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/Parser.h

@@ -0,0 +1,87 @@
+/*
+ * 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/String.h>
+#include <AK/StringView.h>
+#include <LibSQL/AST.h>
+#include <LibSQL/Lexer.h>
+#include <LibSQL/Token.h>
+
+namespace SQL {
+
+class Parser {
+    struct Position {
+        size_t line { 0 };
+        size_t column { 0 };
+    };
+
+    struct Error {
+        String message;
+        Position position;
+
+        String to_string() const
+        {
+            return String::formatted("{} (line: {}, column: {})", message, position.line, position.column);
+        }
+    };
+
+public:
+    explicit Parser(Lexer lexer);
+
+    NonnullRefPtr<Statement> next_statement();
+
+    bool has_errors() const { return m_parser_state.m_errors.size(); }
+    const Vector<Error>& errors() const { return m_parser_state.m_errors; }
+
+private:
+    struct ParserState {
+        explicit ParserState(Lexer);
+
+        Lexer m_lexer;
+        Token m_token;
+        Vector<Error> m_errors;
+    };
+
+    NonnullRefPtr<ColumnDefinition> parse_column_definition();
+    NonnullRefPtr<CreateTable> parse_create_table_statement();
+    NonnullRefPtr<TypeName> parse_type_name();
+    NonnullRefPtr<SignedNumber> parse_signed_number();
+
+    Token consume();
+    Token consume(TokenType type);
+    bool match(TokenType type) const;
+
+    void expected(StringView what);
+    void syntax_error(String message);
+
+    Position position() const;
+
+    ParserState m_parser_state;
+};
+
+}