Ichthyostega
a90b9e5f16
In the Lumiera code base, we use C-String constants as unique error-IDs. Basically this allows to create new unique error IDs anywhere in the code. However, definition of such IDs in arbitrary namespaces tends to create slight confusion and ambiguities, while maintaining the proper use statements requires some manual work. Thus I introduce a new **standard scheme** * Error-IDs for widespread use shall be defined _exclusively_ into `namespace lumiera::error` * The shorthand-Macro `LERR_()` can now be used to simplify inclusion and referral * (for local or single-usage errors, a local or even hidden definition is OK)
225 lines
9.1 KiB
C++
225 lines
9.1 KiB
C++
/*
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IterChainSearch(Test) - verify chained search operations with backtracking
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Copyright (C) Lumiera.org
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2018, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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* *****************************************************/
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/** @file iter-chain-search-test.cpp
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** unit test \ref IterChainSearch_test
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*/
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#include "lib/test/run.hpp"
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#include "lib/test/test-helper.hpp"
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#include "lib/format-util.hpp"
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#include "lib/iter-chain-search.hpp"
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#include "lib/iter-cursor.hpp"
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#include "lib/util.hpp"
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#include <vector>
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#include <string>
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namespace lib {
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namespace iter{
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namespace test{
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using ::Test;
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using util::join;
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using util::isnil;
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using util::startsWith;
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using util::isSameObject;
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using std::vector;
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using std::string;
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using LERR_(ITER_EXHAUST);
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namespace { // test fixture
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using Spam = vector<string>;
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const Spam SPAM{"spam"
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,"sausage"
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,"spam"
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,"spam"
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,"bacon"
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,"spam"
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,"tomato"
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,"and"
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,"spam"
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};
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/** Diagnostic helper: join all the elements from a _copy_ of the iterator */
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template<class II>
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inline string
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materialise (II&& ii)
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{
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return util::join (std::forward<II> (ii), "-");
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}
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}// (END)fixture
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/*****************************************************************//**
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* @test verify a setup for consecutive searches with backtracking.
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* - demonstrate simple consecutive matches and iterator behaviour
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* - clear the filter underway and thus return to simple iteration
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* - set up two conditions, the second one capturing state at the
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* point where the first one matches
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* - wrap a lib::IterCursor, which allows to toggle the search
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* direction underway; this creates a situation where the
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* first options picked do not lead to a successful solution,
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* so the search has to track back, try further options and
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* in each case re-apply all the following consecutive
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* search conditions.
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*
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* @see iter-chain-search.hpp
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* @see iter-cursor.hpp
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* @see [usage example](\ref event-log.hpp)
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*/
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class IterChainSearch_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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simpleSearch();
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chainedIteration();
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backtracking();
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}
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/** @test simple basic use case. */
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void
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simpleSearch ()
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{
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auto search = chainSearch(SPAM)
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.search("bacon")
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.search("tomato");
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CHECK (search);
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CHECK (not isnil(search));
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CHECK ("tomato" == *search);
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CHECK (isSameObject (*search, SPAM[6]));
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search.clearFilter();
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CHECK ("tomato" == *search);
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++search;
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CHECK ("and" == *search);
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search.search("spam");
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CHECK ("spam" == *search);
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CHECK (isSameObject (*search, SPAM[8]));
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++search;
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CHECK (not search);
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CHECK (isnil (search));
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VERIFY_ERROR (ITER_EXHAUST, *search);
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}
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/** @test verify consecutive application of several functors on the underlying filter.
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* In the general case, each step in the chain is a function working on a copy of the
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* current filter state. Since each such step configures its own copy of the complete
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* pipeline, it may reconfigure this filter pipeline in arbitrary ways. After exhausting
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* the last layer, the evaluation returns to the previous layer, but immediately re-applies
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* the configuration step on the then next element.
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*/
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void
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chainedIteration ()
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{
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auto search = chainSearch(SPAM) // Note: 1st filter step picks all s-words
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.search([](string const& str){ return startsWith (str, "s"); });
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CHECK (materialise (search) =="spam-sausage-spam-spam-spam-spam");
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CHECK ("spam" == *search);
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search.addStep([](auto& filter)
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{ // Note: pick the current value at the point
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string currVal = *filter; // where the 2nd filter step is (re)applied
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filter.setNewFilter ([=](string const& val) // ...and bake this value into the lambda closure
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{
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return val != currVal;
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});
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});
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CHECK ("sausage" == *search);
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CHECK (materialise (search)
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== "sausage-bacon-tomato-and-" // everything in the rest, which is not "spam"
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"spam-spam-bacon-spam-tomato-and-spam-" // everything starting at "sausage" which is not "sausage"
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"bacon-tomato-and-" // any non-spam behind the 2nd spam
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"bacon-tomato-and-" // any non-spam behind the 3rd spam
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"tomato-and" // any non-spam behind the 4th spam
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""); // and any non-spam behind the final spam
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}
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/** @test verify a complex search with backtracking.
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* This becomes relevant when a given search condition can be "too greedy" for the
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* complete chain to succeed. Most notably this is the case when the search is fundamentally
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* reconfigured in some steps, e.g. by switching the search orientation. To demonstrate this,
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* we use a "gear switching" iterator, which allows us to reverse the direction and to search
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* backwards from the current position. We configure the second condition in the chain such
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* that it can not succeed when starting from the first match on the first condition
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*/
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void
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backtracking ()
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{
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using Cursor = IterCursor<decltype(SPAM.begin())>;
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auto search = chainSearch(Cursor{SPAM.begin(), SPAM.end()})
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.search("spam")
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.addStep([](auto& filter)
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{
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filter.switchBackwards(); // switch search direction without moving the cursor
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filter.flipFilter(); // flip from match on "spam" to match on non-spam
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})
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.addStep([](auto& filter)
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{ // filter is still configured to search non-spam backwards
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++filter; // just "advance" this filter by one step (backward)
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});
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CHECK (materialise (search) // Layer-0: 1-3 spam fail altogether, too greedy. Try 4rd spam....
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// Layer-1: turn back, toggle to non-spam, find bacon
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== "sausage-" // Layer-2: non-spam and one step further backwards yields sausage
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//
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// BACKTRACK to Layer-0: pick 5th (and last) spam...
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// Layer-1: turn back, toggle to non-spam, find "and"
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"tomato-bacon-sausage-" // Layer-2: non-spam and one step back yields tomato, next bacon, next sausage.
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// BACKTRACK to Layer-1: take previous one, which is tomato
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"bacon-sausage-" // Layer-2: non-spam and one step further back yields bacon, then next sausage.
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// BACKTRACK to Layer-1: take previous non-spam, which is bacon
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"sausage" // Layer-2: non-spam and one step further back yields sausage.
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""); // BACKTRACK to Layer-1: exhausted, BACKTRACK to Layer-0: exhausted. Done.
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}
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};
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LAUNCHER (IterChainSearch_test, "unit common");
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}}} // namespace lib::iter::test
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