private SparqlUpdateCommand TryParseDeleteCommand(SparqlUpdateParserContext context, bool allowData)
{
IToken next = context.Tokens.Dequeue();
List<Uri> usings = new List<Uri>();
List<Uri> usingNamed = new List<Uri>();
if (allowData)
{
//We are allowed to have an DELETE DATA command here so check for it
if (next.TokenType == Token.DATA) return this.TryParseDeleteDataCommand(context);
}
else
{
if (next.TokenType == Token.DATA) throw ParserHelper.Error("The DATA keyword is not permitted here as this INSERT command forms part of a modification command", next);
}
if (next.TokenType == Token.WHERE)
{
//Parse the WHERE pattern which serves as both the selection and deletion pattern in this case
context.Tokens.Dequeue();
GraphPattern where = this.TryParseModifyTemplate(context);
//Then return the command
return new DeleteCommand(where, where);
}
else
{
//Get the Modification Template
GraphPattern deletions = this.TryParseModifyTemplate(context);
//Then we expect a WHERE keyword
next = context.Tokens.Dequeue();
if (next.TokenType == Token.USING)
{
foreach (KeyValuePair<Uri, bool> kvp in this.TryParseUsingStatements(context))
{
if (kvp.Value)
{
usingNamed.Add(kvp.Key);
}
else
{
usings.Add(kvp.Key);
}
}
next = context.Tokens.Dequeue();
}
if (next.TokenType == Token.WHERE)
{
//Now parse the WHERE pattern
SparqlQueryParserContext subContext = new SparqlQueryParserContext(context.Tokens);
subContext.Query.BaseUri = context.BaseUri;
subContext.Query.NamespaceMap = context.NamespaceMap;
subContext.ExpressionParser.NamespaceMap = context.NamespaceMap;
subContext.ExpressionParser.ExpressionFactories = context.ExpressionFactories;
subContext.ExpressionFactories = context.ExpressionFactories;
GraphPattern where = context.QueryParser.TryParseGraphPattern(subContext, context.Tokens.LastTokenType != Token.LEFTCURLYBRACKET);
//And finally return the command
DeleteCommand cmd = new DeleteCommand(deletions, where);
usings.ForEach(u => cmd.AddUsingUri(u));
usingNamed.ForEach(u => cmd.AddUsingNamedUri(u));
return cmd;
}
else if (next.TokenType == Token.INSERT)
{
InsertCommand insertCmd = (InsertCommand)this.TryParseInsertCommand(context, false);
ModifyCommand cmd = new ModifyCommand(deletions, insertCmd.InsertPattern, insertCmd.WherePattern);
insertCmd.UsingUris.ToList().ForEach(u => cmd.AddUsingUri(u));
insertCmd.UsingNamedUris.ToList().ForEach(u => cmd.AddUsingNamedUri(u));
return cmd;
}
else
{
throw ParserHelper.Error("Unexpected Token '" + next.GetType().ToString() + "' encountered, expected a WHERE keyword as part of a DELETE command", next);
}
}
}
