orx/orx-expression-evaluator

orx-expression-evaluator

Tools to evaluate strings containing mathematical expressions.

Expression evaluator

val expression = "x + y"
val constants = mapOf("x" to 1.0, "y" to 2.0)
evaluateExpression(expression, constants)

Built-in expression functions

Unary functions:

• abs(x)
• acos(x)
• asin(x)
• atan(x)
• ceil(x)
• cos(x)
• degrees(x)
• exps(x)
• floor(x)
• radians(x)
• round(x)
• saturate(x), clamp x to [0.0, 1.0]
• sqrt(x)
• tan(x)

Binary functions:

• atan2(x, y)
• length(x, y), the Euclidean length of the vector (x,y)
• max(x, y),
• min(x, y),
• pow(x, n)
• random(x, y), return a random number in [x, y)

Ternary functions:

• length(x, y, z), the Euclidean length of the vector (x, y, z)
• max(x, y, z)
• min(x, y, z)
• mix(l, r, f)
• smoothstep(e0, e1, x)
• sum(x, y, z)

Quaternary functions:

• length(x, y, z, w), the Euclidean length of the vector (x, y, z)
• max(a, b, c, d)
• min(a, b, c, d)
• sum(a, b, c, d)

Quinary functions:

• map(x0, x1, y0, y1, v)
• max(a, b, c, d, e)
• min(a, b, c, d, e)
• sum(a, b, c, d, e)

Compiled functions

val expression = "x * 5.0 + cos(x)"
val f = compileFunction1(expression, "x")
f(0.0)

val expression = "x * 5.0 + cos(x) * y"
val f = compileFunction2(expression, "x", "y")
f(0.0, 0.4)

Property delegates

val constants = mutableMapOf("width" to 300.0)
val settings = object {
    var xExpression = "cos(t) * 50.0 + width / 2.0"
}
val xFunction by watchingExpression1(settings::xExpression, "t", constants)

xFunction(1.0)

Demos

DemoExpressionEvaluator01

source code

DemoExpressionEvaluator02

Improved version of DemoExpressionEvaluator01, it uses [watchingExpression1] to automatically convert an expression string into a function with a parameter "t".

source code