1 files changed, 91 insertions, 0 deletions
diff --git a/bin/highlight b/bin/highlight
new file mode 100755
index 0000000..70cf5ff
--- /dev/null
+++ b/bin/highlight
@@ -0,0 +1,91 @@
+#!/bin/sh
+set -eu
+
+usage() {
+	cat <<-'EOF'
+		Usage:
+		  highlight -n LINE_NUMBER -e PATTERN -f FILENAME
+		  highlight -h
+	EOF
+}
+
+help() {
+	cat <<-'EOF'
+
+
+		Options:
+		  -n LINE_NUMBER    the specific line number to highligh
+		  -e PATTERN        the pattern to highlight all over the file
+		  -f FILENAME       the file to be processed
+		  -h, --help        show this message
+
+
+		Highlight FILENAME:
+		  a) with an ANSI background color on LINE_NUMBER;
+		  b) with an ANSI foreground color on every occurrence of PATTERN.
+
+		Useful as a tool for development workflow, when one wants to
+		show a specific matched line, and at the same time visualize all
+		other ocurrences of PATTERN.
+
+
+		Examples:
+
+		  Highlight the line 10 of Makefile, and all occurences of "lisp":
+
+		    $ highlight -n10 -e 'lisp' -f Makefile
+	EOF
+}
+
+
+for flag in "$@"; do
+	case "$flag" in
+		--)
+			break
+			;;
+		--help)
+			usage
+			help
+			exit
+			;;
+		*)
+			;;
+	esac
+done
+
+while getopts 'n:e:f:h' flag; do
+	case "$flag" in
+		n)
+			LINE_NUMBER="$OPTARG"
+			;;
+		e)
+			PATTERN="$OPTARG"
+			;;
+		f)
+			FILENAME="$OPTARG"
+			;;
+		h)
+			usage
+			help
+			exit
+			;;
+		*)
+			usage >&2
+			exit 2
+			;;
+	esac
+done
+shift $((OPTIND - 1))
+
+eval "$(assert-arg -- "${LINE_NUMBER:-}" '-n LINE_NUMBER')"
+eval "$(assert-arg -- "${PATTERN:-}"     '-e PATTERN')"
+eval "$(assert-arg -- "${FILENAME:-}"    '-f FILENAME')"
+
+
+
+graybg="$(printf '\033[7;2;40m')"
+end="$(printf '\033[0m')"
+
+grep -E --color=always -e ^ -e "$PATTERN" "$FILENAME" |
+	perl -pe "s/\x1b\[m/${end}${graybg}/g if $. == $LINE_NUMBER" |
+	sed "${LINE_NUMBER}s|^\(.*\)\$|${graybg}\\1${end}|"