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fix unification bugs.

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This commit is contained in:
Mark Thom
2017-01-27 21:54:53 -07:00
parent e7af3dc57a
commit 0c6926b3cb
2 changed files with 61 additions and 14 deletions
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57
src/l0/machine.rs
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@@ -32,12 +32,12 @@ pub struct Machine {
impl Machine {
pub fn new() -> Machine {
Machine { h : 0,
s : 0,
fail : false,
heap : Vec::with_capacity(256),
mode : MachineMode::Write,
program : None,
registers : vec![HeapCell::Ref(0); 33] }
s : 0,
fail : false,
heap : Vec::with_capacity(256),
mode : MachineMode::Write,
program : None,
registers : vec![HeapCell::Ref(0); 33] }
}
fn lookup(&self, a: Addr) -> &HeapCell {
@@ -64,11 +64,44 @@ impl Machine {
};
}
fn is_unbound(hc: &HeapCell, index: usize) -> bool {
match hc {
&HeapCell::Ref(r) => r == index,
_ => false
}
}
//TODO: try to compress this function. currently it is dog shit.
fn bind(&mut self, a: Addr, val: usize) {
match a {
Addr::RegNum(reg) => self.registers[reg] = HeapCell::Ref(val),
Addr::HeapCell(hc) => self.heap[hc] = HeapCell::Ref(val),
};
let mut a = a;
loop {
match a {
Addr::RegNum(reg) => {
if let HeapCell::Ref(hc) = self.registers[reg] {
a = Addr::HeapCell(hc);
} else if Machine::is_unbound(&self.heap[val], val) {
self.heap[val] = self.registers[reg].clone();
break;
} else {
self.fail = true;
break;
}
},
Addr::HeapCell(hc) if Machine::is_unbound(&self.heap[hc], hc) => {
self.heap[hc] = HeapCell::Ref(val);
break;
},
Addr::HeapCell(hc) if Machine::is_unbound(&self.heap[val], val) => {
self.heap[val] = HeapCell::Ref(hc);
break;
},
_ => {
self.fail = true;
break;
}
};
}
}
fn unify(&mut self, a1: Addr, a2: Addr) {
@@ -152,13 +185,13 @@ impl Machine {
}
}
},
&HeapCell::Ref(reg) => {
&HeapCell::Ref(r) => {
self.heap.push(HeapCell::Str(self.h + 1));
self.heap.push(HeapCell::NamedStr(arity, name.clone()));
let h = self.h;
self.bind(Addr::RegNum(reg), h);
self.bind(Addr::HeapCell(r), h);
self.h += 2;
self.mode = MachineMode::Write;