Files
scryer-prolog/src/prolog/machine/machine_state.rs
2018-08-30 00:35:42 -06:00

989 lines
31 KiB
Rust

use prolog::and_stack::*;
use prolog::ast::*;
use prolog::copier::*;
use prolog::heap_print::*;
use prolog::machine::machine_errors::*;
use prolog::num::{BigInt, BigUint, Zero, One};
use prolog::or_stack::*;
use prolog::read::*;
use prolog::string_list::*;
use prolog::tabled_rc::*;
use downcast::Any;
use std::cell::RefCell;
use std::cmp::Ordering;
use std::mem::swap;
use std::ops::{Index, IndexMut};
use std::rc::Rc;
pub(super) struct Ball {
pub(super) boundary: usize, // ball.0
pub(super) stub: MachineStub, // ball.1
}
impl Ball {
pub(super) fn new() -> Self {
Ball { boundary: 0, stub: MachineStub::new() }
}
pub(super) fn reset(&mut self) {
self.boundary = 0;
self.stub.clear();
}
}
#[derive(Clone, Copy)]
pub(crate) struct CodeDirs<'a> {
pub code_dir: &'a CodeDir,
pub op_dir: &'a OpDir,
pub modules: &'a ModuleDir
}
impl<'a> CodeDirs<'a> {
pub(super) fn new(code_dir: &'a CodeDir, op_dir: &'a OpDir, modules: &'a ModuleDir) -> Self {
CodeDirs { code_dir, op_dir, modules }
}
pub(super) fn get(&self, name: ClauseName, arity: usize, in_mod: ClauseName) -> Option<CodeIndex>
{
match in_mod.as_str() {
"user" | "builtin" => self.code_dir.get(&(name, arity)).cloned(),
_ =>
match self.modules.get(&in_mod) {
Some(&Module { ref code_dir, .. }) =>
code_dir.get(&(name, arity)).cloned().map(CodeIndex::from),
None => None
}
}
}
fn get_internal(&self, name: ClauseName, arity: usize, in_mod: ClauseName) -> Option<ModuleCodeIndex> {
self.modules.get(&in_mod)
.and_then(|ref module| module.code_dir.get(&(name, arity)))
.cloned()
}
pub(super) fn get_cleaner_sites(&self) -> (usize, usize) {
let r_w_h = clause_name!("run_cleaners_with_handling");
let r_wo_h = clause_name!("run_cleaners_without_handling");
let builtins = clause_name!("builtins");
let r_w_h = self.get_internal(r_w_h, 0, builtins.clone()).and_then(|item| item.local());
let r_wo_h = self.get_internal(r_wo_h, 1, builtins).and_then(|item| item.local());
if let Some(r_w_h) = r_w_h {
if let Some(r_wo_h) = r_wo_h {
return (r_w_h, r_wo_h);
}
}
return (0, 0);
}
}
pub trait CodeDirsAdapter<'a> {
fn get_code_index(&self, PredicateKey, ClauseName) -> Option<CodeIndex>;
fn get_op(&self, OpDirKey) -> Option<(Specifier, usize, ClauseName)>;
fn op_dir(&self) -> &OpDir;
}
impl<'a> CodeDirsAdapter<'a> for CodeDirs<'a> {
fn get_code_index(&self, key: PredicateKey, module: ClauseName) -> Option<CodeIndex> {
self.get(key.0, key.1, module)
}
fn get_op(&self, key: OpDirKey) -> Option<(Specifier, usize, ClauseName)> {
self.op_dir.get(&key).cloned()
}
fn op_dir(&self) -> &OpDir {
&self.op_dir
}
}
impl<'a> CodeDirsAdapter<'a> for &'a Module {
fn get_code_index(&self, key: PredicateKey, _: ClauseName) -> Option<CodeIndex> {
self.code_dir.get(&key)
.cloned()
.map(|ModuleCodeIndex(ptr, module)| CodeIndex(Rc::new(RefCell::new((ptr, module)))))
}
fn get_op(&self, key: OpDirKey) -> Option<(Specifier, usize, ClauseName)> {
self.op_dir.get(&key).cloned()
}
fn op_dir(&self) -> &OpDir {
&self.op_dir
}
}
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.stub[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.stub[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.stub.len()
}
fn push(&mut self, hcv: HeapCellValue) {
self.state.ball.stub.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
}
#[derive(Clone, Copy)]
pub enum DoubleQuotes {
Atom, Chars, // Codes
}
impl DoubleQuotes {
pub fn is_chars(self) -> bool {
if let DoubleQuotes::Chars = self {
true
} else {
false
}
}
}
impl Default for DoubleQuotes {
fn default() -> Self {
DoubleQuotes::Chars
}
}
#[derive(Clone, Copy)]
pub struct MachineFlags {
pub double_quotes: DoubleQuotes
}
impl Default for MachineFlags {
fn default() -> Self {
MachineFlags { double_quotes: DoubleQuotes::default() }
}
}
pub struct MachineState {
pub(crate) atom_tbl: TabledData<Atom>,
pub(crate) string_tbl: TabledData<StringListWrapper>,
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: LocalCodePtr,
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: Ball,
pub(super) interms: Vec<Number>, // intermediate numbers.
pub(super) last_call: bool,
pub(super) flags: MachineFlags
}
fn call_at_index(machine_st: &mut MachineState, module_name: ClauseName, arity: usize, idx: usize)
{
machine_st.cp.assign_if_local(machine_st.p.clone() + 1);
machine_st.num_of_args = arity;
machine_st.b0 = machine_st.b;
machine_st.p = dir_entry!(idx, module_name);
}
fn execute_at_index(machine_st: &mut MachineState, module_name: ClauseName, arity: usize, idx: usize)
{
machine_st.num_of_args = arity;
machine_st.b0 = machine_st.b;
machine_st.p = dir_entry!(idx, module_name);
}
pub(crate) type CallResult = Result<(), Vec<HeapCellValue>>;
pub(crate) trait CallPolicy: Any {
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 context_call(&mut self, machine_st: &mut MachineState, name: ClauseName, arity: usize,
idx: CodeIndex, code_dirs: CodeDirs)
-> CallResult
{
if machine_st.last_call {
self.try_execute(machine_st, name, arity, idx, code_dirs)
} else {
self.try_call(machine_st, name, arity, idx, code_dirs)
}
}
fn try_call<'a>(&mut self, machine_st: &mut MachineState, name: ClauseName, arity: usize,
idx: CodeIndex, code_dirs: CodeDirs)
-> CallResult
{
match idx.0.borrow().0 {
IndexPtr::Module => {
let stub = MachineError::functor_stub(name.clone(), arity);
let module_name = idx.0.borrow().1.clone();
let h = machine_st.heap.h;
if let Some(ref idx) = code_dirs.get_code_index((name.clone(), arity), module_name.clone())
{
if let IndexPtr::Index(compiled_tl_index) = idx.0.borrow().0 {
call_at_index(machine_st, module_name, arity, compiled_tl_index);
return Ok(());
}
}
let err = MachineError::module_resolution_error(h, module_name, name, arity);
return Err(machine_st.error_form(err, stub));
},
IndexPtr::Undefined => {
let stub = MachineError::functor_stub(name.clone(), arity);
let h = machine_st.heap.h;
return Err(machine_st.error_form(MachineError::existence_error(h, name, arity),
stub));
},
IndexPtr::Index(compiled_tl_index) => {
let module_name = idx.0.borrow().1.clone();
call_at_index(machine_st, module_name, arity, compiled_tl_index)
}
}
Ok(())
}
fn try_execute<'a>(&mut self, machine_st: &mut MachineState, name: ClauseName,
arity: usize, idx: CodeIndex, code_dirs: CodeDirs)
-> CallResult
{
match idx.0.borrow().0 {
IndexPtr::Module => {
let stub = MachineError::functor_stub(name.clone(), arity);
let module_name = idx.0.borrow().1.clone();
let h = machine_st.heap.h;
if let Some(ref idx) = code_dirs.get_code_index((name.clone(), arity), module_name.clone())
{
if let IndexPtr::Index(compiled_tl_index) = idx.0.borrow().0 {
execute_at_index(machine_st, module_name, arity, compiled_tl_index);
return Ok(());
}
}
let err = MachineError::module_resolution_error(h, module_name, name, arity);
return Err(machine_st.error_form(err, stub));
},
IndexPtr::Undefined => {
let stub = MachineError::functor_stub(name.clone(), arity);
let h = machine_st.heap.h;
return Err(machine_st.error_form(MachineError::existence_error(h, name, arity),
stub));
},
IndexPtr::Index(compiled_tl_index) => {
let module_name = idx.0.borrow().1.clone();
execute_at_index(machine_st, module_name, arity, compiled_tl_index);
}
}
Ok(())
}
fn call_builtin<'a>(&mut self, machine_st: &mut MachineState, ct: &BuiltInClauseType,
code_dirs: CodeDirs)
-> CallResult
{
match ct {
&BuiltInClauseType::AcyclicTerm => {
let addr = machine_st[temp_v!(1)].clone();
machine_st.fail = machine_st.is_cyclic_term(addr);
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Arg => {
machine_st.try_arg()?;
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::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!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::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!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::CyclicTerm => {
let addr = machine_st[temp_v!(1)].clone();
machine_st.fail = !machine_st.is_cyclic_term(addr);
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Read => {
let mut reader = Reader::new(machine_st);
match reader.read_stdin(code_dirs.op_dir()) {
Ok(offset) => {
let addr = reader.machine_st[temp_v!(1)].clone();
reader.machine_st.unify(addr, Addr::HeapCell(offset));
},
Err(e) => {
let h = reader.machine_st.heap.h;
let stub = MachineError::functor_stub(clause_name!("read"), 1);
let err = MachineError::syntax_error(h, e);
let err = reader.machine_st.error_form(err, stub);
return Err(err);
}
};
return_from_clause!(reader.machine_st.last_call, reader.machine_st)
},
&BuiltInClauseType::Writeq => {
let output = machine_st.print_term(machine_st[temp_v!(1)].clone(),
WriteqFormatter {},
PrinterOutputter::new());
println!("{}", output.result());
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::DuplicateTerm => {
machine_st.duplicate_term();
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Eq => {
let a1 = machine_st[temp_v!(1)].clone();
let a2 = machine_st[temp_v!(2)].clone();
machine_st.fail = if let Ordering::Equal = machine_st.compare_term_test(&a1, &a2) {
false
} else {
true
};
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Ground => {
machine_st.fail = machine_st.ground_test();
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Functor => {
machine_st.try_functor()?;
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::NotEq => {
let a1 = machine_st[temp_v!(1)].clone();
let a2 = machine_st[temp_v!(2)].clone();
machine_st.fail = if let Ordering::Equal = machine_st.compare_term_test(&a1, &a2) {
true
} else {
false
};
return_from_clause!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Sort => {
machine_st.check_sort_errors()?;
let stub = MachineError::functor_stub(clause_name!("sort"), 2);
let mut list = machine_st.try_from_list(temp_v!(1), stub)?;
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!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::KeySort => {
machine_st.check_keysort_errors()?;
let stub = MachineError::functor_stub(clause_name!("keysort"), 2);
let mut list = machine_st.try_from_list(temp_v!(1), stub)?;
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!(machine_st.last_call, machine_st)
},
&BuiltInClauseType::Is(r, ref at) => {
let a1 = machine_st[r].clone();
let a2 = machine_st.get_number(at)?;
machine_st.unify(a1, Addr::Con(Constant::Number(a2)));
return_from_clause!(machine_st.last_call, machine_st)
},
}
}
fn call_n<'a>(&mut self, machine_st: &mut MachineState, arity: usize,
code_dirs: CodeDirs)
-> CallResult
{
if let Some((name, arity)) = machine_st.setup_call_n(arity) {
let user = clause_name!("user");
match ClauseType::from(name.clone(), arity, None) {
ClauseType::CallN => {
machine_st.handle_internal_call_n(arity);
if machine_st.fail {
return Ok(());
}
machine_st.p = CodePtr::CallN(arity, machine_st.p.local());
},
ClauseType::BuiltIn(built_in) => {
machine_st.setup_built_in_call(built_in.clone());
self.call_builtin(machine_st, &built_in, code_dirs)?;
},
ClauseType::Inlined(inlined) =>
machine_st.execute_inlined(&inlined),
ClauseType::Op(..) | ClauseType::Named(..) =>
if let Some(idx) = code_dirs.get_code_index((name.clone(), arity), user) {
self.context_call(machine_st, name, arity, idx, code_dirs)?;
} else {
let h = machine_st.heap.h;
let stub = MachineError::functor_stub(clause_name!("call"), arity + 1);
return Err(machine_st.error_form(MachineError::existence_error(h, name, arity),
stub));
},
ClauseType::System(_) => {
let name = Addr::Con(Constant::Atom(name));
let stub = MachineError::functor_stub(clause_name!("call"), arity + 1);
return Err(machine_st.error_form(MachineError::type_error(ValidType::Callable,
name),
stub));
}
};
}
Ok(())
}
}
impl CallPolicy for CWILCallPolicy {
fn context_call<'a>(&mut self, machine_st: &mut MachineState, name: ClauseName,
arity: usize, idx: CodeIndex, code_dirs: CodeDirs)
-> CallResult
{
self.prev_policy.context_call(machine_st, name, arity, idx, code_dirs)?;
self.increment(machine_st)
}
fn retry_me_else(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
self.prev_policy.retry_me_else(machine_st, offset)?;
self.increment(machine_st)
}
fn retry(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
self.prev_policy.retry(machine_st, offset)?;
self.increment(machine_st)
}
fn trust_me(&mut self, machine_st: &mut MachineState) -> CallResult
{
self.prev_policy.trust_me(machine_st)?;
self.increment(machine_st)
}
fn trust(&mut self, machine_st: &mut MachineState, offset: usize) -> CallResult
{
self.prev_policy.trust(machine_st, offset)?;
self.increment(machine_st)
}
fn call_builtin<'a>(&mut self, machine_st: &mut MachineState, ct: &BuiltInClauseType,
code_dirs: CodeDirs)
-> CallResult
{
self.prev_policy.call_builtin(machine_st, ct, code_dirs)?;
self.increment(machine_st)
}
fn call_n<'a>(&mut self, machine_st: &mut MachineState, arity: usize,
code_dirs: CodeDirs)
-> CallResult
{
self.prev_policy.call_n(machine_st, arity, code_dirs)?;
self.increment(machine_st)
}
}
downcast!(CallPolicy);
pub(crate) struct DefaultCallPolicy {}
impl CallPolicy for DefaultCallPolicy {}
pub(crate) struct CWILCallPolicy {
pub(crate) prev_policy: Box<CallPolicy>,
count: BigUint,
limits: Vec<(BigUint, usize)>,
inference_limit_exceeded: bool
}
impl CWILCallPolicy {
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 = CWILCallPolicy { prev_policy,
count: BigUint::zero(),
limits: vec![],
inference_limit_exceeded: false };
*policy = Box::new(new_policy);
}
fn increment(&mut self, machine_st: &MachineState) -> CallResult {
if self.inference_limit_exceeded || machine_st.ball.stub.len() > 0 {
return Ok(());
}
if let Some(&(ref limit, bp)) = self.limits.last() {
if self.count == *limit {
self.inference_limit_exceeded = true;
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
}
}
pub(crate) trait CutPolicy: Any {
// returns true iff we fail or cut redirected the MachineState's p itself
fn cut(&mut self, &mut MachineState, RegType) -> bool;
}
downcast!(CutPolicy);
fn cut_body(machine_st: &mut MachineState, addr: Addr) -> bool {
let b = machine_st.b;
if let Addr::Con(Constant::Usize(b0)) = addr {
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 true;
}
false
}
pub(crate) struct DefaultCutPolicy {}
pub(super) fn deref_cut(machine_st: &mut MachineState, r: RegType) {
let addr = machine_st.store(machine_st.deref(machine_st[r].clone()));
cut_body(machine_st, addr);
}
impl CutPolicy for DefaultCutPolicy {
fn cut(&mut self, machine_st: &mut MachineState, r: RegType) -> bool {
let addr = machine_st[r].clone();
cut_body(machine_st, addr)
}
}
pub(crate) struct SCCCutPolicy {
// locations of cleaners, cut points, the previous block
cont_pts: Vec<(Addr, usize, usize)>,
r_c_w_h: usize,
r_c_wo_h: usize
}
impl SCCCutPolicy {
pub(crate) fn new(r_c_w_h: usize, r_c_wo_h: usize) -> Self {
SCCCutPolicy { cont_pts: vec![], r_c_w_h, r_c_wo_h }
}
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, prev_b: usize) {
self.cont_pts.push((addr, b, prev_b));
}
pub(crate) fn pop_cont_pt(&mut self) -> Option<(Addr, usize, usize)> {
self.cont_pts.pop()
}
fn run_cleaners(&self, machine_st: &mut MachineState) -> bool {
if let Some(&(_, b_cutoff, prev_block)) = self.cont_pts.last() {
if machine_st.b < b_cutoff {
let builtins = clause_name!("builtins");
let (idx, arity) = if machine_st.block < prev_block {
(self.r_c_w_h, 0)
} else {
machine_st[temp_v!(1)] = Addr::Con(Constant::Usize(b_cutoff));
(self.r_c_wo_h, 1)
};
if machine_st.last_call {
execute_at_index(machine_st, builtins, arity, idx);
} else {
call_at_index(machine_st, builtins, arity, idx);
}
return true;
}
}
false
}
}
impl CutPolicy for SCCCutPolicy {
fn cut(&mut self, machine_st: &mut MachineState, r: RegType) -> bool {
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 true;
}
self.run_cleaners(machine_st)
}
}