Trim leading whitespace from wrapped lines

m/linewrapper.go

@@ -7,15 +7,28 @@ func wrapLine(width int, line []twin.Cell) [][]twin.Cell {
 		return [][]twin.Cell{{}}
 	}
 
-	// Unclear how to represent trailing whitespace while wrapping
+	// Trailing space risks showing up by itself on a line, which would just
+	// look weird.
 	line = twin.TrimSpaceRight(line)
 
 	wrapped := make([][]twin.Cell, 0, len(line)/width)
 	for len(line) > width {
 		firstPart := line[:width]
+		if len(wrapped) > 0 {
+			// Leading whitespace on wrapped lines would just look like
+			// indentation, which would be weird for wrapped text.
+			firstPart = twin.TrimSpaceLeft(firstPart)
+		}
+
 		wrapped = append(wrapped, firstPart)
 
-		line = line[width:]
+		line = twin.TrimSpaceLeft(line[width:])
+	}
+
+	if len(wrapped) > 0 {
+		// Leading whitespace on wrapped lines would just look like
+		// indentation, which would be weird for wrapped text.
+		line = twin.TrimSpaceLeft(line)
 	}
 
 	if len(line) > 0 {

m/linewrapper_test.go

@@ -57,14 +57,32 @@ func TestWordLongerThanLine(t *testing.T) {
 	})
 }
 
+func TestLeadingSpaceNoWrap(t *testing.T) {
+	toWrap := tokenize(" abc")
+	wrapped := wrapLine(20, toWrap)
+	assertEqual(t, wrapped, [][]twin.Cell{
+		tokenize(" abc"),
+	})
+}
+
+func TestLeadingSpaceWithWrap(t *testing.T) {
+	toWrap := tokenize(" abc")
+	wrapped := wrapLine(2, toWrap)
+	assertEqual(t, wrapped, [][]twin.Cell{
+		tokenize(" a"),
+		tokenize("bc"),
+	})
+}
+
+func TestLeadingWrappedSpace(t *testing.T) {
+	toWrap := tokenize("ab cd")
+	wrapped := wrapLine(2, toWrap)
+	assertEqual(t, wrapped, [][]twin.Cell{
+		tokenize("ab"),
+		tokenize("cd"),
+	})
+}
+
 // FIXME: Test word wrapping
 
-// FIXME: Test wrapping with multiple consecutive spaces
-
 // FIXME: Test wrapping on single dashes
-
-// FIXME: Test wrapping with double dashes (not sure what we should do with those)
-
-// FIXME: Test wrapping formatted strings, is there formatting that should affect the wrapping
-
-// FIXME: Test wrapping with trailing whitespace

twin/cell.go

@@ -36,3 +36,18 @@ func TrimSpaceRight(cells []Cell) []Cell {
 	// All whitespace, return empty
 	return []Cell{}
 }
+
+// Returns a slice of cells with leading whitespace cells removed
+func TrimSpaceLeft(cells []Cell) []Cell {
+	for i := 0; i < len(cells); i++ {
+		cell := cells[i]
+		if !unicode.IsSpace(cell.Rune) {
+			return cells[i:]
+		}
+
+		// That was a space, keep looking
+	}
+
+	// All whitespace, return empty
+	return []Cell{}
+}