ -n "${DEBUG_LOCALRC+set}" ]; then
echo "sourced $localrc with __UNDO_DIR as '$__UNDO_DIR'"
fi
fi
unset -v __UNDO_DIR
fi
}
# Undo the changes made by "$1" and its parents unless we find "$2" and stop
function __undo_localrc_changes() {
# Undo the changes for our parent directory if we aren't at the common root
if [ "$1" != "$2" ]; then
# If there is a command to undo the changes for that directory, do it
[ -n "${DEBUG_LOCALRC+set}" ] && echo "Looking at undoing $1"
if [ -n "${__undo_commands[$1]+set}" ]; then
eval "${__undo_commands[$1]}"
[ -n "${DEBUG_LOCALRC+set}" ] && echo "undid $1/.localrc"
fi
# FIXME: condition should be unnecessary, but is there to avoid loops
[ "$1" != '/' ] && __undo_localrc_changes "$(dirname "$1")" "$2"
fi
}
# Return the closest common parent directory of "$1" and "$2"
function common_parent() {
local directories=("$1")
while [ "${directories[-1]}" != '/' ]; do
directories+=("$(dirname "${directories[-1]}")")
done
for candidate in "${directories[@]}"; do
case "$2" in
"$candidate"*) printf "%s" "$candidate"; break;;
esac
done
}
function __source_localrc_files() {
# Only do it if we changed our directory since the last command
if [ "$__LAST_PWD" = "$PWD" ]; then
return 0
fi
# Find the closest common parent directory
local parent='/'
if [ -n "$__LAST_PWD" ]; then
parent=$(common_parent "$__LAST_PWD" "$PWD")
fi
if [ -n "${DEBUG_LOCALRC+set}" ]; then
echo "DEBUG"
echo "LAST: $__LAST_PWD"
echo "CUR: $PWD"
echo "PARENT: $parent"
fi
__undo_localrc_changes "$__LAST_PWD" "$parent"
__source_localrc_files_rec "$PWD" "$parent"
# Update our last seen working directory
__LAST_PWD="$PWD"
}
# Execute this command every time
if [ -n "$BASH_VERSION" ]; then
[ -n "${DEBUG_LOCALRC+set}" ] && echo "Loaded Bash"
PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND; }__source_localrc_files"
elif [ -n "$ZSH_VERSION" ]; then
[ -n "${DEBUG_LOCALRC+set}" ] && echo "Loaded Zsh"
precmd_functions+=( __source_localrc_files)
fi