k3s/vendor/k8s.io/kubectl/pkg/explain/formatter.go
2020-08-28 17:18:31 -07:00

179 lines
3.9 KiB
Go

/*
Copyright 2017 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package explain
import (
"fmt"
"io"
"regexp"
"strings"
)
// Formatter helps you write with indentation, and can wrap text as needed.
type Formatter struct {
IndentLevel int
Wrap int
Writer io.Writer
}
// Indent creates a new Formatter that will indent the code by that much more.
func (f Formatter) Indent(indent int) *Formatter {
f.IndentLevel = f.IndentLevel + indent
return &f
}
// Write writes a string with the indentation set for the
// Formatter. This is not wrapping text.
func (f *Formatter) Write(str string, a ...interface{}) error {
// Don't indent empty lines
if str == "" {
_, err := io.WriteString(f.Writer, "\n")
return err
}
indent := ""
for i := 0; i < f.IndentLevel; i++ {
indent = indent + " "
}
if len(a) > 0 {
str = fmt.Sprintf(str, a...)
}
_, err := io.WriteString(f.Writer, indent+str+"\n")
return err
}
// WriteWrapped writes a string with the indentation set for the
// Formatter, and wraps as needed.
func (f *Formatter) WriteWrapped(str string, a ...interface{}) error {
if f.Wrap == 0 {
return f.Write(str, a...)
}
text := fmt.Sprintf(str, a...)
strs := wrapString(text, f.Wrap-f.IndentLevel)
for _, substr := range strs {
if err := f.Write(substr); err != nil {
return err
}
}
return nil
}
type line struct {
wrap int
words []string
}
func (l *line) String() string {
return strings.Join(l.words, " ")
}
func (l *line) Empty() bool {
return len(l.words) == 0
}
func (l *line) Len() int {
return len(l.String())
}
// Add adds the word to the line, returns true if we could, false if we
// didn't have enough room. It's always possible to add to an empty line.
func (l *line) Add(word string) bool {
newLine := line{
wrap: l.wrap,
words: append(l.words, word),
}
if newLine.Len() <= l.wrap || len(l.words) == 0 {
l.words = newLine.words
return true
}
return false
}
var bullet = regexp.MustCompile(`^(\d+\.?|-|\*)\s`)
func shouldStartNewLine(lastWord, str string) bool {
// preserve line breaks ending in :
if strings.HasSuffix(lastWord, ":") {
return true
}
// preserve code blocks
if strings.HasPrefix(str, " ") {
return true
}
str = strings.TrimSpace(str)
// preserve empty lines
if len(str) == 0 {
return true
}
// preserve lines that look like they're starting lists
if bullet.MatchString(str) == true {
return true
}
// otherwise combine
return false
}
func wrapString(str string, wrap int) []string {
wrapped := []string{}
l := line{wrap: wrap}
// track the last word added to the current line
lastWord := ""
flush := func() {
if !l.Empty() {
lastWord = ""
wrapped = append(wrapped, l.String())
l = line{wrap: wrap}
}
}
// iterate over the lines in the original description
for _, str := range strings.Split(str, "\n") {
// preserve code blocks and blockquotes as-is
if strings.HasPrefix(str, " ") {
flush()
wrapped = append(wrapped, str)
continue
}
// preserve empty lines after the first line, since they can separate logical sections
if len(wrapped) > 0 && len(strings.TrimSpace(str)) == 0 {
flush()
wrapped = append(wrapped, "")
continue
}
// flush if we should start a new line
if shouldStartNewLine(lastWord, str) {
flush()
}
words := strings.Fields(str)
for _, word := range words {
lastWord = word
if !l.Add(word) {
flush()
if !l.Add(word) {
panic("Couldn't add to empty line.")
}
}
}
}
flush()
return wrapped
}