92 lines
2.9 KiB
C++
92 lines
2.9 KiB
C++
// Copyright 2010-2025 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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#ifndef ORTOOLS_MATH_OPT_CPP_FORMATTERS_H_
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#define ORTOOLS_MATH_OPT_CPP_FORMATTERS_H_
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#include <cmath>
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#include <iostream>
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#include <ostream>
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#include "ortools/util/fp_roundtrip_conv.h"
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namespace operations_research::math_opt {
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// Streaming formatter for a coefficient of a linear/quadratic term, along with
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// any leading "+"/"-"'s to connect it with preceding terms in a sum, and
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// potentially a "*" postfix. The `is_first` parameter specifies if the term is
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// the first appearing in the sum, in which case the handling of the +/-
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// connectors is different.
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struct LeadingCoefficientFormatter {
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LeadingCoefficientFormatter(const double coeff, const bool is_first)
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: coeff(coeff), is_first(is_first) {}
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const double coeff;
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const bool is_first;
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};
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inline std::ostream& operator<<(std::ostream& out,
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const LeadingCoefficientFormatter formatter) {
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const double coeff = formatter.coeff;
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if (formatter.is_first) {
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if (coeff == 1.0) {
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// Do nothing.
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} else if (coeff == -1.0) {
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out << "-";
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} else {
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out << RoundTripDoubleFormat(coeff) << "*";
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}
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} else {
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if (coeff == 1.0) {
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out << " + ";
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} else if (coeff == -1.0) {
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out << " - ";
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} else if (std::isnan(coeff)) {
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out << " + nan*";
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} else if (coeff >= 0) {
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out << " + " << RoundTripDoubleFormat(coeff) << "*";
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} else {
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out << " - " << RoundTripDoubleFormat(-coeff) << "*";
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}
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}
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return out;
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}
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// Streaming formatter for a constant in a linear/quadratic expression.
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struct ConstantFormatter {
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ConstantFormatter(const double constant, const bool is_first)
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: constant(constant), is_first(is_first) {}
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const double constant;
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const bool is_first;
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};
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inline std::ostream& operator<<(std::ostream& out,
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const ConstantFormatter formatter) {
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const double constant = formatter.constant;
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if (formatter.is_first) {
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out << RoundTripDoubleFormat(constant);
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} else if (constant == 0) {
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// Do nothing.
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} else if (std::isnan(constant)) {
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out << " + nan";
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} else if (constant > 0) {
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out << " + " << RoundTripDoubleFormat(constant);
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} else {
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out << " - " << RoundTripDoubleFormat(-constant);
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}
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return out;
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}
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} // namespace operations_research::math_opt
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#endif // ORTOOLS_MATH_OPT_CPP_FORMATTERS_H_
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