lang: core: strings, util: Add left and right padding functions

Golang didn't want these in the standard library, but they are useful.

util/pad.go

@@ -0,0 +1,60 @@
+// Mgmt
+// Copyright (C) 2013-2024+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+// Additional permission under GNU GPL version 3 section 7
+//
+// If you modify this program, or any covered work, by linking or combining it
+// with embedded mcl code and modules (and that the embedded mcl code and
+// modules which link with this program, contain a copy of their source code in
+// the authoritative form) containing parts covered by the terms of any other
+// license, the licensors of this program grant you additional permission to
+// convey the resulting work. Furthermore, the licensors of this program grant
+// the original author, James Shubin, additional permission to update this
+// additional permission if he deems it necessary to achieve the goals of this
+// additional permission.
+
+package util
+
+// LeftPad adds multiples of the pad string to the left of the input string
+// until it reaches a minimum length. If the padding string is not an integer
+// multiple of the missing length to pad, then this will overshoot. It is better
+// to overshoot than to undershoot because if you need a string of a precise
+// length, then it's easier to truncate the result, rather than having to pad
+// even more. Most scenarios pad with a single char meaning this is not even an
+// issue.
+func LeftPad(s string, pad string, length int) string {
+	out := s
+	for len(out) < length {
+		out = pad + out
+	}
+	return out
+}
+
+// RightPad adds multiples of the pad string to the right of the input string
+// until it reaches a minimum length. If the padding string is not an integer
+// multiple of the missing length to pad, then this will overshoot. It is better
+// to overshoot than to undershoot because if you need a string of a precise
+// length, then it's easier to truncate the result, rather than having to pad
+// even more. Most scenarios pad with a single char meaning this is not even an
+// issue.
+func RightPad(s string, pad string, length int) string {
+	out := s
+	for len(out) < length {
+		out += pad
+	}
+	return out
+}