JarCastingFormula Evaluator
Goal
Goal of this Library is to make calculation codes with BigDecimals much more readable and a lot of Java Code. By defining the formula with a string expression, the code should be better understandable and maintainable.
Usage
Simple usage:
BigDecimal result = FormulaEvaluator.create("IF(a >= 8, a * betta ^ 3, a / gamma)")
.with("a", a).and("beta", beta).and("gamma", gamma)
.eval();
Configuration option
Precisions
Define with which precision the calculations should be performed.
Methods:
setPrecision(int): Sets calculation and result precisionsetResultPrecision(int): Sets result precisionsetCalculationPrecision(int): Sets calculation precision (see MathContext)
Rounding modes
Define how values should be rounded.
Method: setRoundingMode(RoundingMode): Sets the rounding Mode (see RoundingMode)
Default NULL handling
Define the generic behavior of null values.
Method: setDefaultNullHandling(DefaultNullHandling)
Available options:
EXCEPTION: Throw an exception if one value is null (default).NULL: Return null if at least one value of an operation or function is nullZERO: Null is equal to 0
Example:
BigDecimal result = FormulaEvaluator.create("a / b")
.setDefaultNullHandling(NULL)
.with("a", null)
.with("b", ONE)
.eval();
Specific NULL handling
Define for some basic operations their handling of null values.
Methods: setPlusMinusNullHandling(BasicOperationsNullHandling) setMultiplicationNullHandling(BasicOperationsNullHandling) setDivisionNullHandling(BasicOperationsNullHandling)
Available options:
INHERIT: Use default handling (default).IDENTITY: Operation should return the same value (+-: 0, */: 1)
Specific Division through zero handling
Define how the calculation should behave on division by zero.
Method:
setDivisionByZeroHandling(DivisionByZeroHandling)
Available options:
INHERIT: Inherit checks from default.ONE: Zero is treated as 1. (a / 0 = a)NULL: When denominator is zero it returns null.
Supported operators and functions
Operators
+(Addition)-(Subtraction)*(Multiplication)/(Division)%(Modulo)^(Exponentiation)&&(logical and)||(logical or)>(greater)>=(greater equal)<(smaller)<=(smaller equal)==or=(greater)!=or<>(not equal)
Functions
NOT(term)IF(condTerm, trueTerm, falseTerm)RANDOM()SIN(term),COS(term),TAN(term),SINH(term),COSH(term),TANH(term)DEG(term),RAD(term)MIN(term1, term2),MAX(term1, term2)LOG(term),LOG10(term)ROUND(valueTerm, precisionTerm)FLOOR(term)CEILING(term)ABS(term)SQRT(term)
Additional operators and functions
It is possible to extend the FormulaEvaluator with custom Operators and Functions by registering them in BigDecimalTermFactory
How does it works
- In a first step the formula will be parsed and converted into PRN notation
- As next based on the PRN a calculation tree is built up which will later be used for the calculations
- Now this tree (Term) can be evaluated by passing all variables
Caching
Already evaluated and built up terms will be cached to improve future calculations.