大改，整理项目结构，完成rust ffi调用，写好tcp接口

chusql-core/engine/app/Main.hs

@@ -0,0 +1,82 @@
+module Main where
+
+import ChuSQL.Core.Engine.Algebra.Op (renderPlan)
+import ChuSQL.Core.Engine.Algebra.Optimize (optimize)
+import ChuSQL.Core.Engine.Algebra.Planner (translate)
+import ChuSQL.Core.Engine
+import ChuSQL.Core.Model
+import ChuSQL.Core.Engine.Syntax.AST
+import ChuSQL.Core.Engine.Syntax.Parser
+
+-- 命令行演示入口：跑几条语句并打印结果与优化前后的计划。
+
+users :: Table
+users =
+    Table
+        { tableName = "users"
+        , tableCols = [("id", TInt), ("name", TStr), ("age", TInt)]
+        , tableRows =
+            [ [("id", VInt 1), ("name", VStr "Alice"), ("age", VInt 25)]
+            , [("id", VInt 2), ("name", VStr "Bob"), ("age", VInt 17)]
+            , [("id", VInt 3), ("name", VStr "Carol"), ("age", VInt 30)]
+            ]
+        }
+
+orders :: Table
+orders =
+    Table
+        { tableName = "orders"
+        , tableCols = [("id", TInt), ("user_id", TInt), ("product", TStr)]
+        , tableRows =
+            [ [("id", VInt 1), ("user_id", VInt 1), ("product", VStr "Book")]
+            , [("id", VInt 2), ("user_id", VInt 2), ("product", VStr "Pen")]
+            , [("id", VInt 3), ("user_id", VInt 1), ("product", VStr "Cup")]
+            ]
+        }
+
+db :: Database
+db = [("users", users), ("orders", orders)]
+
+-- | 跑演示语句，打印结果与优化前后的计划
+main :: IO ()
+main = do
+    putStrLn "==================== Engine ====================="
+    let q1 = makeSelect ["name"] "users" (Just (Gt (Col "age") (LitInt 18)))
+    print (rowsOf (runStatement db q1))
+
+    let q2 = makeSelect ["*"] "users" Nothing
+    print (rowsOf (runStatement db q2))
+
+    let q3 = makeSelect ["name"] "nonexistent" Nothing
+    print (rowsOf (runStatement db q3))
+
+    let q4 =
+            makeSelect
+                ["name"]
+                "users"
+                ( Just
+                    ( Or
+                        (Lt (Col "age") (LitInt 18))
+                        (Gt (Col "age") (LitInt 30))
+                    )
+                )
+    print (rowsOf (runStatement db q4))
+
+    let parsed = parseStatement "SELECT name FROM users WHERE age > 18 AND name = 'Alice'"
+    print (rowsOf (parsed >>= runStatement db))
+
+    putStrLn "\n==================== Optimizer ====================="
+    let planSql =
+            "SELECT u.name, o.product FROM users u \
+            \JOIN orders o ON u.id = o.user_id WHERE u.age > 18"
+    case parseStatement planSql of
+        Left err -> putStrLn err
+        Right query -> case translate query of
+            Left err -> putStrLn err
+            Right plan -> do
+                putStrLn "--- plan before optimization ---"
+                putStrLn (renderPlan plan)
+                putStrLn "--- plan after optimization ---"
+                putStrLn (renderPlan (optimize db plan))
+                putStrLn "--- rows ---"
+                print (rowsOf (runStatement db query))