/// <summary>
/// Instantiates a WebAssembly module for the given host.
/// </summary>
/// <param name="wasi">The WASI instance to use for WASI imports.</param>
/// <param name="host">The host to use for the WebAssembly module's instance.</param>
/// <returns>Returns a new <see cref="Instance" />.</returns>
public Instance Instantiate(Wasi wasi, IHost host = null)
{
if (!(host?.Instance is null))
{
throw new InvalidOperationException("The host has already been associated with an instantiated module.");
}
var instance = new Instance(this, wasi, host);
if (!(host is null))
{
host.Instance = instance;
return(instance);
}
return(instance);
}
internal Instance(Module module, Wasi wasi = null, IHost host = null)
{
Host = host;
Module = module;
// Save the bindings to root the objects.
// Otherwise the GC may collect the callback delegates from FunctionHandles for example.
_bindings = Binding.GetImportBindings(module, wasi, host)
.Select(b => b.Bind(module.Store, host))
.ToArray();
unsafe
{
Handle = Interop.wasm_instance_new(
Module.Store.Handle,
Module.Handle,
_bindings.Select(h => ToExtern(h)).ToArray(),
out var trap);
if (trap != IntPtr.Zero)
{
throw TrapException.FromOwnedTrap(trap);
}
}
if (Handle.IsInvalid)
{
throw new WasmtimeException($"Failed to instantiate module '{module.Name}'.");
}
Interop.wasm_instance_exports(Handle, out _externs);
Externs = new Wasmtime.Externs.Externs(Module.Exports, _externs);
_functions = Externs.Functions.ToDictionary(f => f.Name);
_globals = Externs.Globals.ToDictionary(g => g.Name);
}