ChainNameParser.h

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef TrigCompositeUtils_ChainNameParser_h
#define TrigCompositeUtils_ChainNameParser_h
 
#include <string>
#include <vector>
#include <set>
#include <iterator>
#include "xAODBase/ObjectType.h"
 
namespace ChainNameParser {
    struct LegInfo
    {
        std::string legName() const;
        xAODType::ObjectType type() const;
        std::size_t multiplicity{};
        std::string signature{};
        int threshold{-1};
        std::vector<std::string> legParts;
    };

    class LegInfoIterator
    {
    public:
        using iterator_category = std::input_iterator_tag;
        using value_type = LegInfo;
        using reference = const value_type &;
        using pointer = const value_type *;
        using difference_type = std::ptrdiff_t;

        LegInfoIterator() = default;

        LegInfoIterator(const std::string &chain);

        bool operator==(const LegInfoIterator &other) const;
        bool operator!=(const LegInfoIterator &other) const;

        reference operator *() const;
        pointer operator->() const;

        LegInfoIterator &operator++();
        LegInfoIterator operator++(int);

        bool exhausted() const;
    private:
        std::string::const_iterator m_itr;
        std::string::const_iterator m_end;
        LegInfo m_current;
        std::size_t m_peekMultiplicity{0};
        std::string m_peekSignature{""};
        int m_peekThreshold{-1};
        bool advance();
    };

    class HLTChainInfo {
    public:
        using const_iterator = LegInfoIterator;
 
        HLTChainInfo(const std::string &chain) : m_chain(chain) {}

        const std::string &chain() const { return m_chain; }

        const_iterator begin() const { return LegInfoIterator(m_chain); }
        const_iterator end() const { return LegInfoIterator(); }
        std::string l1Item() const;
 
    private:
        std::string m_chain;
    }; //> end class HLTChainInfo

    const std::vector<std::string> &allSignatures();

    const std::vector<std::string> &allSignaturePostfixQualifiers();

    const std::set<std::string> &singleLegIdentifiers();
 
    /*
     * @brief The regex pattern to match the part at the start of each leg
     *
     * The pattern has three capture groups, the first contains the multiplicity which is either
     * a digit or empty (implying a multiplicity of 1). The second is the signature and the third
     * is the threshold. The threshold will usually be an integer but can also be empty.
     */
    std::string legHeadPattern();
 
   /*
    * returns multiplicities of the chain legs given the chain name.
    * e.g. for: HLT_2g10_loose_mu20 it would be [ 2 1 ]
    */
    std::vector<int> multiplicities(const std::string& chain);
    /*
    * returns signatures of the chain given the name
    * e.g. for: HLT_2g10_loose_mu20 it would be [ "g" "mu" ]
    * It matches the the multiplicities returned by the above method
    */
    std::vector<std::string> signatures(const std::string& chain);
    
}
 
#endif //