IFileAccess.h

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* (c) Copyright 1998-2025 CERN for the benefit of the LHCb and ATLAS collaborations *
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* This software is distributed under the terms of the Apache version 2 licence,     *
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#pragma once
 
#include <GaudiKernel/IInterface.h>
#include <istream>
#include <memory>
#include <optional>
#include <string>
#include <vector>

class GAUDI_API IFileAccess : virtual public IInterface {
public:
  DeclareInterfaceID( IFileAccess, 3, 1 );

  virtual std::unique_ptr<std::istream> open( std::string const& url ) = 0;

  virtual std::optional<std::string> read( std::string const& url ) {
    auto is = open( url );
    if ( !is || !is->good() ) return std::nullopt;
    auto s = std::string{ std::istreambuf_iterator<char>{ *is }, std::istreambuf_iterator<char>{} };
    if ( is->fail() || is->bad() ) return std::nullopt;
    if ( is->peek() != std::istream::traits_type::eof() ) return std::nullopt;
    return s;
  }

  virtual const std::vector<std::string>& protocols() const = 0;
};