/// <summary>
/// Parser method which parses the Header Object of the Result Set
/// </summary>
private void ParseHeaderObject(SparqlJsonParserContext context)
{
//Can we read the Head Object
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.Null)
{
//Null Header so this must be a Boolean Result Set
}
else if (context.Input.TokenType == JsonToken.StartObject)
{
//Header Object
this.ParseHeaderProperties(context);
//When we get control back we should have already read the last token which should be an End Object
if (context.Input.TokenType != JsonToken.EndObject)
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, end of the Header Object of the JSON Result Set was expected");
}
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Header Object of the JSON Result Set");
}
}
/// <summary>
/// Parser method which parses the Body of the Result Set which may be either a 'results' or 'boolean' property of the top level Json Object
/// </summary>
private void ParseBody(SparqlJsonParserContext context)
{
//Can we read the Boolean/Results Property
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.PropertyName)
{
//Check the Property Name is head
String propName = context.Input.Value.ToString();
if (propName.Equals("results"))
{
this.ParseResults(context, true);
}
else if (propName.Equals("boolean"))
{
ParseBoolean(context);
}
else
{
throw Error(context, "Unexpected Property Name '" + propName + "' encountered, expected the 'results' or 'boolean' property of the JSON Result Set Object");
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, the 'results' or 'boolean' property of the JSON Result Set Object was expected");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Body of the JSON Result Set Object");
}
}
/// <summary>
/// Parser method which parses the 'bindings' property of the Results Object
/// </summary>
private void ParseBindings(SparqlJsonParserContext context, bool headSeen)
{
//Can we start reading Objects
if (context.Input.Read())
{
while (context.Input.TokenType != JsonToken.EndArray)
{
if (context.Input.TokenType == JsonToken.StartObject)
{
this.ParseBinding(context, headSeen);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected the start of a Binding Object");
}
if (!context.Input.Read())
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Binding Objects");
}
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Binding Objects");
}
}
/// <summary>
/// Parser method which parses the 'head' property of the top level Json Object which represents the Header of the Result Set
/// </summary>
private void ParseHeader(SparqlJsonParserContext context)
{
//Can we read the Head Property
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.PropertyName)
{
//Check the Property Name is head
String propName = context.Input.Value.ToString();
if (!propName.Equals("head"))
{
throw Error(context, "Unexpected Property Name '" + propName + "' encountered, expected the 'head' property of the JSON Result Set Object");
}
this.ParseHeaderObject(context);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, the 'head' property of the JSON Result Set Object was expected");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Head property of the JSON Result Set Object");
}
}
/// <summary>
/// Checks whether a JSON Token is valid as the value for a RDF term
/// </summary>
/// <param name="context">Context</param>
/// <returns></returns>
private static bool IsValidValue(SparqlJsonParserContext context)
{
switch (context.Input.TokenType)
{
case JsonToken.String:
case JsonToken.Date:
return(true);
default:
return(false);
}
}
/// <summary>
/// Parser method which parses the Properties of the Header Object
/// </summary>
private void ParseHeaderProperties(SparqlJsonParserContext context, bool bodySeen)
{
bool varsSeen = false;
//Can we read the Header properties
if (context.Input.Read())
{
while (context.Input.TokenType != JsonToken.EndObject)
{
if (context.Input.TokenType == JsonToken.PropertyName)
{
//Only expecting Property Name Tokens
String propName = context.Input.Value.ToString();
if (propName.Equals("vars"))
{
//Variables property
if (varsSeen)
{
throw Error(context, "Unexpected Property Name 'vars' encountered, a 'vars' property has already been seen in the Header Object of the JSON Result Set");
}
varsSeen = true;
this.ParseVariables(context, bodySeen);
}
else if (propName.Equals("link"))
{
//Link property
this.ParseLink(context);
}
else
{
//Invalid property
throw Error(context, "Unexpected Property Name '" + propName + "' encountered, expected a 'link' or 'vars' property of the Header Object of the JSON Result Set");
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected a Property Name for a property of the Header Object of the JSON Result Set");
}
//Read next Token
context.Input.Read();
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the properties of the Header Object of the JSON Result Set");
}
}
/// <summary>
/// Helper method for raising Error messages with attached Line Information
/// </summary>
/// <param name="context">Parser Context</param>
/// <param name="message">Error Message</param>
/// <returns></returns>
private static RdfParseException Error(SparqlJsonParserContext context, String message)
{
StringBuilder error = new StringBuilder();
if (context.Input.HasLineInfo())
{
error.Append("[Line " + context.Input.LineNumber + " Column " + context.Input.LinePosition + "] ");
}
error.AppendLine(context.Input.TokenType.ToString());
error.Append(message);
if (context.Input.HasLineInfo())
{
return(new RdfParseException(error.ToString(), context.Input.LineNumber, context.Input.LinePosition));
}
return(new RdfParseException(error.ToString()));
}
/// <summary>
/// Parser method which parses the top level Json Object which represents the overall Result Set
/// </summary>
private void ParseResultSetObject(SparqlJsonParserContext context)
{
try
{
context.Handler.StartResults();
//Can we read the overall Graph Object
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.StartObject)
{
//Parse the Header and the Body
if (this.ParseHeader(context))
{
// For SPARQL Results JSON with an unexpected ordering the act of parsing the header may cause us to parse the body
this.ParseBody(context);
// Check we now get the End of the Result Set Object
context.Input.Read();
if (context.Input.TokenType != JsonToken.EndObject)
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, end of the JSON Result Set Object was expected");
}
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, start of the JSON Result Set Object was expected");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse start of the JSON Result Set Object");
}
context.Handler.EndResults(true);
}
catch (RdfParsingTerminatedException)
{
context.Handler.EndResults(true);
}
catch
{
context.Handler.EndResults(false);
throw;
}
}
/// <summary>
/// Parser method which parses a Binding Object which occurs in the array of Bindings
/// </summary>
private void ParseBinding(SparqlJsonParserContext context, bool headSeen)
{
//Can we read some properties
if (context.Input.Read())
{
SparqlResult result = new SparqlResult();
while (context.Input.TokenType != JsonToken.EndObject)
{
if (context.Input.TokenType == JsonToken.PropertyName)
{
//Each Property Name should be for a variable
this.ParseBoundVariable(context, context.Input.Value.ToString(), result, headSeen);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected a Property Name giving the Binding for a Variable for this Result");
}
//Get Next Token
if (!context.Input.Read())
{
throw new RdfParseException("Unexpected End of Input while trying to parse a Binding Object");
}
}
//Check that all Variables are bound for a given result binding nulls where appropriate
foreach (String v in context.Variables)
{
if (!result.HasValue(v))
{
result.SetValue(v, null);
}
}
//Add to Results
result.SetVariableOrdering(context.Variables);
if (!context.Handler.HandleResult(result))
{
ParserHelper.Stop();
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse a Binding Object");
}
}
/// <summary>
/// Parser method which parses the 'link' property of the Header Object
/// </summary>
private void ParseLink(SparqlJsonParserContext context)
{
//Expect an array - Discard this information as we don't use it
if (context.Input.Read())
{
while (context.Input.TokenType != JsonToken.EndArray)
{
if (!context.Input.Read())
{
throw new RdfParseException("Unexpected End of Input while trying to parse the 'link' property of the Header Object of the JSON Result Set");
}
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the 'link' property of the Header Object of the JSON Result Set");
}
}
/// <summary>
/// Parser method which parses the 'boolean' property of the Result Set
/// </summary>
private static void ParseBoolean(SparqlJsonParserContext context)
{
//Expect a Boolean
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.Boolean)
{
Boolean result = Boolean.Parse(context.Input.Value.ToString());
context.Handler.HandleBooleanResult(result);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected a Boolean value for the 'boolean' property of the JSON Result Set");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the 'boolean' property of the JSON Result Set Object");
}
}
/// <summary>
/// Parser method which parses the 'head' property of the top level Json Object which represents the Header of the Result Set
/// </summary>
private bool ParseHeader(SparqlJsonParserContext context, bool bodySeen)
{
//Can we read the Head Property
if (!context.Input.Read())
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Head property of the JSON Result Set Object");
}
if (context.Input.TokenType != JsonToken.PropertyName)
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, the 'head'" + (bodySeen ? String.Empty : "'results'/'boolean'") + " property of the JSON Result Set Object was expected");
}
//Check the Property Name is head/results/boolean
String propName = context.Input.Value.ToString();
switch (propName)
{
case "head":
this.ParseHeaderObject(context, bodySeen);
return(true);
case "results":
// We've seen the results before the header, still expect to see a header afterwards
this.ParseResults(context, false);
this.ParseHeader(context, true);
return(false);
case "boolean":
// We've seen the boolean result before the header, still expect to see a header afterwards
ParseBoolean(context);
this.ParseHeader(context, false);
return(false);
default:
// TODO Technically we should probably allow and ignore unknown objects
throw Error(context, "Unexpected Property Name '" + propName + "' encountered, expected the 'head' property of the JSON Result Set Object");
}
}
/// <summary>
/// Parser method which parses the 'vars' property of the Header Object
/// </summary>
private void ParseVariables(SparqlJsonParserContext context)
{
//Can we read the Variable Array
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.StartArray)
{
context.Input.Read();
while (context.Input.TokenType != JsonToken.EndArray)
{
if (context.Input.TokenType == JsonToken.String)
{
//Add to Variables
if (!context.Handler.HandleVariable(context.Input.Value.ToString()))
{
ParserHelper.Stop();
}
context.Variables.Add(context.Input.Value.ToString());
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, expected a String giving the name of a Variable for the Result Set");
}
context.Input.Read();
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, expected the Start of an Array giving the list of Variables for the 'vars' property of the Header Object of the JSON Result Set");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the 'vars' property of the Header Object of the JSON Result Set");
}
}
/// <summary>
/// Parser method which parses the Header Object of the Result Set
/// </summary>
private void ParseHeaderObject(SparqlJsonParserContext context, bool bodySeen)
{
//Can we read the Head Object
if (context.Input.Read())
{
switch (context.Input.TokenType)
{
case JsonToken.Null:
break;
case JsonToken.StartObject:
this.ParseHeaderProperties(context, bodySeen);
if (context.Input.TokenType != JsonToken.EndObject)
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, end of the Header Object of the JSON Result Set was expected");
}
break;
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the Header Object of the JSON Result Set");
}
}
private void SkipToEndOfArray(SparqlJsonParserContext context, bool issueWarning)
{
if (issueWarning)
{
this.RaiseWarning("Found extra JSON array which will be ignored and discarded");
}
int depth = 1;
while (depth > 0)
{
// Try to read next token
try
{
if (!context.Input.Read())
{
throw Error(context, "Unexpected EOF while trying to skip to end of JSON array");
}
}
catch (JsonReaderException ex)
{
throw Error(context, ex.Message);
}
// Decide how to skip based on next token
switch (context.Input.TokenType)
{
case JsonToken.Boolean:
case JsonToken.Comment:
case JsonToken.Bytes:
case JsonToken.Date:
case JsonToken.Float:
case JsonToken.Integer:
case JsonToken.Null:
case JsonToken.PropertyName:
case JsonToken.Raw:
case JsonToken.String:
// Ignore and continue
continue;
case JsonToken.StartArray:
// Increment depth to avoid recursion
depth++;
break;
case JsonToken.EndArray:
// Decrement depth and exit if we've reached end of object
depth--;
if (depth == 0)
{
return;
}
break;
case JsonToken.StartObject:
// Need to separately skip the object
this.SkipToEndOfObject(context, false);
break;
case JsonToken.EndObject:
// Illegal syntax
throw Error(context, "Illegal end of object while trying to skip to end of JSON array");
default:
// Anything else is illegal syntax
throw Error(context, "Illegal JSON token of type " + context.Input.TokenType + " with value " + context.Input.Value + " while trying to skip to end of JSON array");
}
}
}
/// <summary>
/// Parser method which parses a Bound Variable Object which occurs within a Binding Object
/// </summary>
/// <param name="context">Parser Context</param>
/// <param name="var">Variable Name</param>
/// <param name="r">Result Object that is being constructed from the Binding Object</param>
/// <param name="headSeen"></param>
private void ParseBoundVariable(SparqlJsonParserContext context, string var, SparqlResult r, bool headSeen)
{
String nodeType, nodeLang, nodeDatatype;
string nodeValue = nodeType = nodeLang = nodeDatatype = null;
//Can we read the start of an Object
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.StartObject)
{
context.Input.Read();
while (context.Input.TokenType != JsonToken.EndObject)
{
String token = context.Input.Value.ToString().ToLower();
//Check that we get a Property Value as a String
context.Input.Read();
if (!IsValidValue(context))
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected a Property Value describing one of the properties of an Variable Binding");
}
//Extract the Information from the Object
if (token.Equals("value"))
{
nodeValue = context.Input.Value.ToString();
}
else if (token.Equals("type"))
{
nodeType = context.Input.Value.ToString().ToLower();
}
else if (token.Equals("lang") || token.Equals("xml:lang"))
{
if (nodeLang == null && nodeDatatype == null)
{
nodeLang = context.Input.Value.ToString();
}
else
{
throw Error(context, "Unexpected Language Property specified for an Object Node where a Language or Datatype has already been specified");
}
}
else if (token.Equals("datatype"))
{
if (nodeDatatype == null && nodeLang == null)
{
nodeDatatype = context.Input.Value.ToString();
}
else
{
throw Error(context, "Unexpected Datatype Property specified for an Object Node where a Language or Datatype has already been specified");
}
}
else
{
throw Error(context, "Unexpected Property '" + token + "' specified for an Object Node, only 'value', 'type', 'lang' and 'datatype' are valid properties");
}
//Get Next Token
if (!context.Input.Read())
{
throw new RdfParseException("Unexpected End of Input while trying to parse a Bound Variable Object");
}
}
//Validate the Information
if (nodeType == null)
{
throw new RdfParseException("Cannot parse a Node from the JSON where no 'type' property was specified in the JSON Object representing the Node");
}
if (nodeValue == null)
{
throw new RdfParseException("Cannot parse a Node from the JSON where no 'value' property was specified in the JSON Object representing the Node");
}
//Turn this information into a Node
INode n;
if (nodeType.Equals("uri"))
{
n = ParserHelper.TryResolveUri(context, nodeValue);
}
else if (nodeType.Equals("bnode"))
{
if (nodeValue.StartsWith("_:"))
{
n = context.Handler.CreateBlankNode(nodeValue.Substring(2));
}
else if (nodeValue.Contains("://"))
{
n = context.Handler.CreateBlankNode(nodeValue.Substring(nodeValue.IndexOf("://", StringComparison.Ordinal) + 3));
}
else if (nodeValue.Contains(":"))
{
n = context.Handler.CreateBlankNode(nodeValue.Substring(nodeValue.LastIndexOf(':') + 1));
}
else
{
n = context.Handler.CreateBlankNode(nodeValue);
}
}
else if (nodeType.Equals("literal") || nodeType.Equals("typed-literal"))
{
if (nodeLang != null)
{
n = context.Handler.CreateLiteralNode(nodeValue, nodeLang);
}
else if (nodeDatatype != null)
{
Uri dtUri = ((IUriNode)ParserHelper.TryResolveUri(context, nodeDatatype)).Uri;
n = context.Handler.CreateLiteralNode(nodeValue, dtUri);
}
else
{
n = context.Handler.CreateLiteralNode(nodeValue);
}
}
else
{
throw new RdfParseException("Cannot parse a Node from the JSON where the 'type' property has a value of '" + nodeType + "' which is not one of the permitted values 'uri', 'bnode', 'literal' or 'typed-literal' in the JSON Object representing the Node");
}
//Check that the Variable was defined in the Header
if (!context.Variables.Contains(var))
{
if (headSeen)
{
throw new RdfParseException("Unable to Parse a SPARQL Result Set since a Binding Object attempts to bind a value to the variable '" + var + "' which is not defined in the Header Object in the value for the 'vars' property!");
}
context.Variables.Add(var);
}
//Add to the result
r.SetValue(var, n);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected the start of a Bound Variable Object");
}
}
else
{
throw Error(context, "Unexpected End of Input while trying to parse a Bound Variable Object");
}
}
/// <summary>
/// Parser method which parses the Results Object of the Result Set
/// </summary>
private void ParseResults(SparqlJsonParserContext context, bool headSeen)
{
//Can we read the Results Object
if (context.Input.Read())
{
//Should get a Start Object
if (context.Input.TokenType == JsonToken.StartObject)
{
//Should be a Property Name for 'bindings' next
context.Input.Read();
if (context.Input.TokenType == JsonToken.PropertyName)
{
String propName = context.Input.Value.ToString();
//Wait till we get the bindings property
//There's a couple of deprecated properties we need to support
while (!propName.Equals("bindings"))
{
//Distinct and Ordered properties are no longer in the Specifcation but have to support them for compatability
if (propName.Equals("distinct") || propName.Equals("ordered"))
{
//Should then be a Boolean
context.Input.Read();
if (context.Input.TokenType != JsonToken.Boolean)
{
throw Error(context, "Deprecated Property '" + propName + "' used incorrectly, only a Boolean may be given for this property and this property should no longer be used according to the W3C Specification");
}
//Hopefully then we get another Property Name else the Results object is invalid
context.Input.Read();
if (context.Input.TokenType == JsonToken.PropertyName)
{
propName = context.Input.Value.ToString();
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected the 'bindings' property for the Results Object");
}
}
else
{
//Unexpected Property
throw Error(context, "Unexpected Property Name '" + propName + "' encountered, expected the 'bindings' property of the Results Object");
}
}
//Then should get the start of an array
context.Input.Read();
if (context.Input.TokenType == JsonToken.StartArray)
{
this.ParseBindings(context, headSeen);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected the start of an Array for the 'bindings' property of the Results Object");
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected the 'bindings' property for the Results Object");
}
// Skip to the End of the Results Object
this.SkipToEndOfObject(context, true);
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected the start of the Results Object");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the 'results' property of the JSON Result Set Object");
}
}
/// <summary>
/// Parser method which parses the 'head' property of the top level Json Object which represents the Header of the Result Set
/// </summary>
private bool ParseHeader(SparqlJsonParserContext context)
{
return(this.ParseHeader(context, false));
}
/// <summary>
/// Parser method which parses the 'vars' property of the Header Object
/// </summary>
private void ParseVariables(SparqlJsonParserContext context, bool bodySeen)
{
//Can we read the Variable Array
if (context.Input.Read())
{
if (context.Input.TokenType == JsonToken.StartArray)
{
context.Input.Read();
List <String> vars = new List <string>();
while (context.Input.TokenType != JsonToken.EndArray)
{
if (context.Input.TokenType == JsonToken.String)
{
//Add to Variables
if (!context.Handler.HandleVariable(context.Input.Value.ToString()))
{
ParserHelper.Stop();
}
if (bodySeen)
{
// We've already seen the body in which case store locally for now
vars.Add(context.Input.Value.ToString());
}
else
{
// We're seeing the header first so just add to list of variables
context.Variables.Add(context.Input.Value.ToString());
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType + "' with value '" + context.Input.Value + "' encountered, expected a String giving the name of a Variable for the Result Set");
}
context.Input.Read();
}
// If we've already seen the body check for variable conflicts
if (!bodySeen)
{
return;
}
foreach (String var in context.Variables)
{
if (!vars.Contains(var))
{
throw new RdfParseException("Unable to Parse a SPARQL Result Set since a Binding Object binds a value to the variable '" + var + "' which is not defined in the Header Object in the value for the 'vars' property!");
}
}
foreach (String var in context.Variables)
{
if (!context.Handler.HandleVariable(var))
{
ParserHelper.Stop();
}
}
}
else
{
throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' with value '" + context.Input.Value + "' encountered, expected the Start of an Array giving the list of Variables for the 'vars' property of the Header Object of the JSON Result Set");
}
}
else
{
throw new RdfParseException("Unexpected End of Input while trying to parse the 'vars' property of the Header Object of the JSON Result Set");
}
}
