/// <summary>
/// Parses an object path expression from a string.
/// </summary>
/// <param name="expression">The expression text to parse</param>
/// <returns>The parsed expression</returns>
public static ObjectPathExpression Parse(string expression)
{
if (expression == null)
{
throw new ArgumentNullException("path cannot be null");
}
if (expression.Length == 0)
{
throw new FormatException("Cannot parse empty string");
}
Tokenizer <ObjectPathToken> tokenizer = new Tokenizer <ObjectPathToken>();
tokenizer.TokenFactory = ObjectPathToken.TokenFactoryImpl;
tokenizer.WhitespaceBehavior = WhitespaceBehavior.DelimitAndInclude;
tokenizer.DoubleQuoteBehavior = DoubleQuoteBehavior.IncludeQuotedTokensAsStringLiterals;
tokenizer.Delimiters.Add("[");
tokenizer.Delimiters.Add("]");
tokenizer.Delimiters.Add(".");
List <ObjectPathToken> tokens = tokenizer.Tokenize(expression);
TokenReader <ObjectPathToken> reader = new TokenReader <ObjectPathToken>(tokens);
List <IObjectPathElement> pathElements = new List <IObjectPathElement>();
bool lastTokenWasNavigation = false;
while (reader.CanAdvance(skipWhitespace: true))
{
var currentToken = reader.Advance(skipWhitespace: true);
if (lastTokenWasNavigation == true && currentToken.TokenType != ObjectPathTokenType.Identifier)
{
throw new FormatException("Expected property, got '" + currentToken.Value + "'" + " at " + currentToken.Position);
}
lastTokenWasNavigation = false;
if (currentToken.TokenType == ObjectPathTokenType.IndexerOpen)
{
// read index value
if (reader.TryAdvance(out currentToken, skipWhitespace: true) == false)
{
throw new FormatException("Expected index value, got end of string");
}
if (currentToken.TokenType != ObjectPathTokenType.Identifier && currentToken.TokenType != ObjectPathTokenType.StringLiteral)
{
throw new ArgumentException("Unexpected token '" + currentToken.Value + "' at " + currentToken.Position);
}
string indexValueText = currentToken.Value;
if (currentToken.TokenType == ObjectPathTokenType.StringLiteral)
{
indexValueText = indexValueText.Substring(1, indexValueText.Length - 2);
}
object indexValue;
int indexValueInt;
if (int.TryParse(indexValueText, out indexValueInt) == false)
{
indexValue = indexValueText;
}
else
{
indexValue = indexValueInt;
}
// read index close
if (reader.TryAdvance(out currentToken, skipWhitespace: true) == false)
{
throw new FormatException("Expected ']', got end of string");
}
if (currentToken.TokenType != ObjectPathTokenType.IndexerClose)
{
throw new FormatException("Expected ']', got '" + currentToken.Value + "' at " + currentToken.Position);
}
IndexerPathElement el = new IndexerPathElement(indexValue);
pathElements.Add(el);
}
else if (currentToken.TokenType == ObjectPathTokenType.Identifier)
{
PropertyPathElement el = new PropertyPathElement(currentToken.Value);
pathElements.Add(el);
}
else if (currentToken.TokenType == ObjectPathTokenType.NavigationElement)
{
lastTokenWasNavigation = true;
}
else
{
throw new ArgumentException("Expected property name or indexer, got '" + currentToken.Value + "' at " + currentToken.Position);
}
}
return(new ObjectPathExpression(pathElements));
}
