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/*
 * SonarQube JavaScript Plugin
 * Copyright (C) 2011-2018 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.javascript.se.sv;

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import java.util.Optional;
import org.sonar.javascript.se.Constraint;
import org.sonar.javascript.se.ProgramState;

import static org.sonar.javascript.se.Constraint.NAN;
import static org.sonar.javascript.se.Constraint.NEGATIVE_NUMBER_PRIMITIVE;
import static org.sonar.javascript.se.Constraint.NUMBER_PRIMITIVE;
import static org.sonar.javascript.se.Constraint.POSITIVE_NUMBER_PRIMITIVE;
import static org.sonar.javascript.se.Constraint.ZERO;
import static org.sonar.javascript.se.sv.IncDecSymbolicValue.Sign.MINUS;
import static org.sonar.javascript.se.sv.IncDecSymbolicValue.Sign.PLUS;

/**
 * This symbolic value represents "plus 1" or "minus 1" operation (used for increment and decrement)
 */
public class IncDecSymbolicValue implements SymbolicValue {

  public enum Sign {
    PLUS,
    MINUS
  }

  private static final Table CONSTRAINT_TRANSITIONS = HashBasedTable.create();

  private final Sign sign;

  private final SymbolicValue operandValue;
  public IncDecSymbolicValue(Sign sign, SymbolicValue operandValue) {
    this.sign = sign;
    this.operandValue = operandValue;
  }

  @Override
  public Optional constrainDependencies(ProgramState state, Constraint constraint) {
    return Optional.of(state);
  }

  @Override
  public Constraint baseConstraint(ProgramState state) {
    Constraint constraint = CONSTRAINT_TRANSITIONS.get(sign, state.getConstraint(operandValue));
    if (constraint == null) {
      return NUMBER_PRIMITIVE;
    }
    return constraint;
  }

  public Sign sign() {
    return sign;
  }

  static {
    CONSTRAINT_TRANSITIONS.put(PLUS, POSITIVE_NUMBER_PRIMITIVE, POSITIVE_NUMBER_PRIMITIVE);
    CONSTRAINT_TRANSITIONS.put(PLUS, NEGATIVE_NUMBER_PRIMITIVE, NEGATIVE_NUMBER_PRIMITIVE.or(ZERO));
    CONSTRAINT_TRANSITIONS.put(PLUS, ZERO, POSITIVE_NUMBER_PRIMITIVE);
    CONSTRAINT_TRANSITIONS.put(PLUS, NAN, NAN);

    CONSTRAINT_TRANSITIONS.put(MINUS, POSITIVE_NUMBER_PRIMITIVE, POSITIVE_NUMBER_PRIMITIVE.or(ZERO));
    CONSTRAINT_TRANSITIONS.put(MINUS, NEGATIVE_NUMBER_PRIMITIVE, NEGATIVE_NUMBER_PRIMITIVE);
    CONSTRAINT_TRANSITIONS.put(MINUS, ZERO, NEGATIVE_NUMBER_PRIMITIVE);
    CONSTRAINT_TRANSITIONS.put(MINUS, NAN, NAN);
  }
}