From 1124356ee9f4d6065953d8aecf6e06c617e930c1 Mon Sep 17 00:00:00 2001
From: Kerin Millar <kfm@plushkava.net>
Date: Mon, 3 Jun 2024 02:39:20 +0100
Subject: Add the hr() function to print a horizontal rule

As based on the implementation in Maarten Billemont's bashlib library.

Signed-off-by: Kerin Millar <kfm@plushkava.net>
---
 functions.sh   | 28 ++++++++++++++++++++++++++++
 test-functions | 24 ++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/functions.sh b/functions.sh
index 30c2447..c077290 100644
--- a/functions.sh
+++ b/functions.sh
@@ -363,6 +363,34 @@ has_systemd()
 	test -d /run/systemd
 }
 
+#
+# Prints a horizontal rule. If specified, the first parameter shall be taken as
+# a string to be repeated in the course of composing the rule. Otherwise, it
+# shall default to the <hyphen-minus>. If specified, the second parameter shall
+# define the length of the rule in characters. Otherwise, it shall default to
+# the width of the terminal if such can be determined, or 80 if it cannot be.
+#
+hr()
+{
+	local length
+
+	if is_int "$2"; then
+		length=$2
+	elif _update_tty_level <&1; [ "${genfun_tty}" -eq 2 ]; then
+		length=${genfun_cols}
+	else
+		length=80
+	fi
+	PATTERN=${1:--} awk -v "width=${length}" -f - <<-'EOF'
+		BEGIN {
+			while (length(rule) < width) {
+				rule = rule substr(ENVIRON["PATTERN"], 1, width - length(rule))
+			}
+			print rule
+		}
+	EOF
+}
+
 #
 # Determines whether the first parameter is a valid identifier (variable name).
 #
diff --git a/test-functions b/test-functions
index bbb74f1..d90462e 100755
--- a/test-functions
+++ b/test-functions
@@ -484,6 +484,29 @@ test_trim() {
 	iterate_tests 4 "$@"
 }
 
+test_hr() {
+	# shellcheck disable=2183
+	set -- \
+		eq  0  "$(printf '%80s' | tr ' ' -)"  N/A  N/A  \
+		eq  0  "$(printf '%80s' | tr ' ' -)"  -    N/A  \
+		eq  0  ''                             -    0    \
+		eq  0  -                              -    1    \
+		eq  0  -----                          -    5    \
+		eq  0  ''                             xyz  0    \
+		eq  0  x                              xyz  1    \
+		eq  0  xyzxy                          xyz  5
+
+	callback() {
+		shift
+		expected=$1
+		shift
+		test_description="hr $(_print_args "$@")"
+		test "$(hr "$@")" = "${expected}"
+	}
+
+	iterate_tests 5 "$@"
+}
+
 iterate_tests() {
 	slice_width=$1
 	shift
@@ -547,6 +570,7 @@ test_edo || rc=1
 test_srandom || rc=1
 test_newest || rc=1
 test_trim || rc=1
+test_hr || rc=1
 
 cleanup_tmpdir
 
-- 
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