/// <summary>
/// Visit invocation expressions to strip out invocations of the identity function.
/// </summary>
/// <param name="node">Expression to analyze and rewrite.</param>
/// <returns>The original node if the invocation does not apply an identity function; otherwise, the operand of the identity function application.</returns>
protected override Expression VisitInvocation(InvocationExpression node)
{
var visited = base.VisitInvocation(node);
if (visited is InvocationExpression invoke && invoke.Expression.NodeType == ExpressionType.Parameter)
{
var target = (ParameterExpression)invoke.Expression;
if (target.Name == Constants.IdentityFunctionUri)
{
if (HasIdentitySignature(target.Type))
{
return(invoke.Arguments[0]);
}
throw new InvalidOperationException(
string.Format(
CultureInfo.InvariantCulture,
"Received invocation target type '{0}' in expression '{1}'; cannot call the identity function when argument type does not equal result type.",
target.Type.ToCSharpStringPretty(),
node.ToCSharpString(true)));
}
}
return(visited);
}
