/// <summary>
/// Gets the function as specified by the function key.
/// All parameters are assumed to be <see cref="ParameterMode.In"/>.
/// </summary>
/// <param name="functionName">Name of the function</param>
/// <param name="parameterTypes">types of the parameters</param>
/// <param name="ignoreCase">true for case-insensitive lookup</param>
/// <param name="function">The function that needs to be returned</param>
/// <returns> The function as specified in the function key or null</returns>
/// <exception cref="System.ArgumentNullException">if functionName or parameterTypes argument is null</exception>
/// <exception cref="System.ArgumentException">if no function is found with the given name or with given input parameters</exception>
internal bool TryGetFunction(string functionName, TypeUsage[] parameterTypes, bool ignoreCase, out EdmFunction function)
{
EntityUtil.GenericCheckArgumentNull(functionName, "functionName");
EntityUtil.GenericCheckArgumentNull(parameterTypes, "parameterTypes");
string functionIdentity = EdmFunction.BuildIdentity(functionName, parameterTypes);
GlobalItem item = null;
function = null;
if (TryGetValue(functionIdentity, ignoreCase, out item) && Helper.IsEdmFunction(item))
{
function = (EdmFunction)item;
return(true);
}
return(false);
}