LibSQL: Move Lexer and Parser machinery to AST directory

The SQL engine is expected to be a fairly sizeable piece of software.
Therefore we're starting to restructure the codebase for growth.

Userland/Libraries/LibSQL/AST/Token.cpp

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2021, Tim Flynn <trflynn89@pm.me>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Token.h"
+#include <AK/Assertions.h>
+#include <AK/String.h>
+#include <stdlib.h>
+
+namespace SQL::AST {
+
+StringView Token::name(TokenType type)
+{
+    switch (type) {
+#define __ENUMERATE_SQL_TOKEN(value, type, category) \
+    case TokenType::type:                            \
+        return #type;
+        ENUMERATE_SQL_TOKENS
+#undef __ENUMERATE_SQL_TOKEN
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+TokenCategory Token::category(TokenType type)
+{
+    switch (type) {
+#define __ENUMERATE_SQL_TOKEN(value, type, category) \
+    case TokenType::type:                            \
+        return TokenCategory::category;
+        ENUMERATE_SQL_TOKENS
+#undef __ENUMERATE_SQL_TOKEN
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+double Token::double_value() const
+{
+    VERIFY(type() == TokenType::NumericLiteral);
+    String value(m_value);
+
+    if (value[0] == '0' && value.length() >= 2) {
+        if (value[1] == 'x' || value[1] == 'X')
+            return static_cast<double>(strtoul(value.characters() + 2, nullptr, 16));
+    }
+
+    return strtod(value.characters(), nullptr);
+}
+
+}