ExprK

A simple mathematical expression evaluator for Kotlin and Java, written in Kotlin.

Features:

• Uses BigDecimal for calculations and results
• Allows you to define variables using values or expressions
• Variable definition expressions can reference previously defined variables
• Configurable precision and rounding mode
• Functions and the ability to define new ones

Supported operators

Arithmetic operators

Logical operators

Pre-defined variables

Pre-defined functions

Examples:

val result = Expressions()
    .eval("(5+5)*10") // returns 100

You can define variables with the define method.

val result = Expressions()
    .define("x", 5)
    .eval("x*10") // returns 50

The define method returns the expression instance to allow chaining definition method calls together.

val result = Expressions()
    .define("x", 5)
    .define("y", "5*2")
    .eval("x*y") // returns 50

Variable definition expressions can reference previously defined variables.

val result = Expressions()
    .define("x", 5)
    .define("y", "x^2")
    .eval("y*x") // returns 125

You can add new functions with the addFunction method.

val result = Expressions()
    .addFunction("min") { arguments ->
        if (arguments.isEmpty()) throw ExpressionException(
                "min requires at least one argument")

        arguments.min()!!
    }
    .eval("min(4, 8, 16)") // returns 4

You can set the precision and rounding mode with setPrecision and setRoundingMode.

val result = Expressions()
    .setPrecision(128)
    .setRoundingMode(RoundingMode.UP)
    .eval("222^3/5.5")