ObjectBufferBuilder

1 files changed, 40 insertions, 1 deletions

diff --git a/common/object/src/buffer.rs b/common/object/src/buffer.rs
index 829cade..703e203 100644
--- a/common/object/src/buffer.rs
+++ b/common/object/src/buffer.rs
@@ -4,7 +4,7 @@
     Copyright (C) 2026 metamuffin <metamuffin.org>
 */
 
-use crate::{Object, Tag, ValueStore};
+use crate::{Object, Tag, TypedTag, ValueStore};
 use bytemuck::{try_cast_slice, try_cast_vec};
 use log::trace;
 use std::borrow::Cow;
@@ -54,6 +54,45 @@ impl ObjectBuffer {
     }
 }
 
+#[derive(Default)]
+pub struct ObjectBufferBuilder(Vec<(Tag, u32, Vec<u32>)>);
+impl ObjectBufferBuilder {
+    pub fn push<T: ValueStore>(&mut self, tag: TypedTag<T>, value: T) {
+        let ty = value.get_type();
+        let tyb = (ty as u32) << 2;
+        if ty.is_aligned() {
+            let mut buf = Vec::new();
+            value.store_aligned(&mut buf);
+            self.0.push((tag.0, tyb, buf));
+        } else {
+            let mut buf = Vec::new();
+            value.store_unaligned(&mut buf);
+            let pad = pad_vec(&mut buf);
+            self.0.push((tag.0, tyb | pad, vec_u8_to_u32(buf)));
+        }
+    }
+    pub fn finish(mut self) -> ObjectBuffer {
+        let mut tags = Vec::new();
+        let mut offsets = Vec::new();
+        let mut values = Vec::new();
+        self.0.sort_by_key(|(t, _, _)| t.0);
+        for (tag, mut off, buf) in self.0 {
+            tags.push(tag.0);
+            off |= (values.len() as u32) << 5;
+            offsets.push(off);
+            values.extend(buf);
+        }
+        ObjectBuffer(
+            [tags.len() as u32]
+                .into_iter()
+                .chain(tags)
+                .chain(offsets)
+                .chain(values)
+                .collect(),
+        )
+    }
+}
+
 impl From<Vec<u8>> for ObjectBuffer {
     fn from(value: Vec<u8>) -> Self {
         ObjectBuffer(vec_u8_to_u32(value))