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util.go
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util.go
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package tview
import (
"math"
"regexp"
"sort"
"strconv"
"github.com/gdamore/tcell/v2"
runewidth "github.com/mattn/go-runewidth"
"github.com/rivo/uniseg"
)
// Text alignment within a box.
const (
AlignLeft = iota
AlignCenter
AlignRight
)
// Common regular expressions.
var (
colorPattern = regexp.MustCompile(`\[([a-zA-Z]+|#[0-9a-zA-Z]{6}|\-)?(:([a-zA-Z]+|#[0-9a-zA-Z]{6}|\-)?(:([lbidrus]+|\-)?)?)?\]`)
regionPattern = regexp.MustCompile(`\["([a-zA-Z0-9_,;: \-\.]*)"\]`)
escapePattern = regexp.MustCompile(`\[([a-zA-Z0-9_,;: \-\."#]+)\[(\[*)\]`)
nonEscapePattern = regexp.MustCompile(`(\[[a-zA-Z0-9_,;: \-\."#]+\[*)\]`)
boundaryPattern = regexp.MustCompile(`(([,\.\-:;!\?&#+]|\n)[ \t\f\r]*|([ \t\f\r]+))`)
spacePattern = regexp.MustCompile(`\s+`)
)
// Positions of substrings in regular expressions.
const (
colorForegroundPos = 1
colorBackgroundPos = 3
colorFlagPos = 5
)
// Predefined InputField acceptance functions.
var (
// InputFieldInteger accepts integers.
InputFieldInteger func(text string, ch rune) bool
// InputFieldFloat accepts floating-point numbers.
InputFieldFloat func(text string, ch rune) bool
// InputFieldMaxLength returns an input field accept handler which accepts
// input strings up to a given length. Use it like this:
//
// inputField.SetAcceptanceFunc(InputFieldMaxLength(10)) // Accept up to 10 characters.
InputFieldMaxLength func(maxLength int) func(text string, ch rune) bool
)
// Package initialization.
func init() {
// Initialize the predefined input field handlers.
InputFieldInteger = func(text string, ch rune) bool {
if text == "-" {
return true
}
_, err := strconv.Atoi(text)
return err == nil
}
InputFieldFloat = func(text string, ch rune) bool {
if text == "-" || text == "." || text == "-." {
return true
}
_, err := strconv.ParseFloat(text, 64)
return err == nil
}
InputFieldMaxLength = func(maxLength int) func(text string, ch rune) bool {
return func(text string, ch rune) bool {
return len([]rune(text)) <= maxLength
}
}
}
// styleFromTag takes the given style, defined by a foreground color (fgColor),
// a background color (bgColor), and style attributes, and modifies it based on
// the substrings (tagSubstrings) extracted by the regular expression for color
// tags. The new colors and attributes are returned where empty strings mean
// "don't modify" and a dash ("-") means "reset to default".
func styleFromTag(fgColor, bgColor, attributes string, tagSubstrings []string) (newFgColor, newBgColor, newAttributes string) {
if tagSubstrings[colorForegroundPos] != "" {
color := tagSubstrings[colorForegroundPos]
if color == "-" {
fgColor = "-"
} else if color != "" {
fgColor = color
}
}
if tagSubstrings[colorBackgroundPos-1] != "" {
color := tagSubstrings[colorBackgroundPos]
if color == "-" {
bgColor = "-"
} else if color != "" {
bgColor = color
}
}
if tagSubstrings[colorFlagPos-1] != "" {
flags := tagSubstrings[colorFlagPos]
if flags == "-" {
attributes = "-"
} else if flags != "" {
attributes = flags
}
}
return fgColor, bgColor, attributes
}
// overlayStyle calculates a new style based on "style" and applying tag-based
// colors/attributes to it (see also styleFromTag()).
func overlayStyle(style tcell.Style, fgColor, bgColor, attributes string) tcell.Style {
_, _, defAttr := style.Decompose()
if fgColor != "" && fgColor != "-" {
style = style.Foreground(tcell.GetColor(fgColor))
}
if bgColor != "" && bgColor != "-" {
style = style.Background(tcell.GetColor(bgColor))
}
if attributes == "-" {
style = style.Bold(defAttr&tcell.AttrBold > 0).
Italic(defAttr&tcell.AttrItalic > 0).
Blink(defAttr&tcell.AttrBlink > 0).
Reverse(defAttr&tcell.AttrReverse > 0).
Underline(defAttr&tcell.AttrUnderline > 0).
Dim(defAttr&tcell.AttrDim > 0)
} else if attributes != "" {
style = style.Normal()
for _, flag := range attributes {
switch flag {
case 'l':
style = style.Blink(true)
case 'b':
style = style.Bold(true)
case 'i':
style = style.Italic(true)
case 'd':
style = style.Dim(true)
case 'r':
style = style.Reverse(true)
case 'u':
style = style.Underline(true)
case 's':
style = style.StrikeThrough(true)
}
}
}
return style
}
// decomposeString returns information about a string which may contain color
// tags or region tags, depending on which ones are requested to be found. It
// returns the indices of the color tags (as returned by
// re.FindAllStringIndex()), the color tags themselves (as returned by
// re.FindAllStringSubmatch()), the indices of region tags and the region tags
// themselves, the indices of an escaped tags (only if at least color tags or
// region tags are requested), the string stripped by any tags and escaped, and
// the screen width of the stripped string.
func decomposeString(text string, findColors, findRegions bool) (colorIndices [][]int, colors [][]string, regionIndices [][]int, regions [][]string, escapeIndices [][]int, stripped string, width int) {
// Shortcut for the trivial case.
if !findColors && !findRegions {
return nil, nil, nil, nil, nil, text, stringWidth(text)
}
// Get positions of any tags.
if findColors {
colorIndices = colorPattern.FindAllStringIndex(text, -1)
colors = colorPattern.FindAllStringSubmatch(text, -1)
}
if findRegions {
regionIndices = regionPattern.FindAllStringIndex(text, -1)
regions = regionPattern.FindAllStringSubmatch(text, -1)
}
escapeIndices = escapePattern.FindAllStringIndex(text, -1)
// Because the color pattern detects empty tags, we need to filter them out.
for i := len(colorIndices) - 1; i >= 0; i-- {
if colorIndices[i][1]-colorIndices[i][0] == 2 {
colorIndices = append(colorIndices[:i], colorIndices[i+1:]...)
colors = append(colors[:i], colors[i+1:]...)
}
}
// Make a (sorted) list of all tags.
allIndices := make([][3]int, 0, len(colorIndices)+len(regionIndices)+len(escapeIndices))
for indexType, index := range [][][]int{colorIndices, regionIndices, escapeIndices} {
for _, tag := range index {
allIndices = append(allIndices, [3]int{tag[0], tag[1], indexType})
}
}
sort.Slice(allIndices, func(i int, j int) bool {
return allIndices[i][0] < allIndices[j][0]
})
// Remove the tags from the original string.
var from int
buf := make([]byte, 0, len(text))
for _, indices := range allIndices {
if indices[2] == 2 { // Escape sequences are not simply removed.
buf = append(buf, []byte(text[from:indices[1]-2])...)
buf = append(buf, ']')
from = indices[1]
} else {
buf = append(buf, []byte(text[from:indices[0]])...)
from = indices[1]
}
}
buf = append(buf, text[from:]...)
stripped = string(buf)
// Get the width of the stripped string.
width = stringWidth(stripped)
return
}
// Print prints text onto the screen into the given box at (x,y,maxWidth,1),
// not exceeding that box. "align" is one of AlignLeft, AlignCenter, or
// AlignRight. The screen's background color will not be changed.
//
// You can change the colors and text styles mid-text by inserting a color tag.
// See the package description for details.
//
// Returns the number of actual bytes of the text printed (including color tags)
// and the actual width used for the printed runes.
func Print(screen tcell.Screen, text string, x, y, maxWidth, align int, color tcell.Color) (int, int) {
bytes, width, _, _ := printWithStyle(screen, text, x, y, 0, maxWidth, align, tcell.StyleDefault.Foreground(color), true)
return bytes, width
}
// printWithStyle works like Print() but it takes a style instead of just a
// foreground color. The skipWidth parameter specifies the number of cells
// skipped at the beginning of the text. It also returns the start and end index
// (exclusively) of the text actually printed. If maintainBackground is "true",
// The existing screen background is not changed (i.e. the style's background
// color is ignored).
func printWithStyle(screen tcell.Screen, text string, x, y, skipWidth, maxWidth, align int, style tcell.Style, maintainBackground bool) (int, int, int, int) {
totalWidth, totalHeight := screen.Size()
if maxWidth <= 0 || len(text) == 0 || y < 0 || y >= totalHeight {
return 0, 0, 0, 0
}
// Decompose the text.
colorIndices, colors, _, _, escapeIndices, strippedText, strippedWidth := decomposeString(text, true, false)
// We want to reduce all alignments to AlignLeft.
if align == AlignRight {
if strippedWidth-skipWidth <= maxWidth {
// There's enough space for the entire text.
return printWithStyle(screen, text, x+maxWidth-strippedWidth+skipWidth, y, skipWidth, maxWidth, AlignLeft, style, maintainBackground)
}
// Trim characters off the beginning.
var (
bytes, width, colorPos, escapePos, tagOffset, from, to int
foregroundColor, backgroundColor, attributes string
)
originalStyle := style
iterateString(strippedText, func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
// Update color/escape tag offset and style.
if colorPos < len(colorIndices) && textPos+tagOffset >= colorIndices[colorPos][0] && textPos+tagOffset < colorIndices[colorPos][1] {
foregroundColor, backgroundColor, attributes = styleFromTag(foregroundColor, backgroundColor, attributes, colors[colorPos])
style = overlayStyle(originalStyle, foregroundColor, backgroundColor, attributes)
tagOffset += colorIndices[colorPos][1] - colorIndices[colorPos][0]
colorPos++
}
if escapePos < len(escapeIndices) && textPos+tagOffset >= escapeIndices[escapePos][0] && textPos+tagOffset < escapeIndices[escapePos][1] {
tagOffset++
escapePos++
}
if strippedWidth-screenPos <= maxWidth {
// We chopped off enough.
if escapePos > 0 && textPos+tagOffset-1 >= escapeIndices[escapePos-1][0] && textPos+tagOffset-1 < escapeIndices[escapePos-1][1] {
// Unescape open escape sequences.
escapeCharPos := escapeIndices[escapePos-1][1] - 2
text = text[:escapeCharPos] + text[escapeCharPos+1:]
}
// Print and return.
bytes, width, from, to = printWithStyle(screen, text[textPos+tagOffset:], x, y, 0, maxWidth, AlignLeft, style, maintainBackground)
from += textPos + tagOffset
to += textPos + tagOffset
return true
}
return false
})
return bytes, width, from, to
} else if align == AlignCenter {
if strippedWidth-skipWidth == maxWidth {
// Use the exact space.
return printWithStyle(screen, text, x, y, skipWidth, maxWidth, AlignLeft, style, maintainBackground)
} else if strippedWidth-skipWidth < maxWidth {
// We have more space than we need.
half := (maxWidth - strippedWidth + skipWidth) / 2
return printWithStyle(screen, text, x+half, y, skipWidth, maxWidth-half, AlignLeft, style, maintainBackground)
} else {
// Chop off runes until we have a perfect fit.
var choppedLeft, choppedRight, leftIndex, rightIndex int
rightIndex = len(strippedText)
for rightIndex-1 > leftIndex && strippedWidth-skipWidth-choppedLeft-choppedRight > maxWidth {
if skipWidth > 0 || choppedLeft < choppedRight {
// Iterate on the left by one character.
iterateString(strippedText[leftIndex:], func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
if skipWidth > 0 {
skipWidth -= screenWidth
strippedWidth -= screenWidth
} else {
choppedLeft += screenWidth
}
leftIndex += textWidth
return true
})
} else {
// Iterate on the right by one character.
iterateStringReverse(strippedText[leftIndex:rightIndex], func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
choppedRight += screenWidth
rightIndex -= textWidth
return true
})
}
}
// Add tag offsets and determine start style.
var (
colorPos, escapePos, tagOffset int
foregroundColor, backgroundColor, attributes string
)
originalStyle := style
for index := range strippedText {
// We only need the offset of the left index.
if index > leftIndex {
// We're done.
if escapePos > 0 && leftIndex+tagOffset-1 >= escapeIndices[escapePos-1][0] && leftIndex+tagOffset-1 < escapeIndices[escapePos-1][1] {
// Unescape open escape sequences.
escapeCharPos := escapeIndices[escapePos-1][1] - 2
text = text[:escapeCharPos] + text[escapeCharPos+1:]
}
break
}
// Update color/escape tag offset.
if colorPos < len(colorIndices) && index+tagOffset >= colorIndices[colorPos][0] && index+tagOffset < colorIndices[colorPos][1] {
if index <= leftIndex {
foregroundColor, backgroundColor, attributes = styleFromTag(foregroundColor, backgroundColor, attributes, colors[colorPos])
style = overlayStyle(originalStyle, foregroundColor, backgroundColor, attributes)
}
tagOffset += colorIndices[colorPos][1] - colorIndices[colorPos][0]
colorPos++
}
if escapePos < len(escapeIndices) && index+tagOffset >= escapeIndices[escapePos][0] && index+tagOffset < escapeIndices[escapePos][1] {
tagOffset++
escapePos++
}
}
bytes, width, from, to := printWithStyle(screen, text[leftIndex+tagOffset:], x, y, 0, maxWidth, AlignLeft, style, maintainBackground)
from += leftIndex + tagOffset
to += leftIndex + tagOffset
return bytes, width, from, to
}
}
// Draw text.
var (
drawn, drawnWidth, colorPos, escapePos, tagOffset, from, to int
foregroundColor, backgroundColor, attributes string
)
iterateString(strippedText, func(main rune, comb []rune, textPos, length, screenPos, screenWidth int) bool {
// Skip character if necessary.
if skipWidth > 0 {
skipWidth -= screenWidth
from = textPos + length
to = from
return false
}
// Only continue if there is still space.
if drawnWidth+screenWidth > maxWidth || x+drawnWidth >= totalWidth {
return true
}
// Handle color tags.
for colorPos < len(colorIndices) && textPos+tagOffset >= colorIndices[colorPos][0] && textPos+tagOffset < colorIndices[colorPos][1] {
foregroundColor, backgroundColor, attributes = styleFromTag(foregroundColor, backgroundColor, attributes, colors[colorPos])
tagOffset += colorIndices[colorPos][1] - colorIndices[colorPos][0]
colorPos++
}
// Handle escape tags.
if escapePos < len(escapeIndices) && textPos+tagOffset >= escapeIndices[escapePos][0] && textPos+tagOffset < escapeIndices[escapePos][1] {
if textPos+tagOffset == escapeIndices[escapePos][1]-2 {
tagOffset++
escapePos++
}
}
// Memorize positions.
to = textPos + length
// Print the rune sequence.
finalX := x + drawnWidth
finalStyle := style
if maintainBackground {
_, _, existingStyle, _ := screen.GetContent(finalX, y)
_, background, _ := existingStyle.Decompose()
finalStyle = finalStyle.Background(background)
}
finalStyle = overlayStyle(finalStyle, foregroundColor, backgroundColor, attributes)
for offset := screenWidth - 1; offset >= 0; offset-- {
// To avoid undesired effects, we populate all cells.
if offset == 0 {
screen.SetContent(finalX+offset, y, main, comb, finalStyle)
} else {
screen.SetContent(finalX+offset, y, ' ', nil, finalStyle)
}
}
// Advance.
drawn += length
drawnWidth += screenWidth
return false
})
return drawn + tagOffset + len(escapeIndices), drawnWidth, from, to
}
// PrintSimple prints white text to the screen at the given position.
func PrintSimple(screen tcell.Screen, text string, x, y int) {
Print(screen, text, x, y, math.MaxInt32, AlignLeft, Styles.PrimaryTextColor)
}
// TaggedStringWidth returns the width of the given string needed to print it on
// screen. The text may contain color tags which are not counted.
func TaggedStringWidth(text string) int {
_, _, _, _, _, _, width := decomposeString(text, true, false)
return width
}
// stringWidth returns the number of horizontal cells needed to print the given
// text. It splits the text into its grapheme clusters, calculates each
// cluster's width, and adds them up to a total.
func stringWidth(text string) (width int) {
state := -1
for len(text) > 0 {
var (
chWidth int
cl string
)
cl, text, _, state = uniseg.FirstGraphemeClusterInString(text, state)
for _, r := range cl {
chWidth = runewidth.RuneWidth(r)
if chWidth > 0 {
break // Our best guess at this point is to use the width of the first non-zero-width rune.
}
}
width += chWidth
}
return
}
// WordWrap splits a text such that each resulting line does not exceed the
// given screen width. Possible split points are after any punctuation or
// whitespace. Whitespace after split points will be dropped.
//
// This function considers color tags to have no width.
//
// Text is always split at newline characters ('\n').
func WordWrap(text string, width int) (lines []string) {
colorTagIndices, _, _, _, escapeIndices, strippedText, _ := decomposeString(text, true, false)
// Find candidate breakpoints.
breakpoints := boundaryPattern.FindAllStringSubmatchIndex(strippedText, -1)
// Results in one entry for each candidate. Each entry is an array a of
// indices into strippedText where a[6] < 0 for newline/punctuation matches
// and a[4] < 0 for whitespace matches.
// Process stripped text one character at a time.
var (
colorPos, escapePos, breakpointPos, tagOffset int
lastBreakpoint, lastContinuation, currentLineStart int
lineWidth, overflow int
forceBreak bool
)
unescape := func(substr string, startIndex int) string {
// A helper function to unescape escaped tags.
for index := escapePos; index >= 0; index-- {
if index < len(escapeIndices) && startIndex > escapeIndices[index][0] && startIndex < escapeIndices[index][1]-1 {
pos := escapeIndices[index][1] - 2 - startIndex
return substr[:pos] + substr[pos+1:]
}
}
return substr
}
iterateString(strippedText, func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
// Handle tags.
for {
if colorPos < len(colorTagIndices) && textPos+tagOffset >= colorTagIndices[colorPos][0] && textPos+tagOffset < colorTagIndices[colorPos][1] {
// Colour tags.
tagOffset += colorTagIndices[colorPos][1] - colorTagIndices[colorPos][0]
colorPos++
} else if escapePos < len(escapeIndices) && textPos+tagOffset == escapeIndices[escapePos][1]-2 {
// Escape tags.
tagOffset++
escapePos++
} else {
break
}
}
// Is this a breakpoint?
if breakpointPos < len(breakpoints) && textPos+tagOffset == breakpoints[breakpointPos][0] {
// Yes, it is. Set up breakpoint infos depending on its type.
lastBreakpoint = breakpoints[breakpointPos][0] + tagOffset
lastContinuation = breakpoints[breakpointPos][1] + tagOffset
overflow = 0
forceBreak = main == '\n'
if breakpoints[breakpointPos][6] < 0 && !forceBreak {
lastBreakpoint++ // Don't skip punctuation.
}
breakpointPos++
}
// Check if a break is warranted.
if forceBreak || lineWidth > 0 && lineWidth+screenWidth > width {
breakpoint := lastBreakpoint
continuation := lastContinuation
if forceBreak {
breakpoint = textPos + tagOffset
continuation = textPos + tagOffset + 1
lastBreakpoint = 0
overflow = 0
} else if lastBreakpoint <= currentLineStart {
breakpoint = textPos + tagOffset
continuation = textPos + tagOffset
overflow = 0
}
lines = append(lines, unescape(text[currentLineStart:breakpoint], currentLineStart))
currentLineStart, lineWidth, forceBreak = continuation, overflow, false
}
// Remember the characters since the last breakpoint.
if lastBreakpoint > 0 && lastContinuation <= textPos+tagOffset {
overflow += screenWidth
}
// Advance.
lineWidth += screenWidth
// But if we're still inside a breakpoint, skip next character (whitespace).
if textPos+tagOffset < currentLineStart {
lineWidth -= screenWidth
}
return false
})
// Flush the rest.
if currentLineStart < len(text) {
lines = append(lines, unescape(text[currentLineStart:], currentLineStart))
}
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[]")
}
// iterateString iterates through the given string one printed character at a
// time. For each such character, the callback function is called with the
// Unicode code points of the character (the first rune and any combining runes
// which may be nil if there aren't any), the starting position (in bytes)
// within the original string, its length in bytes, the screen position of the
// character, and the screen width of it. The iteration stops if the callback
// returns true. This function returns true if the iteration was stopped before
// the last character.
func iterateString(text string, callback func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool) bool {
var screenPos, textPos int
state := -1
for len(text) > 0 {
var cluster string
cluster, text, _, state = uniseg.FirstGraphemeClusterInString(text, state)
var width int
runes := make([]rune, 0, len(cluster))
for _, r := range cluster {
runes = append(runes, r)
w := runewidth.RuneWidth(r)
if width == 0 && w > 0 {
width = w // Our best guess at this point is to use the width of the first non-zero-width rune.
}
}
var comb []rune
if len(runes) > 1 {
comb = runes[1:]
}
if callback(runes[0], comb, textPos, len(cluster), screenPos, width) {
return true
}
screenPos += width
textPos += len(cluster)
}
return false
}
// iterateStringReverse iterates through the given string in reverse, starting
// from the end of the string, one printed character at a time. For each such
// character, the callback function is called with the Unicode code points of
// the character (the first rune and any combining runes which may be nil if
// there aren't any), the starting position (in bytes) within the original
// string, its length in bytes, the screen position of the character, and the
// screen width of it. The iteration stops if the callback returns true. This
// function returns true if the iteration was stopped before the last character.
func iterateStringReverse(text string, callback func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool) bool {
type cluster struct {
main rune
comb []rune
textPos, textWidth, screenPos, screenWidth int
}
// Create the grapheme clusters.
var clusters []cluster
iterateString(text, func(main rune, comb []rune, textPos int, textWidth int, screenPos int, screenWidth int) bool {
clusters = append(clusters, cluster{
main: main,
comb: comb,
textPos: textPos,
textWidth: textWidth,
screenPos: screenPos,
screenWidth: screenWidth,
})
return false
})
// Iterate in reverse.
for index := len(clusters) - 1; index >= 0; index-- {
if callback(
clusters[index].main,
clusters[index].comb,
clusters[index].textPos,
clusters[index].textWidth,
clusters[index].screenPos,
clusters[index].screenWidth,
) {
return true
}
}
return false
}
// stripTags strips colour tags from the given string. (Region tags are not
// stripped.)
func stripTags(text string) string {
stripped := colorPattern.ReplaceAllStringFunc(text, func(match string) string {
if len(match) > 2 {
return ""
}
return match
})
return escapePattern.ReplaceAllString(stripped, `[$1$2]`)
}