LUMIERA.clone/tests/library/iter-chain-search-test.cpp
Ichthyostega 05e6e7f316 ChainSearch: remould construction to get the logic correct
on closer investigation it turned out that the logic of the
first design attempt was broken altogether. It did not properly
support backtracking (which was the reason to start this whole
exercise) and it caused dangling references within the lambda
closure once the produced iterator pipeline was moved out
into the target location.

Reasoning from first principles then indicated that the only sane
way to build such a search evaluation component is to use *two*
closely collaborating layers. The actual filter configuration
and evaluation logic can not reside and work from within the
expander. Rather, it must sit in a layer on top and work in
a conventional, imperative way (with a while loop).

Sometimes, functional programming is *not* the natural way
of doing things, and we should then stop attempting to force
matters against their nature.
2018-09-16 01:08:45 +02:00

188 lines
5.9 KiB
C++

/*
IterChainSearch(Test) - verify chained search operations with backtracking
Copyright (C) Lumiera.org
2018, Hermann Vosseler <Ichthyostega@web.de>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
* *****************************************************/
/** @file iter-chain-search-test.cpp
** unit test \ref IterChainSearch_test
*/
#include "lib/test/run.hpp"
#include "lib/test/test-helper.hpp"
#include "lib/format-util.hpp" /////////////////////////////TODO necessary?
#include "lib/format-cout.hpp" /////////////////////////////TODO necessary?
#include "lib/iter-chain-search.hpp"
#include "lib/util.hpp"
#include <vector>
#include <string>
namespace lib {
namespace iter{
namespace test{
using ::Test;
using util::join;
using util::isnil;
using util::startsWith;
using util::isSameObject;
using std::vector;
using std::string;
using lumiera::error::LERR_(ITER_EXHAUST);
namespace { // test fixture
using Spam = vector<string>;
const Spam SPAM{"spam"
,"sausage"
,"spam"
,"spam"
,"bacon"
,"spam"
,"tomato"
,"and"
,"spam"
};
} // (END)fixture
///////////////////////////////////////////////////TODO WIP
#define SHOW_TYPE(_TY_) \
cout << "typeof( " << STRINGIFY(_TY_) << " )= " << lib::meta::typeStr<_TY_>() <<endl;
#define SHOW_EXPR(_XX_) \
cout << "Probe " << STRINGIFY(_XX_) << " ? = " << _XX_ <<endl;
/** Diagnostic helper: join all the elements from a _copy_ of the iterator */
template<class II>
inline string
materialise (II&& ii)
{
return util::join (std::forward<II> (ii), "-");
}
///////////////////////////////////////////////////TODO WIP
/*****************************************************************//**
* @test verify a setup for consecutive searches with backtracking.
*
* @see iter-chain-search.hpp
* @see iter-cursor.hpp
* @see [usage example](event-log.hpp)
*/
class IterChainSearch_test : public Test
{
virtual void
run (Arg)
{
simpleSearch();
chainedIteration();
backtracking();
}
/** @test simple basic use case. */
void
simpleSearch ()
{
auto search = chainSearch(SPAM)
.search("bacon")
.search("tomato");
CHECK (search);
CHECK (not isnil(search));
CHECK ("tomato" == *search);
CHECK (isSameObject (*search, SPAM[6]));
search.clearFilter();
CHECK ("tomato" == *search);
++search;
CHECK ("and" == *search);
search.search("spam");
CHECK ("spam" == *search);
CHECK (isSameObject (*search, SPAM[8]));
++search;
CHECK (not search);
CHECK (isnil (search));
VERIFY_ERROR (ITER_EXHAUST, *search);
}
/** @test verify consecutive application of several functors on the underlying filter.
* In the general case, each step in the chain is a function working on a copy of the
* current filter state. Since each such step configures its own copy of the complete
* pipeline, it may reconfigure this filter pipeline in arbitrary ways. After exhausting
* the last layer, the evaluation returns to the previous layer, but immediately re-applies
* the configuration step on the then next element.
*/
void
chainedIteration ()
{
auto search = chainSearch(SPAM)
.search([](string const& str){ return startsWith (str, "s"); });
///////////////////////////////////////////////////TODO WIP
cout << materialise (search) <<endl;
///////////////////////////////////////////////////TODO WIP
CHECK (search);
search.addStep([](auto filter)
{
string currVal = *filter;
filter.setNewFilter ([=](string const& val){
return val != currVal; });
});
///////////////////////////////////////////////////TODO WIP
cout << materialise (search) <<endl;
///////////////////////////////////////////////////TODO WIP
}
/** @test verify a complex search with backtracking.
* This becomes relevant when a given search condition can be "too greedy" for the
* complete chain to succeed. Most notably this is the case when the search is fundamentally
* reconfigured in some steps, e.g. by switching the search orientation. To demonstrate this,
* we use a "gear switching" iterator, which allows us to reverse the direction and to search
* backwards from the current position. We configure the second condition in the chain such
* that it can not succeed when starting from the first match on the first condition
*/
void
backtracking ()
{
}
};
LAUNCHER (IterChainSearch_test, "unit common");
}}} // namespace lib::iter::test