HandlerExtensions.cs

/*
// <copyright>
// dotNetRDF is free and open source software licensed under the MIT License
// -------------------------------------------------------------------------
// 
// Copyright (c) 2009-2023 dotNetRDF Project (http://dotnetrdf.org/)
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
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using System;
using System.Collections.Generic;
using System.Linq;
using VDS.RDF.Query;

namespace VDS.RDF.Parsing.Handlers
{
    /// <summary>
    /// Static Class of extension methods for use with Handler classes.
    /// </summary>
    public static class HandlerExtensions
    {
        /// <summary>
        /// Gets the Base URI from the RDF Handler.
        /// </summary>
        /// <param name="handler">RDF Handler.</param>
        /// <returns></returns>
        internal static Uri GetBaseUri(this IRdfHandler handler)
        {
            if (handler is GraphHandler)
            {
                return ((GraphHandler)handler).BaseUri;
            }
            else if (handler is IWrappingRdfHandler)
            {
                IRdfHandler temp = ((IWrappingRdfHandler)handler).InnerHandlers.FirstOrDefault(h => h.GetBaseUri() != null);
                if (temp == null)
                {
                    return null;
                }
                else 
                {
                   return temp.GetBaseUri();
                }
            }
            else
            {
                return null;
            }
        }

        /// <summary>
        /// Applies the triples of a Graph to an RDF Handler.
        /// </summary>
        /// <param name="handler">RDF Handler.</param>
        /// <param name="g">Graph.</param>
        public static void Apply(this IRdfHandler handler, IGraph g)
        {
            try
            {
                handler.StartRdf();
                if (g != null)
                {
                    // Handle the Base URI if present
                    if (g.BaseUri != null)
                    {
                        if (!handler.HandleBaseUri(g.BaseUri)) ParserHelper.Stop();
                    }
                    // Handle any namespaces
                    foreach (var prefix in g.NamespaceMap.Prefixes)
                    {
                        if (!handler.HandleNamespace(prefix, g.NamespaceMap.GetNamespaceUri(prefix))) ParserHelper.Stop();
                    }
                    // Finally handle triples
                    foreach (Triple t in g.Triples)
                    {
                        if (!handler.HandleTriple(t))
                        {
                            ParserHelper.Stop();
                        }
                    }
                }

                handler.EndRdf(true);
            }
            catch (RdfParsingTerminatedException)
            {
                handler.EndRdf(true);
            }
            catch
            {
                handler.EndRdf(false);
                throw;
            }
        }

        /// <summary>
        /// Applies the triples to an RDF Handler.
        /// </summary>
        /// <param name="handler">RDF Handler.</param>
        /// <param name="ts">Triples.</param>
        public static void Apply(this IRdfHandler handler, IEnumerable<Triple> ts)
        {
            try
            {
                handler.StartRdf();
                foreach (Triple t in ts)
                {
                    if (!handler.HandleTriple(t))
                    {
                        ParserHelper.Stop();
                    }
                }
                handler.EndRdf(false);
            }
            catch (RdfParsingTerminatedException)
            {
                handler.EndRdf(true);
            }
            catch
            {
                handler.EndRdf(false);
                throw;
            }
        }

        /// <summary>
        /// Applies the result set to a Results Handler.
        /// </summary>
        /// <param name="handler">Results Handler.</param>
        /// <param name="results">Result Set.</param>
        public static void Apply(this ISparqlResultsHandler handler, SparqlResultSet results)
        {
            try
            {
                handler.StartResults();

                switch (results.ResultsType)
                {
                    case SparqlResultsType.Boolean:
                        handler.HandleBooleanResult(results.Result);
                        break;
                    case SparqlResultsType.VariableBindings:
                        foreach (var var in results.Variables)
                        {
                            if (!handler.HandleVariable(var)) ParserHelper.Stop();
                        }
                        foreach (ISparqlResult r in results)
                        {
                            if (!handler.HandleResult(r)) ParserHelper.Stop();
                        }
                        break;
                    default:
                        // Does nothing     
                        break;
                }

                handler.EndResults(true);
            }
            catch (RdfParsingTerminatedException)
            {
                handler.EndResults(true);
            }
            catch
            {
                handler.EndResults(false);
                throw;
            }
        }
    }
}