/*
* Encog(tm) Core v3.4 - Java Version
* http://www.heatonresearch.com/encog/
* https://github.com/encog/encog-java-core
* Copyright 2008-2016 Heaton Research, Inc.
*
* 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.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.ml.prg.expvalue;
import org.encog.Encog;
/**
* Simple utility class that performs some basic operations on ExpressionValue
* objects.
*/
public final class EvaluateExpr {
/**
* Perform an add on two expression values. a+b
*
* @param a
* The first argument.
* @param b
* The second argument.
* @return The result of adding two numbers. Concat for strings. If one is a
* string, the other is converted to string. If no string, then if
* one is float, both are converted to int.
*/
public static ExpressionValue add(final ExpressionValue a,
final ExpressionValue b) {
if (a.isString() || b.isString()) {
return new ExpressionValue(a.toStringValue() + b.toStringValue());
}
if (a.isInt() && b.isInt()) {
return new ExpressionValue(a.toIntValue() + b.toIntValue());
} else {
return new ExpressionValue(a.toFloatValue() + b.toFloatValue());
}
}
/**
* Perform a division on two expression values. a/b An Encog division by
* zero exception can occur. If one param is a float, the other is converted
* to a float.
*
* @param a
* The first argument, must be numeric.
* @param b
* The second argument, must be numeric.
* @return The result of the operation.
*/
public static ExpressionValue div(final ExpressionValue a,
final ExpressionValue b) {
if (a.isInt() && b.isInt()) {
final long i = b.toIntValue();
if (i == 0) {
throw new DivisionByZeroError();
}
return new ExpressionValue(a.toIntValue() / i);
}
final double denom = b.toFloatValue();
if (Math.abs(denom) < Encog.DEFAULT_DOUBLE_EQUAL) {
throw new DivisionByZeroError();
}
return new ExpressionValue(a.toFloatValue() / denom);
}
/**
* Perform an equal on two expressions. Booleans, ints and strings must
* exactly equal. Floating point must be equal within the default Encog
* tolerance.
*
* @param a
* The first parameter to check.
* @param b
* The second parameter to check.
* @return True/false.
*/
public static ExpressionValue equ(final ExpressionValue a,
final ExpressionValue b) {
if (a.getExpressionType() == ValueType.booleanType) {
return new ExpressionValue(a.toBooleanValue() == b.toBooleanValue());
} else if (a.getExpressionType() == ValueType.enumType) {
return new ExpressionValue(a.toIntValue() == b.toIntValue()
&& a.getEnumType() == b.getEnumType());
} else if (a.getExpressionType() == ValueType.stringType) {
return new ExpressionValue(a.toStringValue().equals(
b.toStringValue()));
} else {
final double diff = Math.abs(a.toFloatValue() - b.toFloatValue());
return new ExpressionValue(diff < Encog.DEFAULT_DOUBLE_EQUAL);
}
}
/**
* Perform a multiply on two expression values. a*b If one param is a float,
* the other is converted to a float.
*
* @param a
* The first argument, must be numeric.
* @param b
* The second argument, must be numeric.
* @return The result of the operation.
*/
public static ExpressionValue mul(final ExpressionValue a,
final ExpressionValue b) {
if (a.isInt() && b.isInt()) {
return new ExpressionValue(a.toIntValue() * b.toIntValue());
}
return new ExpressionValue(a.toFloatValue() * b.toFloatValue());
}
/**
* Perform a non-equal on two expressions. Booleans, ints and strings must
* exactly non-equal. Floating point must be non-equal within the default
* Encog tolerance.
*
* @param a
* The first parameter to check.
* @param b
* The second parameter to check.
* @return True/false.
*/
public static ExpressionValue notequ(final ExpressionValue a,
final ExpressionValue b) {
if (a.getExpressionType() == ValueType.booleanType) {
return new ExpressionValue(a.toBooleanValue() != b.toBooleanValue());
} else if (a.getExpressionType() == ValueType.enumType) {
return new ExpressionValue(a.toIntValue() != b.toIntValue()
&& a.getEnumType() == b.getEnumType());
} else if (a.getExpressionType() == ValueType.stringType) {
return new ExpressionValue(!a.toStringValue().equals(
b.toStringValue()));
} else {
final double diff = Math.abs(a.toFloatValue() - b.toFloatValue());
return new ExpressionValue(diff > Encog.DEFAULT_DOUBLE_EQUAL);
}
}
/**
* Perform a protected div on two expression values. a/b If one param is a
* float, the other is converted to a float.
*
* @param a
* The first argument, must be numeric.
* @param b
* The second argument, must be numeric.
* @return The result of the operation.
*/
public static ExpressionValue pow(final ExpressionValue a,
final ExpressionValue b) {
if (a.isInt() && b.isInt()) {
return new ExpressionValue(Math.pow(a.toIntValue(), b.toIntValue()));
}
return new ExpressionValue(Math.pow(a.toFloatValue(), b.toFloatValue()));
}
/**
* Perform a protected div on two expression values. a/b Division by zero
* results in 1.
*
* @param a
* The first argument, must be numeric.
* @param b
* The second argument, must be numeric.
* @return The result of the operation.
*/
public static ExpressionValue protectedDiv(final ExpressionValue a,
final ExpressionValue b) {
if (a.isInt() && b.isInt()) {
final long i = b.toIntValue();
if (i == 0) {
return new ExpressionValue(1);
}
return new ExpressionValue(a.toIntValue() / i);
}
final double denom = b.toFloatValue();
if (Math.abs(denom) < Encog.DEFAULT_DOUBLE_EQUAL) {
return new ExpressionValue(1);
}
return new ExpressionValue(a.toFloatValue() / denom);
}
/**
* Perform a subtract on two expression values. a-b If one param is a float,
* the other is converted to a float.
*
* @param a
* The first argument, must be numeric.
* @param b
* The second argument, must be numeric.
* @return The result of the operation.
*/
public static ExpressionValue sub(final ExpressionValue a,
final ExpressionValue b) {
if (a.isInt() && b.isInt()) {
return new ExpressionValue(a.toIntValue() - b.toIntValue());
} else {
return new ExpressionValue(a.toFloatValue() - b.toFloatValue());
}
}
/**
* Private constructor.
*/
private EvaluateExpr() {
}
}
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