AffineExpression.java

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// Copyright 2010-2021 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.ortools.sat;

public final class AffineExpression implements LinearExpr {
  private final int varIndex;
  private final long coefficient;
  private final long offset;

  public AffineExpression(int varIndex, long coefficient, long offset) {
    this.varIndex = varIndex;
    this.coefficient = coefficient;
    this.offset = offset;
  }

  // LinearArgument interface.
  @Override
  public LinearExpr build() {
    return this;
  }

  // LinearExpr interface.
  @Override
  public int numElements() {
    return 1;
  }

  @Override
  public int getVariableIndex(int index) {
    if (index != 0) {
      throw new IllegalArgumentException("wrong index in LinearExpr.getIndex(): " + index);
    }
    return varIndex;
  }

  @Override
  public long getCoefficient(int index) {
    if (index != 0) {
      throw new IllegalArgumentException("wrong index in LinearExpr.getCoefficient(): " + index);
    }
    return coefficient;
  }

  @Override
  public long getOffset() {
    return offset;
  }
}