86 lines
2.7 KiB
Rust
86 lines
2.7 KiB
Rust
use prolog::machine::*;
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pub static VERIFY_ATTRS: &str = include_str!("attributed_variables.pl");
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pub(super) type Bindings = Vec<(usize, Addr)>;
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pub(super) struct AttrVarInitializer {
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pub(super) bindings: Bindings,
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cp_stack: Vec<CodePtr>,
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pub(super) registers: Registers,
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pub(super) verify_attrs_loc: usize
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}
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impl AttrVarInitializer {
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pub(super) fn new(p: usize) -> Self {
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AttrVarInitializer {
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bindings: vec![],
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verify_attrs_loc: p,
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cp_stack: vec![],
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registers: vec![Addr::HeapCell(0); MAX_ARITY + 1]
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}
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}
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#[inline]
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pub(super) fn pop_code_ptr(&mut self) -> CodePtr {
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self.cp_stack.pop().unwrap()
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}
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#[inline]
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pub(super) fn reset(&mut self) {
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self.cp_stack.clear();
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self.bindings.clear();
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}
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}
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impl MachineState {
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pub(super) fn push_attr_var_binding(&mut self, h: usize, addr: Addr)
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{
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if self.attr_var_init.bindings.is_empty() {
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self.attr_var_init.cp_stack.push(self.p.clone() + 1);
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self.p = CodePtr::VerifyAttrInterrupt(self.attr_var_init.verify_attrs_loc);
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}
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self.attr_var_init.bindings.push((h, addr));
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}
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fn populate_var_and_value_lists(&mut self) -> (Addr, Addr) {
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let iter = self.attr_var_init.bindings.iter().map(|(ref h, _)| Addr::AttrVar(*h));
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let var_list_addr = Addr::HeapCell(self.heap.to_list(iter));
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let iter = self.attr_var_init.bindings.iter().map(|(_, ref addr)| addr.clone());
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let value_list_addr = Addr::HeapCell(self.heap.to_list(iter));
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(var_list_addr, value_list_addr)
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}
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pub(super)
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fn verify_attributes(&mut self)
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{
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/* STEP 1: Undo bindings in machine.
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STEP 2: Write the list of bindings to two lists in the heap, one for vars, one for values.
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STEP 3: Swap the machine's Registers for attr_var_init's Registers.
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STEP 4: Pass the addresses of the lists to iterate in the attr_vars special form.
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Call verify_attributes/3 wherever applicable.
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STEP 5: Redo the bindings.
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STEP 6: Call the goals.
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STEP 7: Pop the top of AttrVarInitializer::cp_stack to self.p.
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STEP 8: Swap the AttrVarInitializer's Registers back for the machine's Registers.
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*/
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// STEP 1.
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for (h, _) in &self.attr_var_init.bindings {
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self.heap[*h] = HeapCellValue::Addr(Addr::AttrVar(*h));
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}
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// STEP 2.
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let (var_list_addr, value_list_addr) = self.populate_var_and_value_lists();
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// STEP 3.
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mem::swap(&mut self.registers, &mut self.attr_var_init.registers);
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// STEP 4.
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self[temp_v!(1)] = var_list_addr;
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self[temp_v!(2)] = value_list_addr;
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}
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}
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