tcell-widgets/helpers/text_helpers.go

/*
Copyright © Brian Buller <brian@bullercodeworks.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
package helpers

import (
	"bytes"
	"fmt"
	"strings"
	"unicode"
)

type Align int

const (
	AlignLeft = iota
	AlignCenter
	AlignRight
)

func Center(txt string, width int) string {
	if len(txt) >= width {
		// Trim from beg & end until width
		for len(txt) > width {
			txt = txt[:len(txt)-1]
			if len(txt) > width {
				txt = txt[1:]
			}
		}
		return txt
	}
	for len(txt) < width {
		txt = fmt.Sprintf(" %s", txt)
		if len(txt) < width {
			txt = fmt.Sprintf("%s ", txt)
		}
	}
	return txt
}

func CenterBetween(txt, left, right string, width int) string {
	if len(txt) >= width {
		return Center(txt, width)
	}
	for len(txt) < width {
		txt = fmt.Sprintf("%s%s", left, txt)
		if len(txt) < width {
			txt = fmt.Sprintf("%s%s", txt, right)
		}
	}
	return txt
}

func PadR(txt string, width int) string {
	if len(txt) < width {
		txt = fmt.Sprintf("%s%s", txt, strings.Repeat(" ", width-len(txt)))
	}
	return txt
}

func PadL(txt string, width int) string {
	if len(txt) < width {
		txt = fmt.Sprintf("%s%s", strings.Repeat(" ", width-len(txt)), txt)
	}
	return txt
}

// WrapText inserts new lines to make the text
// wrap at width 'w'
func WrapText(txt string, w int) string {
	init := make([]byte, 0, len(txt))
	buf := bytes.NewBuffer(init)
	var current uint
	var wordBuf, spaceBuf bytes.Buffer
	var wordBufLen, spaceBufLen uint
	writeBufs := func() {
		current += spaceBufLen + wordBufLen
		spaceBuf.WriteTo(buf)
		spaceBuf.Reset()
		spaceBufLen = 0
		wordBuf.WriteTo(buf)
		wordBuf.Reset()
		wordBufLen = 0
	}
	for _, char := range txt {
		if char == '\n' {
			// _Must_ wrap at newline
			if wordBuf.Len() == 0 {
				if int(current+spaceBufLen) > w {
					current = 0
				} else {
					current += spaceBufLen
					spaceBuf.WriteTo(buf)
				}
				spaceBuf.Reset()
				spaceBufLen = 0
			} else {
				writeBufs()
			}
			buf.WriteRune(char)
			current = 0
		} else if unicode.IsSpace(char) && char != 0xA0 {
			// Can wrap at whitespace
			if spaceBuf.Len() == 0 || wordBuf.Len() > 0 {
				writeBufs()
			}
			spaceBuf.WriteRune(char)
			spaceBufLen++
		} else {
			wordBuf.WriteRune(char)
			wordBufLen++
			if int(current+wordBufLen+spaceBufLen) > w && int(wordBufLen) < w {
				buf.WriteRune('\n')
				current = 0
				spaceBuf.Reset()
				spaceBufLen = 0
			}
		}
	}

	if wordBuf.Len() == 0 {
		if int(current+spaceBufLen) <= w {
			spaceBuf.WriteTo(buf)
		}
	} else {
		spaceBuf.WriteTo(buf)
		wordBuf.WriteTo(buf)
	}
	return buf.String()
}

func Longest(of []string) int {
	var ret int
	for i := range of {
		tst := len(of[i])
		if tst > ret {
			ret = tst
		}
	}
	return ret
}

func WrapStringToSlice(s string, width int) []string {
	return strings.Split(WrapText(s, width), "\n")
}