optimized line_crop

tests/test_segment_tools.py

@@ -0,0 +1,55 @@
+from rich.segment import Segment
+from rich.style import Style
+
+
+from textual._segment_tools import line_crop
+
+
+def test_line_crop():
+    bold = Style(bold=True)
+    italic = Style(italic=True)
+    segments = [
+        Segment("Hello", bold),
+        Segment(" World!", italic),
+    ]
+
+    assert line_crop(segments, 1, 2) == [Segment("e", bold)]
+    assert line_crop(segments, 4, 20) == [
+        Segment("o", bold),
+        Segment(" World!", italic),
+    ]
+
+
+def test_line_crop_emoji():
+    bold = Style(bold=True)
+    italic = Style(italic=True)
+    segments = [
+        Segment("Hello", bold),
+        Segment("💩💩💩", italic),
+    ]
+    assert line_crop(segments, 8, 11) == [Segment(" 💩", italic)]
+    assert line_crop(segments, 9, 11) == [Segment("💩", italic)]
+
+
+def test_line_crop_edge():
+    segments = [Segment("foo"), Segment("bar"), Segment("baz")]
+    assert line_crop(segments, 2, 9) == [Segment("o"), Segment("bar"), Segment("baz")]
+    assert line_crop(segments, 3, 9) == [Segment("bar"), Segment("baz")]
+    assert line_crop(segments, 4, 9) == [Segment("ar"), Segment("baz")]
+    assert line_crop(segments, 4, 8) == [Segment("ar"), Segment("ba")]
+
+
+def test_line_crop_edge_2():
+    segments = [
+        Segment("╭─"),
+        Segment(
+            "────── Placeholder ───────",
+        ),
+        Segment(
+            "─╮",
+        ),
+    ]
+    result = line_crop(segments, 30, 60)
+    expected = []
+    print(repr(result))
+    assert result == expected