package text
import (
"strings"
"github.com/mattn/go-runewidth"
)
// Force runewidth not to treat ambiguous runes as wide chars, so that things
// like unicode ellipsis/up/down/left/right glyphs can have correct runewidth
// and can be displayed correctly in terminals.
func init() {
runewidth.DefaultCondition.EastAsianWidth = false
}
// Wrap a text for a given line size.
// Handle properly terminal color escape code
func Wrap(text string, lineWidth int) (string, int) {
return WrapLeftPadded(text, lineWidth, 0)
}
// WrapLeftPadded wrap a text for a given line size with a left padding.
// Handle properly terminal color escape code
func WrapLeftPadded(text string, lineWidth int, leftPad int) (string, int) {
pad := strings.Repeat(" ", leftPad)
return WrapWithPad(text, lineWidth, pad)
}
// WrapWithPad wrap a text for a given line size with a custom left padding
// Handle properly terminal color escape code
func WrapWithPad(text string, lineWidth int, pad string) (string, int) {
return WrapWithPadIndent(text, lineWidth, pad, pad)
}
// WrapWithPad wrap a text for a given line size with a custom left padding
// This function also align the result depending on the requested alignment.
// Handle properly terminal color escape code
func WrapWithPadAlign(text string, lineWidth int, pad string, align Alignment) (string, int) {
return WrapWithPadIndentAlign(text, lineWidth, pad, pad, align)
}
// WrapWithPadIndent wrap a text for a given line size with a custom left padding
// and a first line indent. The padding is not effective on the first line, indent
// is used instead, which allow to implement indents and outdents.
// Handle properly terminal color escape code
func WrapWithPadIndent(text string, lineWidth int, indent string, pad string) (string, int) {
return WrapWithPadIndentAlign(text, lineWidth, indent, pad, NoAlign)
}
// WrapWithPadIndentAlign wrap a text for a given line size with a custom left padding
// and a first line indent. The padding is not effective on the first line, indent
// is used instead, which allow to implement indents and outdents.
// This function also align the result depending on the requested alignment.
// Handle properly terminal color escape code
func WrapWithPadIndentAlign(text string, lineWidth int, indent string, pad string, align Alignment) (string, int) {
var lines []string
nbLine := 0
// Start with the indent
padStr := indent
padLen := Len(indent)
// tabs are formatted as 4 spaces
text = strings.Replace(text, "\t", " ", -1)
// NOTE: text is first segmented into lines so that softwrapLine can handle.
for i, line := range strings.Split(text, "\n") {
// on the second line, use the padding instead
if i == 1 {
padStr = pad
padLen = Len(pad)
}
if line == "" || strings.TrimSpace(line) == "" {
// nothing in the line, we just add the non-empty part of the padding
lines = append(lines, strings.TrimRight(padStr, " "))
nbLine++
continue
}
wrapped := softwrapLine(line, lineWidth-padLen)
split := strings.Split(wrapped, "\n")
if i == 0 && len(split) > 1 {
// the very first line got wrapped
// that means we need to switch to the normal padding
// use the first wrapped line, ignore everything else and
// wrap the remaining of the line with the normal padding.
content := LineAlign(strings.TrimRight(split[0], " "), lineWidth-padLen, align)
lines = append(lines, padStr+content)
nbLine++
line = strings.TrimPrefix(line, split[0])
line = strings.TrimLeft(line, " ")
padStr = pad
padLen = Len(pad)
wrapped = softwrapLine(line, lineWidth-padLen)
split = strings.Split(wrapped, "\n")
}
for j, seg := range split {
if j == 0 {
// keep the left padding of the wrapped line
content := LineAlign(strings.TrimRight(seg, " "), lineWidth-padLen, align)
lines = append(lines, padStr+content)
} else {
content := LineAlign(strings.TrimSpace(seg), lineWidth-padLen, align)
lines = append(lines, padStr+content)
}
nbLine++
}
}
return strings.Join(lines, "\n"), nbLine
}
// Break a line into several lines so that each line consumes at most
// 'textWidth' cells. Lines break at groups of white spaces and multibyte
// chars. Nothing is removed from the original text so that it behaves like a
// softwrap.
//
// Required: The line shall not contain '\n'
//
// WRAPPING ALGORITHM: The line is broken into non-breakable chunks, then line
// breaks ("\n") are inserted between these groups so that the total length
// between breaks does not exceed the required width. Words that are longer than
// the textWidth are broken into pieces no longer than textWidth.
func softwrapLine(line string, textWidth int) string {
escaped, escapes := ExtractTermEscapes(line)
chunks := segmentLine(escaped)
// Reverse the chunk array so we can use it as a stack.
for i, j := 0, len(chunks)-1; i < j; i, j = i+1, j-1 {
chunks[i], chunks[j] = chunks[j], chunks[i]
}
// for readability, minimal implementation of a stack:
pop := func() string {
result := chunks[len(chunks)-1]
chunks = chunks[:len(chunks)-1]
return result
}
push := func(chunk string) {
chunks = append(chunks, chunk)
}
peek := func() string {
return chunks[len(chunks)-1]
}
empty := func() bool {
return len(chunks) == 0
}
var out strings.Builder
// helper to write in the output while interleaving the escape
// sequence at the correct places.
// note: the final algorithm will add additional line break in the original
// text. Those line break are *not* fed to this helper so the positions don't
// need to be offset, which make the whole thing much easier.
currPos := 0
currItem := 0
outputString := func(s string) {
for _, r := range s {
for currItem < len(escapes) && currPos == escapes[currItem].Pos {
out.WriteString(escapes[currItem].Item)
currItem++
}
out.WriteRune(r)
currPos++
}
}
width := 0
for !empty() {
wl := Len(peek())
if width+wl <= textWidth {
// the chunk fit in the available space
outputString(pop())
width += wl
if width == textWidth && !empty() {
// only add line break when there is more chunk to come
out.WriteRune('\n')
width = 0
}
} else if wl > textWidth {
// words too long for a full line are split to fill the remaining space.
// But if the long words is the first non-space word in the middle of the
// line, preceding spaces shall not be counted in word splitting.
splitWidth := textWidth - width
if strings.HasSuffix(out.String(), "\n"+strings.Repeat(" ", width)) {
splitWidth += width
}
left, right := splitWord(pop(), splitWidth)
// remainder is pushed back to the stack for next round
push(right)
outputString(left)
out.WriteRune('\n')
width = 0
} else {
// normal line overflow, we add a line break and try again
out.WriteRune('\n')
width = 0
}
}
// Don't forget the trailing escapes, if any.
for currItem < len(escapes) && currPos >= escapes[currItem].Pos {
out.WriteString(escapes[currItem].Item)
currItem++
}
return out.String()
}
// Segment a line into chunks, where each chunk consists of chars with the same
// type and is not breakable.
func segmentLine(s string) []string {
var chunks []string
var word string
wordType := none
flushWord := func() {
chunks = append(chunks, word)
word = ""
wordType = none
}
for _, r := range s {
// A WIDE_CHAR itself constitutes a chunk.
thisType := runeType(r)
if thisType == wideChar {
if wordType != none {
flushWord()
}
chunks = append(chunks, string(r))
continue
}
// Other type of chunks starts with a char of that type, and ends with a
// char with different type or end of string.
if thisType != wordType {
if wordType != none {
flushWord()
}
word = string(r)
wordType = thisType
} else {
word += string(r)
}
}
if word != "" {
flushWord()
}
return chunks
}
type RuneType int
// Rune categories
//
// These categories are so defined that each category forms a non-breakable
// chunk. It IS NOT the same as unicode code point categories.
const (
none RuneType = iota
wideChar
invisible
shortUnicode
space
visibleAscii
)
// Determine the category of a rune.
func runeType(r rune) RuneType {
rw := runewidth.RuneWidth(r)
if rw > 1 {
return wideChar
} else if rw == 0 {
return invisible
} else if r > 127 {
return shortUnicode
} else if r == ' ' {
return space
} else {
return visibleAscii
}
}
// splitWord split a word at the given length, while ignoring the terminal escape sequences
func splitWord(word string, length int) (string, string) {
runes := []rune(word)
var result []rune
added := 0
escape := false
if length == 0 {
return "", word
}
for _, r := range runes {
if r == '\x1b' {
escape = true
}
width := runewidth.RuneWidth(r)
if width+added > length {
// wide character made the length overflow
break
}
result = append(result, r)
if !escape {
added += width
if added >= length {
break
}
}
if r == 'm' {
escape = false
}
}
leftover := runes[len(result):]
return string(result), string(leftover)
}
