/// <summary>Attempts to parse nullable values (only positional values, no name-value pairs) from the specified text.</summary>
/// <param name='text'>Text to parse (not null).</param>
/// <param name='values'>After invocation, the parsed skiptoken/etag values as strings.</param>
/// <returns>
/// true if the given values were parsed; false if there was a
/// syntactic error.
/// </returns>
/// <remarks>
/// The returned collection contains only string values. They must be converted later.
/// </remarks>
internal static bool TryParseNullableTokens(string text, out IList<object> values)
{
Debug.Assert(text != null, "text != null");
List<object> positionalValues = new List<object>();
values = positionalValues;
#if ODATALIB
ExpressionLexer lexer = new ExpressionLexer(text, true, false);
#else
ExpressionLexer lexer = new ExpressionLexer(text);
#endif
ExpressionToken currentToken = lexer.CurrentToken;
if (currentToken.Kind == ExpressionTokenKind.End)
{
return true;
}
do
{
if (currentToken.IsLiteral)
{
// Positional value.
positionalValues.Add(lexer.CurrentToken.Text);
}
else
{
return false;
}
// Read the next token. We should be at the end, or find
// we have a comma followed by something.
lexer.NextToken();
currentToken = lexer.CurrentToken;
if (currentToken.Kind == ExpressionTokenKind.Comma)
{
lexer.NextToken();
currentToken = lexer.CurrentToken;
if (currentToken.Kind == ExpressionTokenKind.End)
{
// Trailing comma.
return false;
}
}
}
while (currentToken.Kind != ExpressionTokenKind.End);
return true;
}
/// <summary>Reads a $select clause.</summary>
/// <param name="value">Value to read.</param>
/// <param name="dataServiceProviderWrapper">The provider wrapper for the service.</param>
/// <returns>A list of paths, each of which is a list of identifiers.</returns>
private static IList<IList<string>> SplitSelect(string value, DataServiceProviderWrapper dataServiceProviderWrapper)
{
Debug.Assert(!String.IsNullOrEmpty(value), "!String.IsNullOrEmpty(value)");
List<IList<string>> result = new List<IList<string>>();
List<string> currentPath = null;
ExpressionLexer lexer = new ExpressionLexer(value);
while (lexer.CurrentToken.Kind != ExpressionTokenKind.End)
{
string identifier;
bool lastSegment = false;
if (lexer.CurrentToken.Kind == ExpressionTokenKind.Star)
{
identifier = lexer.CurrentToken.Text;
lexer.NextToken();
lastSegment = true;
}
else
{
identifier = lexer.ReadDottedIdentifier(true /*allowEndWithDotStar*/);
bool nameIsContainerQualifed;
if (dataServiceProviderWrapper.GetNameFromContainerQualifiedName(identifier, out nameIsContainerQualifed) == "*")
{
lastSegment = true;
}
}
if (currentPath == null)
{
currentPath = new List<string>();
result.Add(currentPath);
}
currentPath.Add(identifier);
// Check whether we're at the end, whether we're drilling in,
// or whether we're finishing with this path.
ExpressionTokenKind tokenId = lexer.CurrentToken.Kind;
if (tokenId != ExpressionTokenKind.End)
{
if (lastSegment || tokenId != ExpressionTokenKind.Slash)
{
lexer.ValidateToken(ExpressionTokenKind.Comma);
currentPath = null;
}
lexer.NextToken();
}
}
return result;
}