ATLVirtualMachine

@MainActor final class ATLVirtualMachine

Overview

The ATL Virtual Machine orchestrates the execution of Atlas Transformation Language modules, coordinating matched rule evaluation, called rule invocation, and helper function execution. It provides a concurrent execution environment that maintains transformation state consistency while enabling parallel rule processing.

Overview

The virtual machine operates through several execution phases:

• Initialisation: Module validation and execution context setup

• Matched Rule Execution: Automatic rule triggering for matching elements

• Lazy Binding Resolution: Deferred property binding and reference resolution

• Called Rule Processing: Explicit rule invocation as requested

• Finalisation: Target model validation and resource cleanup

Execution Model

ATL transformations follow a hybrid declarative-imperative model:

• Declarative Phase: Matched rules execute automatically for all matching source elements

• Imperative Phase: Called rules execute on-demand through explicit invocations

• Resolution Phase: Lazy bindings resolve forward references and circular dependencies

Concurrency Design

The virtual machine is implemented as an actor to ensure thread-safe transformation execution. Rule processing can occur concurrently for independent elements while maintaining serialised access to shared transformation state.

Example Usage

let vm = ATLVirtualMachine(module: transformationModule)

try await vm.execute(
    sources: ["IN": sourceResource],
    targets: ["OUT": targetResource]
)