/// <summary>
/// Gets or adds a shared expression (created by the <paramref name="expressionFactory"/> if it's not already cached) with the given name, type, optionally
/// for the given <paramref name="requestingType"/>.
/// </summary>
/// <param name="type">The runtime type of the Expression.</param>
/// <param name="name">The runtime name of the Expression - and also the name used to retrieve it later.</param>
/// <param name="expressionFactory">The factory method to use to construct the shared expression from scratch, if it's not already cached.</param>
/// <param name="requestingType">Optional - to avoid naming clashes with shared expressions created by other targets, you can pass a type here
/// (usually the runtime type of your <see cref="ITarget"/> implementation).</param>
/// <returns>Expression.</returns>
public Expression GetOrAddSharedExpression(Type type, string name, Func <Type, string, Expression> expressionFactory, Type requestingType = null)
{
if (this._sharedExpressions == null)
{
return(ParentContext.GetOrAddSharedExpression(type, name, expressionFactory, requestingType));
}
if (type == null)
{
throw new ArgumentNullException(nameof(type));
}
if (expressionFactory == null)
{
throw new ArgumentNullException(nameof(expressionFactory));
}
// if this is
SharedExpressionKey key = new SharedExpressionKey(type, name, requestingType);
if (!this._sharedExpressions.TryGetValue(key, out Expression toReturn))
{
this._sharedExpressions[key] = toReturn = expressionFactory(type, name);
}
return(toReturn);
}
