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handle non-list cases in '', add '' as a built-in (re: issue #31)

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This commit is contained in:
Mark Thom
2018-05-01 10:11:27 -06:00
parent 516b67460d
commit 0458a70527
5 changed files with 24 additions and 8 deletions
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13
src/prolog/machine/machine_state_impl.rs
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@@ -1759,8 +1759,9 @@ impl MachineState {
},
HeapCellValue::Addr(Addr::Con(Constant::EmptyList)) =>
return CycleSearchResult::PartialOrProperList(steps, hare),
HeapCellValue::Addr(Addr::HeapCell(hc)) if hc == hare =>
return CycleSearchResult::PartialOrProperList(steps, hare),
HeapCellValue::Addr(ref hc @ Addr::HeapCell(_))
if Addr::HeapCell(hare) == self.store(self.deref(hc.clone())) =>
return CycleSearchResult::PartialOrProperList(steps, hare),
HeapCellValue::Addr(ref sc @ Addr::StackCell(..))
if *sc == self.store(self.deref(sc.clone())) =>
return CycleSearchResult::PartialOrProperList(steps, hare),
@@ -1787,7 +1788,7 @@ impl MachineState {
======================================================================================
?N, -Xs0 : N = 0, Xs = Xs0.
?N, +Xs0 : Xs0 is a proper or partial list, Xs0 = [X1, X2, ..., XN | Xs], N = Max,
if |Xs0| >= Max, or, Xs = [] and N = |Xs0|.
if |Xs0| >= Max, or, Xs = Xs0 and N = |Xs0|.
*/
pub(super) fn skip_max_list(&mut self) {
let max = self.store(self.deref(self[temp_v!(2)].clone()));
@@ -1814,8 +1815,10 @@ impl MachineState {
self.finalize_skip_max_list(0, Addr::Con(Constant::EmptyList)),
CycleSearchResult::PartialOrProperList(n, hc) =>
self.finalize_skip_max_list(n, Addr::HeapCell(hc)),
CycleSearchResult::NotList =>
self.fail = true
CycleSearchResult::NotList => {
let xs0 = self[temp_v!(3)].clone();
self.finalize_skip_max_list(0, xs0);
}
}
}
}