/// <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 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()) { throw new RdfParseException(error.ToString(), context.Input.LineNumber, context.Input.LinePosition); } else { throw new RdfParseException(error.ToString()); } }
/// <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> private void ParseBoundVariable(SparqlJsonParserContext context, String var, SparqlResult r) { String token, nodeValue, nodeType, nodeLang, nodeDatatype; 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) { token = context.Input.Value.ToString().ToLower(); //Check that we get a Property Value as a String context.Input.Read(); if (context.Input.TokenType != JsonToken.String) { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' 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 = context.Handler.CreateUriNode(new Uri(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("://") + 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) { n = context.Handler.CreateLiteralNode(nodeValue, new Uri(nodeDatatype)); } 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)) { 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!"); } //Add to the result r.SetValue(var, n); } else { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' 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 'boolean' property of the Result Set /// </summary> private 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.ToString() + "' 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 'bindings' property of the Results Object /// </summary> private void ParseBindings(SparqlJsonParserContext context) { //Can we start reading Objects if (context.Input.Read()) { while (context.Input.TokenType != JsonToken.EndArray) { if (context.Input.TokenType == JsonToken.StartObject) { this.ParseBinding(context); } else { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' 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 a Binding Object which occurs in the array of Bindings /// </summary> private void ParseBinding(SparqlJsonParserContext context) { //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); } else { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' 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 if (!context.Handler.HandleResult(result)) throw ParserHelper.Stop(); } else { throw new RdfParseException("Unexpected End of Input while trying to parse a Binding Object"); } }
/// <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); } else if (propName.Equals("boolean")) { this.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.ToString() + "' 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 Results Object of the Result Set /// </summary> private void ParseResults(SparqlJsonParserContext context) { //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.ToString() + "' 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); } else { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, expected the start of an Array for the 'bindings' property of the Results Object"); } } else { throw Error(context,"Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, expected the 'bindings' property for the Results Object"); } //Expect the End of the Results Object context.Input.Read(); if (context.Input.TokenType != JsonToken.EndObject) { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' encountered, expected the end of the Results Object"); } } else { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' 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 '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 '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())) throw 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 Properties of the Header Object /// </summary> private void ParseHeaderProperties(SparqlJsonParserContext context) { 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); } 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.ToString() + "' 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> /// 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 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 this.ParseHeader(context); 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.ToString() + "' encountered, end of the JSON Result Set Object was expected"); } } else { throw Error(context, "Unexpected Token '" + context.Input.TokenType.ToString() + "' 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; } }