Cthulhu is no longer a fork. Now it is a screen reader written in Golang.

internal/review/document_caret_line.go

@@ -0,0 +1,168 @@
+// Cthulhu screen reader.
+// Copyright (c) 2026 Storm Dragon
+// Authors: Storm Dragon, Angus Kola
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package review
+
+import (
+	"context"
+	"errors"
+	"strings"
+
+	"git.stormux.org/storm/cthulhu/internal/atspi"
+)
+
+// move_caret_line handles line and document boundaries under the cursor lock
+// held by MoveCaret. Text-unit movement has its separate traversal helper.
+func move_caret_object_line(ctx context.Context, reader DocumentCaretReader, doc atspi.DocumentSnapshot, place *documentPlace, indices []int, current int, command DocumentCaretCommand) (DocumentCaretMove, error) {
+	unit := atspi.DocumentCaretLine
+	if command == CaretReadLine {
+		unit = atspi.DocumentCaretLineRemainder
+	}
+	position := 0
+	for position < len(indices) && indices[position] < current {
+		position++
+	}
+	backwards := command == CaretPreviousLine || command == CaretDocumentEnd
+	if command == CaretDocumentStart {
+		position = 0
+	} else if command == CaretDocumentEnd {
+		position = len(indices) - 1
+	}
+	offset := place.offset
+	if position == len(indices) || indices[position] != current || command == CaretDocumentStart {
+		offset = 0
+	}
+	if command == CaretDocumentEnd {
+		offset = doc.Nodes[indices[position]].Snapshot.CharacterCount - 1
+	}
+	if backwards && command != CaretDocumentEnd && (position == len(indices) || indices[position] != current) {
+		position--
+		if position < 0 {
+			return DocumentCaretMove{Position: documentPosition(doc, *place)}, nil
+		}
+		offset = doc.Nodes[indices[position]].Snapshot.CharacterCount - 1
+	}
+	initialPosition := position
+	for attempts := 0; attempts < len(indices)+1; attempts++ {
+		if position < 0 || position >= len(indices) {
+			return DocumentCaretMove{Position: documentPosition(doc, *place)}, nil
+		}
+		node := doc.Nodes[indices[position]]
+		if node.Snapshot.CharacterCount == 0 || wholeCaretNode(node.Snapshot) {
+			if (command == CaretNextLine || command == CaretPreviousLine) && node.Reference == place.object {
+				if backwards {
+					position--
+					if position >= 0 {
+						offset = doc.Nodes[indices[position]].Snapshot.CharacterCount - 1
+					}
+				} else {
+					position++
+					offset = 0
+				}
+				continue
+			}
+			place.object, place.offset, place.origin = node.Reference, 0, CaretNavigation
+			return DocumentCaretMove{Position: documentPosition(doc, *place), Moved: true}, nil
+		}
+		if offset < 0 {
+			offset = 0
+		}
+		if command == CaretReadLine && offset >= node.Snapshot.CharacterCount {
+			position++
+			offset = 0
+			continue
+		}
+		if offset >= node.Snapshot.CharacterCount {
+			offset = node.Snapshot.CharacterCount - 1
+		}
+		piece, readErr := reader.ReadDocumentCaret(ctx, node.Reference, offset, unit)
+		if readErr != nil && !errors.Is(readErr, atspi.ErrNoDocumentCaret) {
+			return DocumentCaretMove{}, readErr
+		}
+		if readErr == nil && piece.End > piece.Start && strings.TrimSpace(piece.Text) != "\ufffc" {
+			nextOffset := offset
+			sameCurrent := node.Reference == place.object ||
+				place.origin == StructuralNavigation && position == initialPosition && indices[position] >= current
+			switch command {
+			case CaretNextLine:
+				if sameCurrent {
+					nextOffset = piece.End
+					if nextOffset < piece.CharacterCount {
+						piece, readErr = reader.ReadDocumentCaret(ctx, node.Reference, nextOffset, unit)
+						if readErr != nil {
+							return DocumentCaretMove{}, readErr
+						}
+					} else {
+						position++
+						if position >= len(indices) {
+							return DocumentCaretMove{Position: documentPosition(doc, *place)}, nil
+						}
+						offset = 0
+						continue
+					}
+				}
+				nextOffset = piece.Start
+			case CaretPreviousLine:
+				if sameCurrent {
+					if piece.Start > 0 {
+						piece, readErr = reader.ReadDocumentCaret(ctx, node.Reference, piece.Start-1, unit)
+						if readErr != nil {
+							return DocumentCaretMove{}, readErr
+						}
+					} else {
+						position--
+						if position < 0 {
+							return DocumentCaretMove{Position: documentPosition(doc, *place)}, nil
+						}
+						offset = doc.Nodes[indices[position]].Snapshot.CharacterCount - 1
+						continue
+					}
+				}
+				nextOffset = piece.Start
+			case CaretLineStart:
+				nextOffset = piece.Start
+			case CaretLineEnd, CaretDocumentEnd:
+				nextOffset = max(piece.Start, piece.End-1)
+			case CaretDocumentStart:
+				nextOffset = piece.Start
+			}
+			if piece.End <= piece.Start || strings.TrimSpace(piece.Text) == "\ufffc" {
+				// An embedded-object placeholder is a container, not spoken text.
+				if backwards {
+					position--
+					if position >= 0 {
+						offset = doc.Nodes[indices[position]].Snapshot.CharacterCount - 1
+					}
+				} else {
+					position++
+					offset = 0
+				}
+				continue
+			}
+			spoken := piece.Text
+			if command == CaretLineStart || command == CaretLineEnd {
+				character, charErr := reader.ReadDocumentCaret(ctx, node.Reference, nextOffset, atspi.DocumentCaretCharacter)
+				if charErr != nil {
+					return DocumentCaretMove{}, charErr
+				}
+				spoken = character.Text
+			}
+			place.object = node.Reference
+			place.offset = nextOffset
+			place.origin = CaretNavigation
+			return DocumentCaretMove{Position: documentPosition(doc, *place), Text: spoken, RawText: piece.RawText, Misspelled: piece.Misspelled, Moved: true, Start: piece.Start, End: piece.End}, nil
+		}
+		if backwards {
+			position--
+			if position >= 0 {
+				offset = doc.Nodes[indices[position]].Snapshot.CharacterCount - 1
+			}
+		} else {
+			position++
+			offset = 0
+		}
+	}
+	return DocumentCaretMove{Position: documentPosition(doc, *place)}, nil
+}