Merge 'Implement RowData opcode' from meteorgan

The `RowData` opcode is required to implement #1575.
I haven't found a ideal way to test this PR independently, but I
verified its functionality while working on #1575(to be committed soon),
and it performs effectively.

Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>

Closes #1756

core/vdbe/execute.rs

@@ -1917,6 +1917,36 @@ pub fn op_blob(
     Ok(InsnFunctionStepResult::Step)
 }
 
+pub fn op_row_data(
+    program: &Program,
+    state: &mut ProgramState,
+    insn: &Insn,
+    pager: &Rc<Pager>,
+    mv_store: Option<&Rc<MvStore>>,
+) -> Result<InsnFunctionStepResult> {
+    let Insn::RowData { cursor_id, dest } = insn else {
+        unreachable!("unexpected Insn {:?}", insn)
+    };
+
+    let record = {
+        let mut cursor_ref =
+            must_be_btree_cursor!(*cursor_id, program.cursor_ref, state, "RowData");
+        let cursor = cursor_ref.as_btree_mut();
+        let record_option = return_if_io!(cursor.record());
+
+        let ret = record_option
+            .ok_or_else(|| LimboError::InternalError("RowData: cursor has no record".to_string()))?
+            .clone();
+        ret
+    };
+
+    let reg = &mut state.registers[*dest];
+    *reg = Register::Record(record);
+
+    state.pc += 1;
+    Ok(InsnFunctionStepResult::Step)
+}
+
 pub fn op_row_id(
     program: &Program,
     state: &mut ProgramState,

core/vdbe/explain.rs

@@ -1603,6 +1603,15 @@ pub fn insn_to_str(
                 0,
                 format!("roots={:?} message_register={}", roots, message_register),
             ),
+            Insn::RowData { cursor_id, dest } => (
+                "RowData",
+                *cursor_id as i32,
+                *dest as i32,
+                0,
+                Value::build_text(""),
+                0,
+                format!("r[{}] = data", *dest),
+            ),
         };
     format!(
         "{:<4}  {:<17}  {:<4}  {:<4}  {:<4}  {:<13}  {:<2}  {}",

core/vdbe/insn.rs

@@ -510,6 +510,12 @@ pub enum Insn {
         dest: usize,
     },
 
+    /// Read a complete row of data from the current cursor and write it to the destination register.
+    RowData {
+        cursor_id: CursorID,
+        dest: usize,
+    },
+
     /// Read the rowid of the current row.
     RowId {
         cursor_id: CursorID,
@@ -1034,6 +1040,7 @@ impl Insn {
             Insn::RealAffinity { .. } => execute::op_real_affinity,
             Insn::String8 { .. } => execute::op_string8,
             Insn::Blob { .. } => execute::op_blob,
+            Insn::RowData { .. } => execute::op_row_data,
             Insn::RowId { .. } => execute::op_row_id,
             Insn::IdxRowId { .. } => execute::op_idx_row_id,
             Insn::SeekRowid { .. } => execute::op_seek_rowid,

core/vdbe/mod.rs

@@ -317,7 +317,7 @@ impl ProgramState {
         self.json_cache.clear()
     }
 
-    pub fn get_cursor<'a>(&'a self, cursor_id: CursorID) -> std::cell::RefMut<'a, Cursor> {
+    pub fn get_cursor(&self, cursor_id: CursorID) -> std::cell::RefMut<Cursor> {
         let cursors = self.cursors.borrow_mut();
         std::cell::RefMut::map(cursors, |c| {
             c.get_mut(cursor_id)