https://github.com/jeevanjames/policyevaluation

Library for evaluating policies in a logical expression
https://github.com/jeevanjames/policyevaluation

Last synced: about 1 month ago
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Library for evaluating policies in a logical expression

• Host: GitHub
• URL: https://github.com/jeevanjames/policyevaluation
• Owner: JeevanJames
• License: mit
• Created: 2023-08-26T13:23:13.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2024-01-10T18:45:17.000Z (10 months ago)
• Last Synced: 2024-10-09T16:32:59.871Z (about 1 month ago)
• Language: C#
• Size: 96.7 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 10
• Metadata Files:
  • Readme: README.md
  • Contributing: .github/CONTRIBUTING.md
  • License: LICENSE
  • Code of conduct: .github/CODE_OF_CONDUCT.md
  • Security: .github/SECURITY.md

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# PolicyEvaluation

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PolicyEvaluation is a small library for parsing logical expressions containing policy names, to evaluate if the expression passes or fails. The policy evaluation itself is provided externally (through a delegate); the main job of this library is to evaluate the policies in the context of a logical expression.

A few sample expressions (where `Policy1`, `Policy2`, `Policy3` and `Policy4` are policy names):

* `Policy1 AND Policy2`

* `Policy1 OR Policy2`

* `Policy1 AND (Policy2 OR Policy3)`

* `(Policy1 AND Policy2) OR Policy3`

* `(Policy1 OR Policy2) AND (Policy3 OR Policy4)`

Rules for expressions:

* Policy names should start with a letter, followed by alphanumeric characters and underscores.

* Only AND and OR logical operators are allowed, and they are case-sensitive.

* Nesting is allowed using parentheses. Only one level of nesting is allowed.

## Installation

Via Package Manager:

```

PM> Install-Package Jeevan.PolicyEvaluation

```

Via `dotnet` CLI:

```

dotnet add package Jeevan.PolicyEvaluation

dotnet add  package Jeevan.PolicyEvaluation

```

## Usage

```cs

// Import the namespace Jeevan.PolicyEvaluation

using Jeevan.PolicyEvaluation;

// Declare a function to evaluate a policy, given its name.

Func policyEvaluatorLogic = policyName =>

{

    // Perform policy evaluation here.

    // Use methods from PolicyOutcome to generate the result.

};

// Instantiate the PolicyEvaluator class

PolicyEvaluator evaluator = new(policyEvaluatorLogic);

// Call the EvaluateExpression method to evaluate an expression.

const string expression = "Policy1 AND (Policy2 OR Policy3)";

var result = evaluator.EvaluateExpression(expression);

// You can check whether the expression was satisfied.

if (result.IsSatisfied)

    Console.WriteLine("Expression was satisfied.");

// OR you can check whether the expression was not satisfied and get the reason and which policy

// caused the expression to fail.

if (result.IsNotSatisfied(out string? policyName, out string? failureMessage))

    Console.WriteLine($"Policy {policyName} failed with error {failureMessage}.");

```