subsonic-tui/vendor/github.com/rivo/tview/strings.go
Sagi Dayan 26e526f07e
initial commit
Signed-off-by: Sagi Dayan <sagidayan@gmail.com>
2024-02-20 19:10:14 +02:00

612 lines
18 KiB
Go

package tview
import (
"math/rand"
"regexp"
"strconv"
"strings"
"unicode/utf8"
"github.com/gdamore/tcell/v2"
"github.com/rivo/uniseg"
)
// escapedTagPattern matches an escaped tag, e.g. "[red[]", at the beginning of
// a string.
var escapedTagPattern = regexp.MustCompile(`^\[[^\[\]]+\[+\]`)
// stepOptions is a bit field of options for [step]. A value of 0 results in
// [step] having the same behavior as uniseg.Step, i.e. no tview-related parsing
// is performed.
type stepOptions int
// Bit fields for [stepOptions].
const (
stepOptionsNone stepOptions = 0
stepOptionsStyle stepOptions = 1 << iota // Parse style tags.
stepOptionsRegion // Parse region tags.
)
// stepState represents the current state of the parser implemented in [step].
type stepState struct {
unisegState int // The state of the uniseg parser.
boundaries int // Information about boundaries, as returned by uniseg.Step.
style tcell.Style // The current style.
region string // The current region.
escapedTagState int // States for parsing escaped tags (defined in [step]).
grossLength int // The length of the cluster, including any tags not returned.
// The styles for the initial call to [step].
initialForeground tcell.Color
initialBackground tcell.Color
initialAttributes tcell.AttrMask
}
// IsWordBoundary returns true if the boundary between the returned grapheme
// cluster and the one following it is a word boundary.
func (s *stepState) IsWordBoundary() bool {
return s.boundaries&uniseg.MaskWord != 0
}
// IsSentenceBoundary returns true if the boundary between the returned grapheme
// cluster and the one following it is a sentence boundary.
func (s *stepState) IsSentenceBoundary() bool {
return s.boundaries&uniseg.MaskSentence != 0
}
// LineBreak returns whether the string can be broken into the next line after
// the returned grapheme cluster. If optional is true, the line break is
// optional. If false, the line break is mandatory, e.g. after a newline
// character.
func (s *stepState) LineBreak() (lineBreak, optional bool) {
switch s.boundaries & uniseg.MaskLine {
case uniseg.LineCanBreak:
return true, true
case uniseg.LineMustBreak:
return true, false
}
return false, false // uniseg.LineDontBreak.
}
// Width returns the grapheme cluster's width in cells.
func (s *stepState) Width() int {
return s.boundaries >> uniseg.ShiftWidth
}
// GrossLength returns the grapheme cluster's length in bytes, including any
// tags that were parsed but not explicitly returned.
func (s *stepState) GrossLength() int {
return s.grossLength
}
// Style returns the style for the grapheme cluster.
func (s *stepState) Style() tcell.Style {
return s.style
}
// step uses uniseg.Step to iterate over the grapheme clusters of a string but
// (optionally) also parses the string for style or region tags.
//
// This function can be called consecutively to extract all grapheme clusters
// from str, without returning any contained (parsed) tags. The return values
// are the first grapheme cluster, the remaining string, and the new state. Pass
// the remaining string and the returned state to the next call. If the rest
// string is empty, parsing is complete. Call the returned state's methods for
// boundary and width information.
//
// The returned cluster may be empty if the given string consists of only
// (parsed) tags. The boundary and width information will be meaningless in
// this case but the style will describe the style at the end of the string.
//
// Pass nil for state on the first call. This will assume an initial style with
// [Styles.PrimitiveBackgroundColor] as the background color and
// [Styles.PrimaryTextColor] as the text color, no current region. If you want
// to start with a different style or region, you can set the state accordingly
// but you must then set [state.unisegState] to -1.
//
// There is no need to call uniseg.HasTrailingLineBreakInString on the last
// non-empty cluster as this function will do this for you and adjust the
// returned boundaries accordingly.
func step(str string, state *stepState, opts stepOptions) (cluster, rest string, newState *stepState) {
// Set up initial state.
if state == nil {
state = &stepState{
unisegState: -1,
style: tcell.StyleDefault.Background(Styles.PrimitiveBackgroundColor).Foreground(Styles.PrimaryTextColor),
}
}
if state.unisegState < 0 {
state.initialForeground, state.initialBackground, state.initialAttributes = state.style.Decompose()
}
if len(str) == 0 {
newState = state
return
}
// Get a grapheme cluster.
preState := state.unisegState
cluster, rest, state.boundaries, state.unisegState = uniseg.StepString(str, preState)
state.grossLength = len(cluster)
if rest == "" {
if !uniseg.HasTrailingLineBreakInString(cluster) {
state.boundaries &^= uniseg.MaskLine
}
}
// Parse tags.
if opts != 0 {
const (
etNone int = iota
etStart
etChar
etClosing
)
// Finite state machine for escaped tags.
switch state.escapedTagState {
case etStart:
if cluster[0] == '[' || cluster[0] == ']' { // Invalid escaped tag.
state.escapedTagState = etNone
} else { // Other characters are allowed.
state.escapedTagState = etChar
}
case etChar:
if cluster[0] == ']' { // In theory, this should not happen.
state.escapedTagState = etNone
} else if cluster[0] == '[' { // Starting closing sequence.
// Swallow the first one.
cluster, rest, state.boundaries, state.unisegState = uniseg.StepString(rest, preState)
state.grossLength += len(cluster)
if cluster[0] == ']' {
state.escapedTagState = etNone
} else {
state.escapedTagState = etClosing
}
} // More characters. Remain in etChar.
case etClosing:
if cluster[0] != '[' {
state.escapedTagState = etNone
}
}
// Regular tags.
if state.escapedTagState == etNone {
if cluster[0] == '[' {
// We've already opened a tag. Parse it.
length, style, region := parseTag(str, state)
if length > 0 {
state.style = style
state.region = region
cluster, rest, state.boundaries, state.unisegState = uniseg.StepString(str[length:], preState)
state.grossLength = len(cluster) + length
if rest == "" {
if !uniseg.HasTrailingLineBreakInString(cluster) {
state.boundaries &^= uniseg.MaskLine
}
}
}
// Is this an escaped tag?
if escapedTagPattern.MatchString(str[length:]) {
state.escapedTagState = etStart
}
}
if len(rest) > 0 && rest[0] == '[' {
// A tag might follow the cluster. If so, we need to fix the state
// for the boundaries to be correct.
if length, _, _ := parseTag(rest, state); length > 0 {
if len(rest) > length {
_, l := utf8.DecodeRuneInString(rest[length:])
cluster += rest[length : length+l]
}
var taglessRest string
cluster, taglessRest, state.boundaries, state.unisegState = uniseg.StepString(cluster, preState)
if taglessRest == "" {
if !uniseg.HasTrailingLineBreakInString(cluster) {
state.boundaries &^= uniseg.MaskLine
}
}
}
}
}
}
newState = state
return
}
// parseTag parses str for consecutive style and/or region tags, assuming that
// str starts with the opening bracket for the first tag. It returns the string
// length of all valid tags (0 if the first tag is not valid) and the updated
// style and region for valid tags (based on the provided state).
func parseTag(str string, state *stepState) (length int, style tcell.Style, region string) {
// Automata states for parsing tags.
const (
tagStateNone = iota
tagStateDoneTag
tagStateStart
tagStateRegionStart
tagStateEndForeground
tagStateStartBackground
tagStateNumericForeground
tagStateNameForeground
tagStateEndBackground
tagStateStartAttributes
tagStateNumericBackground
tagStateNameBackground
tagStateAttributes
tagStateRegionEnd
tagStateRegionName
tagStateEndAttributes
tagStateStartURL
tagStateEndURL
tagStateURL
)
// Helper function which checks if the given byte is one of a list of
// characters, including letters and digits.
isOneOf := func(b byte, chars string) bool {
if b >= 'a' && b <= 'z' || b >= 'A' && b <= 'Z' || b >= '0' && b <= '9' {
return true
}
return strings.IndexByte(chars, b) >= 0
}
// Attribute map.
attrs := map[byte]tcell.AttrMask{
'B': tcell.AttrBold,
'U': tcell.AttrUnderline,
'I': tcell.AttrItalic,
'L': tcell.AttrBlink,
'D': tcell.AttrDim,
'S': tcell.AttrStrikeThrough,
'R': tcell.AttrReverse,
}
var (
tagState, tagLength int
tempStr strings.Builder
)
tStyle := state.style
tRegion := state.region
// Process state transitions.
for len(str) > 0 {
ch := str[0]
str = str[1:]
tagLength++
// Transition.
switch tagState {
case tagStateNone:
if ch == '[' { // Start of a tag.
tagState = tagStateStart
} else { // Not a tag. We're done.
return
}
case tagStateStart:
if ch == '"' { // Start of a region tag.
tempStr.Reset()
tagState = tagStateRegionStart
} else if !isOneOf(ch, "#:-") { // Invalid style tag.
return
} else if ch == '-' { // Reset foreground color.
tStyle = tStyle.Foreground(state.initialForeground)
tagState = tagStateEndForeground
} else if ch == ':' { // No foreground color.
tagState = tagStateStartBackground
} else {
tempStr.Reset()
tempStr.WriteByte(ch)
if ch == '#' { // Numeric foreground color.
tagState = tagStateNumericForeground
} else { // Letters or numbers.
tagState = tagStateNameForeground
}
}
case tagStateEndForeground:
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' {
tagState = tagStateStartBackground
} else { // Invalid tag.
return
}
case tagStateNumericForeground:
if ch == ']' || ch == ':' {
if tempStr.Len() != 7 { // Must be #rrggbb.
return
}
tStyle = tStyle.Foreground(tcell.GetColor(tempStr.String()))
}
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of background color.
tagState = tagStateStartBackground
} else if strings.IndexByte("0123456789abcdefABCDEF", ch) >= 0 { // Hex digit.
tempStr.WriteByte(ch)
tagState = tagStateNumericForeground
} else { // Invalid tag.
return
}
case tagStateNameForeground:
if ch == ']' || ch == ':' {
name := tempStr.String()
if name[0] >= '0' && name[0] <= '9' { // Must not start with a digit.
return
}
tStyle = tStyle.Foreground(tcell.ColorNames[name])
}
if !isOneOf(ch, "]:") { // Invalid tag.
return
} else if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of background color.
tagState = tagStateStartBackground
} else { // Letters or numbers.
tempStr.WriteByte(ch)
}
case tagStateStartBackground:
if !isOneOf(ch, "#:-]") { // Invalid style tag.
return
} else if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == '-' { // Reset background color.
tStyle = tStyle.Background(state.initialBackground)
tagState = tagStateEndBackground
} else if ch == ':' { // No background color.
tagState = tagStateStartAttributes
} else {
tempStr.Reset()
tempStr.WriteByte(ch)
if ch == '#' { // Numeric background color.
tagState = tagStateNumericBackground
} else { // Letters or numbers.
tagState = tagStateNameBackground
}
}
case tagStateEndBackground:
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of attributes.
tagState = tagStateStartAttributes
} else { // Invalid tag.
return
}
case tagStateNumericBackground:
if ch == ']' || ch == ':' {
if tempStr.Len() != 7 { // Must be #rrggbb.
return
}
tStyle = tStyle.Background(tcell.GetColor(tempStr.String()))
}
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of attributes.
tagState = tagStateStartAttributes
} else if strings.IndexByte("0123456789abcdefABCDEF", ch) >= 0 { // Hex digit.
tempStr.WriteByte(ch)
tagState = tagStateNumericBackground
} else { // Invalid tag.
return
}
case tagStateNameBackground:
if ch == ']' || ch == ':' {
name := tempStr.String()
if name[0] >= '0' && name[0] <= '9' { // Must not start with a digit.
return
}
tStyle = tStyle.Background(tcell.ColorNames[name])
}
if !isOneOf(ch, "]:") { // Invalid tag.
return
} else if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of background color.
tagState = tagStateStartAttributes
} else { // Letters or numbers.
tempStr.WriteByte(ch)
}
case tagStateStartAttributes:
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == '-' { // Reset attributes.
tStyle = tStyle.Attributes(state.initialAttributes)
tagState = tagStateEndAttributes
} else if ch == ':' { // Start of URL.
tagState = tagStateStartURL
} else if strings.IndexByte("buildsrBUILDSR", ch) >= 0 { // Attribute tag.
tempStr.Reset()
tempStr.WriteByte(ch)
tagState = tagStateAttributes
} else { // Invalid tag.
return
}
case tagStateAttributes:
if ch == ']' || ch == ':' {
flags := tempStr.String()
_, _, a := tStyle.Decompose()
for index := 0; index < len(flags); index++ {
ch := flags[index]
if ch >= 'a' && ch <= 'z' {
a |= attrs[ch-('a'-'A')]
} else {
a &^= attrs[ch]
}
}
tStyle = tStyle.Attributes(a)
}
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of URL.
tagState = tagStateStartURL
} else if strings.IndexByte("buildsrBUILDSR", ch) >= 0 { // Attribute tag.
tempStr.WriteByte(ch)
} else { // Invalid tag.
return
}
case tagStateEndAttributes:
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == ':' { // Start of URL.
tagState = tagStateStartURL
} else { // Invalid tag.
return
}
case tagStateStartURL:
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else if ch == '-' { // Reset URL.
tStyle = tStyle.Url("").UrlId("")
tagState = tagStateEndURL
} else { // URL character.
tempStr.Reset()
tempStr.WriteByte(ch)
tStyle = tStyle.UrlId(strconv.Itoa(int(rand.Uint32()))) // Generate a unique ID for this URL.
tagState = tagStateURL
}
case tagStateEndURL:
if ch == ']' { // End of tag.
tagState = tagStateDoneTag
} else { // Invalid tag.
return
}
case tagStateURL:
if ch == ']' { // End of tag.
tStyle = tStyle.Url(tempStr.String())
tagState = tagStateDoneTag
} else { // URL character.
tempStr.WriteByte(ch)
}
case tagStateRegionStart:
if ch == '"' { // End of region tag.
tagState = tagStateRegionEnd
} else if isOneOf(ch, "_,;: -.") { // Region name.
tempStr.WriteByte(ch)
tagState = tagStateRegionName
} else { // Invalid tag.
return
}
case tagStateRegionEnd:
if ch == ']' { // End of tag.
tRegion = tempStr.String()
tagState = tagStateDoneTag
} else { // Invalid tag.
return
}
case tagStateRegionName:
if ch == '"' { // End of region tag.
tagState = tagStateRegionEnd
} else if isOneOf(ch, "_,;: -.") { // Region name.
tempStr.WriteByte(ch)
} else { // Invalid tag.
return
}
}
// The last transition led to a tag end. Make the tag permanent.
if tagState == tagStateDoneTag {
length, style, region = tagLength, tStyle, tRegion
tagState = tagStateNone // Reset state.
}
}
return
}
// TaggedStringWidth returns the width of the given string needed to print it on
// screen. The text may contain style tags which are not counted.
func TaggedStringWidth(text string) (width int) {
var state *stepState
for len(text) > 0 {
_, text, state = step(text, state, stepOptionsStyle)
width += state.Width()
}
return
}
// WordWrap splits a text such that each resulting line does not exceed the
// given screen width. Split points are determined using the algorithm described
// in [Unicode Standard Annex #14].
//
// This function considers style tags to have no width.
//
// [Unicode Standard Annex #14]: https://www.unicode.org/reports/tr14/
func WordWrap(text string, width int) (lines []string) {
if width <= 0 {
return
}
var (
state *stepState
lineWidth, lineLength, lastOption, lastOptionWidth int
)
str := text
for len(str) > 0 {
// Parse the next character.
_, str, state = step(str, state, stepOptionsStyle)
cWidth := state.Width()
// Would it exceed the line width?
if lineWidth+cWidth > width {
if lastOptionWidth == 0 {
// No split point so far. Just split at the current position.
lines = append(lines, text[:lineLength])
text = text[lineLength:]
lineWidth, lineLength, lastOption, lastOptionWidth = 0, 0, 0, 0
} else {
// Split at the last split point.
lines = append(lines, text[:lastOption])
text = text[lastOption:]
lineWidth -= lastOptionWidth
lineLength -= lastOption
lastOption, lastOptionWidth = 0, 0
}
}
// Move ahead.
lineWidth += cWidth
lineLength += state.GrossLength()
// Check for split points.
if lineBreak, optional := state.LineBreak(); lineBreak {
if optional {
// Remember this split point.
lastOption = lineLength
lastOptionWidth = lineWidth
} else {
// We must split here.
lines = append(lines, strings.TrimRight(text[:lineLength], "\n\r"))
text = text[lineLength:]
lineWidth, lineLength, lastOption, lastOptionWidth = 0, 0, 0, 0
}
}
}
lines = append(lines, text)
return
}
// Escape escapes the given text such that color and/or region tags are not
// recognized and substituted by the print functions of this package. For
// example, to include a tag-like string in a box title or in a TextView:
//
// box.SetTitle(tview.Escape("[squarebrackets]"))
// fmt.Fprint(textView, tview.Escape(`["quoted"]`))
func Escape(text string) string {
return nonEscapePattern.ReplaceAllString(text, "$1[]")
}
// stripTags strips style tags from the given string. (Region tags are not
// stripped.)
func stripTags(text string) string {
var (
str strings.Builder
state *stepState
)
for len(text) > 0 {
var c string
c, text, state = step(text, state, stepOptionsStyle)
str.WriteString(c)
}
return str.String()
}