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122 lines
2.4 KiB
C++
122 lines
2.4 KiB
C++
// Copyright (c) 2018-2019 Emil Dotchevski
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// Copyright (c) 2018-2019 Second Spectrum, Inc.
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// Program demonstrates the use of leaf::accumulate to print the path an error takes
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// as is bubbles up the call stack. The path is only printed if:
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// - An error occurrs, and
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// - A handler that takes e_error_log argument is present.
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// Otherwse none of the error log machinery will be invoked by LEAF.
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#include <boost/leaf/preload.hpp>
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#include <boost/leaf/handle_all.hpp>
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#include <boost/leaf/result.hpp>
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#include <iostream>
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#include <cstdlib>
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#define ENABLE_ERROR_LOG 1
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namespace leaf = boost::leaf;
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struct e_error_log
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{
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struct rec
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{
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char const * file;
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int line;
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friend std::ostream & operator<<( std::ostream & os, rec const & x )
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{
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return os << x.file << '(' << x.line << ')';
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}
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};
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e_error_log()
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{
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std::cerr << "Error! Log:" << std::endl;
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}
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template <class T>
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friend std::ostream & operator<<( e_error_log const &, T const & x )
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{
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return std::cerr << x << std::endl;
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}
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};
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namespace boost { namespace leaf {
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template <> struct is_e_type<e_error_log>: std::true_type { };
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} }
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#define ERROR_LOG auto _log = leaf::accumulate( [ ]( e_error_log & log ) { log << e_error_log::rec{__FILE__, __LINE__}; } )
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int const failure_percent = 25;
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leaf::result<void> f1()
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{
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ERROR_LOG;
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if( (std::rand()%100) > failure_percent )
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return { };
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else
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return leaf::new_error();
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}
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leaf::result<void> f2()
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{
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ERROR_LOG;
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if( (std::rand()%100) > failure_percent )
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return f1();
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else
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return leaf::new_error();
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}
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leaf::result<void> f3()
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{
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ERROR_LOG;
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if( (std::rand()%100) > failure_percent )
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return f2();
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else
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return leaf::new_error();
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}
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leaf::result<void> f4()
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{
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ERROR_LOG;
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if( (std::rand()%100) > failure_percent )
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return f3();
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else
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return leaf::new_error();
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}
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leaf::result<void> f5()
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{
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ERROR_LOG;
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if( (std::rand()%100) > failure_percent )
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return f4();
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else
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return leaf::new_error();
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}
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int main()
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{
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for( int i=0; i!=10; ++i )
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leaf::handle_all(
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[&]() -> leaf::result<void>
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{
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std::cout << "Run # " << i << ": ";
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LEAF_CHECK(f5());
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std::cout << "Success!" << std::endl;
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return { };
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},
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#if ENABLE_ERROR_LOG
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[ ]( e_error_log const & )
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{
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},
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#endif
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[ ]
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{
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std::cerr << "Error!" << std::endl;
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} );
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return 0;
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}
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