// Copyright 2023 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once

#include <Parsers/IParserBase.h>

namespace DB
{

/** Parse specified keyword such as SELECT or compound keyword such as ORDER BY.
  * All case insensitive. Requires word boundary.
  * For compound keywords, any whitespace characters and comments could be in the middle.
  */
/// Example: ORDER/* Hello */BY
class ParserKeyword : public IParserBase
{
private:
    const char * s;

public:
    ParserKeyword(const char * s_);

protected:
    const char * getName() const override;

    bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
};


class ParserToken : public IParserBase
{
private:
    TokenType token_type;

public:
    ParserToken(TokenType token_type)
        : token_type(token_type)
    {}

protected:
    const char * getName() const override { return "token"; }

    bool parseImpl(Pos & pos, ASTPtr & /*node*/, Expected & expected) override
    {
        if (pos->type != token_type)
        {
            expected.add(pos, getTokenName(token_type));
            return false;
        }
        ++pos;
        return true;
    }
};

} // namespace DB