PlQuery Constructor (goal)

SWI-Prolog SbsSW.SwiPlCs

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Swi-cs-pl - A CSharp class library to connect .NET languages with SWI-Prolog PlQuery Constructor (goal)

With this constructor a query is created from a string.

Uppercase parameters are interpreted a variables but can't be nested in sub terms. If you need a variable in a nested term use PlQuery(String, PlTermV). See the examples for details.

Declaration Syntax

Visual Basic

Visual C++

public PlQuery(
	string goal
)

Public Sub New ( _
	goal As String _
)

public:
PlQuery(
	String^ goal
)

Parameters

goal (String): A string for a prolog query

Remarks

Muddy Waters sang:"I'am build for comfort, I ain't build for speed"

Examples

CopyC#

public void queryStringForeach()
{
    string mm = "abc";
    PlQuery q = new PlQuery("member(A, [a,b,c])");
    int i = 0;
    foreach (PlTermV s in q.Solutions)
    {
        Assert.AreEqual(mm[i++].ToString(), s[0].ToString());
    }
    // or with named variables
    i = 0;
    foreach (PlQueryVariables s in q.SolutionVariables)
    {
        Assert.AreEqual(mm[i++].ToString(), s["A"].ToString());
    }
}

This sample shows a query with two variables.

CopyC#

public void queryString2()
{
    PlQuery q = new PlQuery("append(A, B, [a,b,c])");
    Assert.IsTrue(q.NextSolution());
    Assert.AreEqual("[]", q.Args[0].ToString());
    Assert.AreEqual("[a,b,c]", q.Args[1].ToString());
    Assert.IsTrue(q.NextSolution());
    Assert.AreEqual("[a]", q.Args[0].ToString());
    Assert.AreEqual("[b,c]", q.Args[1].ToString());
}

And the same with named variables.

CopyC#

public void queryStringNamed()
{
    PlQuery q = new PlQuery("append(A, B, [a,b,c])");
    Assert.IsTrue(q.NextSolution());
    Assert.AreEqual("[]", q.Variables["A"].ToString());
    Assert.AreEqual("[a,b,c]", q.Variables["B"].ToString());
    Assert.IsTrue(q.NextSolution());
    Assert.AreEqual("[a]", q.Variables["A"].ToString());
    Assert.AreEqual("[b,c]", q.Variables["B"].ToString());
}

This sample shows what happens if the argument vector is used with compound terms.

CopyC#

public void PlCallQueryCompound_string()
{
    string[] mm = { "comp(aa,aa1)", "comp(aa,aa2)", "comp(aa,aa3)" };
    build_pred();   // create: test(comp(X,Y)) :- member(Z,[1,2,3]), atomic_list_concat([X,Z],Y).
    PlQuery q = new PlQuery("test(comp(aa,X))");
    int i = 0;
    foreach (PlTermV s in q.Solutions)
    {
        Assert.AreEqual(mm[i++].ToString(), s[0].ToString());
    }
}

And here how to get the results with named variables with compound terms.

CopyC#

public void PlCallQueryCompoundNamed_string()
{
    string[] mm = { "aa1", "aa2", "aa3" };
    build_pred();   // create: test(comp(X,Y)) :- member(Z,[1,2,3]), atomic_list_concat([X,Z],Y).
    PlQuery q = new PlQuery("test(comp(aa,X))");
    int i = 0;
    foreach (PlQueryVariables v in q.SolutionVariables)
    {
        Assert.AreEqual(mm[i++].ToString(), v["X"].ToString());
    }
}

Assembly: SwiPlCs (Module: SwiPlCs) Version: 1.1.60301.0 (1.1.60301.0)

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