stdin support, added optional highlight(1) dependency

en

@@ -7,15 +7,17 @@
 # permitted in any medium without royalty provided the copyright notice and this
 # notice are preserved.	This file is offered as-is, without any warranty.
 
-if test -z "$1"; then
+if command -v highlight >/dev/null 2>&1
-	printf "Usage: %s file...\n" "$0" 1>&2
+then
-	exit 64 # sysexits.h(3) EX_USAGE
+	HIGHLIGHT_OPTIONS='--out-format=ansi'; export HIGHLIGHT_OPTIONS
+else
+	alias highlight=cat
 fi
 
-if ! command -v mktemp >/dev/null 2>&1
+if test -z "$1"; then
-then
+	set -- /dev/stdin
-	printf "%s: mktemp(1): missing dependency" "$0"
+	HIGHLIGHT_OPTIONS="$HIGHLIGHT_OPTIONS --syntax=none"
-	exit 69 # sysexits.h(3) EX_UNAVAILABLE
+	export HIGHLIGHT_OPTIONS
 fi
 
 help="$(printf "Commands:\n\
@@ -25,30 +27,17 @@ a – append a line to the current buffer\n\
 c – clear the screen\n\
 d – delete a line\n\
 e – evaluate a command in the shell environment\n\
+h – change syntax highlighting language\n\
 i – insert a line into the buffer at position line\n\
 p – print the current buffer\n\
 q – terminate editing\n\
-r – applie a regular expression to the current buffer\n\
+r – apply a regular expression to the current buffer\n\
 x – exit the program without writing output\n\
 \n\
 en(1) Copyright (c) 2023–2024 Emma Tebibyte\n")"
 
 while test -n "$1"; do
 	content="$(cat "$1")"
-	file="$(printf "%s\n" "$1" | tr -d '/')"
-	temp_highlight="$(mktemp -t "XXXXX$file")"
-
-	# use bat for syntax highlighting if it’s available, but remove the frills
-	if command -v bat >/dev/null
-	then
-		# make bat use terminal theme
-		BAT_THEME=ansi; export BAT_THEME
-		# there has to be a temp file for writing the highlighted text to
-		syntax_h() {
-			printf "%s\n" "$1" >"$temp_highlight"
-			bat -pp --color always "$temp_highlight"
-		}
-	fi
 
 	while true; do
 		printf ">> " >/dev/tty
@@ -66,7 +55,7 @@ while test -n "$1"; do
 				if test -z "$args"; then
 					printf "%s: %s\n" "$0" "$help"
 				else
-					printf "%s: command-specific help not implemented\n" "$0" 1>&2
+					printf "%s: %s: %s invalid argument\n" "$0" "$command" "$args" 1>&2
 					continue
 				fi
 				;;
@@ -78,9 +67,7 @@ while test -n "$1"; do
 					content="$(printf "%s\n%s" "$content" "$append")"
 				fi
 				;;
-			"c")
+			"c") clear ;;
-				clear
-				;;
 			"d")
 				if test -z "$args"; then
 					printf "%s: %s: Missing argument.\n" "$0" "$command" 1>&2
@@ -95,22 +82,22 @@ while test -n "$1"; do
 			"e")
 				eval "$args" || true
 				;;
+			"h")
+				HIGHLIGHT_OPTIONS="$HIGHLIGHT_OPTIONS --syntax=$args"
+				export HIGHLIGHT_OPTIONS
+				;;
 			"i")
 				printf "%s: i: Command not implemented.\n" "$0" 1>&2
 				;;
 			"p")
-				out="$(syntax_h "$content" 2>/dev/null || printf "%s\n" "$content")"
+				printf "%s\n" "$content" | highlight | nl -ba >/dev/tty
-				printf "%s\n" "$out" | nl -ba >/dev/tty
-				;;
-			"q")
-				break
 				;;
+			"q") break ;;
 			"r")
 				content="$(printf "%s" "$content" | sed -e "$args")"
 				;;
-			"x")
+			"x") exit ;;
-				exit
+			"") ;;
-				;;
 			*)
 				printf "%s: %s: unrecognized command\n" "$0" "$command"
 				;;