Multi fields; object buffer constructor; unit tests

1 files changed, 50 insertions, 0 deletions

diff --git a/common/object/src/buffer.rs b/common/object/src/buffer.rs
new file mode 100644
index 0000000..56b8caf
--- /dev/null
+++ b/common/object/src/buffer.rs
@@ -0,0 +1,50 @@
+/*
+    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
+    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
+    Copyright (C) 2026 metamuffin <metamuffin.org>
+*/
+
+use crate::{Object, Tag, ValueStore};
+
+pub struct ObjectBuffer(pub Vec<u32>);
+
+impl ObjectBuffer {
+    pub fn empty() -> Self {
+        Self(vec![0])
+    }
+    pub fn as_object<'a>(&'a self) -> Object<'a> {
+        Object::load(&self.0).unwrap()
+    }
+    pub fn new(fields: &mut [(Tag, &dyn ValueStore)]) -> ObjectBuffer {
+        let mut tags = Vec::new();
+        let mut offsets = Vec::new();
+        let mut values = Vec::new();
+        fields.sort_by_key(|(t, _)| t.0);
+        let mut temp = Vec::new();
+        for (tag, val) in fields {
+            tags.push(tag.0);
+            if val.is_aligned() {
+                offsets.push((values.len() as u32) << 2);
+                val.store_aligned(&mut values);
+            } else {
+                temp.clear();
+                val.store_unaligned(&mut temp);
+                let mut pad = 0;
+                while temp.len() % 4 != 0 {
+                    pad += 1;
+                    temp.push(0);
+                }
+                offsets.push(((values.len() as u32) << 2) | pad);
+                values.extend(bytemuck::cast_slice(&temp)); // ok bc. temp length is a whole number of dwords
+            }
+        }
+        ObjectBuffer(
+            [tags.len() as u32]
+                .into_iter()
+                .chain(tags)
+                .chain(offsets)
+                .chain(values)
+                .collect(),
+        )
+    }
+}