From fa59d02692426d2122a2b197ce17ccd01d725299 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Fri, 23 Apr 2021 14:54:37 -0400
Subject: [PATCH] LibSQL: Parse IN / NOT IN expressions with a nested SELECT
 statement

---
 Userland/Libraries/LibSQL/AST.h               | 14 +++++++++++
 Userland/Libraries/LibSQL/Parser.cpp          |  4 ++--
 .../LibSQL/Tests/TestSqlExpressionParser.cpp  | 23 +++++++++++++++++++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/Userland/Libraries/LibSQL/AST.h b/Userland/Libraries/LibSQL/AST.h
index 1c7a90eb26..44c5134ba3 100644
--- a/Userland/Libraries/LibSQL/AST.h
+++ b/Userland/Libraries/LibSQL/AST.h
@@ -624,6 +624,20 @@ private:
     NonnullRefPtr<Expression> m_expression;
 };
 
+class InSelectionExpression : public InvertibleNestedExpression {
+public:
+    InSelectionExpression(NonnullRefPtr<Expression> expression, NonnullRefPtr<Select> select_statement, bool invert_expression)
+        : InvertibleNestedExpression(move(expression), invert_expression)
+        , m_select_statement(move(select_statement))
+    {
+    }
+
+    const NonnullRefPtr<Select>& select_statement() const { return m_select_statement; }
+
+private:
+    NonnullRefPtr<Select> m_select_statement;
+};
+
 class InChainedExpression : public InvertibleNestedExpression {
 public:
     InChainedExpression(NonnullRefPtr<Expression> expression, NonnullRefPtr<ChainedExpression> expression_chain, bool invert_expression)
diff --git a/Userland/Libraries/LibSQL/Parser.cpp b/Userland/Libraries/LibSQL/Parser.cpp
index cd9e46afdb..3ac2527b6f 100644
--- a/Userland/Libraries/LibSQL/Parser.cpp
+++ b/Userland/Libraries/LibSQL/Parser.cpp
@@ -628,8 +628,8 @@ Optional<NonnullRefPtr<Expression>> Parser::parse_in_expression(NonnullRefPtr<Ex
 
     if (consume_if(TokenType::ParenOpen)) {
         if (match(TokenType::Select)) {
-            // FIXME: Parse "select-stmt".
-            return {};
+            auto select_statement = parse_select_statement({});
+            return create_ast_node<InSelectionExpression>(move(expression), move(select_statement), invert_expression);
         }
 
         // FIXME: Consolidate this with parse_chained_expression(). That method consumes the opening paren as
diff --git a/Userland/Libraries/LibSQL/Tests/TestSqlExpressionParser.cpp b/Userland/Libraries/LibSQL/Tests/TestSqlExpressionParser.cpp
index 1e7a2ef187..a3d2e6d32f 100644
--- a/Userland/Libraries/LibSQL/Tests/TestSqlExpressionParser.cpp
+++ b/Userland/Libraries/LibSQL/Tests/TestSqlExpressionParser.cpp
@@ -580,4 +580,27 @@ TEST_CASE(in_chained_expression)
     validate("15 NOT IN (15, 16)", 2, true);
 }
 
+TEST_CASE(in_selection_expression)
+{
+    EXPECT(parse("IN (SELECT)").is_error());
+    EXPECT(parse("IN (SELECT * FROM table, SELECT * FROM table);").is_error());
+    EXPECT(parse("NOT IN (SELECT)").is_error());
+    EXPECT(parse("NOT IN (SELECT * FROM table, SELECT * FROM table);").is_error());
+
+    auto validate = [](StringView sql, bool expected_invert_expression) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto expression = result.release_value();
+        EXPECT(is<SQL::InSelectionExpression>(*expression));
+
+        const auto& in = static_cast<const SQL::InSelectionExpression&>(*expression);
+        EXPECT(!is<SQL::ErrorExpression>(*in.expression()));
+        EXPECT_EQ(in.invert_expression(), expected_invert_expression);
+    };
+
+    validate("15 IN (SELECT * FROM table)", false);
+    validate("15 NOT IN (SELECT * FROM table)", true);
+}
+
 TEST_MAIN(SqlExpressionParser)