Expressions

Fzzy Config contains a math expression evaluation engine. It can be used to evaluate a wide array of basic math expressions with variable support. See the documentation for an overview of every supported math expression. Expressions can be chained and nested, and variables are supported via the use of Character placeholders ('x', 'y', etc)

Expression

Creating an Expression

The basis of an Expression is a string representation of the math equation you want evaluated. This string is parsed into an Expression with parse() Variable values are provided at evaluation time, see below.

// kotlin
val math = "(x + 5) ^ 2 + x"
val mathExpression = Expression.parse(math)

// java
String math = "(x + 5) ^ 2 + x";
Expression mathExpression = Expression.parse(math);

Evaluating an Expression

Once you have your expression, outputs are evaluated by passing replacement values for each placeholder character, as applicable, into the eval or evalSafe (recommended) methods.

// kotlin
val mathMap = mapOf('x' to 2.5)
val mathResult = mathExpression.evalSafe(mathMap, 20.0) // evalSafe fails soft with a fallback value. eval throws exceptions if there is a problem.

// java
Map mathMap = Map.of('x', 2.5);
double mathResult = mathExpression.evalSafe(mathMap, 20.0); // evalSafe fails soft with a fallback value. eval throws exceptions if there is a problem.

Validating an Expression

ValdiatedExpression wraps a default expression and allowable characters into a ValidatedField with GUI support etc.

// kotlin
// example validated Expression; automatically parses and caches the Math Expression input in string form.
// The user can input any equation they like as long as it uses x, y, both, or neither expected variables passed in the set
var validatedExpression = ValidatedExpression("2.5 * x ^ 2 - 45 * y", setOf('x', 'y'))

// java
// example validated Expression; automatically parses and caches the Math Expression input in string form.
// The user can input any equation they like as long as it uses x, y, both, or neither expected variables passed in the set
ValidatedExpression validatedExpression = new ValidatedExpression("2.5 * x ^ 2 - 45 * y", Set.of('x', 'y'));