5 files changed, 284 insertions, 1 deletions

diff --git a/Userland/Libraries/LibSQL/AST.h b/Userland/Libraries/LibSQL/AST.h
index e90fcb7777..0bf1d33e8c 100644
--- a/Userland/Libraries/LibSQL/AST.h
+++ b/Userland/Libraries/LibSQL/AST.h
@@ -101,6 +101,62 @@ private:
     NonnullRefPtr<TypeName> m_type_name;
 };
 
+class CommonTableExpression : public ASTNode {
+public:
+    CommonTableExpression(String table_name, Vector<String> column_names)
+        : m_table_name(move(table_name))
+        , m_column_names(move(column_names))
+    {
+    }
+
+    const String& table_name() const { return m_table_name; }
+    const Vector<String>& column_names() const { return m_column_names; }
+
+private:
+    String m_table_name;
+    Vector<String> m_column_names;
+};
+
+class QualifiedTableName : public ASTNode {
+public:
+    QualifiedTableName(String schema_name, String table_name, String alias)
+        : m_schema_name(move(schema_name))
+        , m_table_name(move(table_name))
+        , m_alias(move(alias))
+    {
+    }
+
+    const String& schema_name() const { return m_schema_name; }
+    const String& table_name() const { return m_table_name; }
+    const String& alias() const { return m_alias; }
+
+private:
+    String m_schema_name;
+    String m_table_name;
+    String m_alias;
+};
+
+class ReturningClause : public ASTNode {
+public:
+    struct ColumnClause {
+        NonnullRefPtr<Expression> expression;
+        String column_alias;
+    };
+
+    ReturningClause() = default;
+
+    explicit ReturningClause(Vector<ColumnClause> columns)
+        : m_columns(move(columns))
+    {
+    }
+
+    bool return_all_columns() const { return m_columns.is_empty(); };
+    const Vector<ColumnClause>& columns() const { return m_columns; }
+
+private:
+    Vector<ColumnClause> m_columns;
+};
+
 //==================================================================================================
 // Expressions
 //==================================================================================================
@@ -495,4 +551,29 @@ private:
     bool m_is_error_if_table_does_not_exist;
 };
 
+class Delete : public Statement {
+public:
+    Delete(bool recursive, RefPtr<CommonTableExpression> common_table_expression, NonnullRefPtr<QualifiedTableName> qualified_table_name, RefPtr<Expression> where_clause, RefPtr<ReturningClause> returning_clause)
+        : m_recursive(recursive)
+        , m_common_table_expression(move(common_table_expression))
+        , m_qualified_table_name(move(qualified_table_name))
+        , m_where_clause(move(where_clause))
+        , m_returning_clause(move(returning_clause))
+    {
+    }
+
+    bool recursive() const { return m_recursive; }
+    const RefPtr<CommonTableExpression>& common_table_expression() const { return m_common_table_expression; }
+    const NonnullRefPtr<QualifiedTableName>& qualified_table_name() const { return m_qualified_table_name; }
+    const RefPtr<Expression>& where_clause() const { return m_where_clause; }
+    const RefPtr<ReturningClause>& returning_clause() const { return m_returning_clause; }
+
+private:
+    bool m_recursive;
+    RefPtr<CommonTableExpression> m_common_table_expression;
+    NonnullRefPtr<QualifiedTableName> m_qualified_table_name;
+    RefPtr<Expression> m_where_clause;
+    RefPtr<ReturningClause> m_returning_clause;
+};
+
 }
diff --git a/Userland/Libraries/LibSQL/Forward.h b/Userland/Libraries/LibSQL/Forward.h
index 0430a97bb5..b05cbe342b 100644
--- a/Userland/Libraries/LibSQL/Forward.h
+++ b/Userland/Libraries/LibSQL/Forward.h
@@ -37,7 +37,9 @@ class ChainedExpression;
 class CollateExpression;
 class ColumnDefinition;
 class ColumnNameExpression;
+class CommonTableExpression;
 class CreateTable;
+class Delete;
 class DropTable;
 class ErrorExpression;
 class ErrorStatement;
@@ -55,6 +57,8 @@ class NullExpression;
 class NullLiteral;
 class NumericLiteral;
 class Parser;
+class QualifiedTableName;
+class ReturningClause;
 class SignedNumber;
 class Statement;
 class StringLiteral;
diff --git a/Userland/Libraries/LibSQL/Parser.cpp b/Userland/Libraries/LibSQL/Parser.cpp
index e35398db15..aa97202f5e 100644
--- a/Userland/Libraries/LibSQL/Parser.cpp
+++ b/Userland/Libraries/LibSQL/Parser.cpp
@@ -41,8 +41,11 @@ NonnullRefPtr<Statement> Parser::next_statement()
         return parse_create_table_statement();
     case TokenType::Drop:
         return parse_drop_table_statement();
+    case TokenType::Delete:
+    case TokenType::With:
+        return parse_delete_statement();
     default:
-        expected("CREATE or DROP");
+        expected("CREATE, DROP, or DELETE");
         return create_ast_node<ErrorStatement>();
     }
 }
@@ -125,6 +128,34 @@ NonnullRefPtr<DropTable> Parser::parse_drop_table_statement()
     return create_ast_node<DropTable>(move(schema_name), move(table_name), is_error_if_table_does_not_exist);
 }
 
+NonnullRefPtr<Delete> Parser::parse_delete_statement()
+{
+    // https://sqlite.org/lang_delete.html
+
+    bool recursive = false;
+    RefPtr<CommonTableExpression> common_table_expression;
+    if (consume_if(TokenType::With)) {
+        recursive = consume_if(TokenType::Recursive);
+        common_table_expression = parse_common_table_expression();
+    }
+
+    consume(TokenType::Delete);
+    consume(TokenType::From);
+    auto qualified_table_name = parse_qualified_table_name();
+
+    RefPtr<Expression> where_clause;
+    if (consume_if(TokenType::Where))
+        where_clause = parse_expression();
+
+    RefPtr<ReturningClause> returning_clause;
+    if (match(TokenType::Returning))
+        returning_clause = parse_returning_clause();
+
+    consume(TokenType::SemiColon);
+
+    return create_ast_node<Delete>(recursive, move(common_table_expression), move(qualified_table_name), move(where_clause), move(returning_clause));
+}
+
 NonnullRefPtr<Expression> Parser::parse_expression()
 {
     // https://sqlite.org/lang_expr.html
@@ -620,6 +651,87 @@ NonnullRefPtr<SignedNumber> Parser::parse_signed_number()
     return create_ast_node<SignedNumber>(0);
 }
 
+NonnullRefPtr<CommonTableExpression> Parser::parse_common_table_expression()
+{
+    // https://sqlite.org/syntax/common-table-expression.html
+    auto table_name = consume(TokenType::Identifier).value();
+
+    Vector<String> column_names;
+    if (consume_if(TokenType::ParenOpen)) {
+        do {
+            column_names.append(consume(TokenType::Identifier).value());
+            if (match(TokenType::ParenClose))
+                break;
+
+            consume(TokenType::Comma);
+        } while (!match(TokenType::Eof));
+
+        consume(TokenType::ParenClose);
+    }
+
+    consume(TokenType::As);
+    consume(TokenType::ParenOpen);
+    // FIXME: Parse "select-stmt".
+    consume(TokenType::ParenClose);
+
+    return create_ast_node<CommonTableExpression>(move(table_name), move(column_names));
+}
+
+NonnullRefPtr<QualifiedTableName> Parser::parse_qualified_table_name()
+{
+    // https://sqlite.org/syntax/qualified-table-name.html
+    String schema_or_table_name = consume(TokenType::Identifier).value();
+    String schema_name;
+    String table_name;
+
+    if (consume_if(TokenType::Period)) {
+        schema_name = move(schema_or_table_name);
+        table_name = consume(TokenType::Identifier).value();
+    } else {
+        table_name = move(schema_or_table_name);
+    }
+
+    String alias;
+    if (consume_if(TokenType::As))
+        alias = consume(TokenType::Identifier).value();
+
+    // Note: The qualified-table-name spec may include an "INDEXED BY index-name" or "NOT INDEXED" clause. This is a SQLite extension
+    // "designed to help detect undesirable query plan changes during regression testing", and "application developers are admonished
+    // to omit all use of INDEXED BY during application design, implementation, testing, and tuning". Our implementation purposefully
+    // omits parsing INDEXED BY for now until there is good reason to add support.
+
+    return create_ast_node<QualifiedTableName>(move(schema_name), move(table_name), move(alias));
+}
+
+NonnullRefPtr<ReturningClause> Parser::parse_returning_clause()
+{
+    // https://sqlite.org/syntax/returning-clause.html
+    consume(TokenType::Returning);
+
+    if (consume_if(TokenType::Asterisk))
+        return create_ast_node<ReturningClause>();
+
+    Vector<ReturningClause::ColumnClause> columns;
+
+    do {
+        auto expression = parse_expression();
+
+        consume_if(TokenType::As); // 'AS' is optional.
+
+        String column_alias;
+        if (match(TokenType::Identifier))
+            column_alias = consume().value();
+
+        columns.append({ move(expression), move(column_alias) });
+        if (!match(TokenType::Comma))
+            break;
+
+        consume(TokenType::Comma);
+    } while (!match(TokenType::Eof));
+
+    return create_ast_node<ReturningClause>(move(columns));
+}
+
 Token Parser::consume()
 {
     auto old_token = m_parser_state.m_token;
diff --git a/Userland/Libraries/LibSQL/Parser.h b/Userland/Libraries/LibSQL/Parser.h
index 9b0ea5d2ab..41c526a4d3 100644
--- a/Userland/Libraries/LibSQL/Parser.h
+++ b/Userland/Libraries/LibSQL/Parser.h
@@ -72,6 +72,7 @@ private:
 
     NonnullRefPtr<CreateTable> parse_create_table_statement();
     NonnullRefPtr<DropTable> parse_drop_table_statement();
+    NonnullRefPtr<Delete> parse_delete_statement();
 
     NonnullRefPtr<Expression> parse_primary_expression();
     NonnullRefPtr<Expression> parse_secondary_expression(NonnullRefPtr<Expression> primary);
@@ -93,6 +94,9 @@ private:
     NonnullRefPtr<ColumnDefinition> parse_column_definition();
     NonnullRefPtr<TypeName> parse_type_name();
     NonnullRefPtr<SignedNumber> parse_signed_number();
+    NonnullRefPtr<CommonTableExpression> parse_common_table_expression();
+    NonnullRefPtr<QualifiedTableName> parse_qualified_table_name();
+    NonnullRefPtr<ReturningClause> parse_returning_clause();
 
     Token consume();
     Token consume(TokenType type);
diff --git a/Userland/Libraries/LibSQL/Tests/TestSqlParser.cpp b/Userland/Libraries/LibSQL/Tests/TestSqlParser.cpp
index c7701c641d..fee4c0cf80 100644
--- a/Userland/Libraries/LibSQL/Tests/TestSqlParser.cpp
+++ b/Userland/Libraries/LibSQL/Tests/TestSqlParser.cpp
@@ -157,4 +157,86 @@ TEST_CASE(drop_table)
     validate("DROP TABLE IF EXISTS test;", {}, "test", false);
 }
 
+TEST_CASE(delete_)
+{
+    EXPECT(parse("DELETE").is_error());
+    EXPECT(parse("DELETE FROM").is_error());
+    EXPECT(parse("DELETE FROM table").is_error());
+    EXPECT(parse("DELETE FROM table WHERE").is_error());
+    EXPECT(parse("DELETE FROM table WHERE 15").is_error());
+    EXPECT(parse("DELETE FROM table WHERE 15 RETURNING").is_error());
+    EXPECT(parse("DELETE FROM table WHERE 15 RETURNING *").is_error());
+    EXPECT(parse("DELETE FROM table WHERE (');").is_error());
+    EXPECT(parse("WITH DELETE FROM table;").is_error());
+    EXPECT(parse("WITH table DELETE FROM table;").is_error());
+    EXPECT(parse("WITH table AS DELETE FROM table;").is_error());
+    EXPECT(parse("WITH RECURSIVE table DELETE FROM table;").is_error());
+    EXPECT(parse("WITH RECURSIVE table AS DELETE FROM table;").is_error());
+
+    struct SelectedTable {
+        bool recursive { false };
+        StringView table_name {};
+        Vector<StringView> column_names {};
+    };
+
+    auto validate = [](StringView sql, SelectedTable expected_selected_table, StringView expected_schema, StringView expected_table, StringView expected_alias, bool expect_where_clause, bool expect_returning_clause, Vector<StringView> expected_returned_column_aliases) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto statement = result.release_value();
+        EXPECT(is<SQL::Delete>(*statement));
+
+        const auto& delete_ = static_cast<const SQL::Delete&>(*statement);
+        EXPECT_EQ(delete_.recursive(), expected_selected_table.recursive);
+
+        const auto& common_table_expression = delete_.common_table_expression();
+        EXPECT_EQ(common_table_expression.is_null(), expected_selected_table.table_name.is_empty());
+        if (common_table_expression) {
+            EXPECT_EQ(common_table_expression->table_name(), expected_selected_table.table_name);
+            EXPECT_EQ(common_table_expression->column_names().size(), expected_selected_table.column_names.size());
+            for (size_t i = 0; i < common_table_expression->column_names().size(); ++i)
+                EXPECT_EQ(common_table_expression->column_names()[i], expected_selected_table.column_names[i]);
+        }
+
+        const auto& qualified_table_name = delete_.qualified_table_name();
+        EXPECT_EQ(qualified_table_name->schema_name(), expected_schema);
+        EXPECT_EQ(qualified_table_name->table_name(), expected_table);
+        EXPECT_EQ(qualified_table_name->alias(), expected_alias);
+
+        const auto& where_clause = delete_.where_clause();
+        EXPECT_EQ(where_clause.is_null(), !expect_where_clause);
+        if (where_clause)
+            EXPECT(!is<SQL::ErrorExpression>(*where_clause));
+
+        const auto& returning_clause = delete_.returning_clause();
+        EXPECT_EQ(returning_clause.is_null(), !expect_returning_clause);
+        if (returning_clause) {
+            EXPECT_EQ(returning_clause->columns().size(), expected_returned_column_aliases.size());
+
+            for (size_t i = 0; i < returning_clause->columns().size(); ++i) {
+                const auto& column = returning_clause->columns()[i];
+                const auto& expected_column_alias = expected_returned_column_aliases[i];
+
+                EXPECT(!is<SQL::ErrorExpression>(*column.expression));
+                EXPECT_EQ(column.column_alias, expected_column_alias);
+            }
+        }
+    };
+
+    validate("DELETE FROM table;", {}, {}, "table", {}, false, false, {});
+    validate("DELETE FROM schema.table;", {}, "schema", "table", {}, false, false, {});
+    validate("DELETE FROM schema.table AS alias;", {}, "schema", "table", "alias", false, false, {});
+    validate("DELETE FROM table WHERE (1 == 1);", {}, {}, "table", {}, true, false, {});
+    validate("DELETE FROM table RETURNING *;", {}, {}, "table", {}, false, true, {});
+    validate("DELETE FROM table RETURNING column;", {}, {}, "table", {}, false, true, { {} });
+    validate("DELETE FROM table RETURNING column AS alias;", {}, {}, "table", {}, false, true, { "alias" });
+    validate("DELETE FROM table RETURNING column1 AS alias1, column2 AS alias2;", {}, {}, "table", {}, false, true, { "alias1", "alias2" });
+
+    // FIXME: When parsing of SELECT statements are supported, the common-table-expressions below will become invalid due to the empty "AS ()" clause.
+    validate("WITH table AS () DELETE FROM table;", { false, "table", {} }, {}, "table", {}, false, false, {});
+    validate("WITH table (column) AS () DELETE FROM table;", { false, "table", { "column" } }, {}, "table", {}, false, false, {});
+    validate("WITH table (column1, column2) AS () DELETE FROM table;", { false, "table", { "column1", "column2" } }, {}, "table", {}, false, false, {});
+    validate("WITH RECURSIVE table AS () DELETE FROM table;", { true, "table", {} }, {}, "table", {}, false, false, {});
+}
+
 TEST_MAIN(SqlParser)