tdpeuter/2025LogProg-project-GhentProlog
tdpeuter/2025LogProg-project-GhentProlog
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Backtracking fixed

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This commit is contained in:
Tibo De Peuter 2025-05-05 20:11:44 +02:00
parent a85169dced
commit fd16c4cedc
Signed by: tdpeuter
GPG key ID: 38297DE43F75FFE2
18 changed files with 213 additions and 39 deletions
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18
src/prolog/builtins/controlOperators.kt
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@ -7,13 +7,16 @@ import prolog.ast.logic.LogicOperator
import prolog.ast.terms.Atom
import prolog.ast.terms.Body
import prolog.ast.terms.Goal
import prolog.ast.terms.Structure
import prolog.flags.AppliedCut
import prolog.logic.applySubstitution
/**
* Always fail.
*/
object Fail : Atom("fail"), Body {
override fun satisfy(subs: Substitutions): Answers = emptySequence()
override fun applySubstitution(subs: Substitutions): Fail = Fail
}
/**
@ -26,6 +29,7 @@ typealias False = Fail
*/
object True : Atom("true"), Body {
override fun satisfy(subs: Substitutions): Answers = sequenceOf(Result.success(emptyMap()))
override fun applySubstitution(subs: Substitutions): True = True
}
// TODO Repeat/0
@ -34,6 +38,8 @@ class Cut() : Atom("!") {
override fun satisfy(subs: Substitutions): Answers {
return sequenceOf(Result.failure(AppliedCut(emptyMap())))
}
override fun applySubstitution(subs: Substitutions): Cut = Cut()
}
/**
@ -94,6 +100,11 @@ class Conjunction(val left: LogicOperand, private val right: LogicOperand) :
)
}
}
override fun applySubstitution(subs: Substitutions): Conjunction = Conjunction(
applySubstitution(left, subs) as LogicOperand,
applySubstitution(right, subs) as LogicOperand
)
}
/**
@ -105,6 +116,11 @@ open class Disjunction(private val left: LogicOperand, private val right: LogicO
yieldAll(left.satisfy(subs))
yieldAll(right.satisfy(subs))
}
override fun applySubstitution(subs: Substitutions): Disjunction = Disjunction(
applySubstitution(left, subs) as LogicOperand,
applySubstitution(right, subs) as LogicOperand
)
}
@Deprecated("Use Disjunction instead")
@ -127,4 +143,6 @@ class Not(private val goal: Goal) : LogicOperator(Atom("\\+"), rightOperand = go
// If the goal cannot be proven, return a sequence with an empty map
return sequenceOf(Result.success(emptyMap()))
}
override fun applySubstitution(subs: Substitutions): Not = Not(applySubstitution(goal, subs) as Goal)
}