ClickHouse/src/Parsers/IParserBase.h

#pragma once

#include <Parsers/IParser.h>


namespace DB
{

/** Base class for most parsers
  */
class IParserBase : public IParser
{
public:
    template <typename F>
    static bool wrapParseImpl(Pos & pos, const F & func)
    {
        Pos begin = pos;
        bool res = func();
        if (!res)
          pos = begin;
        return res;
    }

    struct IncreaseDepthTag {};

    template <typename F>
    static bool wrapParseImpl(Pos & pos, IncreaseDepthTag, const F & func)
    {
        Pos begin = pos;
        pos.increaseDepth();
        bool res = func();
        pos.decreaseDepth();
        if (!res)
          pos = begin;
        return res;
    }

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

protected:
    virtual bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) = 0;
};

}