Add document and half-page motions

src/session.zig

@@ -42,6 +42,8 @@ pub const Command = union(enum) {
     replace_char: []const u8,
     move_line_start,
     move_line_end,
+    move_document_start,
+    move_document_end,
 };
 
 pub const Snapshot = struct {
@@ -104,6 +106,8 @@ pub const Buffer = struct {
             .replace_char => |text| try self.replaceChar(text),
             .move_line_start => self.moveLineStart(),
             .move_line_end => self.moveLineEnd(),
+            .move_document_start => self.moveDocumentStart(),
+            .move_document_end => self.moveDocumentEnd(),
         }
     }
 
@@ -263,6 +267,24 @@ pub const Buffer = struct {
         self.refreshCellResetPreferred();
     }
 
+    pub fn moveDocumentStart(self: *Buffer) void {
+        self.cursor.byte = 0;
+        self.refreshCellResetPreferred();
+    }
+
+    pub fn moveDocumentEnd(self: *Buffer) void {
+        if (self.bytes.items.len == 0) {
+            self.cursor.byte = 0;
+            self.refreshCellResetPreferred();
+            return;
+        }
+        var at = self.bytes.items.len;
+        if (at > 0 and self.bytes.items[at - 1] == '\n') at -= 1;
+        while (at > 0 and self.bytes.items[at - 1] != '\n') at -= 1;
+        self.cursor.byte = at;
+        self.refreshCellResetPreferred();
+    }
+
     const LineRange = struct { start: usize, end: usize };
 
     fn currentLineRange(self: *const Buffer, include_newline: bool) LineRange {
@@ -757,3 +779,19 @@ test "regular: line object selection includes the newline byte" {
     const snap = try session.snapshot();
     try std.testing.expectEqualStrings("abc\n", snap.bytes[snap.selection.?.anchor..snap.selection.?.cursor]);
 }
+
+test "regular: document motions jump to top and bottom line" {
+    var session = Session.init(std.testing.allocator);
+    defer session.deinit();
+
+    try session.openFixtureAt("one\ntwo\nthree\n", 4);
+    try session.dispatch(.move_document_end);
+    var snap = try session.snapshot();
+    try std.testing.expectEqual(@as(usize, 8), snap.cursor_byte);
+    try std.testing.expectEqual(@as(usize, 0), snap.cursor_cell);
+
+    try session.dispatch(.move_document_start);
+    snap = try session.snapshot();
+    try std.testing.expectEqual(@as(usize, 0), snap.cursor_byte);
+    try std.testing.expectEqual(@as(usize, 0), snap.cursor_cell);
+}