PSScriptAnalyzer 2.0

PSScriptAnalyzer 2.0 seeks to re-architect the core of the PSScriptAnalyzer engine with the following goals:

• Performance: both startup and repeated use should be fast
• Hostability: it should be possible to embed PSScriptAnalyzer in other projects with a minimum of difficulty or overhead
• Code reuse: problems should be solved once and shared, solutions that are applicable to other projects should ideally go upstream
• Static reproducibility: analysis should work the same everywhere when possible and not depend on the analysis host's state
• Configurability: configuration should be preferred over opinion, and configuration mechanisms should be discoverable and self-validating

Building

To build the project, run:

./build.ps1

For now this will just produce the module.

Support

PSScriptAnalyzer 2.0 supports PowerShell 5.1 and 7, and also seeks to support PowerShell versions post-7.

There is no plan to support older versions of PowerShell to host PSScriptAnalyzer, but analyzing scripts with PowerShell 3 or 4 as a target platform is a goal.

Defining rules

A rule can currently be defined like this:

[RuleDescription("<Description of rule>")]
[Rule("<RuleName>")]
public class MyRule : ScriptRule
{
    public MyRule(RuleInfo ruleInfo)
        : base(ruleInfo)
    {
    }

    public override IEnumerable<ScriptDiagnostic> AnalyzeScript(Ast ast, IReadOnlyList<Token> tokens, string fileName)
    {
        // Implementation
    }
}

To improve performance with a TypeRuleProvider, it's possible to add other hints about the lifetime of a rule:

• The [IdempotentRule] attribute indicates that a rule instance can be reused, rather than reinstantiated each time
• The [ThreadsafeRule] attribute indicates that a rule instance can be run in parallel with other rules in an analysis run
• Implementing the IResettable interface will mean that a rule's Reset() method is called before the same instance is reused for runs
• Implementing the IDisposable interface will mean that the rule will be disposed after an analysis run

Architecture

The main entry point of PSScriptAnalyzer is the ScriptAnalyzer class. This composes:

• An IRuleExecutorFactory, which produces IRuleExecutors, which provide an execution strategy for rules (such as executing them in parallel).
• An IRuleProvider, which provides rule instances. Currently the main form of this is TypeRuleProvider, which wraps a rule type and creates a factory internally to instantiate rules of that type.