ILSense

ILSense is an independent, embeddable language service for ILAsm and Common Intermediate Language (CIL). It provides context-aware completion, diagnostics, navigation, semantic tokens, and metadata-only assembly indexing for editors, language servers, and custom tooling.

The NuGet package, library assembly, and root C# namespace are named EleCho.ILSense. The product and repository name are ILSense. The project is currently pre-release, so public APIs may change before the first stable version.

Highlights

• Context-aware completion for declarations, signatures, instructions, operands, labels, assembly qualifiers, types, methods, fields, and constructors.
• IL directives, keywords, primitive types, opcode families, arguments, locals, workspace symbols, and imported metadata.
• Diagnostics with exact UTF-16 source ranges suitable for editor squiggles.
• Hover, signature help, definitions, symbols, folding, semantic tokens, and code actions.
• Metadata-only assembly indexing from files, memory, streams, sequences, and custom providers without Assembly.Load.
• Configurable completion providers, filters, rankers, insert-text formatters, diagnostic providers, compilers, and IL dialects.
• A Monaco-based Demo with LSP 3.17, IL compilation, PE inspection, and decompiled C# output.

No assembly import is required for directives, IL keywords, primitive types, or opcodes. Import assemblies only when external assembly, type, or member completion is needed.

Projects

Project	Target frameworks	Purpose
EleCho.ILSense	netstandard2.0;net10.0	Embeddable language engine and metadata catalog
EleCho.ILSense.Demo	net10.0	Monaco workbench, HTTP/LSP host, and IL build adapter

Run the Demo

Install a .NET SDK that supports .NET 10 or later, then run:

dotnet restore ILSense.slnx
dotnet run --project .\src\EleCho.ILSense.Demo\EleCho.ILSense.Demo.csproj --urls http://127.0.0.1:5187

Open http://127.0.0.1:5187. The Demo provides one IL editor with completion, diagnostics, build output, decompiled C#, PE metadata, and imported assemblies.

The Demo never executes the generated user assembly. Assembly metadata is read without loading the assembly, and compilation and artifact inspection run in bounded child processes. Those processes provide failure and timeout containment, not an operating-system sandbox.

Use the Library

After the package is published:

dotnet add package EleCho.ILSense --version 0.1.0

Create an engine and request completion from an immutable workspace snapshot:

using System.Collections.Immutable;
using EleCho.ILSense;
using EleCho.ILSense.Contracts;

var source = """
    .method public static void M() cil managed
    {
      ld
    }
    """;

var document = DocumentSnapshot.Create("Program.il", version: 1, text: source);
var workspace = new WorkspaceSnapshot(
    schemaVersion: CoreSchemaVersion.Current,
    revision: 1,
    selectionRevision: 1,
    languageId: "il",
    referenceSetId: "default",
    activeFile: document.Id,
    sourceOrder: ImmutableArray.Create(document.Id),
    files: ImmutableArray.Create(document));

IILLanguageEngine engine = ILLanguageEngine.Create();
var result = engine.Complete(new CompletionRequest(
    requestId: "example-1",
    snapshot: workspace,
    document: document.Id,
    position: new SourcePosition(line: 2, character: 4),
    trigger: CompletionTrigger.Explicit));

The same engine provides diagnostics, hover, signature help, semantic tokens, symbols, folding ranges, navigation, and build abstractions.

Import Assembly Metadata

The built-in catalog accepts file and in-memory assemblies:

using EleCho.ILSense;
using EleCho.ILSense.Metadata;
using EleCho.ILSense.Metadata.Index;

var catalog = new ILMetadataCatalog();
await catalog.AddAsync(new AssemblySource.File(@"C:\references\Example.dll"));

ReadOnlyMemory<byte> image = await File.ReadAllBytesAsync("Contracts.dll");
await catalog.AddAsync(new AssemblySource.Bytes(image, "Contracts.dll"));

var engine = ILLanguageEngine.Create(new ILLanguageEngineOptions
{
    MetadataCatalog = catalog,
});

Imported images are copied into catalog-owned immutable storage and read with PEReader and MetadataReader. ILSense does not execute module initializers or resolve runtime Type instances while indexing metadata.

Completion Behavior

Completion follows the syntactic and semantic slot at the cursor:

[|                                      -> assemblies only
[System.Con|                           -> System.Console assembly
[System.Console]System.Con|            -> System.Console type
[System.Console]System.Console::Write| -> Write/WriteLine methods

Explicit assembly scopes exclude primitive, workspace, and unrelated assembly candidates. Array shapes such as string[|] are not treated as assembly qualifiers.

Opcode families can offer both forms such as ldarg and ldarg.0. Opcode completion inserts only the opcode by default; operand snippets and the optional method marker for call can be enabled independently.

Extensibility

ILLanguageEngineOptions supports custom completion context rules, synchronous and asynchronous completion providers, filters, rankers, insert-text formatters, diagnostic providers, metadata catalogs, language services, compilers, and IL dialects. Snippet shortcuts such as cw and postfix transformations such as .await belong in host-provided completion extensions rather than the built-in ILAsm grammar.

Build and Package

The repository does not pin a specific SDK version. Any SDK that supports .NET 10 or later may be used.

dotnet restore ILSense.slnx
dotnet build ILSense.slnx -c Release --no-restore
dotnet pack .\src\EleCho.ILSense\EleCho.ILSense.csproj -c Release --no-build --no-restore -o .\artifacts\packages

Licensing

ILSense is licensed under the MIT License. Third-party components retain their respective upstream licenses.