lumiera_documentation/tests/library/iter-chain-search-test.cpp
Ichthyostega 29d2c151b3 ChainSearch: add builder function just to replace the filter
Up to now, we had a very simplistic configuration option just
to search for a match, and we had the complete full-blown reconfiguration
builder option, which accepts a functor to work on and reconfigure the
embedded Filter chain.

It occurred to me that in many cases you'd rather want some intermediary
level of flexibility: you want to replace the filter predicate entirely
by some explicitly given functor, yet you don't need the full ability
to re-shape the Filter chain as a whole. In fact the intended use case
for IterChainSearch (which is the EventLog I am about to augment with
backtracking capabilities) will only ever need that intermediate level.


Thus wer're adding this intermediary level of configurability now.

The only twist is that doing so requires us to pass an "arbitrary function like thing"
(captured by universal reference) through a "layer of lambdas". Which means,
we have to capture an "arbitrary thingie" by value.

Fortunately, as I just found out today, C++14 allows something which comes
close to that requirement: the value capture of a lambda is allowe to have
an intialiser. Which means, we can std::forward into the value captured
by the intermediary lambda. I just hope I never need to know or understand
the actual type this captured "value" takes on.... :-)
2018-09-14 21:06:15 +02:00

177 lines
5.4 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
}
/** @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