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

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Golang didn't want these in the standard library, but they are useful.
This commit is contained in:
James Shubin
2024-10-02 14:33:16 -04:00
parent d6914d3437
commit 74119a0a53
3 changed files with 221 additions and 0 deletions
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75
lang/core/strings/pad_func.go Normal file
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// 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 corestrings
import (
"context"
"github.com/purpleidea/mgmt/lang/funcs/simple"
"github.com/purpleidea/mgmt/lang/types"
"github.com/purpleidea/mgmt/util"
)
func init() {
simple.ModuleRegister(ModuleName, "left_pad", &simple.Scaffold{
T: types.NewType("func(s str, pad str, len int) str"),
F: LeftPad,
})
simple.ModuleRegister(ModuleName, "right_pad", &simple.Scaffold{
T: types.NewType("func(s str, pad str, len int) str"),
F: RightPad,
})
}
// 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(ctx context.Context, input []types.Value) (types.Value, error) {
return &types.StrValue{
V: util.LeftPad(input[0].Str(), input[1].Str(), int(input[2].Int())),
}, nil
}
// 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(ctx context.Context, input []types.Value) (types.Value, error) {
return &types.StrValue{
V: util.RightPad(input[0].Str(), input[1].Str(), int(input[2].Int())),
}, nil
}

60
util/pad.go Normal file
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// 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
}

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util/pad_test.go Normal file
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// 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.
//go:build !root
package util
import (
"testing"
)
func TestLeftPad(t *testing.T) {
tests := []struct {
s string
pad string
length int
result string
}{
{"", "", 0, ""},
{"", "x", 0, ""},
{"", "x", 2, "xx"},
{"", "ab", 3, "abab"},
{"hello", " ", 7, " hello"},
{"hello", "ab", 5, "hello"},
{"hello", "ab", 6, "abhello"},
{"hello", "ab", 8, "ababhello"},
}
for i, test := range tests {
actual := LeftPad(test.s, test.pad, test.length)
if actual != test.result {
t.Errorf("index: %d, expected: %s, actual: %s", i, test.result, actual)
}
}
}
func TestRightPad(t *testing.T) {
tests := []struct {
s string
pad string
length int
result string
}{
{"", "", 0, ""},
{"", "x", 0, ""},
{"", "x", 2, "xx"},
{"", "ab", 3, "abab"},
{"hello", " ", 7, "hello "},
{"hello", "ab", 5, "hello"},
{"hello", "ab", 6, "helloab"},
{"hello", "ab", 8, "helloabab"},
}
for i, test := range tests {
actual := RightPad(test.s, test.pad, test.length)
if actual != test.result {
t.Errorf("index: %d, expected: %s, actual: %s", i, test.result, actual)
}
}
}