/// <summary>
/// <para>Create a <see cref="ReadOnlyCollection<T>"/> of <see cref="PlQueryVariables"/>.</para>
/// <para>If calling ToList() all solutions of the query are generated and stored in the Collection.</para>
/// </summary>
/// <returns>A ReadOnlyCollection of PlQueryVariables containing all solutions of the query.</returns>
/// <example>
/// <code source="..\..\TestSwiPl\LinqSwiPl.cs" region="Test_multi_goal_ToList_doc" />
/// </example>
public ReadOnlyCollection <PlQueryVariables> ToList()
{
var list = new List <PlQueryVariables>();
EraseRecords();
while (NextSolution())
{
for (int i = 0; i < _queryVariables.Count; i++)
{
_records.Add(LibPl.PL_record(_queryVariables[i].Value.TermRef)); // to keep the PlTerms
}
}
var qv = new PlQueryVariables(); // dummy to make the compiler happy
int avIdx = _queryVariables.Count;
foreach (uintptr_t recordTerm in _records)
{
var ptrTerm = LibPl.PL_new_term_ref();
LibPl.PL_recorded(recordTerm, ptrTerm);
if (avIdx == _queryVariables.Count)
{
qv = new PlQueryVariables();
list.Add(qv);
avIdx = 0;
}
//qv.Add(new PlQueryVar(GetVariableName(avIdx), new PlTerm(term))); // If this line is deleted -> update comment in PlTern(term_ref)
qv.Add(new PlQueryVar(_queryVariables[avIdx].Name, new PlTerm(ptrTerm))); // If this line is deleted -> update comment in PlTern(term_ref)
avIdx++;
//av[avIdx++].TermRef = term_t;
}
return(new ReadOnlyCollection <PlQueryVariables>(list));
}
/// <summary>
/// Provide the next solution to the query. Prolog exceptions are mapped to C# exceptions.
/// </summary>
/// <returns>return true if successful and false if there are no (more) solutions.</returns>
/// <remarks>
/// <para>If the query is closed it will be opened. If the last solution was generated the query will be closed.</para>
/// <para>If an exception is thrown while parsing (open) the query the _qid is set to zero.</para>
/// </remarks>
/// <exception cref="PlException">Is thrown if <see href="http://gollem.science.uva.nl/SWI-Prolog/Manual/foreigninclude.html#PL_next_solution()">SWI-Prolog Manual PL_next_solution()</see> returns false </exception>
public bool NextSolution()
{
if (0 == _qid)
{
Check.Require(!string.IsNullOrEmpty(_name), "PlQuery.NextSolution() _name is required");
IntPtr p = LibPl.PL_predicate(_name, _av.Size, _module);
_qid = LibPl.PL_open_query((IntPtr)0, LibPl.PL_Q_CATCH_EXCEPTION, p, _av.A0);
}
int rval = LibPl.PL_next_solution(_qid);
if (0 == rval)
{ // error
uintptr_t ex; // term_t
if ((ex = LibPl.PL_exception(_qid)) > 0)
{
_qid = 0; // to avoid an AccessViolationException on Dispose. E.g. if the query is miss spelled.
var etmp = new PlException(new PlTerm(ex));
etmp.Throw();
}
}
if (rval <= 0)
{
Free(false);
}
return(rval > 0);
}
/// <summary>
/// Discards the query, but does not delete any of the data created by the query if discardData is false.
/// It just invalidate qid, allowing for a new PlQuery object in this context.
/// </summary>
/// <remarks>see <see href="http://gollem.science.uva.nl/SWI-Prolog/Manual/foreigninclude.html#PL_cut_query()"/></remarks>
/// <param name="discardData">if true all bindings of the query are destroyed</param>
private void Free(bool discardData)
{
if (_qid > 0 && PlEngine.IsInitialized)
{
try
{
if (discardData)
{
// <"leider werden dann die gebundenen variablen der query wieder frei e.g. in PlCall(goal)"/>
// unfortunately this statement detaches the bound variables of the query e.g. in PlCall(goal)
LibPl.PL_close_query(_qid);
}
else
{
LibPl.PL_cut_query(_qid);
}
}
catch (AccessViolationException ex)
{
TraceAccessViolationException(ex);
}
}
_qid = 0;
}
/// <summary>
/// <para>Obtain status information on the Prolog system. The actual argument type depends on the information required.
/// The parameter queryType describes what information is wanted.</para>
/// <para>Returning pointers and integers as a long is bad style. The signature of this function should be changed.</para>
/// <see>PlQuerySwitch</see>
/// </summary>
/// <example>
/// <para>This sample shows how to get SWI-Prologs version number</para>
/// <code source="..\..\TestSwiPl\PlQuery.cs" region="get_prolog_version_number_doc" />
/// </example>
/// <param name="queryType">A <see>PlQuerySwitch</see>.</param>
/// <returns>A int depending on the given queryType</returns>
public static long Query(PlQuerySwitch queryType)
{
Check.Require(queryType != PlQuerySwitch.None, "PlQuerySwitch (None) is not valid");
return(LibPl.PL_query((uint)queryType));
}
#pragma warning disable 1573
/// <inheritdoc cref="PlQuery(string)" />
/// <summary>locating the predicate in the named module.</summary>
/// <param name="module">locating the predicate in the named module.</param>
public PlQuery(string module, string goal)
{
if (string.IsNullOrEmpty(goal))
{
throw new ArgumentNullException("goal");
}
_module = module;
var queryString = goal;
try
{
// call read_term(Term_of_query_string, [variable_names(VN)]).
// read_term_from_atom('noun(ş,C)', T, [variable_names(Vars)]).
// befor 2014 with redirected IO-Streams (PlQuery_Old_Kill_unused)
var atom = new PlTerm("'" + goal.Replace("'", @"\'") + "'");
PlTerm term = PlTerm.PlVar();
PlTerm options = PlTerm.PlVar();
PlTerm variablenames = PlTerm.PlVar();
PlTerm l = PlTerm.PlTail(options);
l.Append(PlTerm.PlCompound("variable_names", variablenames));
l.Close();
var args = new PlTermV(atom, term, options);
if (!PlCall("read_term_from_atom", args))
{
throw new PlLibException("PlCall read_term_from_atom/3 fails! goal:" + queryString);
}
// set list of variables and variable_names into _queryVariables
foreach (PlTerm t in variablenames.ToList())
{
// t[0]='=' , t[1]='VN', t[2]=_G123
_queryVariables.Add(new PlQueryVar(t[1].ToString(), t[2]));
}
// Build the query
_name = term.Name;
// is ok e.g. for listing/0.
// Check.Require(term.Arity > 0, "PlQuery(PlTerm t): t.Arity must be greater than 0.");
_av = new PlTermV(term.Arity);
for (int index = 0; index < term.Arity; index++)
{
if (0 == LibPl.PL_get_arg(index + 1, term.TermRef, _av[index].TermRef))
{
throw new PlException("PL_get_arg in PlQuery " + term.ToString());
}
}
}
#if _DEBUG
catch (Exception ex)
{
System.Diagnostics.Debug.Print(ex.Message);
Console.WriteLine(ex.Message);
}
#endif
finally
{
// NBT
}
}
