Continuations

tests/prolog/builtins/DelimitedContinuationsOperatorsTests.kt

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+package prolog.builtins
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import prolog.ast.Database.Program
+import prolog.ast.arithmetic.Integer
+import prolog.ast.lists.List.Cons
+import prolog.ast.lists.List.Empty
+import prolog.ast.logic.Rule
+import prolog.ast.terms.Atom
+import prolog.ast.terms.Structure
+import prolog.ast.terms.Variable
+import java.io.ByteArrayOutputStream
+import java.io.PrintStream
+
+class DelimitedContinuationsOperatorsTests {
+    @BeforeEach
+    fun setup() {
+        Program.reset()
+    }
+
+    @Test
+    fun `example member`() {
+        val member = Member(Variable("X"), Cons(Integer(1), Cons(Integer(2), Cons(Integer(3), Empty))))
+        val reset = Reset(member, Variable("Ball"), Variable("Cont"))
+
+        val result = reset.satisfy(emptyMap()).toList()
+
+        assertEquals(3, result.size, "Expected 3 results")
+
+        assertTrue(result[0].isSuccess, "Expected success for first result")
+        val subs0 = result[0].getOrNull()!!
+        assertEquals(2, subs0.size, "Expected 2 substitutions for first result")
+        assertEquals(Integer(1), subs0[Variable("X")])
+        assertEquals(Integer(0), subs0[Variable("Cont")])
+
+        assertTrue(result[1].isSuccess, "Expected success for second result")
+        val subs1 = result[1].getOrNull()!!
+        assertEquals(2, subs1.size, "Expected 2 substitutions for second result")
+        assertEquals(Integer(2), subs1[Variable("X")])
+        assertEquals(Integer(0), subs1[Variable("Cont")])
+
+        assertTrue(result[2].isSuccess, "Expected success for third result")
+        val subs2 = result[2].getOrNull()!!
+        assertEquals(2, subs2.size, "Expected 2 substitutions for third result")
+        assertEquals(Integer(3), subs2[Variable("X")])
+        assertEquals(Integer(0), subs2[Variable("Cont")])
+    }
+
+    @Test
+    fun `example with output`() {
+        val reset = Reset(Atom("test_"), Variable("Term"), Variable("Cont"))
+        val isOp = Is(Variable("X"), Add(Integer(1), Multiply(Integer(2), Variable("Y"))))
+        Program.load(
+            listOf(
+                Rule(
+                    Structure(Atom("test"), listOf(Variable("Cont"), Variable("Term"))),
+                    Conjunction(WriteLn("Inside test"), Conjunction(reset, WriteLn("After reset")))
+                ),
+                Rule(
+                    Atom("test_"),
+                    Conjunction(WriteLn("Entering reset"), Conjunction(Shift(Variable("Y")), Conjunction(isOp, Conjunction(Write("In test X = "), Conjunction(Write(Variable("X")), WriteLn("; done"))))))
+                )
+            )
+        )
+
+        val notNot2 = Not(Not(Conjunction(WriteLn("calling Cont(2)"), Conjunction(Unify(Variable("Term"), Integer(2)), Call(Variable("Cont"))))))
+        val notNot4 = Not(Not(Conjunction(WriteLn("calling Cont(4)"), Conjunction(Unify(Variable("Term"), Integer(4)), Call(Variable("Cont"))))))
+        val query = Conjunction(Structure(Atom("test"), listOf(Variable("Cont"), Variable("Term"))), Conjunction(notNot2, notNot4))
+
+        val result = query.satisfy(emptyMap()).toList()
+    }
+}