cg-diff

#!/usr/bin/env bash
#
# Show changes in the diff format
# Copyright (c) Petr Baudis, 2005
#
# Outputs a diff for converting the first tree to the second one.
# By default compares the current working tree to the state at the
# last commit. The output will automatically be displayed in a pager
# unless it is piped to a program.
#
# OPTIONS
# -------
# -c:: Colorize
#	Colorize the output. You can customize the colors using the
#	$CG_COLORS environment variable (see below).
#
# --diffcore ARGS:: Diffcore arguments to pass the Git diff command
#	Pass the given diffcore arguments the called Git diff command.
#	See e.g. git-diff-tree(1) documentation for the list of possible
#	arguments; '-R', '-B', and '-C' might be of particular interest
#	('-M' is already passed by default).
#
# --no-renames:: Do not detect renames
#	By default, `cg-diff` will automatically detect file renames.
#	Diff produced by the rename-aware `cg-diff` will be unappliable
#	using patch(1) (you need to use `cg-patch`) and the renames
#	detection can add slight extra performance penalty. This switch
#	will turn the rename detection off.
#
# -p:: Diff against commit parent
#	Show diff to the parent of the current commit (or the commit
#	specified by the -r parameter).
#
# -s:: Summarize and show diff stat
#	Summarize the diff by showing a histogram for removed and added
#	lines (similar to the output of diffstat(1)) and information
#	about added and renamed files and mode changes.
#
# -r FROM_ID[..TO_ID]:: Limit to revision range
#	Specify the revisions to diff using either '-r rev1..rev2' or
#	'-r rev1 -r rev2'. If no revision is specified, the current
#	working tree is implied. Note that no revision is different from
#	empty revision which means '-r rev..' compares between 'rev' and
#	'HEAD', while '-r rev' compares between 'rev' and working tree.
#
# -m:: Base the diff at the merge base
#	Base the diff at the merge base of the -r arguments (defaulting
#	to HEAD and 'origin' or the current branch's default remote
#	branch, see `cg-fetch` for details).
#
# ENVIRONMENT VARIABLES
# ---------------------
# PAGER::
#	The pager to display log information in, defaults to `less`.
#
# PAGER_FLAGS::
#	Flags to pass to the pager.
#
# CG_COLORS::
#	Colon-separated list of 'name=color' pairs, where name is
#	one of diffhdr, diffhdradd, diffhdrmod, diffhdrrem, diffadd,
#	diffmod, diffrem, diffhunk, diffctx, default, and value is
#	an ECMA-48 SGR sequence (see e.g. console_codes(4)).
#
# CG_COLORS_AUTO::
#	Even if -c was passed or specified in ~/.cgrc, if this option
#	is set, use colors only when the output is a terminal and it
#	supports colors.
#
# CG_LESS::
#	This is what the $LESS environment variable value will be set
#	to before invoking $PAGER. It defaults to $LESS concatenated
#	with the `R` flag to allow displaying of colorized output.
#
# CONFIGURATION VARIABLES
# -----------------------
# The following GIT configuration file variables are recognized:
#
# diff.usecolor::
#	If enabled, colorify the output like with -c if the output
#	is a terminal.
#
# NOTES
# -----
# The ':' is equivalent to '..' in revisions range specification (to make
# things more comfortable to SVN users). See cogito(7) for more details
# about revision specification.

# Testsuite: TODO

USAGE="cg-diff [-c] [-m] [-s] [-p] [-r FROM_ID[..TO_ID]] [FILE]..."
_git_wc_unneeded=1

. "${COGITO_LIB}"cg-Xlib || exit 1


setup_colors()
{
	colorify_setup "$colorify_diffcolors"
	# It could've been turned on by diff.usecolor
	opt_color=1
}

colorize()
{
	if [ "$opt_color" ]; then
		sed -e '
			s/^diff --git.*/'$coldiffhdr'&'$coldefault'/
			s/^+++.*/'$coldiffhdradd'&'$coldefault'/
			s/^---.*/'$coldiffhdrrem'&'$coldefault'/
			s/^[+].*/'$coldiffadd'&'$coldefault'/
			s/^[-].*/'$coldiffrem'&'$coldefault'/
			s/^new\( file\)\{0,1\} mode .*/'$coldiffadd'&'$coldefault'/
			s/^\(deleted file\|old\) mode .*/'$coldiffrem'&'$coldefault'/
			s/^rename to .*/'$coldiffadd'&'$coldefault'/
			s/^rename from .*/'$coldiffrem'&'$coldefault'/
			s/^\(@@ -.* +.* @@\)\(.*\)/'$coldiffhunk'\1'$coldiffctx'\2'$coldefault'/
		'
	else
		cat
	fi
}


id1=" " # means HEAD
id2=" " # means working copy
diffcore=
parent=
opt_color=
mergebase=
style=-p
renames=-M

while optparse; do
	if optparse -c; then
		opt_color=1
	elif optparse --diffcore=; then
		diffcore="$OPTARG"
	elif optparse -p; then
		[ "$mergebase" ] && optconflict -m
		parent=1
	elif optparse -R || optparse --no-renames; then
		renames=
	elif optparse -s; then
		style="--stat"
	elif optparse -r=; then
		if echo "$OPTARG" | fgrep -q '..'; then
			id2="${OPTARG#*..}"
			id1="${OPTARG%..*}"
		elif echo "$OPTARG" | grep -q ':'; then
			id2="${OPTARG#*:}"
			id1="${OPTARG%:*}"
		elif [ "$id1" = " " ]; then
			id1="$OPTARG"
		elif [ "$id2" = " " ]; then
			id2="$OPTARG"
		else
			die "too many revisions"
		fi
	elif optparse -m; then
		[ "$parent" ] && optconflict -p
		mergebase=1
	else
		optfail
	fi
done


colorify_detect "$opt_color" diff && setup_colors

[ "$id1" = " " ] && id1=HEAD

if [ "$parent" ]; then
	[ "$id2" = " " ] || die "too many revisions"
	id2="$id1"

	ids="$(cg-object-id -p "$id2")" || exit 1
	[ "$(echo "$ids" | wc -l)" -gt 1 ] && \
		warn "choosing the first parent of a merge commit. This may not be what you want."
	id1="$(echo "$ids" | head -n 1)" || exit 1

elif [ "$mergebase" ]; then
	[ "$id2" = " " ] && { id2="$(choose_origin refs/heads "what to diff against?")" || exit 1; }

	id1="$(cg-object-id -c "$id1")" || exit 1
	id2="$(cg-object-id -c "$id2")" || exit 1

	conservative_merge_base "$id1" "$id2" || exit 1
	[ "$_cg_base_conservative" ] &&
		warn -b "multiple merge bases, picking the most conservative one"
	id1="$_cg_baselist"

else
	id1="$(cg-object-id -t "$id1")" || exit 1
fi


if [ "$id2" = " " ]; then
	[ "$_git_no_wc" ] && die "only cg-diff between two revisions allowed outside a working copy"

	# Make sure we only diff modified files
	git-update-index --refresh >/dev/null

	diffprog=git-diff-index
	diffargs=(-m "$id1")

else
	id2="$(cg-object-id -t "$id2")" || exit 1
	[ "$id1" = "$id2" ] && exit 0

	diffprog=git-diff-tree
	diffargs=("$id1" "$id2")
fi


diffargs[${#diffargs[@]}]="--"
if [ ! "$ARGS" ]; then
	diffargs[${#diffargs[@]}]="${_git_relpath:-.}"
else
	for file in "${ARGS[@]}"; do
		diffargs[${#diffargs[@]}]="$_git_relpath$file"
	done
fi

# FIXME: Update ret based on what did we match. And take "$@"
# to account after all.
#ret=
$diffprog -r $renames $diffcore $style "${diffargs[@]}" | colorize | pager
#[ "$ret" ] && die "no files matched"
#exit $ret
exit 0