diff options
Diffstat (limited to 'util/text/text.go')
| -rw-r--r-- | util/text/text.go | 306 |
1 files changed, 230 insertions, 76 deletions
diff --git a/util/text/text.go b/util/text/text.go index cffb4ee2..81cc870b 100644 --- a/util/text/text.go +++ b/util/text/text.go @@ -1,12 +1,18 @@ package text import ( - "bytes" - "strings" - "github.com/mattn/go-runewidth" + "strings" + "unicode/utf8" ) +// 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 an exact line size // Handle properly terminal color escape code func Wrap(text string, lineWidth int) (string, int) { @@ -16,98 +22,248 @@ func Wrap(text string, lineWidth int) (string, int) { // Wrap a text for an exact line size with a left padding // Handle properly terminal color escape code func WrapLeftPadded(text string, lineWidth int, leftPad int) (string, int) { - var textBuffer bytes.Buffer - var lineBuffer bytes.Buffer - nbLine := 1 - firstLine := true + var lines []string + nbLine := 0 pad := strings.Repeat(" ", leftPad) // tabs are formatted as 4 spaces - text = strings.Replace(text, "\t", " ", 4) - + text = strings.Replace(text, "\t", " ", -1) + // NOTE: text is first segmented into lines so that softwrapLine can handle. for _, line := range strings.Split(text, "\n") { - spaceLeft := lineWidth - leftPad - - if !firstLine { - textBuffer.WriteString("\n") + if line == "" || strings.TrimSpace(line) == "" { + lines = append(lines, "") nbLine++ + } else { + wrapped := softwrapLine(line, lineWidth-leftPad) + firstLine := true + for _, seg := range strings.Split(wrapped, "\n") { + if firstLine { + lines = append(lines, pad+strings.TrimRight(seg, " ")) + firstLine = false + } else { + lines = append(lines, pad+strings.TrimSpace(seg)) + } + nbLine++ + } } + } + return strings.Join(lines, "\n"), nbLine +} - firstWord := true +// 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 broen into pieces no longer than textWidth. +// +func softwrapLine(line string, textWidth int) string { + // NOTE: terminal escapes are stripped out of the line so the algorithm is + // simpler. Do not try to mix them in the wrapping algorithm, as it can get + // complicated quickly. + line1, termEscapes := extractTermEscapes(line) + + chunks := segmentLine(line1) + // 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] + } + var line2 string = "" + var width int = 0 + for len(chunks) > 0 { + thisWord := chunks[len(chunks)-1] + wl := wordLen(thisWord) + if width+wl <= textWidth { + line2 += chunks[len(chunks)-1] + chunks = chunks[:len(chunks)-1] + width += wl + if width == textWidth && len(chunks) > 0 { + // NOTE: new line begins when current line is full and there are more + // chunks to come. + line2 += "\n" + width = 0 + } + } else if wl > textWidth { + // NOTE: By default, long words are splited to fill the remaining space. + // But if the long words is the first non-space word in the middle of the + // line, preceeding spaces shall not be counted in word spliting. + splitWidth := textWidth - width + if strings.HasSuffix(line2, "\n"+strings.Repeat(" ", width)) { + splitWidth += width + } + left, right := splitWord(chunks[len(chunks)-1], splitWidth) + chunks[len(chunks)-1] = right + line2 += left + "\n" + width = 0 + } else { + line2 += "\n" + width = 0 + } + } - for _, word := range strings.Split(line, " ") { - wordLength := wordLen(word) + line3 := applyTermEscapes(line2, termEscapes) + return line3 +} - if !firstWord { - lineBuffer.WriteString(" ") - spaceLeft -= 1 +// EscapeItem: Storage of terminal escapes in a line. 'item' is the actural +// escape command, and 'pos' is the index in the rune array where the 'item' +// shall be inserted back. For example, the escape item in "F\x1b33mox" is +// {"\x1b33m", 1}. +type escapeItem struct { + item string + pos int +} - if spaceLeft <= 0 { - textBuffer.WriteString(pad + strings.TrimRight(lineBuffer.String(), " ")) - textBuffer.WriteString("\n") - lineBuffer.Reset() - spaceLeft = lineWidth - leftPad - nbLine++ - firstLine = false - } +// Extract terminal escapes out of a line, returns a new line without terminal +// escapes and a slice of escape items. The terminal escapes can be inserted +// back into the new line at rune index 'item.pos' to recover the original line. +// +// Required: The line shall not contain "\n" +// +func extractTermEscapes(line string) (string, []escapeItem) { + var termEscapes []escapeItem + var line1 string + + pos := 0 + item := "" + occupiedRuneCount := 0 + inEscape := false + for i, r := range []rune(line) { + if r == '\x1b' { + pos = i + item = string(r) + inEscape = true + continue + } + if inEscape { + item += string(r) + if r == 'm' { + termEscapes = append(termEscapes, escapeItem{item, pos - occupiedRuneCount}) + occupiedRuneCount += utf8.RuneCountInString(item) + inEscape = false } + continue + } + line1 += string(r) + } + + return line1, termEscapes +} - // Word fit in the current line - if spaceLeft >= wordLength { - lineBuffer.WriteString(word) - spaceLeft -= wordLength - firstWord = false +// Apply the extracted terminal escapes to the edited line. The only edit +// allowed is to insert "\n" like that in softwrapLine. Callers shall ensure +// this since this function is not able to check it. +func applyTermEscapes(line string, escapes []escapeItem) string { + if len(escapes) == 0 { + return line + } + + var out string = "" + + currPos := 0 + currItem := 0 + for _, r := range line { + if currItem < len(escapes) && currPos == escapes[currItem].pos { + // NOTE: We avoid terminal escapes at the end of a line by move them one + // pass the end of line, so that algorithms who trim right spaces are + // happy. But algorithms who trim left spaces are still unhappy. + if r == '\n' { + out += "\n" + escapes[currItem].item } else { - // Break a word longer than a line - if wordLength > lineWidth { - for wordLength > 0 && wordLen(word) > 0 { - l := minInt(spaceLeft, wordLength) - part, leftover := splitWord(word, l) - word = leftover - wordLength = wordLen(word) - - lineBuffer.WriteString(part) - textBuffer.WriteString(pad) - textBuffer.Write(lineBuffer.Bytes()) - lineBuffer.Reset() - - spaceLeft -= l - - if spaceLeft <= 0 { - textBuffer.WriteString("\n") - nbLine++ - spaceLeft = lineWidth - leftPad - } - - if wordLength <= 0 { - break - } - } - } else { - // Normal break - textBuffer.WriteString(pad + strings.TrimRight(lineBuffer.String(), " ")) - textBuffer.WriteString("\n") - lineBuffer.Reset() - lineBuffer.WriteString(word) - firstWord = false - spaceLeft = lineWidth - leftPad - wordLength - nbLine++ - } + out += escapes[currItem].item + string(r) + currPos++ } + currItem++ + } else { + if r != '\n' { + currPos++ + } + out += string(r) } + } - if lineBuffer.Len() > 0 { - textBuffer.WriteString(pad + strings.TrimRight(lineBuffer.String(), " ")) - lineBuffer.Reset() - } + return out +} - firstLine = false +// 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 } - return textBuffer.String(), nbLine + 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 +} + +// 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 int = iota + wideChar + invisible + shortUnicode + space + visibleAscii +) + +// Determine the category of a rune. +func runeType(r rune) int { + 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 + } } -// wordLen return the length of a word, while ignoring the terminal escape sequences +// wordLen return the length of a word, while ignoring the terminal escape +// sequences func wordLen(word string) int { length := 0 escape := false @@ -116,11 +272,9 @@ func wordLen(word string) int { if char == '\x1b' { escape = true } - if !escape { length += runewidth.RuneWidth(rune(char)) } - if char == 'm' { escape = false } |