rishi/scryer-prolog
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system calls preliminary

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This commit is contained in:
Mark Thom
2018-05-07 22:27:58 -06:00
parent a1bfcf4c9d
commit 1a0f50200f
5 changed files with 52 additions and 187 deletions
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169
src/prolog/machine/machine_state_impl.rs
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@@ -100,12 +100,12 @@ impl MachineState {
where Fmt: HCValueFormatter, Outputter: HCValueOutputter
{
let orig_len = output.len();
output.begin_new_var();
output.append(var.as_str());
output.append(" = ");
let printer = HCPrinter::from_heap_locs(&self, fmt, output, var_dir);
let mut output = printer.print(addr);
@@ -125,7 +125,7 @@ impl MachineState {
let printer = HCPrinter::from_heap_locs_as_seen(&self, fmt, output, var_dir);
printer.print(addr)
}
pub(super)
fn print_term<Fmt, Outputter>(&self, addr: Addr, fmt: Fmt, output: Outputter) -> Outputter
where Fmt: HCValueFormatter, Outputter: HCValueOutputter
@@ -1106,10 +1106,10 @@ impl MachineState {
self.heap.h - self.ball.boundary
}
}
pub(super) fn copy_and_align_ball_to_heap(&mut self) -> usize {
let diff = self.heap_ball_boundary_diff();
for heap_value in self.ball.stub.iter().cloned() {
self.heap.push(match heap_value {
HeapCellValue::Addr(addr) => HeapCellValue::Addr(addr - diff),
@@ -1186,7 +1186,7 @@ impl MachineState {
self.p += 1;
}
pub(super) fn compare_term(&mut self, qt: CompareTermQT) {
let a1 = self[temp_v!(1)].clone();
let a2 = self[temp_v!(2)].clone();
@@ -1441,7 +1441,7 @@ impl MachineState {
try_or_fail!(self, call_policy.trust_me(self));
},
&BuiltInInstruction::EraseBall => {
self.ball.reset();
self.ball.reset();
self.p += 1;
},
&BuiltInInstruction::GetArg(lco) =>
@@ -1621,7 +1621,7 @@ impl MachineState {
let mut duplicator = DuplicateBallTerm::new(self);
duplicator.duplicate_term(addr);
};
self.p += 1;
},
&BuiltInInstruction::SetCutPoint(r) =>
@@ -1841,157 +1841,6 @@ impl MachineState {
}
}
pub(super) fn detect_cycles_with_max(&self, max_steps: usize, addr: Addr) -> CycleSearchResult
{
let addr = self.store(self.deref(addr));
let mut hare = match addr {
Addr::Lis(offset) if max_steps > 0 => offset + 1,
Addr::Lis(offset) => return CycleSearchResult::UntouchedList(offset),
Addr::Con(Constant::EmptyList) => return CycleSearchResult::EmptyList,
_ => return CycleSearchResult::NotList
};
// use Brent's algorithm to detect cycles.
let mut tortoise = hare;
let mut power = 2;
let mut steps = 1;
loop {
if steps == max_steps {
return CycleSearchResult::PartialList(steps, hare);
}
match self.heap[hare].clone() {
HeapCellValue::Addr(Addr::Lis(l)) => {
hare = l + 1;
steps += 1;
if tortoise == hare {
return CycleSearchResult::NotList;
} else if steps == power {
tortoise = hare;
power <<= 1;
}
},
HeapCellValue::NamedStr(..) =>
return CycleSearchResult::NotList,
HeapCellValue::Addr(addr) =>
match self.store(self.deref(addr)) {
Addr::Con(Constant::EmptyList) =>
return CycleSearchResult::ProperList(steps),
Addr::HeapCell(_) | Addr::StackCell(..) =>
return CycleSearchResult::PartialList(steps, hare),
_ =>
return CycleSearchResult::NotList
}
}
}
}
pub(super) fn detect_cycles(&self, addr: Addr) -> CycleSearchResult
{
let addr = self.store(self.deref(addr));
let mut hare = match addr {
Addr::Lis(offset) => offset + 1,
Addr::Con(Constant::EmptyList) => return CycleSearchResult::EmptyList,
_ => return CycleSearchResult::NotList
};
// use Brent's algorithm to detect cycles.
let mut tortoise = hare;
let mut power = 2;
let mut steps = 1;
loop {
match self.heap[hare].clone() {
HeapCellValue::Addr(Addr::Lis(l)) => {
hare = l + 1;
steps += 1;
if tortoise == hare {
return CycleSearchResult::NotList;
} else if steps == power {
tortoise = hare;
power <<= 1;
}
},
HeapCellValue::NamedStr(..) =>
return CycleSearchResult::NotList,
HeapCellValue::Addr(addr) =>
match self.store(self.deref(addr)) {
Addr::Con(Constant::EmptyList) =>
return CycleSearchResult::ProperList(steps),
Addr::HeapCell(_) | Addr::StackCell(..) =>
return CycleSearchResult::PartialList(steps, hare),
_ =>
return CycleSearchResult::NotList
}
}
}
}
fn finalize_skip_max_list(&mut self, n: usize, addr: Addr) {
let target_n = self[temp_v!(1)].clone();
self.unify(Addr::Con(integer!(n)), target_n);
if !self.fail {
let xs = self[temp_v!(4)].clone();
self.unify(addr, xs);
}
}
pub(super) fn skip_max_list(&mut self) -> Result<(), MachineError> {
let max_steps = self.arith_eval_by_metacall(temp_v!(2))?;
match max_steps {
Number::Integer(ref max_steps)
if max_steps.to_isize().map(|i| i >= -1).unwrap_or(false) => {
let n = self.store(self.deref(self[temp_v!(1)].clone()));
match n {
Addr::Con(Constant::Number(Number::Integer(ref n))) if n.is_zero() => {
let xs0 = self[temp_v!(3)].clone();
let xs = self[temp_v!(4)].clone();
self.unify(xs0, xs);
},
_ => {
let search_result = if let Some(max_steps) = max_steps.to_isize() {
if max_steps == -1 {
self.detect_cycles(self[temp_v!(3)].clone())
} else {
self.detect_cycles_with_max(max_steps as usize,
self[temp_v!(3)].clone())
}
} else {
self.detect_cycles(self[temp_v!(3)].clone())
};
match search_result {
CycleSearchResult::UntouchedList(l) =>
self.finalize_skip_max_list(0, Addr::Lis(l)),
CycleSearchResult::EmptyList =>
self.finalize_skip_max_list(0, Addr::Con(Constant::EmptyList)),
CycleSearchResult::PartialList(n, hc) =>
self.finalize_skip_max_list(n, Addr::HeapCell(hc)),
CycleSearchResult::ProperList(n) =>
self.finalize_skip_max_list(n, Addr::Con(Constant::EmptyList)),
CycleSearchResult::NotList => {
let xs0 = self[temp_v!(3)].clone();
self.finalize_skip_max_list(0, xs0);
}
}
}
}
},
_ => self.fail = true
};
Ok(())
}
pub(super) fn duplicate_term(&mut self) {
let old_h = self.heap.h;
@@ -2330,7 +2179,7 @@ impl MachineState {
self.or_stack.clear();
self.registers = vec![Addr::HeapCell(0); 64];
self.block = 0;
self.ball.reset();
}
}