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EvalEx is a handy expression evaluator for Java, that allows to evaluate simple mathematical and boolean expressions.
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/*
 * Copyright 2018 Udo Klimaschewski
 *
 * http://UdoJava.com/
 * http://about.me/udo.klimaschewski
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package com.udojava.evalex;

/**
 * Abstract implementation of an operator.
 */
public abstract class AbstractLazyOperator implements LazyOperator {


  /**
   * This operators name (pattern).
   */
  protected String oper;

  /**
   * Operators precedence.
   */
  protected int precedence;

  /**
   * Operator is left associative.
   */
  protected boolean leftAssoc;

  /**
   * Operator is boolean.
   */
  protected boolean booleanOperator = false;

  /**
   * Operator is unary, i.e. 1 or 2 operands expected for this operator.
   */
  protected boolean unaryOperator;


  /**
   * Creates a new unary operator. This constructor allows the use of postfix unary operators.
   *
   * @param oper            The operator name (pattern).
   * @param precedence      The operators precedence.
   * @param leftAssoc       true if the operator is left associative,
   *                        else false.
   * @param booleanOperator Whether this operator is boolean.
   * @param unaryOperator   true if the expected number of operands is 1,
   *                        false if the expected number of operands is 2.
   */
  protected AbstractLazyOperator(String oper, int precedence, boolean leftAssoc,
      boolean booleanOperator, boolean unaryOperator) {
    this.oper = oper;
    this.precedence = precedence;
    this.leftAssoc = leftAssoc;
    this.booleanOperator = booleanOperator;
    this.unaryOperator = unaryOperator;
  }


  /**
   * Creates a new boolean operator.
   *
   * @param oper            The operator name (pattern).
   * @param precedence      The operators precedence.
   * @param leftAssoc       true if the operator is left associative,
   *                        else false.
   * @param booleanOperator Whether this operator is boolean.
   */
  protected AbstractLazyOperator(String oper, int precedence, boolean leftAssoc,
      boolean booleanOperator) {
    this.oper = oper;
    this.precedence = precedence;
    this.leftAssoc = leftAssoc;
    this.booleanOperator = booleanOperator;
    this.unaryOperator = false;
  }


  /**
   * Creates a new operator.
   *
   * @param oper       The operator name (pattern).
   * @param precedence The operators precedence.
   * @param leftAssoc  true if the operator is left associative,
   *                   else false.
   */
  protected AbstractLazyOperator(String oper, int precedence, boolean leftAssoc) {
    this.oper = oper;
    this.precedence = precedence;
    this.leftAssoc = leftAssoc;
    this.unaryOperator = false;
  }


  /**
   * @return The String that is used to denote the operator in the expression.
   */
  public String getOper() {
    return oper;
  }


  /**
   * @return the precedence value of this operator.
   */
  public int getPrecedence() {
    return precedence;
  }


  /**
   * @return true if this operator is left associative.
   */
  public boolean isLeftAssoc() {
    return leftAssoc;
  }


  /**
   * @return true if this operator evaluates to a boolean
   * expression.
   */
  public boolean isBooleanOperator() {
    return booleanOperator;
  }


  /**
   * @return true if the number of operands for this operator is 1,
   * or false if the number of operands is 2.
   */
  public boolean isUnaryOperator() {
    return unaryOperator;
  }

}