rust部分推进：进程间通信（Windows平台命名管线）、内存页表、B+树、WAL恢复系统、动态配置

chusql-engine/src/ChuSQL/Syntax/AST.hs

@@ -1,5 +1,7 @@
 module ChuSQL.Syntax.AST (Query (..), FromClause (..), Expr (..), SortDir (..), makeSelect) where
 
+-- SQL 语法树：四类语句（SELECT / INSERT / DELETE / UPDATE）+ 表达式、FROM 从句、排序方向。
+
 -- 查询语句
 data Query
     = Select
@@ -14,7 +16,7 @@ data Query
     | Update String [(String, Expr)] (Maybe Expr)
     deriving (Show, Eq)
 
--- 从句
+-- FROM 从句：单表或 JOIN。
 data FromClause
     = FromTable (Maybe String) String
     | FromJoin FromClause (Maybe String) String Expr
@@ -33,11 +35,13 @@ data Expr
     | Or Expr Expr
     deriving (Show, Eq)
 
+-- 排序方向
 data SortDir
     = Asc
     | Desc
     deriving (Show, Eq)
 
+-- 便捷构造：造一条最简单的 SELECT（给测试和演示用）。
 makeSelect :: [String] -> String -> Maybe Expr -> Query
 makeSelect cols tbl w =
     Select