rishi/scryer-prolog
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introduce a better binding scheme for attributed variables

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This commit is contained in:
Mark Thom
2019-02-03 15:16:30 -07:00
parent f51405bc04
commit 3cfbbb23a3
9 changed files with 122 additions and 105 deletions
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110
src/prolog/machine/machine_state_impl.rs
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@@ -76,28 +76,47 @@ impl MachineState {
if self.b > 0 { self.or_stack[self.b - 1].global_index } else { 0 }) + 1
}
pub(crate) fn store(&self, a: Addr) -> Addr {
match a {
Addr::AttrVar(h, _) => self.heap[h].as_addr(h),
Addr::HeapCell(h) => self.heap[h].as_addr(h),
pub(crate) fn store(&self, addr: Addr) -> Addr {
match addr {
Addr::AttrVar(h) | Addr::HeapCell(h) => self.heap[h].as_addr(h),
Addr::StackCell(fr, sc) => self.and_stack[fr][sc].clone(),
addr => addr
addr => addr
}
}
pub(crate) fn deref(&self, mut a: Addr) -> Addr {
pub(crate) fn deref(&self, mut addr: Addr) -> Addr {
loop {
let value = self.store(a.clone());
let value = self.store(addr.clone());
if value.is_ref() && value != a {
a = value;
if value.is_ref() && value != addr {
addr = value;
continue;
}
return a;
return addr;
};
}
// from the assumptions active at the call site in bind, we know:
// if addr is a Ref, it precedes h in the heap.
fn bind_attr_var(&mut self, h: usize, addr: Addr) {
match addr.as_var() {
Some(Ref::HeapCell(hc)) => {
self.heap[hc] = HeapCellValue::Addr(Addr::AttrVar(h));
self.trail(TrailRef::from(Ref::HeapCell(hc)));
},
Some(Ref::StackCell(fr, sc)) => {
self.and_stack[fr][sc] = Addr::AttrVar(h);
self.trail(TrailRef::from(Ref::StackCell(fr, sc)));
},
_ => {
// TODO: set up writing to the attribute queue here.
self.heap[h] = HeapCellValue::Addr(addr);
self.trail(TrailRef::from(Ref::AttrVar(h)));
}
}
}
pub(super) fn bind(&mut self, r1: Ref, a2: Addr) {
let t1 = self.store(r1.as_addr());
let t2 = self.store(a2.clone());
@@ -107,7 +126,9 @@ impl MachineState {
Ref::StackCell(fr, sc) =>
self.and_stack[fr][sc] = t2,
Ref::HeapCell(h) =>
self.heap[h] = HeapCellValue::Addr(t2)
self.heap[h] = HeapCellValue::Addr(t2),
Ref::AttrVar(h) =>
return self.bind_attr_var(h, t2)
};
self.trail(TrailRef::from(r1));
@@ -115,12 +136,14 @@ impl MachineState {
match a2.as_var() {
Some(Ref::StackCell(fr, sc)) => {
self.and_stack[fr][sc] = t1;
self.trail(TrailRef::StackCell(fr, sc));
self.trail(TrailRef::Ref(Ref::StackCell(fr, sc)));
},
Some(Ref::HeapCell(h)) => {
self.heap[h] = HeapCellValue::Addr(t1);
self.trail(TrailRef::HeapCell(h));
self.trail(TrailRef::Ref(Ref::HeapCell(h)));
},
Some(Ref::AttrVar(h)) =>
return self.bind_attr_var(h, t1),
None => {}
}
}
@@ -220,10 +243,8 @@ impl MachineState {
if d1 != d2 {
match (self.store(d1.clone()), self.store(d2.clone())) {
(Addr::AttrVar(h, _), addr) | (addr, Addr::AttrVar(h, _)) => {
pdl.push(Addr::HeapCell(h+1));
pdl.push(addr);
},
(Addr::AttrVar(h), addr) | (addr, Addr::AttrVar(h)) =>
self.bind(Ref::AttrVar(h), addr),
(Addr::HeapCell(h), _) =>
self.bind(Ref::HeapCell(h), d2),
(_, Addr::HeapCell(h)) =>
@@ -354,9 +375,14 @@ impl MachineState {
pub(super) fn trail(&mut self, r: TrailRef) {
match r {
TrailRef::HeapCell(h) =>
TrailRef::Ref(Ref::HeapCell(h)) =>
if h < self.hb {
self.trail.push(TrailRef::HeapCell(h));
self.trail.push(TrailRef::Ref(Ref::HeapCell(h)));
self.tr += 1;
},
TrailRef::Ref(Ref::AttrVar(h)) =>
if h < self.hb {
self.trail.push(TrailRef::Ref(Ref::AttrVar(h)));
self.tr += 1;
},
TrailRef::AttrVarLink(h, prev_addr) =>
@@ -364,7 +390,7 @@ impl MachineState {
self.trail.push(TrailRef::AttrVarLink(h, prev_addr));
self.tr += 1;
},
TrailRef::StackCell(fr, sc) => {
TrailRef::Ref(Ref::StackCell(fr, sc)) => {
let fr_gi = self.and_stack[fr].global_index;
let b_gi = if !self.or_stack.is_empty() {
if self.b > 0 {
@@ -378,7 +404,7 @@ impl MachineState {
};
if fr_gi < b_gi {
self.trail.push(TrailRef::StackCell(fr, sc));
self.trail.push(TrailRef::Ref(Ref::StackCell(fr, sc)));
self.tr += 1;
}
}
@@ -391,9 +417,11 @@ impl MachineState {
// backtracking.
for i in (a1 .. a2).rev() {
match self.trail[i].clone() {
TrailRef::HeapCell(h) =>
TrailRef::Ref(Ref::HeapCell(h)) =>
self.heap[h] = HeapCellValue::Addr(Addr::HeapCell(h)),
TrailRef::StackCell(fr, sc) =>
TrailRef::Ref(Ref::AttrVar(h)) =>
self.heap[h] = HeapCellValue::Addr(Addr::AttrVar(h)),
TrailRef::Ref(Ref::StackCell(fr, sc)) =>
self.and_stack[fr][sc] = Addr::StackCell(fr, sc),
TrailRef::AttrVarLink(h, prev_addr) =>
self.heap[h] = HeapCellValue::Addr(prev_addr)
@@ -443,7 +471,9 @@ impl MachineState {
let hb = self.hb;
match tr_i {
TrailRef::HeapCell(tr_i) | TrailRef::AttrVarLink(tr_i, _) =>
TrailRef::Ref(Ref::AttrVar(tr_i))
| TrailRef::Ref(Ref::HeapCell(tr_i))
| TrailRef::AttrVarLink(tr_i, _) =>
if tr_i < hb {
i += 1;
} else {
@@ -453,7 +483,7 @@ impl MachineState {
self.trail.pop();
self.tr -= 1;
},
TrailRef::StackCell(fr, _) => {
TrailRef::Ref(Ref::StackCell(fr, _)) => {
let b = self.b - 1;
let fr_gi = self.and_stack[fr].global_index;
let b_gi = if !self.or_stack.is_empty() {
@@ -489,11 +519,11 @@ impl MachineState {
match self.store(self.deref(addr)) {
Addr::HeapCell(h) => {
self.heap[h] = HeapCellValue::Addr(Addr::Con(c.clone()));
self.trail(TrailRef::HeapCell(h));
self.trail(TrailRef::Ref(Ref::HeapCell(h)));
},
Addr::StackCell(fr, sc) => {
self.and_stack[fr][sc] = Addr::Con(c.clone());
self.trail(TrailRef::StackCell(fr, sc));
self.trail(TrailRef::Ref(Ref::StackCell(fr, sc)));
},
Addr::Con(Constant::String(ref mut s)) =>
self.fail = match c {
@@ -1012,19 +1042,11 @@ impl MachineState {
self.fail = true;
}
},
Addr::HeapCell(hc) => {
addr @ Addr::AttrVar(_) | addr @ Addr::StackCell(..) | addr @ Addr::HeapCell(_) => {
let h = self.heap.h;
self.heap.push(HeapCellValue::Addr(Addr::Lis(h+1)));
self.bind(Ref::HeapCell(hc), Addr::HeapCell(h));
self.mode = MachineMode::Write;
},
Addr::StackCell(fr, sc) => {
let h = self.heap.h;
self.heap.push(HeapCellValue::Addr(Addr::Lis(h+1)));
self.bind(Ref::StackCell(fr, sc), Addr::HeapCell(h));
self.bind(addr.as_var().unwrap(), Addr::HeapCell(h));
self.mode = MachineMode::Write;
},
@@ -1051,7 +1073,7 @@ impl MachineState {
}
}
},
Addr::HeapCell(_) | Addr::StackCell(_, _) => {
Addr::AttrVar(_) | Addr::HeapCell(_) | Addr::StackCell(_, _) => {
let h = self.heap.h;
self.heap.push(HeapCellValue::Addr(Addr::Str(h + 1)));
@@ -1788,8 +1810,8 @@ impl MachineState {
let d = self.store(self.deref(self[r1].clone()));
match d {
Addr::HeapCell(_) | Addr::StackCell(..) => self.fail = true,
Addr::AttrVar(h, _) => {
Addr::AttrVar(_) | Addr::HeapCell(_) | Addr::StackCell(..) => self.fail = true,
/* Addr::AttrVar(h) => {
let addr = self.heap[h].as_addr(h);
if let Some(_) = addr.as_var() {
@@ -1799,7 +1821,7 @@ impl MachineState {
}
self.p += 1;
},
},*/
_ => self.p += 1
};
},
@@ -1807,8 +1829,8 @@ impl MachineState {
let d = self.store(self.deref(self[r1].clone()));
match d {
Addr::HeapCell(_) | Addr::StackCell(_,_) => self.p += 1,
Addr::AttrVar(h, _) => {
Addr::AttrVar(_) | Addr::HeapCell(_) | Addr::StackCell(_,_) => self.p += 1,
/* Addr::AttrVar(h, _) => {
let addr = self.heap[h].as_addr(h);
if let Some(_) = addr.as_var() {
@@ -1818,7 +1840,7 @@ impl MachineState {
}
self.p += 1;
},
},*/
_ => self.fail = true
};
},