fix: wide characters

ranges.go

@@ -8,6 +8,7 @@ import (
 
 // StyleRanges allows to, given a string, style ranges of it differently.
 // The function will take into account existing styles.
+// Ranges should not overlap.
 func StyleRanges(s string, ranges []Range) string {
 	if len(ranges) == 0 {
 		return s
@@ -24,18 +25,13 @@ func StyleRanges(s string, ranges []Range) string {
 		if rng.Start > lastIdx {
 			buf.WriteString(ansi.Cut(s, lastIdx, rng.Start))
 		}
-		if l := len(stripped); rng.End >= l {
-			rng.End = l - 1
-		}
 		// Add the matched range with its highlight
-		buf.WriteString(rng.Style.Render(stripped[rng.Start : rng.End+1]))
-		lastIdx = rng.End + 1
+		buf.WriteString(rng.Style.Render(ansi.Cut(stripped, rng.Start, rng.End)))
+		lastIdx = rng.End
 	}
 
 	// Add any remaining text after the last match
-	if lastIdx < ansi.StringWidth(s) {
-		buf.WriteString(ansi.TruncateLeft(s, lastIdx, ""))
-	}
+	buf.WriteString(ansi.TruncateLeft(s, lastIdx, ""))
 
 	return buf.String()
 }

ranges_test.go

@@ -23,48 +23,48 @@ func TestStyleRanges(t *testing.T) {
 			name:  "single range in middle",
 			input: "hello world",
 			ranges: []Range{
-				NewRange(6, 10, NewStyle().Bold(true)),
+				NewRange(6, 11, NewStyle().Bold(true)),
 			},
 			expected: "hello \x1b[1mworld\x1b[0m",
 		},
 		{
 			name:  "multiple ranges",
 			input: "hello world",
 			ranges: []Range{
-				NewRange(0, 4, NewStyle().Bold(true)),
-				NewRange(6, 10, NewStyle().Italic(true)),
+				NewRange(0, 5, NewStyle().Bold(true)),
+				NewRange(6, 11, NewStyle().Italic(true)),
 			},
 			expected: "\x1b[1mhello\x1b[0m \x1b[3mworld\x1b[0m",
 		},
 		{
 			name:  "overlapping with existing ANSI",
 			input: "hello \x1b[32mworld\x1b[0m",
 			ranges: []Range{
-				NewRange(0, 4, NewStyle().Bold(true)),
+				NewRange(0, 5, NewStyle().Bold(true)),
 			},
 			expected: "\x1b[1mhello\x1b[0m \x1b[32mworld\x1b[0m",
 		},
 		{
 			name:  "style at start",
 			input: "hello world",
 			ranges: []Range{
-				NewRange(0, 4, NewStyle().Bold(true)),
+				NewRange(0, 5, NewStyle().Bold(true)),
 			},
 			expected: "\x1b[1mhello\x1b[0m world",
 		},
 		{
 			name:  "style at end",
 			input: "hello world",
 			ranges: []Range{
-				NewRange(6, 10, NewStyle().Bold(true)),
+				NewRange(6, 11, NewStyle().Bold(true)),
 			},
 			expected: "hello \x1b[1mworld\x1b[0m",
 		},
 		{
 			name:  "multiple styles with gap",
 			input: "hello beautiful world",
 			ranges: []Range{
-				NewRange(0, 4, NewStyle().Bold(true)),
+				NewRange(0, 5, NewStyle().Bold(true)),
 				NewRange(16, 23, NewStyle().Italic(true)),
 			},
 			expected: "\x1b[1mhello\x1b[0m beautiful \x1b[3mworld\x1b[0m",
@@ -73,19 +73,29 @@ func TestStyleRanges(t *testing.T) {
 			name:  "adjacent ranges",
 			input: "hello world",
 			ranges: []Range{
-				NewRange(0, 4, NewStyle().Bold(true)),
-				NewRange(6, 10, NewStyle().Italic(true)),
+				NewRange(0, 5, NewStyle().Bold(true)),
+				NewRange(6, 11, NewStyle().Italic(true)),
 			},
 			expected: "\x1b[1mhello\x1b[0m \x1b[3mworld\x1b[0m",
 		},
+		{
+			name:  "wide-width characters",
+			input: "Hello 你好 世界",
+			ranges: []Range{
+				NewRange(0, 5, NewStyle().Bold(true)),    // "Hello"
+				NewRange(7, 10, NewStyle().Italic(true)), // "你好"
+				NewRange(11, 50, NewStyle().Bold(true)),  // "世界"
+			},
+			expected: "\x1b[1mHello\x1b[0m \x1b[3m你好\x1b[0m \x1b[1m世界\x1b[0m",
+		},
 	}
 
 	for _, tt := range tests {
 		renderer.SetColorProfile(termenv.ANSI)
 		t.Run(tt.name, func(t *testing.T) {
 			result := StyleRanges(tt.input, tt.ranges)
 			if result != tt.expected {
-				t.Errorf("StyleRanges() = %q, want %q", result, tt.expected)
+				t.Errorf("StyleRanges()\n got = %q\nwant = %q\n", result, tt.expected)
 			}
 		})
 	}