//operator char *(void);
/// <inheritdoc />
/// <summary>
/// The exception is translated into a message as produced by print_message/2. The character data is stored in a ring.
/// </summary>
/// <returns>A textual description of the Exception</returns>
override public string ToString()
{
if (libswipl.PL_is_initialised(IntPtr.Zero, IntPtr.Zero) == 0)
{
return("A PlException was thrown but it can't formatted because SwiPrologEngine is not Initialized.");
}
string strRet = "[ERROR: Failed to generate message. Internal error]\n";
using (new SwiPrologFrame())
{
#if USE_PRINT_MESSAGE
PlTermV av = new PlTermV(2);
av[0] = PlTerm.PlCompound("print_message", new PlTermV(new PlTerm("error"), new PlTerm(_exTerm.TermRef)));
PlQuery q = new PlQuery("$write_on_string", av);
if (q.NextSolution())
{
strRet = (string)av[1];
}
q.Free();
#else
var av = new SwiPrologTermVector(2);
av[0] = new SwiPrologTerm(_exTerm.TermRef);
using (var q = new SwiPrologQuery("$messages", "message_to_string", av))
{
if (q.NextSolution())
{
strRet = av[1].ToString();
}
}
#endif
}
return(strRet);
}
#pragma warning disable 1573
/// <inheritdoc cref="SwiPrologQuery(string,SwiPrologTermVector)" />
/// <summary>locating the predicate in the named module.</summary>
/// <param name="module">locating the predicate in the named module.</param>
internal SwiPrologQuery(string module, string name, SwiPrologTermVector termV)
{
//if (null == termV)
// throw new ArgumentNullException("termV");
_av = termV;
_name = name;
_module = module;
}
#pragma warning disable 1573
// Parameter 'predicate' has no matching param tag in the XML comment for 'SbsSW.SwiPlCs.PlQuery.PlCall(string, string, SbsSW.SwiPlCs.PlTermV)' (but other parameters do)
/// <inheritdoc cref="Call(string, SwiPrologTermVector)" />
/// <summary>As <see cref="Call(string, SwiPrologTermVector)"/> but locating the predicate in the named module.</summary>
/// <param name="module">locating the predicate in the named module.</param>
public static bool Call(string module, string predicate, SwiPrologTermVector args)
{
bool bRet;
using (var q = new SwiPrologQuery(module, predicate, args))
{
bRet = q.NextSolution();
q.Free(false);
}
return(bRet);
}
/// <overloads>
/// The main purpose of the static PlCall methods is to call a prolog prove or to do some site effects.
/// <example>
/// <code>
/// Assert.IsTrue(PlQuery.PlCall("is_list", new PlTerm("[a,b,c,d]")));
/// </code>
/// <code>
/// Assert.IsTrue(PlQuery.PlCall("consult", new PlTerm("some_file_name")));
/// // or
/// Assert.IsTrue(PlQuery.PlCall("consult('some_file_name')"));
/// </code>
/// </example>
/// </overloads>
/// <inheritdoc cref="SwiPrologQuery(string,SwiPrologTermVector)" />
/// <remarks>
/// <para>Create a PlQuery from the arguments, generates the first solution by NextSolution() and destroys the query.</para>
/// </remarks>
/// <param name="predicate">defines the name of the predicate</param>
/// <param name="args">Is a <see cref="SwiPrologTermVector"/> of arguments for the predicate</param>
/// <returns>Return true or false as the result of NextSolution() or throw an exception.</returns>
public static bool Call(string predicate, SwiPrologTermVector args)
{
return(Call(ModuleDefault, predicate, args));
}
// public PlQuery(const char *Name, const PlTermV &av)
/// <summary>
/// Create a query where name defines the name of the predicate and av the argument vector.
/// The arity is deduced from av. The predicate is located in the Prolog module user.
/// </summary>
/// <example>
/// <para>This sample shows a query with a compound term as an argument.</para>
/// <code source="..\..\TestSwiPl\PlQuery.cs" region="PlCallQueryCompound_termv_doc" />
/// </example>
/// <param name="name">the name of the predicate</param>
/// <param name="termV">the argument vector containing the parameters</param>
internal SwiPrologQuery(string name, SwiPrologTermVector termV)
: this(ModuleDefault, name, termV)
{
}
#pragma warning disable 1573
/// <inheritdoc cref="SwiPrologQuery(string)" />
/// <summary>locating the predicate in the named module.</summary>
/// <param name="module">locating the predicate in the named module.</param>
public SwiPrologQuery(string module, string goal)
{
if (string.IsNullOrEmpty(goal))
{
throw new ArgumentNullException("goal");
}
if (string.IsNullOrEmpty(module))
{
_module = ModuleDefault;
}
else
{
_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 SwiPrologTerm("'" + goal.Replace(@"\", @"\\").Replace("'", @"\'") + "'");
SwiPrologTerm term = SwiPrologTerm.Variable();
SwiPrologTerm options = SwiPrologTerm.Variable();
SwiPrologTerm variablenames = SwiPrologTerm.Variable();
SwiPrologTerm l = SwiPrologTerm.Tail(options);
l.Append(SwiPrologTerm.Compound("variable_names", variablenames));
l.Close();
var args = new SwiPrologTermVector(atom, term, options);
if (!Call(_module, "read_term_from_atom", args))
{
throw new SwiPrologLibraryException("Call read_term_from_atom/3 fails! goal:" + queryString);
}
// set list of variables and variable_names into _queryVariables
foreach (SwiPrologTerm t in variablenames.ToList())
{
// t[0]='=' , t[1]='VN', t[2]=_G123
_queryVariables.Add(new SwiPrologQueryVariable(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 SwiPrologTermVector(term.Arity);
for (int index = 0; index < term.Arity; index++)
{
if (0 == libswipl.PL_get_arg(index + 1, term.TermRef, _av[index].TermRef))
{
throw new SwiPrologException("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
}
}
