From 1c50e9aadcb16ac5963013444392bab21155bad3 Mon Sep 17 00:00:00 2001
From: Jan de Visser <jan@de-visser.net>
Date: Tue, 2 Nov 2021 16:43:57 -0400
Subject: [PATCH] LibSQL: Add current statement to the ExecutionContext

Because SQL is the craptastic language that it is, sometimes expressions
need to know details about the calling statement. For example the tables
in the 'FROM' clause may be needed to determine which columns are
referenced in 'WHERE' expressions. So the current statement is added
to the ExecutionContext and a new 'execute' overload on Statement is
created which takes the Database and the Statement and builds an
ExecutionContaxt from those.
---
 Tests/LibSQL/TestSqlStatementExecution.cpp   |  3 +--
 Userland/Libraries/LibSQL/AST/AST.h          |  2 ++
 Userland/Libraries/LibSQL/AST/Statement.cpp  | 20 ++++++++++++++++++++
 Userland/Libraries/LibSQL/CMakeLists.txt     |  1 +
 Userland/Services/SQLServer/SQLStatement.cpp |  3 +--
 5 files changed, 25 insertions(+), 4 deletions(-)
 create mode 100644 Userland/Libraries/LibSQL/AST/Statement.cpp

diff --git a/Tests/LibSQL/TestSqlStatementExecution.cpp b/Tests/LibSQL/TestSqlStatementExecution.cpp
index e64ea6b32b1..a7f0c0fbe40 100644
--- a/Tests/LibSQL/TestSqlStatementExecution.cpp
+++ b/Tests/LibSQL/TestSqlStatementExecution.cpp
@@ -25,8 +25,7 @@ RefPtr<SQL::SQLResult> execute(NonnullRefPtr<SQL::Database> database, String con
     EXPECT(!parser.has_errors());
     if (parser.has_errors())
         outln("{}", parser.errors()[0].to_string());
-    SQL::AST::ExecutionContext context { database };
-    auto result = statement->execute(context);
+    auto result = statement->execute(move(database));
     if (result->error().code != SQL::SQLErrorCode::NoError)
         outln("{}", result->error().to_string());
     return result;
diff --git a/Userland/Libraries/LibSQL/AST/AST.h b/Userland/Libraries/LibSQL/AST/AST.h
index ca2c50946bb..b0ee4c72622 100644
--- a/Userland/Libraries/LibSQL/AST/AST.h
+++ b/Userland/Libraries/LibSQL/AST/AST.h
@@ -298,6 +298,7 @@ private:
 struct ExecutionContext {
     NonnullRefPtr<Database> database;
     RefPtr<SQLResult> result { nullptr };
+    class Statement const* statement;
     Tuple* current_row { nullptr };
 };
 
@@ -722,6 +723,7 @@ private:
 
 class Statement : public ASTNode {
 public:
+    RefPtr<SQLResult> execute(AK::NonnullRefPtr<Database> database) const;
     virtual RefPtr<SQLResult> execute(ExecutionContext&) const { return nullptr; }
 };
 
diff --git a/Userland/Libraries/LibSQL/AST/Statement.cpp b/Userland/Libraries/LibSQL/AST/Statement.cpp
new file mode 100644
index 00000000000..b9c379da173
--- /dev/null
+++ b/Userland/Libraries/LibSQL/AST/Statement.cpp
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibSQL/AST/AST.h>
+#include <LibSQL/Database.h>
+#include <LibSQL/Meta.h>
+#include <LibSQL/Row.h>
+
+namespace SQL::AST {
+
+RefPtr<SQLResult> Statement::execute(AK::NonnullRefPtr<Database> database) const
+{
+    ExecutionContext context { move(database), nullptr, this, nullptr };
+    return execute(context);
+}
+
+}
diff --git a/Userland/Libraries/LibSQL/CMakeLists.txt b/Userland/Libraries/LibSQL/CMakeLists.txt
index 744d7980aac..1bfa86baa1e 100644
--- a/Userland/Libraries/LibSQL/CMakeLists.txt
+++ b/Userland/Libraries/LibSQL/CMakeLists.txt
@@ -6,6 +6,7 @@ set(SOURCES
     AST/Lexer.cpp
     AST/Parser.cpp
     AST/Select.cpp
+    AST/Statement.cpp
     AST/SyntaxHighlighter.cpp
     AST/Token.cpp
     BTree.cpp
diff --git a/Userland/Services/SQLServer/SQLStatement.cpp b/Userland/Services/SQLServer/SQLStatement.cpp
index 87c726beee3..5c62b7a9a7f 100644
--- a/Userland/Services/SQLServer/SQLStatement.cpp
+++ b/Userland/Services/SQLServer/SQLStatement.cpp
@@ -67,8 +67,7 @@ void SQLStatement::execute()
             return;
         }
         VERIFY(!connection()->database().is_null());
-        SQL::AST::ExecutionContext context { connection()->database().release_nonnull() };
-        m_result = m_statement->execute(context);
+        m_result = m_statement->execute(connection()->database().release_nonnull());
         if (m_result->error().code != SQL::SQLErrorCode::NoError) {
             report_error(m_result->error());
             return;