87 lines
3.9 KiB
C++
87 lines
3.9 KiB
C++
// Copyright 2010-2018 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// The header defines an interface for functions taking and returning an int64
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// and supporting range queries over their domain and codomain.
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#ifndef OR_TOOLS_UTIL_RANGE_QUERY_FUNCTION_H_
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#define OR_TOOLS_UTIL_RANGE_QUERY_FUNCTION_H_
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#include <functional>
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#include <memory>
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#include "ortools/base/integral_types.h"
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namespace operations_research {
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// RangeIntToIntFunction is an interface to int64->int64 functions supporting
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// fast answer to range queries about their domain/codomain.
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class RangeIntToIntFunction {
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public:
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virtual ~RangeIntToIntFunction() = default;
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// Suppose f is the abstract underlying function.
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// Returns f(argument).
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// TODO(user): Rename to Run
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virtual int64 Query(int64 argument) const = 0;
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// Returns min_x f(x), where x is in [from, to).
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virtual int64 RangeMin(int64 from, int64 to) const = 0;
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// Returns max_x f(x), where x is in [from, to).
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virtual int64 RangeMax(int64 from, int64 to) const = 0;
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// Returns the first x from [range_begin, range_end) for which f(x) is in
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// [interval_begin, interval_end), or range_end if there is no such x.
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virtual int64 RangeFirstInsideInterval(int64 range_begin, int64 range_end,
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int64 interval_begin,
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int64 interval_end) const = 0;
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// Returns the last x from [range_begin, range_end) for which f(x) is in
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// [interval_begin, interval_end), or range_begin-1 if there is no such x.
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virtual int64 RangeLastInsideInterval(int64 range_begin, int64 range_end,
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int64 interval_begin,
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int64 interval_end) const = 0;
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};
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// RangeMinMaxIndexFunction is different from RangeIntToIntFunction in two ways:
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//
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// 1. It does not support codomain or value queries.
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//
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// 2. For domain queries it returns an argument where the minimum/maximum is
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// attained, rather than the minimum/maximum value.
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class RangeMinMaxIndexFunction {
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public:
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virtual ~RangeMinMaxIndexFunction() = default;
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// Suppose f is the abstract underlying function.
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// Returns an x from [from, to), such that f(x) => f(y) for every y from
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// [from, to).
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virtual int64 RangeMaxArgument(int64 from, int64 to) const = 0;
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// Returns an x from [from, to), such that f(x) <= f(y) for every y from
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// [from, to).
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virtual int64 RangeMinArgument(int64 from, int64 to) const = 0;
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};
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// A copy of f is going to be stored in the returned object, so its closure
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// should remain intact as long as the returned object is being used.
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RangeIntToIntFunction *MakeBareIntToIntFunction(std::function<int64(int64)> f);
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// It is assumed that f is defined over the interval [domain_start, domain_end).
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// The function scans f once and it is safe to destroy f and its closure after
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// MakeCachedIntToIntFunction returns.
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RangeIntToIntFunction *
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MakeCachedIntToIntFunction(const std::function<int64(int64)> &f,
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int64 domain_start, int64 domain_end);
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// It is safe to destroy the first argument and its closure after
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// MakeCachedRangeMinMaxIndexFunction returns.
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RangeMinMaxIndexFunction *
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MakeCachedRangeMinMaxIndexFunction(const std::function<int64(int64)> &f,
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int64 domain_start, int64 domain_end);
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} // namespace operations_research
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#endif // OR_TOOLS_UTIL_RANGE_QUERY_FUNCTION_H_
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