LibSQL: Parse ALTER TABLE statement

There are 4 forms an ALTER TABLE statement can take, and each are very
distinct, so they each get their own AST node class.

Userland/Libraries/LibSQL/AST.h

@@ -720,6 +720,82 @@ private:
     bool m_is_error_if_table_exists;
 };
 
+class AlterTable : public Statement {
+public:
+    const String& schema_name() const { return m_schema_name; }
+    const String& table_name() const { return m_table_name; }
+
+protected:
+    AlterTable(String schema_name, String table_name)
+        : m_schema_name(move(schema_name))
+        , m_table_name(move(table_name))
+    {
+    }
+
+private:
+    String m_schema_name;
+    String m_table_name;
+};
+
+class RenameTable : public AlterTable {
+public:
+    RenameTable(String schema_name, String table_name, String new_table_name)
+        : AlterTable(move(schema_name), move(table_name))
+        , m_new_table_name(move(new_table_name))
+    {
+    }
+
+    const String& new_table_name() const { return m_new_table_name; }
+
+private:
+    String m_new_table_name;
+};
+
+class RenameColumn : public AlterTable {
+public:
+    RenameColumn(String schema_name, String table_name, String column_name, String new_column_name)
+        : AlterTable(move(schema_name), move(table_name))
+        , m_column_name(move(column_name))
+        , m_new_column_name(move(new_column_name))
+    {
+    }
+
+    const String& column_name() const { return m_column_name; }
+    const String& new_column_name() const { return m_new_column_name; }
+
+private:
+    String m_column_name;
+    String m_new_column_name;
+};
+
+class AddColumn : public AlterTable {
+public:
+    AddColumn(String schema_name, String table_name, NonnullRefPtr<ColumnDefinition> column)
+        : AlterTable(move(schema_name), move(table_name))
+        , m_column(move(column))
+    {
+    }
+
+    const NonnullRefPtr<ColumnDefinition>& column() const { return m_column; }
+
+private:
+    NonnullRefPtr<ColumnDefinition> m_column;
+};
+
+class DropColumn : public AlterTable {
+public:
+    DropColumn(String schema_name, String table_name, String column_name)
+        : AlterTable(move(schema_name), move(table_name))
+        , m_column_name(move(column_name))
+    {
+    }
+
+    const String& column_name() const { return m_column_name; }
+
+private:
+    String m_column_name;
+};
+
 class DropTable : public Statement {
 public:
     DropTable(String schema_name, String table_name, bool is_error_if_table_does_not_exist)

Userland/Libraries/LibSQL/Forward.h

@@ -7,6 +7,8 @@
 #pragma once
 
 namespace SQL {
+class AddColumn;
+class AlterTable;
 class ASTNode;
 class BetweenExpression;
 class BinaryOperatorExpression;
@@ -21,6 +23,7 @@ class CommonTableExpression;
 class CommonTableExpressionList;
 class CreateTable;
 class Delete;
+class DropColumn;
 class DropTable;
 class ErrorExpression;
 class ErrorStatement;
@@ -45,6 +48,8 @@ class NumericLiteral;
 class OrderingTerm;
 class Parser;
 class QualifiedTableName;
+class RenameColumn;
+class RenameTable;
 class ResultColumn;
 class ReturningClause;
 class Select;

Userland/Libraries/LibSQL/Parser.cpp

@@ -34,6 +34,8 @@ NonnullRefPtr<Statement> Parser::parse_statement()
     switch (m_parser_state.m_token.type()) {
     case TokenType::Create:
         return parse_create_table_statement();
+    case TokenType::Alter:
+        return parse_alter_table_statement();
     case TokenType::Drop:
         return parse_drop_table_statement();
     case TokenType::Insert:
@@ -45,7 +47,7 @@ NonnullRefPtr<Statement> Parser::parse_statement()
     case TokenType::Select:
         return parse_select_statement({});
     default:
-        expected("CREATE, DROP, INSERT, UPDATE, DELETE, or SELECT");
+        expected("CREATE, ALTER, DROP, INSERT, UPDATE, DELETE, or SELECT");
         return create_ast_node<ErrorStatement>();
     }
 }
@@ -102,6 +104,42 @@ NonnullRefPtr<CreateTable> Parser::parse_create_table_statement()
     return create_ast_node<CreateTable>(move(schema_name), move(table_name), move(column_definitions), is_temporary, is_error_if_table_exists);
 }
 
+NonnullRefPtr<CreateTable> Parser::parse_alter_table_statement()
+{
+    // https://sqlite.org/lang_altertable.html
+    consume(TokenType::Alter);
+    consume(TokenType::Table);
+
+    String schema_name;
+    String table_name;
+    parse_schema_and_table_name(schema_name, table_name);
+
+    if (consume_if(TokenType::Add)) {
+        consume_if(TokenType::Column); // COLUMN is optional.
+        auto column = parse_column_definition();
+        return create_ast_node<AddColumn>(move(schema_name), move(table_name), move(column));
+    }
+
+    if (consume_if(TokenType::Drop)) {
+        consume_if(TokenType::Column); // COLUMN is optional.
+        auto column = consume(TokenType::Identifier).value();
+        return create_ast_node<DropColumn>(move(schema_name), move(table_name), move(column));
+    }
+
+    consume(TokenType::Rename);
+
+    if (consume_if(TokenType::To)) {
+        auto new_table_name = consume(TokenType::Identifier).value();
+        return create_ast_node<RenameTable>(move(schema_name), move(table_name), move(new_table_name));
+    }
+
+    consume_if(TokenType::Column); // COLUMN is optional.
+    auto column_name = consume(TokenType::Identifier).value();
+    consume(TokenType::To);
+    auto new_column_name = consume(TokenType::Identifier).value();
+    return create_ast_node<RenameColumn>(move(schema_name), move(table_name), move(column_name), move(new_column_name));
+}
+
 NonnullRefPtr<DropTable> Parser::parse_drop_table_statement()
 {
     // https://sqlite.org/lang_droptable.html

Userland/Libraries/LibSQL/Parser.h

@@ -53,6 +53,7 @@ private:
     NonnullRefPtr<Statement> parse_statement();
     NonnullRefPtr<Statement> parse_statement_with_expression_list(RefPtr<CommonTableExpressionList>);
     NonnullRefPtr<CreateTable> parse_create_table_statement();
+    NonnullRefPtr<CreateTable> parse_alter_table_statement();
     NonnullRefPtr<DropTable> parse_drop_table_statement();
     NonnullRefPtr<Delete> parse_insert_statement(RefPtr<CommonTableExpressionList>);
     NonnullRefPtr<Delete> parse_update_statement(RefPtr<CommonTableExpressionList>);

Userland/Libraries/LibSQL/Tests/TestSqlStatementParser.cpp

@@ -125,6 +125,147 @@ TEST_CASE(create_table)
     validate("CREATE TABLE test ( column1 varchar(1e3) );", {}, "test", { { "column1", "varchar", { 1000 } } });
 }
 
+TEST_CASE(alter_table)
+{
+    // This test case only contains common error cases of the AlterTable subclasses.
+    EXPECT(parse("ALTER").is_error());
+    EXPECT(parse("ALTER TABLE").is_error());
+    EXPECT(parse("ALTER TABLE table").is_error());
+    EXPECT(parse("ALTER TABLE table;").is_error());
+}
+
+TEST_CASE(alter_table_rename_table)
+{
+    EXPECT(parse("ALTER TABLE table RENAME").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME TO").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME TO new_table").is_error());
+
+    auto validate = [](StringView sql, StringView expected_schema, StringView expected_table, StringView expected_new_table) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto statement = result.release_value();
+        EXPECT(is<SQL::RenameTable>(*statement));
+
+        const auto& alter = static_cast<const SQL::RenameTable&>(*statement);
+        EXPECT_EQ(alter.schema_name(), expected_schema);
+        EXPECT_EQ(alter.table_name(), expected_table);
+        EXPECT_EQ(alter.new_table_name(), expected_new_table);
+    };
+
+    validate("ALTER TABLE table RENAME TO new_table;", {}, "table", "new_table");
+    validate("ALTER TABLE schema.table RENAME TO new_table;", "schema", "table", "new_table");
+}
+
+TEST_CASE(alter_table_rename_column)
+{
+    EXPECT(parse("ALTER TABLE table RENAME").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME COLUMN").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME COLUMN column").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME COLUMN column TO").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME COLUMN column TO new_column").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME column").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME column TO").is_error());
+    EXPECT(parse("ALTER TABLE table RENAME column TO new_column").is_error());
+
+    auto validate = [](StringView sql, StringView expected_schema, StringView expected_table, StringView expected_column, StringView expected_new_column) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto statement = result.release_value();
+        EXPECT(is<SQL::RenameColumn>(*statement));
+
+        const auto& alter = static_cast<const SQL::RenameColumn&>(*statement);
+        EXPECT_EQ(alter.schema_name(), expected_schema);
+        EXPECT_EQ(alter.table_name(), expected_table);
+        EXPECT_EQ(alter.column_name(), expected_column);
+        EXPECT_EQ(alter.new_column_name(), expected_new_column);
+    };
+
+    validate("ALTER TABLE table RENAME column TO new_column;", {}, "table", "column", "new_column");
+    validate("ALTER TABLE table RENAME COLUMN column TO new_column;", {}, "table", "column", "new_column");
+    validate("ALTER TABLE schema.table RENAME column TO new_column;", "schema", "table", "column", "new_column");
+    validate("ALTER TABLE schema.table RENAME COLUMN column TO new_column;", "schema", "table", "column", "new_column");
+}
+
+TEST_CASE(alter_table_add_column)
+{
+    EXPECT(parse("ALTER TABLE table ADD").is_error());
+    EXPECT(parse("ALTER TABLE table ADD COLUMN").is_error());
+    EXPECT(parse("ALTER TABLE table ADD COLUMN column").is_error());
+
+    struct Column {
+        StringView name;
+        StringView type;
+        Vector<double> signed_numbers {};
+    };
+
+    auto validate = [](StringView sql, StringView expected_schema, StringView expected_table, Column expected_column) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto statement = result.release_value();
+        EXPECT(is<SQL::AddColumn>(*statement));
+
+        const auto& alter = static_cast<const SQL::AddColumn&>(*statement);
+        EXPECT_EQ(alter.schema_name(), expected_schema);
+        EXPECT_EQ(alter.table_name(), expected_table);
+
+        const auto& column = alter.column();
+        EXPECT_EQ(column->name(), expected_column.name);
+
+        const auto& type_name = column->type_name();
+        EXPECT_EQ(type_name->name(), expected_column.type);
+
+        const auto& signed_numbers = type_name->signed_numbers();
+        EXPECT_EQ(signed_numbers.size(), expected_column.signed_numbers.size());
+
+        for (size_t j = 0; j < signed_numbers.size(); ++j) {
+            double signed_number = signed_numbers[j].value();
+            double expected_signed_number = expected_column.signed_numbers[j];
+            EXPECT_EQ(signed_number, expected_signed_number);
+        }
+    };
+
+    validate("ALTER TABLE test ADD column1;", {}, "test", { "column1", "BLOB" });
+    validate("ALTER TABLE test ADD column1 int;", {}, "test", { "column1", "int" });
+    validate("ALTER TABLE test ADD column1 varchar;", {}, "test", { "column1", "varchar" });
+    validate("ALTER TABLE test ADD column1 varchar(255);", {}, "test", { "column1", "varchar", { 255 } });
+    validate("ALTER TABLE test ADD column1 varchar(255, 123);", {}, "test", { "column1", "varchar", { 255, 123 } });
+
+    validate("ALTER TABLE schema.test ADD COLUMN column1;", "schema", "test", { "column1", "BLOB" });
+    validate("ALTER TABLE schema.test ADD COLUMN column1 int;", "schema", "test", { "column1", "int" });
+    validate("ALTER TABLE schema.test ADD COLUMN column1 varchar;", "schema", "test", { "column1", "varchar" });
+    validate("ALTER TABLE schema.test ADD COLUMN column1 varchar(255);", "schema", "test", { "column1", "varchar", { 255 } });
+    validate("ALTER TABLE schema.test ADD COLUMN column1 varchar(255, 123);", "schema", "test", { "column1", "varchar", { 255, 123 } });
+}
+
+TEST_CASE(alter_table_drop_column)
+{
+    EXPECT(parse("ALTER TABLE table DROP").is_error());
+    EXPECT(parse("ALTER TABLE table DROP COLUMN").is_error());
+    EXPECT(parse("ALTER TABLE table DROP column").is_error());
+    EXPECT(parse("ALTER TABLE table DROP COLUMN column").is_error());
+
+    auto validate = [](StringView sql, StringView expected_schema, StringView expected_table, StringView expected_column) {
+        auto result = parse(sql);
+        EXPECT(!result.is_error());
+
+        auto statement = result.release_value();
+        EXPECT(is<SQL::DropColumn>(*statement));
+
+        const auto& alter = static_cast<const SQL::DropColumn&>(*statement);
+        EXPECT_EQ(alter.schema_name(), expected_schema);
+        EXPECT_EQ(alter.table_name(), expected_table);
+        EXPECT_EQ(alter.column_name(), expected_column);
+    };
+
+    validate("ALTER TABLE table DROP column;", {}, "table", "column");
+    validate("ALTER TABLE table DROP COLUMN column;", {}, "table", "column");
+    validate("ALTER TABLE schema.table DROP column;", "schema", "table", "column");
+    validate("ALTER TABLE schema.table DROP COLUMN column;", "schema", "table", "column");
+}
+
 TEST_CASE(drop_table)
 {
     EXPECT(parse("DROP").is_error());