use while let

src/db/ddl.rs

@@ -284,8 +284,7 @@ impl<'s> Session<'s> {
 
         let it = self.txn.iterator(true, &self.perm_cf);
         it.seek(&prefix);
-        while it.is_valid() {
+        while let Some(val) = it.key() {
-            let val  = it.key().ok_or_else(|| CozoError::LogicError("Failed to get tuple".to_string()))?;
             let cur = Tuple::new(val);
             if !cur.starts_with(&prefix) {
                 break;
@@ -301,8 +300,7 @@ impl<'s> Session<'s> {
 
         let it = self.txn.iterator(false, &self.temp_cf);
         it.seek(&prefix);
-        while it.is_valid() {
+        while let Some(val) = it.key() {
-            let val  = it.key().ok_or_else(|| CozoError::LogicError("Failed to get tuple".to_string()))?;
             let cur = Tuple::new(val);
             if !cur.starts_with(&prefix) {
                 break;

src/db/engine.rs

@@ -241,8 +241,7 @@ mod tests {
             }
             let it = sess.txn.iterator(true, &sess.perm_cf);
             it.to_first();
-            while it.is_valid() {
+            while let Some((key, val)) = it.pair() {
-                let (key, val) = it.pair().unwrap();
                 println!("a: {:?} {:?}", key.as_ref(), val.as_ref());
                 println!("v: {:?} {:?}", Tuple::new(key), Tuple::new(val));
                 it.next();

src/db/env.rs

@@ -101,8 +101,7 @@ impl<'s> Session<'s> {
         let it = self.txn.iterator(false, &self.temp_cf);
         it.seek(&prefix);
         let mut to_delete = vec![];
-        while it.is_valid() {
+        while let Some(val) = it.key() {
-            let val = it.key().ok_or_else(|| CozoError::LogicError("Failed to get tuple".to_string()))?;
             let cur = Tuple::new(val);
             if cur.starts_with(&prefix) {
                 if let Some(name) = cur.get(1) {
@@ -144,8 +143,7 @@ impl<'s> Session<'s> {
         prefix.push_int(self.stack_depth as i64);
         let it = self.txn.iterator(false, &self.temp_cf);
         it.seek(&prefix);
-        while it.is_valid() {
+        while let Some(val) = it.key() {
-            let val = it.key().ok_or_else(|| CozoError::LogicError("Failed to get tuple".to_string()))?;
             let cur = Tuple::new(val);
             if cur.starts_with(&prefix) {
                 let mut ikey = Tuple::with_prefix(cur.get_prefix());

src/db/eval.rs

@@ -156,7 +156,7 @@ impl<'s> Session<'s> {
             Value::Uuid(_) |
             Value::Text(_) |
             Value::EndSentinel) => Ok((true, v)),
-            v@Value::TupleRef(_, _) => Ok((false, v)),
+            v @ Value::TupleRef(_, _) => Ok((false, v)),
             Value::List(l) => {
                 let init_vec = Vec::with_capacity(l.len());
                 let res: Result<(bool, Vec<Value>)> = l.into_iter()
@@ -1210,16 +1210,14 @@ mod tests {
 
             let it = env.txn.iterator(false, &env.perm_cf);
             it.to_first();
-            while it.is_valid() {
+            while let Some((k, v)) = it.pair() {
-                let (k, v) = it.pair().unwrap();
                 println!("{:?}, {:?}", Tuple::new(k), Tuple::new(v));
                 it.next();
             }
 
             let it = env.txn.iterator(false, &env.temp_cf);
             it.to_first();
-            while it.is_valid() {
+            while let Some((k, v)) = it.pair() {
-                let (k, v) = it.pair().unwrap();
                 println!("{:?}, {:?}", Tuple::new(k), Tuple::new(v));
                 it.next();
             }

src/db/mutation.rs

@@ -289,8 +289,7 @@ mod tests {
             sess.rollback().unwrap();
             let it = sess.txn.iterator(true, &sess.perm_cf);
             it.to_first();
-            while it.is_valid() {
+            while let Some((k, v)) = it.pair() {
-                let (k, v) = it.pair().unwrap();
                 println!("K: {:?}, V: {:?}", Tuple::new(k), Tuple::new(v));
                 it.next();
             }
@@ -340,8 +339,7 @@ mod tests {
 
             let it = sess.txn.iterator(true, &sess.perm_cf);
             it.to_first();
-            while it.is_valid() {
+            while let Some((k, v)) = it.pair() {
-                let (k, v) = it.pair().unwrap();
                 println!("K: {:?}, V: {:?}", Tuple::new(k), Tuple::new(v));
                 it.next();
             }

src/db/plan.rs

@@ -1,12 +1,13 @@
 use std::collections::BTreeMap;
 use pest::iterators::Pair;
+use cozorocks::{IteratorPtr, SlicePtr};
 use crate::db::engine::Session;
 use crate::db::query::{FromEl, Selection};
 use crate::db::table::{ColId, TableId, TableInfo};
 use crate::relation::value::{StaticValue, Value};
 use crate::parser::Rule;
 use crate::error::Result;
-use crate::relation::tuple::OwnTuple;
+use crate::relation::tuple::{OwnTuple, Tuple};
 
 #[derive(Clone, Eq, PartialEq, Debug)]
 pub enum QueryPlan {
@@ -132,7 +133,7 @@ impl<'a> Session<'a> {
         Ok(QueryPlan::Projection { arg: Box::new(plan), projection: select_data })
     }
 
-    pub fn iter_table(&self, tid: TableId) -> ! {
+    pub fn iter_table(&self, tid: TableId) -> TableRowIterator {
         let it = if tid.in_root {
             self.txn.iterator(true, &self.perm_cf)
         } else {
@@ -140,19 +141,34 @@ impl<'a> Session<'a> {
         };
         let prefix = OwnTuple::with_prefix(tid.id as u32);
         it.seek(prefix);
-        // it.iter()
+        TableRowIterator {
-        todo!()
+            it,
+            started: false,
+        }
     }
 }
 
-pub struct NodeRowIterator {
+pub struct TableRowIterator<'a> {
-
+    it: IteratorPtr<'a>,
+    started: bool,
 }
 
-pub struct EdgeRowIterator {
+impl<'a> Iterator for TableRowIterator<'a> {
+    type Item = (Tuple<SlicePtr>, Tuple<SlicePtr>);
 
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.started {
+            self.next();
+        }
+        self.it.pair().map(|(k, v)| (Tuple::new(k), Tuple::new(v)))
+    }
 }
 
+
+pub struct NodeRowIterator {}
+
+pub struct EdgeRowIterator {}
+
 #[cfg(test)]
 mod tests {
     use std::collections::BTreeMap;