/// <summary>
/// Given position in the buffer finds index of the function parameter.
/// </summary>
public static int ComputeCurrentParameter(this ISignatureInfo signatureInfo, IEditorBufferSnapshot snapshot, AstRoot ast, int position, IREditorSettings settings)
{
var parameterInfo = ast.GetSignatureInfoFromBuffer(snapshot, position);
var index = 0;
if (parameterInfo != null)
{
index = parameterInfo.ParameterIndex;
if (parameterInfo.NamedParameter)
{
// A function f <- function(foo, bar) is said to have formal parameters "foo" and "bar",
// and the call f(foo=3, ba=13) is said to have (actual) arguments "foo" and "ba".
// R first matches all arguments that have exactly the same name as a formal parameter.
// Two identical argument names cause an error. Then, R matches any argument names that
// partially matches a(yet unmatched) formal parameter. But if two argument names partially
// match the same formal parameter, that also causes an error. Also, it only matches
// formal parameters before ... So formal parameters after ... must be specified using
// their full names. Then the unnamed arguments are matched in positional order to
// the remaining formal arguments.
var argumentIndexInSignature = signatureInfo.GetArgumentIndex(parameterInfo.ParameterName, settings.PartialArgumentNameMatch);
if (argumentIndexInSignature >= 0)
{
index = argumentIndexInSignature;
}
}
}
return(index);
}
