uk.co.cogitolearning.cogpar.FunctionExpressionNode Maven / Gradle / Ivy
The newest version!
/*
* This software and all files contained in it are distrubted under the MIT license.
*
* Copyright (c) 2013 Cogito Learning Ltd
*
* 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 uk.co.cogitolearning.cogpar;
/**
* An ExpressionNode that handles mathematical functions.
* Some pre-defined functions are handled, others can easily be added.
*/
public class FunctionExpressionNode implements ExpressionNode {
/**
* function id for the sin function
*/
private static final int SIN = 1;
/**
* function id for the cos function
*/
private static final int COS = 2;
/**
* function id for the tan function
*/
private static final int TAN = 3;
/**
* function id for the asin function
*/
private static final int ASIN = 4;
/**
* function id for the acos function
*/
private static final int ACOS = 5;
/**
* function id for the atan function
*/
private static final int ATAN = 6;
/**
* function id for the sqrt function
*/
private static final int SQRT = 7;
/**
* function id for the exp function
*/
private static final int EXP = 8;
/**
* function id for the ln function
*/
private static final int LN = 9;
/**
* function id for the log function
*/
private static final int LOG = 10;
/**
* function id for the log2 function
*/
private static final int LOG2 = 11;
/**
* function id for the abs function
*/
private static final int ABS = 12;
/**
* the id of the function to apply to the argument
*/
private final int function;
/**
* the argument of the function
*/
private final ExpressionNode argument;
/**
* Construct a function by id and argument.
*
* @param function the id of the function to apply
* @param argument the argument of the function
*/
FunctionExpressionNode(int function, ExpressionNode argument) {
super();
this.function = function;
this.argument = argument;
}
/**
* Converts a string to a function id.
* If the function is not found this method throws an error.
*
* @param str the name of the function
* @return the id of the function
*/
static int stringToFunction(String str) {
if (str.equals("sin"))
return FunctionExpressionNode.SIN;
if (str.equals("cos"))
return FunctionExpressionNode.COS;
if (str.equals("tan"))
return FunctionExpressionNode.TAN;
if (str.equals("asin"))
return FunctionExpressionNode.ASIN;
if (str.equals("acos"))
return FunctionExpressionNode.ACOS;
if (str.equals("atan"))
return FunctionExpressionNode.ATAN;
if (str.equals("sqrt"))
return FunctionExpressionNode.SQRT;
if (str.equals("exp"))
return FunctionExpressionNode.EXP;
if (str.equals("ln"))
return FunctionExpressionNode.LN;
if (str.equals("log"))
return FunctionExpressionNode.LOG;
if (str.equals("log2"))
return FunctionExpressionNode.LOG2;
if (str.equals("abs"))
return FunctionExpressionNode.ABS;
throw new ParserException("Unexpected Function " + str + " found");
}
/**
* Returns a string with all the function names concatenated by a | symbol.
* This string is used in Tokenizer.createExpressionTokenizer to create a
* regular expression for recognizing function names.
*
* @return a string containing all the function names
*/
static String getAllFunctions() {
return "sin|cos|tan|asin|acos|atan|sqrt|exp|ln|log|log2|abs";
}
/**
* Returns the type of the node, in this case ExpressionNode.FUNCTION_NODE
*/
public int getType() {
return FUNCTION_NODE;
}
/**
* Returns the value of the sub-expression that is rooted at this node.
* The argument is evaluated and then the function is applied to the resulting
* value.
*/
public double getValue() {
switch (function) {
case SIN:
return Math.sin(argument.getValue());
case COS:
return Math.cos(argument.getValue());
case TAN:
return Math.tan(argument.getValue());
case ASIN:
return Math.asin(argument.getValue());
case ACOS:
return Math.acos(argument.getValue());
case ATAN:
return Math.atan(argument.getValue());
case SQRT:
return Math.sqrt(argument.getValue());
case EXP:
return Math.exp(argument.getValue());
case LN:
return Math.log(argument.getValue());
case LOG:
return Math.log(argument.getValue()) * 0.43429448190325182765;
case LOG2:
return Math.log(argument.getValue()) * 1.442695040888963407360;
case ABS:
return Math.abs(argument.getValue());
}
throw new EvaluationException("Invalid function id " + function + "!");
}
/**
* Implementation of the visitor design pattern.
* Calls visit on the visitor and then passes the visitor on to the accept
* method of the argument.
*
* @param visitor the visitor
*/
public void accept(ExpressionNodeVisitor visitor) {
visitor.visit(this);
argument.accept(visitor);
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy