/// <summary>
/// Creates the lambda expression from the statements attached to this entry and the parameter definitions in the provided program context.
/// </summary>
public LambdaExpression CreateLambda(VisualProgram context)
{
if (!context.Environment.EntryDefinitions.TryGetValue(VisualEntryId, out var def))
{
throw new KeyNotFoundException($"Could not find an entry with ID '{VisualEntryId}' in the VisualProgram's entry definitions.");
}
// Create a parameter for each expected/defined parameter
var parameters = def.Parameters.Map(Expression.Parameter);
return(Expression.Lambda(
Expression.Block(
// Before doing the main body of the entry function, make expressions to copy the incoming parameters to variables
ParameterMap
.Where(mapping => !string.IsNullOrWhiteSpace(mapping.Value)) // Exclude any that don't actually map to anything
.Select(p => VariableAccessorFactory.CreateSetterExpression(
context,
VariableReference.Create(def.Parameters[p.Key], p.Value),
parameters[p.Key]
)
).Concat(
// Then do the actual main body
NodeUtils.FlattenExpressions(context, FirstStatement)
)
),
// All lambdas will get a context parameter
// We also pass the defined parameters to the lambda so it knows what types to expect and what signature to have.
// This needs to happen regardless or not of whether the parameters are actually used by the entry function as this determines the delegate's signature.
new[] { context.Variables.compiledInstanceParameter }.Concat(parameters)
));
}
