101 lines
2.3 KiB
Markdown
101 lines
2.3 KiB
Markdown
# orx-expression-evaluator
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Tools to evaluate strings containing mathematical expressions.
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# Expression evaluator
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```kotlin
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val expression = "x + y"
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val constants = mapOf("x" to 1.0, "y" to 2.0)
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evaluateExpression(expression, constants)
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```
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## Built-in expression functions
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Unary functions:
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* `abs(x)`
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* `acos(x)`
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* `asin(x)`
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* `atan(x)`
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* `ceil(x)`
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* `cos(x)`
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* `degrees(x)`
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* `exps(x)`
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* `floor(x)`
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* `radians(x)`
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* `round(x)`
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* `saturate(x)`, clamp x to [0.0, 1.0]
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* `sqrt(x)`
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* `tan(x)`
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Binary functions:
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* `atan2(x, y)`
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* `length(x, y)`, the Euclidean length of the vector (x,y)
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* `max(x, y)`,
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* `min(x, y)`,
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* `pow(x, n)`
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* `random(x, y)`, return a random number in [x, y)
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Ternary functions:
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* `length(x, y, z)`, the Euclidean length of the vector (x, y, z)
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* `max(x, y, z)`
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* `min(x, y, z)`
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* `mix(l, r, f)`
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* `smoothstep(e0, e1, x)`
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* `sum(x, y, z)`
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Quaternary functions:
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* `length(x, y, z, w)`, the Euclidean length of the vector (x, y, z)
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* `max(a, b, c, d)`
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* `min(a, b, c, d)`
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* `sum(a, b, c, d)`
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Quinary functions:
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* `map(x0, x1, y0, y1, v)`
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* `max(a, b, c, d, e)`
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* `min(a, b, c, d, e)`
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* `sum(a, b, c, d, e)`
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# Compiled functions
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```kotlin
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val expression = "x * 5.0 + cos(x)"
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val f = compileFunction1(expression, "x")
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f(0.0)
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```
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```kotlin
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val expression = "x * 5.0 + cos(x) * y"
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val f = compileFunction2(expression, "x", "y")
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f(0.0, 0.4)
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```
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# Property delegates
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```kotlin
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val constants = mutableMapOf("width" to 300.0)
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val settings = object {
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var xExpression = "cos(t) * 50.0 + width / 2.0"
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}
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val xFunction by watchingExpression1(settings::xExpression, "t", constants)
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xFunction(1.0)
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```
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<!-- __demos__ -->
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## Demos
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### DemoExpressionEvaluator01
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[source code](src/jvmDemo/kotlin/DemoExpressionEvaluator01.kt)
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### DemoExpressionEvaluator02
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Improved version of DemoExpressionEvaluator01, it uses [watchingExpression1] to automatically convert an expression
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string into a function with a parameter "t".
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[source code](src/jvmDemo/kotlin/DemoExpressionEvaluator02.kt)
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