refactor(binder): support multi layer binder context

src/binder/mod.rs

@@ -14,22 +14,26 @@ use crate::catalog::{RootCatalogRef, TableCatalog};
 pub struct Binder {
     catalog: RootCatalogRef,
     context: BinderContext,
+    subquery_base_index: usize,
 }
 
-#[derive(Default)]
+// FIXME: remove dead_code after we used parent context
+#[derive(Default, Clone, Debug)]
+#[allow(dead_code)]
 struct BinderContext {
     /// table_name == table_id
     /// table_id -> table_catalog
     tables: HashMap<String, TableCatalog>,
     aliases: HashMap<String, BoundExpr>,
-    subquery_base_index: usize,
+    parent: Option<Box<BinderContext>>,
 }
 
 impl Binder {
     pub fn new(catalog: RootCatalogRef) -> Self {
         Self {
             catalog,
             context: BinderContext::default(),
+            subquery_base_index: 0,
         }
     }
 
@@ -44,6 +48,15 @@ impl Binder {
     }
 }
 
+impl BinderContext {
+    pub fn with_parent(parent: Box<BinderContext>) -> Self {
+        Self {
+            parent: Some(parent),
+            ..Default::default()
+        }
+    }
+}
+
 #[derive(thiserror::Error, Debug)]
 pub enum BindError {
     #[error("unsupported statement {0}")]

src/binder/table/mod.rs

@@ -7,7 +7,7 @@ pub use join::*;
 use sqlparser::ast::{TableFactor, TableWithJoins};
 pub use subquery::*;
 
-use super::{BindError, Binder};
+use super::{BindError, Binder, BinderContext};
 use crate::catalog::{ColumnCatalog, ColumnId, TableCatalog, TableId};
 
 pub static DEFAULT_DATABASE_NAME: &str = "postgres";
@@ -186,6 +186,7 @@ impl Binder {
             } => {
                 // handle subquery as source
                 let query = self.bind_select(subquery)?;
+                self.context = BinderContext::with_parent(Box::new(self.context.clone()));
                 let alias = alias
                     .clone()
                     .map(|a| a.to_string().to_lowercase())

src/binder/table/subquery.rs

@@ -53,8 +53,8 @@ impl BoundSubquery {
 
 impl Binder {
     pub fn gen_subquery_table_id(&mut self) -> String {
-        let id = format!("subquery_{}", self.context.subquery_base_index);
-        self.context.subquery_base_index += 1;
+        let id = format!("subquery_{}", self.subquery_base_index);
+        self.subquery_base_index += 1;
         id
     }
 }

tests/slt/subquery.slt

@@ -2,8 +2,11 @@
 statement error
 select * from (select * from t1 where a > 1) where b > 7;
 
-# TODO: handle multi-layer binder context to resolve current context all columns
-# select * from (select * from t1 where a > 1) t where t.b > 7;
+query III
+select * from (select * from (select * from t1 where c < 2) t_1 where t_1.a > 1) t_2 where t_2.b > 7;
+----
+2 8 1
+
 
 query III
 select t.* from (select * from t1 where a > 1) t where t.b > 7;