Files
scryer-prolog/src/prolog/machine/machine_state.rs

746 lines
22 KiB
Rust

use prolog::and_stack::*;
use prolog::ast::*;
use prolog::copier::*;
use prolog::num::{BigInt, BigUint, Zero, One};
use prolog::or_stack::*;
use prolog::heap_print::*;
use prolog::tabled_rc::*;
use downcast::Any;
use std::cmp::Ordering;
use std::collections::HashMap;
use std::mem::swap;
use std::ops::{Index, IndexMut};
use std::rc::Rc;
pub(crate) struct CodeDirs<'a> {
code_dir: &'a CodeDir,
modules: &'a HashMap<ClauseName, Module>
}
impl<'a> CodeDirs<'a> {
pub(super) fn new(code_dir: &'a CodeDir, modules: &'a HashMap<ClauseName, Module>) -> Self {
CodeDirs { code_dir, modules }
}
fn get_current_code_dir(&self, p: &CodePtr) -> &CodeDir {
let module_name = p.module_name();
match module_name {
ClauseName::BuiltIn("user") | ClauseName::BuiltIn("builtin") => self.code_dir,
_ => &self.modules.get(&module_name).unwrap().code_dir
}
}
pub(super) fn get(&self, name: ClauseName, arity: usize, p: &CodePtr) -> Option<CodeIndex> {
let code_dir = self.get_current_code_dir(p);
code_dir.get(&(name, arity)).cloned()
}
}
pub(super) struct DuplicateTerm<'a> {
state: &'a mut MachineState
}
impl<'a> DuplicateTerm<'a> {
pub(super) fn new(state: &'a mut MachineState) -> Self {
DuplicateTerm { state: state }
}
}
impl<'a> Index<usize> for DuplicateTerm<'a> {
type Output = HeapCellValue;
fn index(&self, index: usize) -> &Self::Output {
&self.state.heap[index]
}
}
impl<'a> IndexMut<usize> for DuplicateTerm<'a> {
fn index_mut(&mut self, index: usize) -> &mut Self::Output {
&mut self.state.heap[index]
}
}
// the ordinary, heap term copier, used by duplicate_term.
impl<'a> CopierTarget for DuplicateTerm<'a> {
fn source(&self) -> usize {
self.state.heap.h
}
fn threshold(&self) -> usize {
self.state.heap.h
}
fn push(&mut self, hcv: HeapCellValue) {
self.state.heap.push(hcv);
}
fn store(&self, a: Addr) -> Addr {
self.state.store(a)
}
fn deref(&self, a: Addr) -> Addr {
self.state.deref(a)
}
fn stack(&mut self) -> &mut AndStack {
&mut self.state.and_stack
}
}
pub(super) struct DuplicateBallTerm<'a> {
state: &'a mut MachineState,
heap_boundary: usize
}
impl<'a> DuplicateBallTerm<'a> {
pub(super) fn new(state: &'a mut MachineState) -> Self {
let hb = state.heap.len();
DuplicateBallTerm { state, heap_boundary: hb }
}
}
impl<'a> Index<usize> for DuplicateBallTerm<'a> {
type Output = HeapCellValue;
fn index(&self, index: usize) -> &Self::Output {
if index < self.heap_boundary {
&self.state.heap[index]
} else {
let index = index - self.heap_boundary;
&self.state.ball.1[index]
}
}
}
impl<'a> IndexMut<usize> for DuplicateBallTerm<'a> {
fn index_mut(&mut self, index: usize) -> &mut Self::Output {
if index < self.heap_boundary {
&mut self.state.heap[index]
} else {
let index = index - self.heap_boundary;
&mut self.state.ball.1[index]
}
}
}
// the ordinary, heap term copier, used by duplicate_term.
impl<'a> CopierTarget for DuplicateBallTerm<'a> {
fn source(&self) -> usize {
self.heap_boundary
}
fn threshold(&self) -> usize {
self.heap_boundary + self.state.ball.1.len()
}
fn push(&mut self, hcv: HeapCellValue) {
self.state.ball.1.push(hcv);
}
fn store(&self, a: Addr) -> Addr {
self.state.store(a)
}
fn deref(&self, a: Addr) -> Addr {
self.state.deref(a)
}
fn stack(&mut self) -> &mut AndStack {
&mut self.state.and_stack
}
}
impl Index<RegType> for MachineState {
type Output = Addr;
fn index(&self, reg: RegType) -> &Self::Output {
match reg {
RegType::Temp(temp) => &self.registers[temp],
RegType::Perm(perm) => {
let e = self.e;
&self.and_stack[e][perm]
}
}
}
}
impl IndexMut<RegType> for MachineState {
fn index_mut(&mut self, reg: RegType) -> &mut Self::Output {
match reg {
RegType::Temp(temp) => &mut self.registers[temp],
RegType::Perm(perm) => {
let e = self.e;
&mut self.and_stack[e][perm]
}
}
}
}
#[derive(Clone, Copy)]
pub(super) enum MachineMode {
Read,
Write
}
pub struct MachineState {
pub(super) atom_tbl: TabledData<Atom>,
pub(super) s: usize,
pub(super) p: CodePtr,
pub(super) b: usize,
pub(super) b0: usize,
pub(super) e: usize,
pub(super) num_of_args: usize,
pub(super) cp: CodePtr,
pub(super) fail: bool,
pub(crate) heap: Heap,
pub(super) mode: MachineMode,
pub(crate) and_stack: AndStack,
pub(super) or_stack: OrStack,
pub(super) registers: Registers,
pub(super) trail: Vec<Ref>,
pub(super) tr: usize,
pub(super) hb: usize,
pub(super) block: usize, // an offset into the OR stack.
pub(super) ball: (usize, Vec<HeapCellValue>), // heap boundary, and a term copy
pub(super) interms: Vec<Number>, // intermediate numbers.
}
pub(crate) type CallResult = Result<(), Vec<HeapCellValue>>;
fn predicate_existence_error(name: ClauseName, arity: usize, h: usize) -> Vec<HeapCellValue>
{
let name = HeapCellValue::Addr(Addr::Con(Constant::Atom(name)));
let mut error = functor!("existence_error", 2, [heap_atom!("procedure"), heap_str!(3 + h)]);
error.append(&mut functor!("/", 2, [name, heap_integer!(arity)], Fixity::In));
error
}
pub(crate) trait CallPolicy: Any {
fn context_call(&mut self, machine_st: &mut MachineState, name: ClauseName,
arity: usize, idx: CodeIndex, lco: bool)
-> CallResult
{
if lco {
self.try_execute(machine_st, name, arity, idx)
} else {
self.try_call(machine_st, name, arity, idx)
}
}
fn try_call(&mut self, machine_st: &mut MachineState, name: ClauseName,
arity: usize, idx: CodeIndex)
-> CallResult
{
match idx.0.get() {
IndexPtr::Undefined =>
return Err(predicate_existence_error(name, arity, machine_st.heap.h)),
IndexPtr::Index(compiled_tl_index) => {
let module_name = idx.1;
machine_st.cp = machine_st.p.clone() + 1;
machine_st.num_of_args = arity;
machine_st.b0 = machine_st.b;
machine_st.p = CodePtr::DirEntry(compiled_tl_index, module_name);
}
}
Ok(())
}
fn try_execute<'a>(&mut self, machine_st: &mut MachineState, name: ClauseName,
arity: usize, idx: CodeIndex)
-> CallResult
{
match idx.0.get() {
IndexPtr::Undefined =>
return Err(predicate_existence_error(name, arity, machine_st.heap.h)),
IndexPtr::Index(compiled_tl_index) => {
let module_name = idx.1;
machine_st.num_of_args = arity;
machine_st.b0 = machine_st.b;
machine_st.p = CodePtr::DirEntry(compiled_tl_index, module_name);
}
}
Ok(())
}
fn retry_me_else(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
let b = machine_st.b - 1;
let n = machine_st.or_stack[b].num_args();
for i in 1 .. n + 1 {
machine_st.registers[i] = machine_st.or_stack[b][i].clone();
}
machine_st.e = machine_st.or_stack[b].e;
machine_st.cp = machine_st.or_stack[b].cp.clone();
machine_st.or_stack[b].bp = machine_st.p.clone() + offset;
let old_tr = machine_st.or_stack[b].tr;
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.hb = machine_st.heap.h;
machine_st.p += 1;
Ok(())
}
fn retry(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
let b = machine_st.b - 1;
let n = machine_st.or_stack[b].num_args();
for i in 1 .. n + 1 {
machine_st.registers[i] = machine_st.or_stack[b][i].clone();
}
machine_st.e = machine_st.or_stack[b].e;
machine_st.cp = machine_st.or_stack[b].cp.clone();
machine_st.or_stack[b].bp = machine_st.p.clone() + 1;
let old_tr = machine_st.or_stack[b].tr;
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.hb = machine_st.heap.h;
machine_st.p += offset;
Ok(())
}
fn trust(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
let b = machine_st.b - 1;
let n = machine_st.or_stack[b].num_args();
for i in 1 .. n + 1 {
machine_st.registers[i] = machine_st.or_stack[b][i].clone();
}
machine_st.e = machine_st.or_stack[b].e;
machine_st.cp = machine_st.or_stack[b].cp.clone();
let old_tr = machine_st.or_stack[b].tr;
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.b = machine_st.or_stack[b].b;
machine_st.or_stack.truncate(machine_st.b);
machine_st.hb = machine_st.heap.h;
machine_st.p += offset;
Ok(())
}
fn trust_me(&mut self, machine_st: &mut MachineState) -> CallResult
{
let b = machine_st.b - 1;
let n = machine_st.or_stack[b].num_args();
for i in 1 .. n + 1 {
machine_st.registers[i] = machine_st.or_stack[b][i].clone();
}
machine_st.e = machine_st.or_stack[b].e;
machine_st.cp = machine_st.or_stack[b].cp.clone();
let old_tr = machine_st.or_stack[b].tr;
let curr_tr = machine_st.tr;
machine_st.unwind_trail(old_tr, curr_tr);
machine_st.tr = machine_st.or_stack[b].tr;
machine_st.trail.truncate(machine_st.tr);
machine_st.heap.truncate(machine_st.or_stack[b].h);
machine_st.b = machine_st.or_stack[b].b;
machine_st.or_stack.truncate(machine_st.b);
machine_st.hb = machine_st.heap.h;
machine_st.p += 1;
Ok(())
}
fn try_call_clause<'a>(&mut self, machine_st: &mut MachineState, code_dirs: CodeDirs<'a>,
ct: &ClauseType, arity: usize, lco: bool)
-> CallResult
{
match ct {
&ClauseType::AcyclicTerm => {
let addr = machine_st[temp_v!(1)].clone();
machine_st.fail = machine_st.is_cyclic_term(addr);
return_from_clause!(lco, machine_st)
},
&ClauseType::Arg => {
if !lco {
machine_st.cp = machine_st.p.clone() + 1;
}
machine_st.num_of_args = 3;
machine_st.b0 = machine_st.b;
machine_st.p = CodePtr::DirEntry(166, clause_name!("builtin"));
Ok(())
},
&ClauseType::Catch => {
if !lco {
machine_st.cp = machine_st.p.clone() + 1;
}
machine_st.num_of_args = 3;
machine_st.b0 = machine_st.b;
machine_st.p = CodePtr::DirEntry(5, clause_name!("builtin"));
Ok(())
},
&ClauseType::CallN =>
if let Some((name, arity)) = machine_st.setup_call_n(arity) {
if let Some(idx) = code_dirs.get(name.clone(), arity, &machine_st.p.clone()) {
self.context_call(machine_st, name, arity, idx, lco)
} else {
Err(predicate_existence_error(name, arity, machine_st.heap.h))
}
} else {
Ok(())
},
&ClauseType::Compare => {
let a1 = machine_st[temp_v!(1)].clone();
let a2 = machine_st[temp_v!(2)].clone();
let a3 = machine_st[temp_v!(3)].clone();
let c = Addr::Con(match machine_st.compare_term_test(&a2, &a3) {
Ordering::Greater => atom!(">"),
Ordering::Equal => atom!("="),
Ordering::Less => atom!("<")
});
machine_st.unify(a1, c);
return_from_clause!(lco, machine_st)
},
&ClauseType::CompareTerm(qt) => {
match qt {
CompareTermQT::Equal =>
machine_st.fail = machine_st.structural_eq_test(),
CompareTermQT::NotEqual =>
machine_st.fail = !machine_st.structural_eq_test(),
_ => machine_st.compare_term(qt)
};
return_from_clause!(lco, machine_st)
},
&ClauseType::CyclicTerm => {
let addr = machine_st[temp_v!(1)].clone();
machine_st.fail = !machine_st.is_cyclic_term(addr);
return_from_clause!(lco, machine_st)
},
&ClauseType::Display => {
let output = machine_st.print_term(machine_st[temp_v!(1)].clone(),
DisplayFormatter {},
PrinterOutputter::new());
println!("{}", output.result());
return_from_clause!(lco, machine_st)
},
&ClauseType::DuplicateTerm => {
machine_st.duplicate_term();
return_from_clause!(lco, machine_st)
},
&ClauseType::Eq => {
machine_st.fail = machine_st.eq_test();
return_from_clause!(lco, machine_st)
},
&ClauseType::Ground => {
machine_st.fail = machine_st.ground_test();
return_from_clause!(lco, machine_st)
},
&ClauseType::Functor => {
machine_st.try_functor()?;
return_from_clause!(lco, machine_st)
},
&ClauseType::NotEq => {
machine_st.fail = !machine_st.eq_test();
return_from_clause!(lco, machine_st)
},
&ClauseType::Sort => {
let mut list = machine_st.try_from_list(temp_v!(1))?;
list.sort_unstable_by(|a1, a2| machine_st.compare_term_test(a1, a2));
machine_st.term_dedup(&mut list);
let heap_addr = Addr::HeapCell(machine_st.to_list(list.into_iter()));
let r2 = machine_st[temp_v!(2)].clone();
machine_st.unify(r2, heap_addr);
return_from_clause!(lco, machine_st)
},
&ClauseType::KeySort => {
let mut list = machine_st.try_from_list(temp_v!(1))?;
let mut key_pairs = Vec::new();
for val in list {
let key = machine_st.project_onto_key(val.clone())?;
key_pairs.push((key, val.clone()));
}
key_pairs.sort_by(|a1, a2| machine_st.compare_term_test(&a1.0, &a2.0));
let key_pairs = key_pairs.into_iter().map(|kp| kp.1);
let heap_addr = Addr::HeapCell(machine_st.to_list(key_pairs));
let r2 = machine_st[temp_v!(2)].clone();
machine_st.unify(r2, heap_addr);
return_from_clause!(lco, machine_st)
},
&ClauseType::Throw => {
if !lco {
machine_st.cp = machine_st.p.clone() + 1;
}
machine_st.goto_throw();
Ok(())
},
&ClauseType::Named(ref name, ref idx) | &ClauseType::Op(ref name, _, ref idx) =>
self.context_call(machine_st, name.clone(), arity, idx.clone(), lco),
&ClauseType::CallWithInferenceLimit => {
machine_st.goto_ptr(CodePtr::DirEntry(409, clause_name!("builtin")), 3, lco);
Ok(())
},
&ClauseType::SetupCallCleanup => {
machine_st.goto_ptr(CodePtr::DirEntry(310, clause_name!("builtin")), 3, lco);
Ok(())
},
&ClauseType::Is => {
let a = machine_st[temp_v!(1)].clone();
let result = machine_st.arith_eval_by_metacall(temp_v!(2))?;
machine_st.unify(a, Addr::Con(Constant::Number(result)));
machine_st.p += 1;
Ok(())
},
&ClauseType::Inlined(ref inlined) => {
machine_st.execute_inlined(inlined, &vec![temp_v!(1), temp_v!(2)]);
Ok(())
}
}
}
}
downcast!(CallPolicy);
pub(crate) struct DefaultCallPolicy {}
impl CallPolicy for DefaultCallPolicy {}
pub(crate) struct CallWithInferenceLimitCallPolicy {
pub(crate) prev_policy: Box<CallPolicy>,
count: BigUint,
limits: Vec<(BigUint, usize)>
}
impl CallWithInferenceLimitCallPolicy {
pub(crate) fn new_in_place(policy: &mut Box<CallPolicy>)
{
let mut prev_policy: Box<CallPolicy> = Box::new(DefaultCallPolicy {});
swap(&mut prev_policy, policy);
let new_policy = CallWithInferenceLimitCallPolicy { prev_policy,
count: BigUint::zero(),
limits: vec![] };
*policy = Box::new(new_policy);
}
fn increment(&mut self) -> CallResult {
if let Some(&(ref limit, bp)) = self.limits.last() {
if self.count == *limit {
return Err(functor!("inference_limit_exceeded", 1,
[HeapCellValue::Addr(Addr::Con(Constant::Usize(bp)))]));
} else {
self.count += BigUint::one();
}
}
Ok(())
}
pub(crate) fn add_limit(&mut self, limit: Rc<BigInt>, b: usize) -> Rc<BigInt> {
let limit = match limit.to_biguint() {
Some(limit) => limit + &self.count,
None => panic!("install_inference_counter: limit must be positive")
};
match self.limits.last().cloned() {
Some((ref inner_limit, _)) if *inner_limit <= limit => {},
_ => self.limits.push((limit, b))
};
Rc::new(BigInt::from(self.count.clone()))
}
pub(crate) fn remove_limit(&mut self, b: usize) -> Rc<BigInt> {
if let Some((_, bp)) = self.limits.last().cloned() {
if bp == b {
self.limits.pop();
}
}
Rc::new(BigInt::from(self.count.clone()))
}
pub(crate) fn is_empty(&self) -> bool {
self.limits.is_empty()
}
pub(crate) fn into_inner(&mut self) -> Box<CallPolicy> {
let mut new_inner: Box<CallPolicy> = Box::new(DefaultCallPolicy {});
swap(&mut self.prev_policy, &mut new_inner);
new_inner
}
}
impl CallPolicy for CallWithInferenceLimitCallPolicy {
fn retry_me_else(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
self.prev_policy.retry_me_else(machine_st, offset)?;
self.increment()
}
fn retry(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
self.prev_policy.retry(machine_st, offset)?;
self.increment()
}
fn trust_me(&mut self, machine_st: &mut MachineState) -> CallResult
{
self.prev_policy.trust_me(machine_st)?;
self.increment()
}
fn trust(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
self.prev_policy.trust(machine_st, offset)?;
self.increment()
}
fn try_call_clause<'a>(&mut self, machine_st: &mut MachineState, code_dirs: CodeDirs<'a>,
ct: &ClauseType, arity: usize, lco: bool)
-> CallResult
{
self.prev_policy.try_call_clause(machine_st, code_dirs, ct, arity, lco)?;
self.increment()
}
}
pub(crate) trait CutPolicy: Any {
fn cut(&mut self, &mut MachineState, RegType);
}
downcast!(CutPolicy);
pub(crate) struct DefaultCutPolicy {}
impl CutPolicy for DefaultCutPolicy {
fn cut(&mut self, machine_st: &mut MachineState, r: RegType) {
let b = machine_st.b;
if let Addr::Con(Constant::Usize(b0)) = machine_st[r].clone() {
if b > b0 {
machine_st.b = b0;
machine_st.tidy_trail();
machine_st.or_stack.truncate(machine_st.b);
}
} else {
machine_st.fail = true;
return;
}
machine_st.p += 1;
}
}
pub(crate) struct SetupCallCleanupCutPolicy {
// locations of cleaners, cut points, the previous block
cont_pts: Vec<(Addr, usize, usize)>
}
impl SetupCallCleanupCutPolicy {
pub(crate) fn new() -> Self {
SetupCallCleanupCutPolicy { cont_pts: vec![] }
}
pub(crate) fn out_of_cont_pts(&self) -> bool {
self.cont_pts.is_empty()
}
pub(crate) fn push_cont_pt(&mut self, addr: Addr, b: usize, block: usize) {
self.cont_pts.push((addr, b, block));
}
pub(crate) fn pop_cont_pt(&mut self) -> Option<(Addr, usize, usize)> {
self.cont_pts.pop()
}
}
impl CutPolicy for SetupCallCleanupCutPolicy {
fn cut(&mut self, machine_st: &mut MachineState, r: RegType) {
let b = machine_st.b;
if let Addr::Con(Constant::Usize(b0)) = machine_st[r].clone() {
if b > b0 {
machine_st.b = b0;
machine_st.tidy_trail();
machine_st.or_stack.truncate(machine_st.b);
}
} else {
machine_st.fail = true;
return;
}
machine_st.p += 1;
if !self.out_of_cont_pts() {
machine_st.cp = machine_st.p.clone();
machine_st.num_of_args = 0;
machine_st.b0 = machine_st.b;
// goto_call run_cleaners_without_handling/0, 370.
machine_st.p = CodePtr::DirEntry(370, clause_name!("builtin"));
}
}
}