From d03a0dbd39dd5a5bfc2f46b461dc5034dae39180 Mon Sep 17 00:00:00 2001
From: ben594 <benli20042013@gmail.com>
Date: Thu, 23 Jan 2025 10:16:35 -0500
Subject: [PATCH] Added parsing of offset clause

---
 core/translate/delete.rs  |  5 +++--
 core/translate/plan.rs    |  4 ++++
 core/translate/planner.rs | 23 +++++++++++++++++------
 core/translate/select.rs  |  6 ++++--
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/core/translate/delete.rs b/core/translate/delete.rs
index 373a74024..6bbe6270b 100644
--- a/core/translate/delete.rs
+++ b/core/translate/delete.rs
@@ -44,8 +44,8 @@ pub fn prepare_delete_plan(
     // Parse the WHERE clause
     let resolved_where_clauses = parse_where(where_clause, &referenced_tables)?;
 
-    // Parse the LIMIT clause
-    let resolved_limit = limit.and_then(|l| parse_limit(*l));
+    // Parse the LIMIT/OFFSET clause
+    let (resolved_limit, resolved_offset) = limit.map_or(Ok((None, None)), |l| parse_limit(*l))?;
 
     let plan = DeletePlan {
         source: SourceOperator::Scan {
@@ -58,6 +58,7 @@ pub fn prepare_delete_plan(
         where_clause: resolved_where_clauses,
         order_by: None,
         limit: resolved_limit,
+        offset: resolved_offset,
         referenced_tables,
         available_indexes: vec![],
         contains_constant_false_condition: false,
diff --git a/core/translate/plan.rs b/core/translate/plan.rs
index 6164428fb..87420b622 100644
--- a/core/translate/plan.rs
+++ b/core/translate/plan.rs
@@ -65,6 +65,8 @@ pub struct SelectPlan {
     pub aggregates: Vec<Aggregate>,
     /// limit clause
     pub limit: Option<usize>,
+    /// offset clause
+    pub offset: Option<usize>,
     /// all the tables referenced in the query
     pub referenced_tables: Vec<TableReference>,
     /// all the indexes available
@@ -88,6 +90,8 @@ pub struct DeletePlan {
     pub order_by: Option<Vec<(ast::Expr, Direction)>>,
     /// limit clause
     pub limit: Option<usize>,
+    /// offset clause
+    pub offset: Option<usize>,
     /// all the tables referenced in the query
     pub referenced_tables: Vec<TableReference>,
     /// all the indexes available
diff --git a/core/translate/planner.rs b/core/translate/planner.rs
index 86132fb60..5c5920896 100644
--- a/core/translate/planner.rs
+++ b/core/translate/planner.rs
@@ -566,19 +566,30 @@ fn parse_join(
     })
 }
 
-pub fn parse_limit(limit: Limit) -> Option<usize> {
+pub fn parse_limit(limit: Limit) -> Result<(Option<usize>, Option<usize>)> {
+    let offset = match limit.offset {
+        Some(offset_expr) => {
+            if let Expr::Literal(ast::Literal::Numeric(n)) = offset_expr {
+                n.parse().ok()
+            } else {
+                crate::bail_parse_error!("Invalid OFFSET clause");
+            }
+        }
+        None => Some(0),
+    };
+
     if let Expr::Literal(ast::Literal::Numeric(n)) = limit.expr {
-        n.parse().ok()
+        Ok((n.parse().ok(), offset))
     } else if let Expr::Id(id) = limit.expr {
         if id.0.eq_ignore_ascii_case("true") {
-            Some(1)
+            Ok((Some(1), offset))
         } else if id.0.eq_ignore_ascii_case("false") {
-            Some(0)
+            Ok((Some(0), offset))
         } else {
-            None
+            crate::bail_parse_error!("Invalid LIMIT clause");
         }
     } else {
-        None
+        crate::bail_parse_error!("Invalid LIMIT clause");
     }
 }
 
diff --git a/core/translate/select.rs b/core/translate/select.rs
index 196a1d284..46226abbd 100644
--- a/core/translate/select.rs
+++ b/core/translate/select.rs
@@ -57,6 +57,7 @@ pub fn prepare_select_plan(
                 order_by: None,
                 aggregates: vec![],
                 limit: None,
+                offset: None,
                 referenced_tables,
                 available_indexes: schema.indexes.clone().into_values().flatten().collect(),
                 contains_constant_false_condition: false,
@@ -326,8 +327,9 @@ pub fn prepare_select_plan(
                 plan.order_by = Some(key);
             }
 
-            // Parse the LIMIT clause
-            plan.limit = select.limit.and_then(|l| parse_limit(*l));
+            // Parse the LIMIT/OFFSET clause
+            (plan.limit, plan.offset) =
+                select.limit.map_or(Ok((None, None)), |l| parse_limit(*l))?;
 
             // Return the unoptimized query plan
             Ok(Plan::Select(plan))