feat: add BocHeader::encode_to_writer

src/boc/ser.rs

@@ -117,6 +117,49 @@ where
         );
     }
 
+    /// Writes cell trees into the writer.
+    ///
+    /// NOTE: Use [`BocHeader::encode`] when possible since it's faster.
+    pub fn encode_to_writer<W: std::io::Write>(&self, mut writer: W) -> std::io::Result<()> {
+        const CELLS_CHUNK_SIZE: usize = 1000;
+        const P95_CELL_SIZE: usize = 128;
+
+        let mut crc = self.include_crc.then_some(0u32);
+        let mut total_size = 0;
+
+        let mut reset_chunk = |chunk: &mut Vec<u8>| {
+            if let Some(crc) = &mut crc {
+                *crc = crc32c::crc32c_append(*crc, chunk);
+            }
+            total_size += chunk.len() as u64;
+            chunk.clear();
+        };
+
+        let mut chunk = Vec::new();
+
+        // Write header
+        let header = self.encode_header(&mut chunk);
+        ok!(writer.write_all(&chunk));
+        reset_chunk(&mut chunk);
+
+        // Write cells
+        for cells in self.rev_cells.rchunks(CELLS_CHUNK_SIZE) {
+            chunk.reserve(cells.len() * P95_CELL_SIZE);
+            self.encode_cells_chunk(cells, header.ref_size, &mut chunk);
+            ok!(writer.write_all(&chunk));
+            reset_chunk(&mut chunk);
+        }
+
+        debug_assert!(chunk.is_empty());
+
+        if let Some(crc) = crc {
+            ok!(writer.write_all(&crc.to_le_bytes()));
+        }
+
+        debug_assert_eq!(total_size, header.total_size);
+        Ok(())
+    }
+
     /// Encodes cell trees into bytes.
     /// Uses `rayon` under the hood.
     #[cfg(feature = "rayon")]