Ichthyostega
fea2bfde7a
- complete documentation - add extensive test coverage for use of the accessors - demonstrate a more contrieved example, including the dangers
316 lines
14 KiB
C++
316 lines
14 KiB
C++
/*
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HeteroData(Test) - verify maintaining chained heterogeneous data in local storage
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Copyright (C)
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2024, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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* *****************************************************************/
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/** @file del-stash-test.cpp
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** unit test \ref HeteroData_test
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*/
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#include "lib/test/run.hpp"
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#include "lib/hetero-data.hpp"
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#include "lib/meta/trait.hpp"
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#include "lib/test/test-helper.hpp"
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#include "lib/uninitialised-storage.hpp"
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#include "lib/util.hpp"
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#include <string>
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namespace lib {
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namespace test{
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using std::string;
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using meta::is_Subclass;
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using util::isSameObject;
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using util::isSameAdr;
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using util::getAdr;
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/******************************************************************//**
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* @test maintain a sequence of data tuples in local storage,
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* providing pre-configured type-safe data access.
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* - the initial block is just a tuple of data in local storage
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* - but further extension segments can be created _elsewhere_
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* and attached to an existing chain
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* - a compile-time »overlay« of constructor- and accessor-functors
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* is provided as _guard rails_ to prevent out-of bounds access.
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* @see lib::HeteroData
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* @see NodeBase_test::verify_TurnoutSystem()
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*/
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class HeteroData_test : public Test
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{
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virtual void
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run (Arg)
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{
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simpleUsage();
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verify_FrontBlock();
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verify_ChainBlock();
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verify_Accessors();
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}
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void
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simpleUsage()
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{
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using F = lib::HeteroData<uint,double>; // define type of the front-end segment
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auto h1 = F::build (1,2.3); // build the front-end, including first data tuple
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using C = F::Chain<bool,string>; // define a constructor type for a follow-up segment
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auto b2 = C::build (true, "Ψ"); // build this follow-up segment free-standing
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b2.linkInto(h1); // link it as second segment into the chain
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C::AccessorFor<string> get4; // get an accessor functor (picked by value type)
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CHECK (get4(h1) == "Ψ"); // use accessor on front-type (involves force-cast)
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}
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/** @test build a free standing data tuple block to start a chain */
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void
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verify_FrontBlock()
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{
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using Block1 = HeteroData<uint,double>;
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CHECK ((is_Subclass<Block1::NewFrame, std::tuple<uint,double>>()));
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auto b1 = Block1::build (42, 1.61803);
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CHECK (1.61803 == b1.get<1>());
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CHECK (42 == b1.get<0>());
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CHECK (showType<Block1::Elm_t<0>>() == "uint"_expect);
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CHECK (showType<Block1::Elm_t<1>>() == "double"_expect);
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Block1 b2;
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CHECK (0.0 == b2.get<1>());
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b2.get<1>() = 3.14;
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CHECK (3.14 == b2.get<1>());
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CHECK (2 == std::tuple_size_v<Block1::NewFrame::Tuple>); // referring to the embedded tuple type
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CHECK (2 == std::tuple_size_v<Block1::NewFrame>); // StorageFrame itself complies to the C++ tuple protocol
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CHECK (2 == std::tuple_size_v<Block1>); // likewise for the complete HeteroData Chain
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auto& [_,p] = b2; // can use structured bindings...
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CHECK (p == 3.14);
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p = 3.14159;
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CHECK (3.14159 == b2.get<1>());
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}
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/** @test construct a follow-up data tuple block and hook it into the chain */
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void
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verify_ChainBlock()
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{
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using Block1 = HeteroData<uint>;
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CHECK ((is_Subclass<Block1::NewFrame, std::tuple<uint>>()));
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using Constructor = Block1::Chain<double,string>;
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using Block2 = Constructor::NewFrame;
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CHECK ((is_Subclass<Block2, std::tuple<double, string>>()));
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auto b1 = Block1::build (41);
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auto b2 = Constructor::build (1.61, "Φ");
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b2.linkInto(b1);
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using Chain2 = Constructor::ChainType;
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Chain2& chain2 = Constructor::recast (b1);
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CHECK (b1.size() == 1);
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CHECK (chain2.size() == 3);
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CHECK (41 == chain2.get<0>());
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CHECK (1.61 == chain2.get<1>());
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CHECK ("Φ" == chain2.get<2>());
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chain2.get<0>()++;
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chain2.get<1>() = (1 + sqrt(5)) / 2;
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CHECK (b1.get<0>() == 42);
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CHECK (chain2.get<0>() == 42);
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CHECK (std::get<0> (b2) == "1.618034"_expect);
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CHECK (isSameObject (chain2.get<0>() ,b1.get<0>()));
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CHECK (isSameObject (chain2.get<2>() ,std::get<1>(b2)));
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CHECK (1 == std::tuple_size_v<Block1::NewFrame::Tuple>); // referring to the embedded tuple type
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CHECK (1 == std::tuple_size_v<Block1::NewFrame>);
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CHECK (1 == std::tuple_size_v<Block1>);
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CHECK (2 == std::tuple_size_v<Block2::Tuple>); // referring to the embedded tuple type
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CHECK (2 == std::tuple_size_v<Block2>);
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CHECK (3 == std::tuple_size_v<Chain2>);
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CHECK ((showType<std::tuple_element_t<0, Chain2>>() == "uint"_expect));
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CHECK ((showType<std::tuple_element_t<1, Chain2>>() == "double"_expect));
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CHECK ((showType<std::tuple_element_t<2, Chain2>>() == "string"_expect));
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CHECK ((showType<std::tuple_element_t<0, Block2>>() == "double"_expect));
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CHECK ((showType<std::tuple_element_t<1, Block2>>() == "string"_expect));
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// CHECK (std::get<0> (chain2) == "42"_expect); // std::tuple is inaccessible base of HeteroData
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CHECK (std::get<0> (b2) == "1.618034"_expect);
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// CHECK (std::get<1> (chain2) == "1.618034"_expect); // does not compile due to range restriction for the base tuple
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// (as such this is correct — yet prevents definition of a custom get-function)
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auto& [u0] = b1;
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CHECK (u0 == "42"_expect);
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auto& [v0,v1] = b2; // b2 is typed as StorageFrame and thus the tuple base is accessible
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CHECK (v0 == "1.618034"_expect);
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CHECK (v1 == "Φ"_expect);
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auto& [x0,x1,x2] = chain2; // Note: structured binding on the fully typed chain uses the get<i>-Member
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CHECK (x0 == "42"_expect);
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CHECK (x1 == "1.618034"_expect);
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CHECK (x2 == "Φ"_expect);
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// auto& [z0,z1,z2,z3] = chain2; // Error: 4 names provided for structured binding, while HeteroData... decomposes into 3 elements
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// auto& [z0,z1,z2] = b1; // Error: HeteroData<Node<StorageFrame<0, uint>, NullType> >' decomposes into 1 element
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}
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/** @test demonstrate elaborate storage layout with several chain frames
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* - follow-up frames shall be built using constructor types
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* - these can be defined prior to any data allocation
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* - individual data elements can be accessed type-safe through accessor functors
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* @warning as demonstrated, this is a dangerous bare-bone memory layout without runtime checks!
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*/
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void
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verify_Accessors()
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{
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using Front = lib::HeteroData<uint,double>;
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using Cons2 = Front::Chain<bool,string>;
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using Data2 = Cons2::NewFrame;
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using List2 = Cons2::ChainType;
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using Acc4 = Cons2::AccessorFor<string>;
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using Acc3 = Cons2::AccessorFor<bool>;
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using Acc2 = Front::Accessor<1>;
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using Acc1 = Front::Accessor<0>;
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using Cons3 = Cons2::ChainExtent<CStr,string>;
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using Data3 = Cons3::NewFrame;
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using List3 = Cons3::ChainType;
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using Acc5 = Cons3::AccessorFor<CStr>;
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using Acc6 = Cons3::AccessorFor<string>;
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CHECK (2 == Front::size());
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CHECK (4 == List2::size());
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CHECK (6 == List3::size());
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//
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// Note: up to now, not a single actual data element has been created
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// Moreover, individual blocks can be created in any order...
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Data2 d2;
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d2.get<1>() = "Ψ";
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Front front;
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CHECK (front.get<1>() == 0.0);
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front.get<1>() = 2.3;
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// Note the pitfall: Chain has not been connected yet,
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// but the Accessors would assume otherwise
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CHECK (Acc2::get(front) == 2.3);
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// Acc3::get(front); // would cause NPE (or assertion failure on debug build)
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Acc4 get4; // could even instantiate the accessors...
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CHECK (sizeof(get4) == 1); // (empty marker object with static methods)
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// get4(front); // likewise NPE or assertion fail
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// Now link the second data element in properly
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d2.linkInto(front);
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CHECK (Acc1::get(front) == 0);
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CHECK (Acc2::get(front) == 2.3);
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CHECK (Acc3::get(front) == false);
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CHECK (get4(front) == "Ψ");
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// further allocations can even be »elsewhere«
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const void* loc;
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{
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Acc6 get6;
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auto magic = Cons3::build("magic","cloud");
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loc = getAdr(magic);
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CHECK (magic.get<0>() == "magic"_expect);
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CHECK (magic.get<1>() == "cloud"_expect);
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// link into the cloud...
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magic.linkInto(front);
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CHECK (get6(front) == "cloud");
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}// aaand...
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// it's gone
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// Evil, evil...
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lib::UninitialisedStorage<Data3, 1> evilSpace;
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Data3& d3 = evilSpace[0]; // note: working with left-over data from expired stack frame
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CHECK (isSameAdr (d3, loc));
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CHECK (d3.get<0>() == "magic"_expect); // const char* points into static data, so the chars are still there
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new(&d3.get<1>()) string{"mushrooms"}; // the "cloud"-string was destroyed by magic's destructor
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auto& [v1,v2,v3,v4,v5,v6] = Cons3::recast(front); // using connectivity from the linked list connecting the segments
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CHECK (v1 == "0"_expect);
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CHECK (v2 == "2.3"_expect);
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CHECK (v3 == "false"_expect);
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CHECK (v4 == "Ψ"_expect);
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CHECK (v5 == "magic"_expect);
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CHECK (v6 == "mushrooms"_expect);
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v1 = 42;
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v2 = 5.5;
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v3 = true;
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CHECK (front.get<0>() == 42);
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CHECK (front.get<1>() == 5.5);
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CHECK (d2.get<0>() == true);
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CHECK (d2.get<1>() == "Ψ");
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CHECK (isSameAdr (Acc1::get(front), v1));
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CHECK (isSameAdr (Acc2::get(front), v2));
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CHECK (isSameAdr (Acc3::get(front), v3));
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CHECK (isSameAdr (Acc4::get(front), v4));
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CHECK (isSameAdr (Acc5::get(front), v5));
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CHECK (isSameAdr (Acc6::get(front), v6));
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CHECK (not isSameAdr (front, v1));
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CHECK (not isSameAdr (d2, v3));
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CHECK (not isSameAdr (d3, v5));
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// we can directly re-cast into another typed front-end
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List3& fullChain = Cons3::recast(front);
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CHECK (isSameAdr (fullChain.get<2>(), std::get<0>(d2)));
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CHECK (isSameAdr (fullChain.get<3>(), std::get<1>(d2)));
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CHECK (isSameAdr (fullChain.get<4>(), std::get<0>(d3)));
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CHECK (isSameAdr (fullChain.get<5>(), std::get<1>(d3)));
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CHECK (isSameAdr (fullChain.get<0>(), v1));
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CHECK (isSameAdr (fullChain.get<1>(), v2));
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CHECK (isSameAdr (fullChain.get<2>(), v3));
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CHECK (isSameAdr (fullChain.get<3>(), v4));
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CHECK (isSameAdr (fullChain.get<4>(), v5));
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CHECK (isSameAdr (fullChain.get<5>(), v6));
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// we can even use partially specified chains
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List2& partChain = Cons2::recast(fullChain);
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CHECK (isSameAdr (partChain.get<0>(), v1));
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CHECK (isSameAdr (partChain.get<1>(), v2));
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CHECK (isSameAdr (partChain.get<2>(), v3));
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CHECK (isSameAdr (partChain.get<3>(), v4));
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// Note: basically we are still using stale memory,
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// previously allocated to the "magic" block,
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// and now covered by the UninitialisedStorage
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CHECK (loc == & d3);
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CHECK (loc < & v5);
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CHECK (loc < & v6);
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// structural binding on partial chains is limited
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CHECK (partChain.size() == 4);
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auto& [w1,w2,w3,w4] = partChain;
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CHECK (isSameObject (v1, w1));
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CHECK (isSameObject (v2, w2));
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CHECK (isSameObject (v3, w3));
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CHECK (isSameObject (v4, w4));
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}
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};
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/** Register this test class... */
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LAUNCHER (HeteroData_test, "unit common");
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}} // namespace lib::test
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