Stupid awk-based diff colorizer

sabdc.bash

#!/bin/bash
# sabdc
# Stupid awk-based diff colorizer

# Licensed under the MIT license:
# Copyright (c) 2011 David H. Bronke
#
#Permission is hereby granted, free of charge, to any person obtaining a copy
#of this software and associated documentation files (the "Software"), to deal
#in the Software without restriction, including without limitation the rights
#to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#copies of the Software, and to permit persons to whom the Software is
#furnished to do so, subject to the following conditions:
#
#The above copyright notice and this permission notice shall be included in
#all copies or substantial portions of the Software.
#
#THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#THE SOFTWARE.


# The easiest way to use this is to create symlinks from sabdc to useful aliases, like 'word-diff' and 'line-diff'.
#
# The following patterns are searched for in the script name at runtime to determine what behavior we should default to:
# - '*word*', '*wdiff*': Wordwise mode (uses `dwdiff` or `wdiff`)
# - (default): Linewise mode (uses 'diff')


######################
## Default Settings ##
# Copy this block to ~/.sabdcrc and customize as desired.

DEFAULT_DIFF_OPTIONS=(-u -d)

# Colors
HEADER_COLOR='1;33' # bold yellow
DIFF_HEADER_COLOR=$HEADER_COLOR
FROM_FILE_COLOR='1;31' # bold red
TO_FILE_COLOR='1;32' # bold green
FOLD_COLOR='1;35' # bold magenta
DELETE_MARKER_COLOR='31' # normal red
ADD_MARKER_COLOR='32' # normal green
DELETE_COLOR='91' # bright red
ADD_COLOR='92' # bright green

# Set to the wordwise diff command (with wdiff-compatible output) you would like to use.
WORDWISE_COMMAND="dwdiff"

# The command-line arguments you'd like to use with `dwdiff` or `wdiff` if we fall back to them
DEFAULT_DWDIFF_ARGS=("-ce:\033[${DELETE_COLOR}m,e:\033[${ADD_COLOR}m" "-w[-" "-x-]" "-y{+" "-z+}" "--wdiff-output" "--diff-input" "-P")
DEFAULT_WDIFF_ARGS=()

# The command-line arguments you'd like to use with WORDWISE_COMMAND
DEFAULT_WORDWISE_ARGS=( ${DEFAULT_DWDIFF_ARGS[@]} )

## End Default Settings ##
##########################


# Load user's config, if it exists
USERCONF=$HOME/.sabdcrc
[ -e $USERCONF ] && . $USERCONF

# Detect whether or not we should default to wordwise mode
WORDWISE=0
case "$0" in
	*word*|*wdiff*) WORDWISE=1 ;;
	*) WORDWISE=0 ;;
esac

# Parse our command-line options
DIFF_ARGS=( )
while [ $# -gt 0 ]
do
    case "$1" in
		--no-word) WORDWISE=0;;
		--word) WORDWISE=1;;
		*) DIFF_ARGS=( "${DIFF_ARGS[@]}" "$1" );;
    esac
    shift
done

COLORSCRIPT_COMMON='
/^=== / {print "\033['$HEADER_COLOR'm" $0 "\033[0m"; next}
/^diff -u -d / {print "\033['$HEADER_COLOR'm=== " $0 "\033[0m"; next}
/^--- / {print "\033['$FROM_FILE_COLOR'm" $0 "\033[0m"; next}
/^\+\+\+ / {print "\033['$TO_FILE_COLOR'm" $0 "\033[0m"; next}
/^@@ / {print "\033['$FOLD_COLOR'm" $0 "\033[0m"; next}'
COLORSCRIPT_LINEWISE='
/^[-<]/ {print "\033['$DELETE_MARKER_COLOR'm" substr($0, 1, 1) "\033['$DELETE_COLOR'm" substr($0, 2) "\033[0m"; next}
/^[+>]/ {print "\033['$ADD_MARKER_COLOR'm" substr($0, 1, 1) "\033['$ADD_COLOR'm" substr($0, 2) "\033[0m"; next}'
COLORSCRIPT_WORDWISE='
{gsub(/\[-/, "\033['$DELETE_MARKER_COLOR'm&\033['$DELETE_COLOR'm"); gsub(/{\+/, "\033['$ADD_MARKER_COLOR'm&\033['$ADD_COLOR'm"); gsub(/\+}/, "\033['$ADD_MARKER_COLOR'm&\033[0m"); gsub(/-\]/, "\033['$DELETE_MARKER_COLOR'm&\033[0m")}'
COLORSCRIPT_END='
{print}'

# Build the appropriate awk script
if [[ $WORDWISE -ne 0 ]]; then
	# Wordwise mode
	COLORSCRIPT="$COLORSCRIPT_COMMON$COLORSCRIPT_WORDWISE$COLORSCRIPT_END"
else
	# Linewise mode
	COLORSCRIPT="$COLORSCRIPT_COMMON$COLORSCRIPT_LINEWISE$COLORSCRIPT_END"
fi

if [[ ${#DIFF_ARGS[@]} -gt 1 ]]; then
	# There's more than one diff arg, so let's assume we're diffing files.
	if [[ $WORDWISE -ne 0 ]]; then
		# We're in wordwise mode! Make sure we have a usable wordwise diff command.
		WORDWISE_COMMAND=$(which $WORDWISE_COMMAND 2> /dev/null)
		WORDWISE_ARGS=${DEFAULT_WORDWISE_ARGS[@]}

		if [[ ! -x "$WORDWISE_COMMAND" ]]; then
			# Fall back to dwdiff
			WORDWISE_COMMAND=$(which dwdiff 2> /dev/null)
			WORDWISE_ARGS=${DEFAULT_DWDIFF_ARGS[@]}

			if [[ ! -x "$WORDWISE_COMMAND" ]]; then
				# Fall back to wdiff
				WORDWISE_COMMAND=$(which wdiff 2> /dev/null)
				WORDWISE_ARGS=${DEFAULT_WDIFF_ARGS[@]}

				if [[ ! -x "$WORDWISE_COMMAND" ]]; then
					# FAIL
					echo "Error: no wordwise diff command found!" >&2
					exit 1
				fi
			fi
		fi

		diff ${DEFAULT_DIFF_OPTIONS[@]} "${DIFF_ARGS[@]}" | $WORDWISE_COMMAND ${WORDWISE_ARGS[@]} | awk "$COLORSCRIPT"

	else
		diff ${DEFAULT_DIFF_OPTIONS[@]} "${DIFF_ARGS[@]}" | awk "$COLORSCRIPT"
	fi

elif [[ ${#DIFF_ARGS[@]} -eq 1 ]]; then
	# There's one diff arg; assume it's a patch or '-'. (which signifies diff-formatted or wdiff-formatted input on stdin)
	cat ${#DIFF_ARGS[@]} | awk "$COLORSCRIPT"

else
	# There's no diff args; assume we're getting diff-formatted or wdiff-formatted input on stdin.
	cat - | awk "$COLORSCRIPT"
fi

### Older Attempts ###

# First attempt... not quite as pretty.
#dwdiff -R -C3 --wdiff-output "$@" | colordiff

# Second attempt... better, but kinda unwieldy.
# Pull out '-u', since it's not supported by dwdiff.
#ARGS=( )
#while [ $# -gt 0 ]
#do
#    case "$1" in
#		-u) ;;
#		*)  ARGS=( ${ARGS[@]} $1 );;
#    esac
#    shift
#done
#
#dwdiff -C3 -c --diff-option=-w "${ARGS[@]}" | awk '/^=== /{print "\033[1;33m" $0 "\033[0m"}; $0 !~ /^=== /{print}'

# Third attempt... this is a bit better.
#diff -u "$@" | dwdiff -c --diff-input | awk '/^=== /{print "\033[1;33m" $0 "\033[0m"; next}; /^--- /{print "\033[1;31m" $0 "\033[0m"; next}; /^+++ /{print "\033[1;32m" $0 "\033[0m"; next}; /^@@ /{print "\033[1;35m" $0 "\033[0m"; next}; {print}'

# Fourth attempt...
#TODO: Fix the fact that it likes to go from the first non-whitespace on an added/deleted line to the end of the leading whitespace on the following line, instead of highlighting the whole added/deleted line
#diff -u -d "$@" | dwdiff -cred,blue -w '[-' -x '-]' -y '{+' -z '+}' --wdiff-output --diff-input | awk '/^=== /{print "\033[1;33m" $0 "\033[0m"; next}; /^diff -u -d /{print "\033[1;33m=== " $0 "\033[0m"; next}; /^--- /{print "\033[1;31m" $0 "\033[0m"; next}; /^+++ /{print "\033[1;34m" $0 "\033[0m"; next}; /^@@ /{print "\033[1;35m" $0 "\033[0m"; next}; {print}'