mirror of
https://github.com/walles/moar.git
synced 2024-09-19 16:08:02 +03:00
ef612a5620
By using a strings.Builder rather than roll-our-own to build a plain string.
607 lines
14 KiB
Go
607 lines
14 KiB
Go
package m
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import (
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"fmt"
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"os"
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"regexp"
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"strconv"
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"strings"
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"unicode"
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log "github.com/sirupsen/logrus"
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"github.com/walles/moar/twin"
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)
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const _TabSize = 4
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const BACKSPACE = '\b'
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var manPageBold = twin.StyleDefault.WithAttr(twin.AttrBold)
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var manPageUnderline = twin.StyleDefault.WithAttr(twin.AttrUnderline)
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// ESC[...m: https://en.wikipedia.org/wiki/ANSI_escape_code#SGR
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var sgrSequencePattern = regexp.MustCompile("\x1b\\[([0-9;]*m)")
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// A Line represents a line of text that can / will be paged
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type Line struct {
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raw *string
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plain *string
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}
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// NewLine creates a new Line from a (potentially ANSI / man page formatted) string
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func NewLine(raw string) *Line {
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return &Line{
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raw: &raw,
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plain: nil,
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}
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}
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// Tokens returns a representation of the string split into styled tokens
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func (line *Line) Tokens() []twin.Cell {
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return cellsFromString(*line.raw)
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}
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// Plain returns a plain text representation of the initial string
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func (line *Line) Plain() string {
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if line.plain == nil {
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plain := withoutFormatting(*line.raw)
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line.plain = &plain
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}
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return *line.plain
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}
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// SetManPageFormatFromEnv parses LESS_TERMCAP_xx environment variables and
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// adapts the moar output accordingly.
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func SetManPageFormatFromEnv() {
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// Requested here: https://github.com/walles/moar/issues/14
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lessTermcapMd := os.Getenv("LESS_TERMCAP_md")
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if lessTermcapMd != "" {
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manPageBold = termcapToStyle(lessTermcapMd)
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}
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lessTermcapUs := os.Getenv("LESS_TERMCAP_us")
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if lessTermcapUs != "" {
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manPageUnderline = termcapToStyle(lessTermcapUs)
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}
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}
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// Used from tests
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func resetManPageFormatForTesting() {
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manPageBold = twin.StyleDefault.WithAttr(twin.AttrBold)
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manPageUnderline = twin.StyleDefault.WithAttr(twin.AttrUnderline)
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}
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func termcapToStyle(termcap string) twin.Style {
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// Add a character to be sure we have one to take the format from
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cells := cellsFromString(termcap + "x")
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return cells[len(cells)-1].Style
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}
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func isPlain(s string) bool {
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for i := 0; i < len(s); i++ {
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byteAtIndex := s[i]
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if byteAtIndex < 32 {
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return false
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}
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if byteAtIndex > 127 {
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return false
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}
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}
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return true
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}
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func withoutFormatting(s string) string {
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if isPlain(s) {
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return s
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}
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stripped := strings.Builder{}
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runeCount := 0
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stripped.Grow(len(s))
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for _, styledString := range styledStringsFromString(s) {
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for _, runeValue := range runesFromStyledString(styledString) {
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switch runeValue {
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case '\x09': // TAB
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for {
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stripped.WriteRune(' ')
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runeCount++
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if runeCount%_TabSize == 0 {
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// We arrived at the next tab stop
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break
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}
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}
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case '<27>': // Go's broken-UTF8 marker
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stripped.WriteRune('?')
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runeCount++
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case BACKSPACE:
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stripped.WriteRune('<')
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runeCount++
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default:
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if !unicode.IsPrint(runeValue) {
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stripped.WriteRune('?')
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runeCount++
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continue
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}
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stripped.WriteRune(runeValue)
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runeCount++
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}
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}
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}
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return stripped.String()
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}
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// Turn a (formatted) string into a series of screen cells
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func cellsFromString(s string) []twin.Cell {
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var cells []twin.Cell
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// Specs: https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit
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styleBrokenUtf8 := twin.StyleDefault.Background(twin.NewColor16(1)).Foreground(twin.NewColor16(7))
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for _, styledString := range styledStringsFromString(s) {
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for _, token := range tokensFromStyledString(styledString) {
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switch token.Rune {
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case '\x09': // TAB
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for {
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cells = append(cells, twin.Cell{
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Rune: ' ',
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Style: styledString.Style,
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})
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if (len(cells))%_TabSize == 0 {
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// We arrived at the next tab stop
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break
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}
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}
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case '<27>': // Go's broken-UTF8 marker
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cells = append(cells, twin.Cell{
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Rune: '?',
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Style: styleBrokenUtf8,
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})
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case BACKSPACE:
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cells = append(cells, twin.Cell{
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Rune: '<',
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Style: styleBrokenUtf8,
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})
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default:
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if !unicode.IsPrint(token.Rune) {
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cells = append(cells, twin.Cell{
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Rune: '?',
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Style: styleBrokenUtf8,
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})
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continue
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}
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cells = append(cells, token)
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}
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}
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}
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return cells
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}
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// Consume 'x<x', where '<' is backspace and the result is a bold 'x'
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func consumeBold(runes []rune, index int) (int, *twin.Cell) {
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if index+2 >= len(runes) {
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// Not enough runes left for a bold
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return index, nil
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}
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if runes[index+1] != BACKSPACE {
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// No backspace in the middle, never mind
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return index, nil
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}
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if runes[index] != runes[index+2] {
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// First and last rune not the same, never mind
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return index, nil
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}
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// We have a match!
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return index + 3, &twin.Cell{
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Rune: runes[index],
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Style: manPageBold,
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}
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}
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// Consume '_<x', where '<' is backspace and the result is an underlined 'x'
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func consumeUnderline(runes []rune, index int) (int, *twin.Cell) {
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if index+2 >= len(runes) {
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// Not enough runes left for a underline
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return index, nil
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}
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if runes[index+1] != BACKSPACE {
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// No backspace in the middle, never mind
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return index, nil
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}
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if runes[index] != '_' {
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// No underline, never mind
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return index, nil
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}
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// We have a match!
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return index + 3, &twin.Cell{
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Rune: runes[index+2],
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Style: manPageUnderline,
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}
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}
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// Consume '+<+<o<o' / '+<o', where '<' is backspace and the result is a unicode bullet.
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//
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// Used on man pages, try "man printf" on macOS for one example.
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func consumeBullet(runes []rune, index int) (int, *twin.Cell) {
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patterns := [][]byte{[]byte("+\bo"), []byte("+\b+\bo\bo")}
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for _, pattern := range patterns {
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if index+len(pattern) > len(runes) {
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// Not enough runes left for a bullet
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continue
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}
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mismatch := false
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for delta, patternByte := range pattern {
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if patternByte != byte(runes[index+delta]) {
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// Bullet pattern mismatch, never mind
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mismatch = true
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break
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}
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}
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if mismatch {
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continue
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}
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// We have a match!
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return index + len(pattern), &twin.Cell{
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Rune: '•', // Unicode bullet point
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Style: twin.StyleDefault,
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}
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}
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return index, nil
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}
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func runesFromStyledString(styledString _StyledString) string {
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hasBackspace := false
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for _, byteValue := range []byte(styledString.String) {
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if byteValue == BACKSPACE {
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hasBackspace = true
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break
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}
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}
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if !hasBackspace {
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// Shortcut when there's no backspace based formatting to worry about
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return styledString.String
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}
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// Special handling for man page formatted lines
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cells := tokensFromStyledString(styledString)
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returnMe := strings.Builder{}
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returnMe.Grow(len(cells))
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for _, cell := range cells {
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returnMe.WriteRune(cell.Rune)
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}
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return returnMe.String()
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}
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func tokensFromStyledString(styledString _StyledString) []twin.Cell {
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runes := []rune(styledString.String)
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hasBackspace := false
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for _, runeValue := range runes {
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if runeValue == BACKSPACE {
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hasBackspace = true
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break
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}
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}
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tokens := make([]twin.Cell, 0, len(runes))
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if !hasBackspace {
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// Shortcut when there's no backspace based formatting to worry about
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for _, runeValue := range runes {
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tokens = append(tokens, twin.Cell{
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Rune: runeValue,
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Style: styledString.Style,
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})
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}
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return tokens
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}
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// Special handling for man page formatted lines
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for index := 0; index < len(runes); index++ {
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nextIndex, token := consumeBullet(runes, index)
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if nextIndex != index {
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tokens = append(tokens, *token)
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index = nextIndex - 1
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continue
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}
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nextIndex, token = consumeBold(runes, index)
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if nextIndex != index {
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tokens = append(tokens, *token)
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index = nextIndex - 1
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continue
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}
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nextIndex, token = consumeUnderline(runes, index)
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if nextIndex != index {
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tokens = append(tokens, *token)
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index = nextIndex - 1
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continue
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}
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tokens = append(tokens, twin.Cell{
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Rune: runes[index],
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Style: styledString.Style,
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})
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}
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return tokens
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}
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type _StyledString struct {
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String string
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Style twin.Style
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}
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func styledStringsFromString(s string) []_StyledString {
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// This function was inspired by the
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// https://golang.org/pkg/regexp/#Regexp.Split source code
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matches := sgrSequencePattern.FindAllStringIndex(s, -1)
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styledStrings := make([]_StyledString, 0, len(matches)+1)
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style := twin.StyleDefault
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beg := 0
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end := 0
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for _, match := range matches {
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end = match[0]
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if end > beg {
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// Found non-zero length string
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styledStrings = append(styledStrings, _StyledString{
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String: s[beg:end],
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Style: style,
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})
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}
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matchedPart := s[match[0]:match[1]]
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style = updateStyle(style, matchedPart)
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beg = match[1]
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}
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if end != len(s) {
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styledStrings = append(styledStrings, _StyledString{
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String: s[beg:],
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Style: style,
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})
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}
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return styledStrings
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}
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// updateStyle parses a string of the form "ESC[33m" into changes to style
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func updateStyle(style twin.Style, escapeSequence string) twin.Style {
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numbers := strings.Split(escapeSequence[2:len(escapeSequence)-1], ";")
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index := 0
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for index < len(numbers) {
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number := numbers[index]
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index++
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switch strings.TrimLeft(number, "0") {
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case "":
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style = twin.StyleDefault
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case "1":
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style = style.WithAttr(twin.AttrBold)
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case "2":
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style = style.WithAttr(twin.AttrDim)
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case "3":
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style = style.WithAttr(twin.AttrItalic)
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case "4":
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style = style.WithAttr(twin.AttrUnderline)
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case "7":
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style = style.WithAttr(twin.AttrReverse)
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case "22":
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style = style.WithoutAttr(twin.AttrBold).WithoutAttr(twin.AttrDim)
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case "23":
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style = style.WithoutAttr(twin.AttrItalic)
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case "24":
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style = style.WithoutAttr(twin.AttrUnderline)
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case "27":
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style = style.WithoutAttr(twin.AttrReverse)
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// Foreground colors, https://pkg.go.dev/github.com/gdamore/tcell#Color
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case "30":
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style = style.Foreground(twin.NewColor16(0))
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case "31":
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style = style.Foreground(twin.NewColor16(1))
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case "32":
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style = style.Foreground(twin.NewColor16(2))
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case "33":
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style = style.Foreground(twin.NewColor16(3))
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case "34":
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style = style.Foreground(twin.NewColor16(4))
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case "35":
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style = style.Foreground(twin.NewColor16(5))
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case "36":
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style = style.Foreground(twin.NewColor16(6))
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case "37":
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style = style.Foreground(twin.NewColor16(7))
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case "38":
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var err error = nil
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var color *twin.Color
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index, color, err = consumeCompositeColor(numbers, index-1)
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if err != nil {
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log.Warnf("Foreground: %s", err.Error())
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return style
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}
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style = style.Foreground(*color)
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case "39":
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style = style.Foreground(twin.ColorDefault)
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// Background colors, see https://pkg.go.dev/github.com/gdamore/Color
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case "40":
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style = style.Background(twin.NewColor16(0))
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case "41":
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style = style.Background(twin.NewColor16(1))
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case "42":
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style = style.Background(twin.NewColor16(2))
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case "43":
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style = style.Background(twin.NewColor16(3))
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case "44":
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style = style.Background(twin.NewColor16(4))
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case "45":
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style = style.Background(twin.NewColor16(5))
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case "46":
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style = style.Background(twin.NewColor16(6))
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case "47":
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style = style.Background(twin.NewColor16(7))
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case "48":
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var err error = nil
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var color *twin.Color
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index, color, err = consumeCompositeColor(numbers, index-1)
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if err != nil {
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log.Warnf("Background: %s", err.Error())
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return style
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}
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style = style.Background(*color)
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case "49":
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style = style.Background(twin.ColorDefault)
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// Bright foreground colors: see https://pkg.go.dev/github.com/gdamore/Color
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//
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// After testing vs less and cat on iTerm2 3.3.9 / macOS Catalina
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// 10.15.4 that's how they seem to handle this, tested with:
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// * TERM=xterm-256color
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// * TERM=screen-256color
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case "90":
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style = style.Foreground(twin.NewColor16(8))
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case "91":
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style = style.Foreground(twin.NewColor16(9))
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case "92":
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style = style.Foreground(twin.NewColor16(10))
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case "93":
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style = style.Foreground(twin.NewColor16(11))
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case "94":
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style = style.Foreground(twin.NewColor16(12))
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case "95":
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style = style.Foreground(twin.NewColor16(13))
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case "96":
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style = style.Foreground(twin.NewColor16(14))
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case "97":
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style = style.Foreground(twin.NewColor16(15))
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default:
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log.Warnf("Unrecognized ANSI SGR code <%s>", number)
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}
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}
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return style
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}
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// numbers is a list of numbers from a ANSI SGR string
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// index points to either 38 or 48 in that string
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//
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// This method will return:
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// * The first index in the string that this function did not consume
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// * A color value that can be applied to a style
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func consumeCompositeColor(numbers []string, index int) (int, *twin.Color, error) {
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baseIndex := index
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if numbers[index] != "38" && numbers[index] != "48" {
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err := fmt.Errorf(
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"unknown start of color sequence <%s>, expected 38 (foreground) or 48 (background): <CSI %sm>",
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numbers[index],
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strings.Join(numbers[baseIndex:], ";"))
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return -1, nil, err
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}
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index++
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if index >= len(numbers) {
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err := fmt.Errorf(
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"incomplete color sequence: <CSI %sm>",
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strings.Join(numbers[baseIndex:], ";"))
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return -1, nil, err
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}
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if numbers[index] == "5" {
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// Handle 8 bit color
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index++
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if index >= len(numbers) {
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err := fmt.Errorf(
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"incomplete 8 bit color sequence: <CSI %sm>",
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strings.Join(numbers[baseIndex:], ";"))
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return -1, nil, err
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}
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colorNumber, err := strconv.Atoi(numbers[index])
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if err != nil {
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return -1, nil, err
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}
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colorValue := twin.NewColor256(uint8(colorNumber))
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||
return index + 1, &colorValue, nil
|
||
}
|
||
|
||
if numbers[index] == "2" {
|
||
// Handle 24 bit color
|
||
rIndex := index + 1
|
||
gIndex := index + 2
|
||
bIndex := index + 3
|
||
if bIndex >= len(numbers) {
|
||
err := fmt.Errorf(
|
||
"incomplete 24 bit color sequence, expected N8;2;R;G;Bm: <CSI %sm>",
|
||
strings.Join(numbers[baseIndex:], ";"))
|
||
return -1, nil, err
|
||
}
|
||
|
||
rValueX, err := strconv.ParseInt(numbers[rIndex], 10, 32)
|
||
if err != nil {
|
||
return -1, nil, err
|
||
}
|
||
rValue := uint8(rValueX)
|
||
|
||
gValueX, err := strconv.Atoi(numbers[gIndex])
|
||
if err != nil {
|
||
return -1, nil, err
|
||
}
|
||
gValue := uint8(gValueX)
|
||
|
||
bValueX, err := strconv.Atoi(numbers[bIndex])
|
||
if err != nil {
|
||
return -1, nil, err
|
||
}
|
||
bValue := uint8(bValueX)
|
||
|
||
colorValue := twin.NewColor24Bit(rValue, gValue, bValue)
|
||
return bIndex + 1, &colorValue, nil
|
||
}
|
||
|
||
err := fmt.Errorf(
|
||
"unknown color type <%s>, expected 5 (8 bit color) or 2 (24 bit color): <CSI %sm>",
|
||
numbers[index],
|
||
strings.Join(numbers[baseIndex:], ";"))
|
||
return -1, nil, err
|
||
}
|