Add composable object selections

src/session.zig

@@ -370,6 +370,44 @@ pub const Session = struct {
             .active_panel_title = panel_state.active_title,
         };
     }
+
+    pub fn moveToByte(self: *Session, byte: usize) !void {
+        if (self.buffer) |*buffer| {
+            if (byte > buffer.bytes.items.len) return error.SelectionOutOfBounds;
+            buffer.cursor.byte = byte;
+            buffer.refreshCell();
+            return;
+        }
+        return error.NoActiveBuffer;
+    }
+
+    pub fn selectRange(self: *Session, start: usize, end: usize) !void {
+        if (self.buffer) |*buffer| {
+            if (start > end or end > buffer.bytes.items.len) return error.SelectionOutOfBounds;
+            buffer.selection = .{ .anchor = start, .cursor = end };
+            buffer.cursor.byte = end;
+            buffer.refreshCell();
+            return;
+        }
+        return error.NoActiveBuffer;
+    }
+
+    pub fn clearSelection(self: *Session) void {
+        if (self.buffer) |*buffer| buffer.selection = null;
+    }
+
+    pub fn replaceRange(self: *Session, start: usize, end: usize, bytes: []const u8) !void {
+        if (!std.unicode.utf8ValidateSlice(bytes)) return error.InvalidUtf8Insertion;
+        if (self.buffer) |*buffer| {
+            if (start > end or end > buffer.bytes.items.len) return error.SelectionOutOfBounds;
+            try buffer.bytes.replaceRange(buffer.allocator, start, end - start, bytes);
+            buffer.cursor.byte = start + bytes.len;
+            buffer.refreshCell();
+            buffer.selection = null;
+            return;
+        }
+        return error.NoActiveBuffer;
+    }
 };
 
 fn isWordSeparator(byte: u8) bool {