v0.1.0 initial commit

tui/text.go

@@ -0,0 +1,192 @@
+package tui
+
+import (
+	"unicode/utf8"
+)
+
+// --- Length calculation ---
+
+// RuneLen returns rune count, used as display width under the package-wide assumption of 1 cell per rune
+// Wide (CJK), emoji, and combining characters are not handled
+func RuneLen(s string) int {
+	return utf8.RuneCountInString(s)
+}
+
+// --- Truncation ---
+
+// Truncate truncates string with … suffix if exceeds maxLen
+func Truncate(s string, maxLen int) string {
+	if maxLen <= 0 {
+		return ""
+	}
+	if utf8.RuneCountInString(s) <= maxLen {
+		return s
+	}
+
+	// Boundary-safe truncation for UTF-8
+	count := 0
+	for i := range s {
+		if count == maxLen-1 {
+			return s[:i] + "…"
+		}
+		count++
+	}
+	return s
+}
+
+// TruncateLeft truncates with … prefix, keeps end of string
+func TruncateLeft(s string, maxLen int) string {
+	if maxLen <= 0 {
+		return ""
+	}
+	runes := []rune(s)
+	if len(runes) <= maxLen {
+		return s
+	}
+	if maxLen <= 1 {
+		return "…"
+	}
+	return "…" + string(runes[len(runes)-maxLen+1:])
+}
+
+// TruncateMiddle keeps start and end, … in middle
+func TruncateMiddle(s string, maxLen int) string {
+	if maxLen <= 0 {
+		return ""
+	}
+	runes := []rune(s)
+	if len(runes) <= maxLen {
+		return s
+	}
+	if maxLen <= 3 {
+		return Truncate(s, maxLen)
+	}
+
+	// Split remaining space between start and end
+	// Favor start slightly: (maxLen-1)/2 for start, rest for end
+	startLen := (maxLen - 1) / 2
+	endLen := maxLen - 1 - startLen
+
+	return string(runes[:startLen]) + "…" + string(runes[len(runes)-endLen:])
+}
+
+// --- Padding ---
+
+// PadRight pads string with spaces to width
+func PadRight(s string, width int) string {
+	runes := []rune(s)
+	if len(runes) >= width {
+		return s
+	}
+	result := make([]rune, width)
+	copy(result, runes)
+	for i := len(runes); i < width; i++ {
+		result[i] = ' '
+	}
+	return string(result)
+}
+
+// PadLeft left-pads string with spaces to width
+func PadLeft(s string, width int) string {
+	runes := []rune(s)
+	if len(runes) >= width {
+		return s
+	}
+	result := make([]rune, width)
+	padding := width - len(runes)
+	for i := 0; i < padding; i++ {
+		result[i] = ' '
+	}
+	copy(result[padding:], runes)
+	return string(result)
+}
+
+// PadCenter centers string within width
+func PadCenter(s string, width int) string {
+	runes := []rune(s)
+	if len(runes) >= width {
+		return s
+	}
+	result := make([]rune, width)
+	leftPad := (width - len(runes)) / 2
+	for i := range result {
+		result[i] = ' '
+	}
+	copy(result[leftPad:], runes)
+	return string(result)
+}
+
+// --- Text wrapping ---
+
+// WrapText wraps text at word boundaries to fit width
+// Returns slice of lines, each no longer than width
+func WrapText(s string, width int) []string {
+	if width <= 0 {
+		return nil
+	}
+
+	runes := []rune(s)
+	if len(runes) == 0 {
+		return []string{""}
+	}
+
+	var lines []string
+	lineStart := 0
+	lastSpace := -1
+
+	for i := 0; i <= len(runes); i++ {
+		// Check if we need to wrap
+		if i-lineStart >= width || i == len(runes) {
+			if i == len(runes) {
+				// End of string
+				if lineStart < len(runes) {
+					lines = append(lines, string(runes[lineStart:]))
+				}
+				break
+			}
+
+			// Need to wrap
+			wrapAt := i
+			if lastSpace > lineStart {
+				// Wrap at last space
+				wrapAt = lastSpace
+			}
+
+			lines = append(lines, string(runes[lineStart:wrapAt]))
+
+			// Skip space at wrap point
+			if wrapAt < len(runes) && runes[wrapAt] == ' ' {
+				lineStart = wrapAt + 1
+			} else {
+				lineStart = wrapAt
+			}
+			lastSpace = -1
+		}
+
+		// Track spaces for word wrapping
+		if i < len(runes) && runes[i] == ' ' {
+			lastSpace = i
+		}
+	}
+
+	if len(lines) == 0 {
+		lines = []string{""}
+	}
+
+	return lines
+}
+
+// --- Repetition ---
+
+// RepeatRune returns a string of n repeated runes, for string repeat use strings.Repeat
+func RepeatRune(r rune, n int) string {
+	if n <= 0 {
+		return ""
+	}
+	runes := make([]rune, n)
+	for i := range runes {
+		runes[i] = r
+	}
+	return string(runes)
+}
+