Pat Garrity
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108 lines
2.7 KiB
Scala
108 lines
2.7 KiB
Scala
package gs.predicate.v0.api
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/** A _Predicate_ is some function that accepts any input and emits some
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* [[Predicate.Result]] (whether the predicate matched).
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*
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* Predicates evaluate input to see if the logic matches that input.
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*/
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trait Predicate:
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/** @return
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* The serializable predicate type.
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*/
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def predicateType: String
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/** Evaluate this predicate against the given input.
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*
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* @return
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* Some [[Predicate.Result]] that describes whether the input matched the
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* predicate.
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*/
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def eval(input: Any): Predicate.Result
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end Predicate
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object Predicate:
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def alwaysTrue: Predicate = True
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def alwaysFalse: Predicate = False
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/** The result of evaluating a [[Predicate]] is a Boolean value where:
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*
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* - `true`: The predicate matched the given input.
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* - `false`: The predicate missed (did not match) the given input.
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*/
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opaque type Result = Boolean
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object Result:
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/** @return
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* A result indicating a predicate matched (`true`).
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*/
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def matched(): Result = true
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/** @return
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* A result indicating a predicate missed (`false`).
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*/
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def missed(): Result = false
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/** Instantiate a new [[Predicate.Result]] from the given value.
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*
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* @param value
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* The underlying `Boolean` value.
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* @return
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* The new predicate result.
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*/
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def apply(value: Boolean): Result = value
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given CanEqual[Result, Result] = CanEqual.derived
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extension (results: List[Result])
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/** @return
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* True if all results are true. False if no results are given.
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*/
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def allMatch(): Result = results.nonEmpty && results.forall(x => x)
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/** @return
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* True if any results match. False if no results are given.
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*/
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def anyMatch(): Result =
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results.nonEmpty && results.find(x => x).isDefined
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extension (result: Result)
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/** @return
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* The underlying value.
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*/
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def unwrap(): Boolean = result
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/** Logical AND operation.
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*
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* @param other
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* The other result.
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* @return
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* True if both results match. False otherwise.
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*/
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def and(other: Result): Result = result && other
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/** Logical OR operation.
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*
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* @param other
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* The other result.
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* @return
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* True if either result matches. False otherwise.
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*/
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def or(other: Result): Result = result || other
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/** @return
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* True if this result is a match. False otherwise.
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*/
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def isMatch: Boolean = result
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/** @return
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* True if this result is a miss. False otherwise.
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*/
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def isMiss: Boolean = !result
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end Result
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end Predicate
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