LibSQL: Create a very barebones SQL parser

This parser builds on the LibSQL lexer and currently only allows users
to parse 'CREATE TABLE' statements.

Userland/Libraries/LibSQL/AST.h

@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2021, Tim Flynn <trflynn89@pm.me>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/RefCounted.h>
+#include <AK/String.h>
+
+namespace SQL {
+
+template<class T, class... Args>
+static inline NonnullRefPtr<T>
+create_ast_node(Args&&... args)
+{
+    return adopt(*new T(forward<Args>(args)...));
+}
+
+class ASTNode : public RefCounted<ASTNode> {
+public:
+    virtual ~ASTNode() { }
+
+protected:
+    ASTNode() = default;
+};
+
+class Statement : public ASTNode {
+};
+
+class ErrorStatement final : public Statement {
+};
+
+class SignedNumber final : public ASTNode {
+public:
+    explicit SignedNumber(double value)
+        : m_value(value)
+    {
+    }
+
+    double value() const { return m_value; }
+
+private:
+    double m_value;
+};
+
+class TypeName : public ASTNode {
+public:
+    TypeName(String name, NonnullRefPtrVector<SignedNumber> signed_numbers)
+        : m_name(move(name))
+        , m_signed_numbers(move(signed_numbers))
+    {
+        VERIFY(m_signed_numbers.size() <= 2);
+    }
+
+    const String& name() const { return m_name; }
+    const NonnullRefPtrVector<SignedNumber> signed_numbers() const { return m_signed_numbers; }
+
+private:
+    String m_name;
+    NonnullRefPtrVector<SignedNumber> m_signed_numbers;
+};
+
+class ColumnDefinition : public ASTNode {
+public:
+    ColumnDefinition(String name, NonnullRefPtr<TypeName> type_name)
+        : m_name(move(name))
+        , m_type_name(move(type_name))
+    {
+    }
+
+    const String& name() const { return m_name; }
+    const NonnullRefPtr<TypeName>& type_name() const { return m_type_name; }
+
+private:
+    String m_name;
+    NonnullRefPtr<TypeName> m_type_name;
+};
+
+class CreateTable : public Statement {
+public:
+    CreateTable(String schema_name, String table_name, NonnullRefPtrVector<ColumnDefinition> columns, bool is_temporary, bool is_error_if_table_exists)
+        : m_schema_name(move(schema_name))
+        , m_table_name(move(table_name))
+        , m_columns(move(columns))
+        , m_is_temporary(is_temporary)
+        , m_is_error_if_table_exists(is_error_if_table_exists)
+    {
+    }
+
+    const String& schema_name() const { return m_schema_name; }
+    const String& table_name() const { return m_table_name; }
+    const NonnullRefPtrVector<ColumnDefinition> columns() const { return m_columns; }
+    bool is_temporary() const { return m_is_temporary; }
+    bool is_error_if_table_exists() const { return m_is_error_if_table_exists; }
+
+private:
+    String m_schema_name;
+    String m_table_name;
+    NonnullRefPtrVector<ColumnDefinition> m_columns;
+    bool m_is_temporary;
+    bool m_is_error_if_table_exists;
+};
+
+}