Struct Evaluator

pub struct Evaluator<'e> { /* private fields */ }

Evaluator object.

Conceptually keeps the evaluation environment as part of its internal state, because we will be repeatedly invoking the evaluator on every policy in a Slice.

Implementations

impl<'e> Evaluator<'e>

pub fn new( q: Request, entities: &'e Entities, extensions: &'e Extensions<'e>, ) -> Self

Create a fresh Evaluator for the given request, which uses the given Entities to resolve entity references. Use the given Extensions when evaluating.

pub fn evaluate(&self, p: &Policy) -> Result<bool, EvaluationError>

Evaluate the given Policy, returning either a bool or an error. The bool indicates whether the policy applies, ie, “is satisfied” for the current request. This is different than “if the current request should be allowed” – it doesn’t consider whether we’re processing a Permit policy or a Forbid policy.

pub fn partial_evaluate( &self, p: &Policy, ) -> Result<Either<bool, Expr>, EvaluationError>

Partially evaluate the given Policy, returning one of:

1. A boolean, if complete evaluation was possible
2. An error, if the policy is guaranteed to error
3. A residual, if complete evaluation was impossible The bool indicates whether the policy applies, ie, “is satisfied” for the current request. This is different than “if the current request should be allowed” – it doesn’t consider whether we’re processing a Permit policy or a Forbid policy.

pub fn interpret( &self, e: &Expr, slots: &SlotEnv, ) -> Result<Value, EvaluationError>

Interpret an Expr into a Value in this evaluation environment.

Ensures the result is not a residual. May return an error, for instance if the Expr tries to access an attribute that doesn’t exist.

pub fn partial_interpret( &self, expr: &Expr, slots: &SlotEnv, ) -> Result<PartialValue, EvaluationError>

Interpret an Expr into a Value in this evaluation environment.

May return a residual expression, if the input expression is symbolic. May return an error, for instance if the Expr tries to access an attribute that doesn’t exist.

Trait Implementations

impl Debug for Evaluator<'_>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.