548 lines
19 KiB
Rust
548 lines
19 KiB
Rust
use prolog::allocator::*;
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use prolog::ast::*;
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use prolog::fixtures::*;
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use prolog::indexing::*;
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use prolog::iterators::*;
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use prolog::targets::*;
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use std::collections::HashMap;
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use std::vec::Vec;
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pub struct CodeGenerator<'a, TermMarker> {
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marker: TermMarker,
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var_count: HashMap<&'a Var, usize>
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}
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pub enum EvalSession<'a> {
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EntryFailure(String),
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EntrySuccess,
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InitialQuerySuccess(AllocVarDict<'a>, HeapVarDict<'a>),
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QueryFailure,
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QueryFailureWithException(String),
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SubsequentQuerySuccess,
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}
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pub struct ConjunctInfo<'a> {
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pub perm_vs: VariableFixtures<'a>,
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pub num_of_chunks: usize,
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pub has_deep_cut: bool
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}
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impl<'a> ConjunctInfo<'a>
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{
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fn new(perm_vs: VariableFixtures<'a>, num_of_chunks: usize, has_deep_cut: bool) -> Self
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{
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ConjunctInfo { perm_vs, num_of_chunks, has_deep_cut }
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}
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fn allocates(&self) -> bool {
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self.perm_vs.size() > 0 || self.num_of_chunks > 1 || self.has_deep_cut
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}
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fn perm_vars(&self) -> usize {
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self.perm_vs.size() + self.perm_var_offset()
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}
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fn perm_var_offset(&self) -> usize {
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self.has_deep_cut as usize
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}
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}
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impl<'a, TermMarker: Allocator<'a>> CodeGenerator<'a, TermMarker>
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{
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pub fn new() -> Self {
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CodeGenerator { marker: Allocator::new(),
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var_count: HashMap::new() }
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}
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pub fn take_vars(self) -> AllocVarDict<'a> {
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self.marker.take_bindings()
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}
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fn update_var_count<Iter>(&mut self, iter: Iter)
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where Iter: Iterator<Item=TermRef<'a>>
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{
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for term in iter {
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if let TermRef::Var(_, _, var) = term {
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let entry = self.var_count.entry(var).or_insert(0);
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*entry += 1;
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}
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}
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}
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fn get_var_count(&self, var: &'a Var) -> usize {
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*self.var_count.get(var).unwrap()
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}
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fn add_or_increment_void_instr<Target>(target: &mut Vec<Target>)
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where Target: CompilationTarget<'a>
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{
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if let Some(ref mut instr) = target.last_mut() {
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if Target::is_void_instr(&*instr) {
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Target::incr_void_instr(instr);
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return;
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}
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}
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target.push(Target::to_void(1));
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}
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fn subterm_to_instr<Target>(&mut self,
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subterm: &'a Term,
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term_loc: GenContext,
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is_exposed: bool,
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target: &mut Vec<Target>)
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where Target: CompilationTarget<'a>
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{
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match subterm {
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&Term::AnonVar if is_exposed =>
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self.marker.mark_anon_var(Level::Deep, target),
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&Term::AnonVar =>
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Self::add_or_increment_void_instr(target),
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&Term::Cons(ref cell, _, _) | &Term::Clause(ref cell, _, _) => {
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self.marker.mark_non_var(Level::Deep, term_loc, cell, target);
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target.push(Target::clause_arg_to_instr(cell.get()));
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},
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&Term::Constant(_, ref constant) =>
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target.push(Target::constant_subterm(constant.clone())),
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&Term::Var(ref cell, ref var) =>
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if is_exposed || self.get_var_count(var) > 1 {
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self.marker.mark_var(var, Level::Deep, cell, term_loc, target);
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} else {
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Self::add_or_increment_void_instr(target);
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}
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};
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}
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fn compile_clause<Target>(&mut self,
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ct: ClauseType<'a>,
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term_loc: GenContext,
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is_exposed: bool,
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terms: &'a Vec<Box<Term>>,
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target: &mut Vec<Target>)
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where Target: CompilationTarget<'a>
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{
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match ct {
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ClauseType::Deep(lvl, cell, atom) => {
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self.marker.mark_non_var(lvl, term_loc, cell, target);
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target.push(Target::to_structure(lvl, atom.clone(), terms.len(), cell.get()));
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for subterm in terms {
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self.subterm_to_instr(subterm.as_ref(), term_loc, is_exposed, target);
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}
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},
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_ => {}
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}
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}
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fn compile_target<Target, Iter>(&mut self, iter: Iter, term_loc: GenContext, is_exposed: bool)
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-> Vec<Target>
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where Target: CompilationTarget<'a>, Iter: Iterator<Item=TermRef<'a>>
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{
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let mut target = Vec::new();
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for term in iter {
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match term {
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TermRef::Clause(ct, terms) =>
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self.compile_clause(ct, term_loc, is_exposed, terms, &mut target),
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TermRef::Cons(lvl, cell, head, tail) => {
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self.marker.mark_non_var(lvl, term_loc, cell, &mut target);
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target.push(Target::to_list(lvl, cell.get()));
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self.subterm_to_instr(head, term_loc, is_exposed, &mut target);
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self.subterm_to_instr(tail, term_loc, is_exposed, &mut target);
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},
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TermRef::Constant(lvl @ Level::Shallow, cell, constant) => {
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self.marker.mark_non_var(lvl, term_loc, cell, &mut target);
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target.push(Target::to_constant(lvl, constant.clone(), cell.get()));
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},
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TermRef::AnonVar(lvl @ Level::Shallow) =>
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if let GenContext::Head = term_loc {
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self.marker.advance_arg();
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} else {
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self.marker.mark_anon_var(lvl, &mut target);
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},
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TermRef::Var(lvl @ Level::Shallow, ref cell, ref var) =>
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self.marker.mark_var(var, lvl, cell, term_loc, &mut target),
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_ => {}
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};
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}
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target
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}
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fn collect_var_data(&mut self, mut iter: ChunkedIterator<'a>) -> ConjunctInfo<'a>
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{
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let mut vs = VariableFixtures::new();
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let at_rule_head = iter.at_rule_head();
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while let Some((chunk_num, last_term_arity, terms)) = iter.next() {
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for (i, term_or_cut_ref) in terms.iter().enumerate() {
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let term_loc = if chunk_num == 0 && i == 0 && at_rule_head {
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GenContext::Head
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} else if i < terms.len() - 1 {
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GenContext::Mid(chunk_num)
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} else {
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GenContext::Last(chunk_num)
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};
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self.update_var_count(term_or_cut_ref.post_order_iter());
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vs.mark_vars_in_chunk(term_or_cut_ref.post_order_iter(),
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last_term_arity,
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chunk_num,
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term_loc);
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}
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}
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let num_of_chunks = iter.chunk_num();
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let has_deep_cut = iter.encountered_deep_cut();
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vs.populate_restricting_sets();
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vs.set_perm_vals(has_deep_cut);
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let vs = self.marker.drain_var_data(vs);
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ConjunctInfo::new(vs, num_of_chunks, has_deep_cut)
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}
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fn add_conditional_call(compiled_query: &mut Code, qt: QueryTermRef, pvs: usize)
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{
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match qt {
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QueryTermRef::CallN(terms) => {
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let call = ControlInstruction::CallN(terms.len());
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compiled_query.push(Line::Control(call));
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},
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QueryTermRef::Catch(_) =>
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compiled_query.push(Line::Control(ControlInstruction::CatchCall)),
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QueryTermRef::Term(&Term::Constant(_, Constant::Atom(ref atom))) => {
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let call = ControlInstruction::Call(atom.clone(), 0, pvs);
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compiled_query.push(Line::Control(call));
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},
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QueryTermRef::Term(&Term::Clause(_, ref atom, ref terms)) => {
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let call = ControlInstruction::Call(atom.clone(), terms.len(), pvs);
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compiled_query.push(Line::Control(call));
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},
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QueryTermRef::Throw(_) =>
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compiled_query.push(Line::Control(ControlInstruction::ThrowCall)),
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_ => {}
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}
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}
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fn lco(body: &mut Code, toc: QueryTermRef<'a>) -> usize
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{
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let last_arity = toc.arity();
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let mut dealloc_index = body.len() - 1;
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match toc {
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QueryTermRef::Term(&Term::Clause(_, ref name, _))
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| QueryTermRef::Term(&Term::Constant(_, Constant::Atom(ref name))) =>
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if let &mut Line::Control(ref mut ctrl) = body.last_mut().unwrap() {
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*ctrl = ControlInstruction::Execute(name.clone(), last_arity);
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},
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QueryTermRef::CallN(terms) =>
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if let &mut Line::Control(ref mut ctrl) = body.last_mut().unwrap() {
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*ctrl = ControlInstruction::ExecuteN(terms.len());
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},
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QueryTermRef::Catch(_) =>
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if let &mut Line::Control(ref mut ctrl) = body.last_mut().unwrap() {
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*ctrl = ControlInstruction::CatchExecute;
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},
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QueryTermRef::Throw(_) =>
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if let &mut Line::Control(ref mut ctrl) = body.last_mut().unwrap() {
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*ctrl = ControlInstruction::ThrowExecute;
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},
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_ => dealloc_index = body.len()
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};
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dealloc_index
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}
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fn compile_seq(&mut self,
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iter: ChunkedIterator<'a>,
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conjunct_info: &ConjunctInfo<'a>,
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body: &mut Code,
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is_exposed: bool)
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{
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for (chunk_num, _, terms) in iter {
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for (i, term) in terms.iter().enumerate()
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{
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let term_loc = if i + 1 < terms.len() {
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GenContext::Mid(chunk_num)
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} else {
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GenContext::Last(chunk_num)
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};
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match term {
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&QueryTermRef::Cut if i + 1 < terms.len() => {
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body.push(if chunk_num == 0 {
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Line::Cut(CutInstruction::NeckCut(Terminal::Non))
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} else {
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Line::Cut(CutInstruction::Cut(Terminal::Non))
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});
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},
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&QueryTermRef::Cut => {
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body.push(if chunk_num == 0 {
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Line::Cut(CutInstruction::NeckCut(Terminal::Terminal))
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} else {
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Line::Cut(CutInstruction::Cut(Terminal::Terminal))
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});
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},
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_ if chunk_num == 0 => {
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self.marker.advance(GenContext::Head, *term);
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let iter = term.post_order_iter();
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body.push(Line::Query(self.compile_target(iter, term_loc, is_exposed)));
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Self::add_conditional_call(body, *term, conjunct_info.perm_vars());
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},
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_ => {
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let num_vars = conjunct_info.perm_vs.vars_above_threshold(i + 1);
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self.compile_query_line(*term, term_loc, body, num_vars, is_exposed);
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},
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};
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self.marker.reset_contents();
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}
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}
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}
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fn compile_seq_prelude(&mut self, conjunct_info: &ConjunctInfo, body: &mut Code)
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{
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if conjunct_info.allocates() {
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let perm_vars = conjunct_info.perm_vars();
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body.push(Line::Control(ControlInstruction::Allocate(perm_vars)));
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if conjunct_info.has_deep_cut {
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body.push(Line::Cut(CutInstruction::GetLevel));
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}
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}
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}
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fn compile_cleanup(body: &mut Code, conjunct_info: &ConjunctInfo, toc: QueryTermRef<'a>)
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{
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let dealloc_index = Self::lco(body, toc);
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if conjunct_info.allocates() {
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body.insert(dealloc_index, Line::Control(ControlInstruction::Deallocate));
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}
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}
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pub fn compile_rule<'b: 'a>(&mut self, rule: &'b Rule) -> Code
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{
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let iter = ChunkedIterator::from_rule(rule);
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let conjunct_info = self.collect_var_data(iter);
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let &Rule { head: (ref p0, ref p1), ref clauses } = rule;
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let mut code = Vec::new();
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self.marker.advance(GenContext::Head, QueryTermRef::Term(p0));
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self.compile_seq_prelude(&conjunct_info, &mut code);
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if p0.is_clause() {
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let iter = FactInstruction::iter(p0);
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code.push(Line::Fact(self.compile_target(iter, GenContext::Head, false)));
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}
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let iter = ChunkedIterator::from_rule_body(p1, clauses);
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self.compile_seq(iter, &conjunct_info, &mut code, false);
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if conjunct_info.allocates() {
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let index = if let &Line::Control(_) = code.last().unwrap() {
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code.len() - 2
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} else {
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code.len() - 1
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};
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if let &mut Line::Query(ref mut query) = &mut code[index] {
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conjunct_info.perm_vs.mark_unsafe_vars_in_rule(p0, query);
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}
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}
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Self::compile_cleanup(&mut code, &conjunct_info, clauses.last().unwrap_or(p1).to_ref());
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code
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}
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fn mark_unsafe_fact_vars(&self, fact: &mut CompiledFact)
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{
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let mut unsafe_vars = HashMap::new();
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for var_status in self.marker.bindings().values() {
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unsafe_vars.insert(var_status.as_reg_type(), false);
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}
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for fact_instr in fact.iter_mut() {
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match fact_instr {
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&mut FactInstruction::UnifyValue(reg) =>
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if let Some(found) = unsafe_vars.get_mut(®) {
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if !*found {
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*found = true;
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*fact_instr = FactInstruction::UnifyLocalValue(reg);
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}
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},
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&mut FactInstruction::UnifyVariable(reg) => {
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if let Some(found) = unsafe_vars.get_mut(®) {
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*found = true;
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}
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},
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_ => {}
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};
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}
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}
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pub fn compile_fact<'b: 'a>(&mut self, term: &'b Term) -> Code
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{
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let iter = ChunkedIterator::from_fact(term);
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self.collect_var_data(iter);
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self.marker.advance(GenContext::Head, QueryTermRef::Term(term));
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let mut code = Vec::new();
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if term.is_clause() {
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let iter = FactInstruction::iter(term);
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let mut compiled_fact = self.compile_target(iter, GenContext::Head, false);
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self.mark_unsafe_fact_vars(&mut compiled_fact);
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code.push(Line::Fact(compiled_fact));
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}
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let proceed = Line::Control(ControlInstruction::Proceed);
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code.push(proceed);
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code
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}
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fn compile_query_line(&mut self,
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term: QueryTermRef<'a>,
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term_loc: GenContext,
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code: &mut Code,
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index: usize,
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is_exposed: bool)
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{
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self.marker.advance(term_loc, term);
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let iter = term.post_order_iter();
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let compiled_query = Line::Query(self.compile_target(iter, term_loc, is_exposed));
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code.push(compiled_query);
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Self::add_conditional_call(code, term, index);
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}
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pub fn compile_query(&mut self, query: &'a Vec<QueryTerm>) -> Code
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{
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let iter = ChunkedIterator::from_term_sequence(query);
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let conjunct_info = self.collect_var_data(iter);
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let mut code = Vec::new();
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self.compile_seq_prelude(&conjunct_info, &mut code);
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let iter = ChunkedIterator::from_term_sequence(query);
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self.compile_seq(iter, &conjunct_info, &mut code, true);
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if conjunct_info.allocates() {
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let index = if let &Line::Control(_) = code.last().unwrap() {
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code.len() - 2
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} else {
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code.len() - 1
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};
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if let &mut Line::Query(ref mut query) = &mut code[index] {
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conjunct_info.perm_vs.mark_unsafe_vars_in_query(query);
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}
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}
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Self::compile_cleanup(&mut code, &conjunct_info, query.last().unwrap().to_ref());
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code
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}
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fn split_predicate(clauses: &Vec<PredicateClause>) -> Vec<(usize, usize)>
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{
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let mut subseqs = Vec::new();
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let mut left_index = 0;
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for (right_index, clause) in clauses.iter().enumerate() {
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if let Some(&Term::Var(_, _)) = clause.first_arg() {
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if left_index < right_index {
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subseqs.push((left_index, right_index));
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}
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subseqs.push((right_index, right_index + 1));
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left_index = right_index + 1;
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}
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}
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if left_index < clauses.len() {
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subseqs.push((left_index, clauses.len()));
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}
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subseqs
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}
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fn compile_pred_subseq<'b: 'a>(&mut self, clauses: &'b [PredicateClause]) -> Code
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{
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let mut code_body = Vec::new();
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let mut code_offsets = CodeOffsets::new();
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let num_clauses = clauses.len();
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for (i, clause) in clauses.iter().enumerate() {
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self.marker.reset();
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let mut clause_code = match clause {
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&PredicateClause::Fact(ref fact) =>
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self.compile_fact(fact),
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&PredicateClause::Rule(ref rule) =>
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self.compile_rule(rule)
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};
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if num_clauses > 1 {
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let choice = match i {
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0 => ChoiceInstruction::TryMeElse(clause_code.len() + 1),
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_ if i == num_clauses - 1 => ChoiceInstruction::TrustMe,
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_ => ChoiceInstruction::RetryMeElse(clause_code.len() + 1)
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};
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code_body.push(Line::Choice(choice));
|
|
}
|
|
|
|
clause.first_arg().map(|arg| {
|
|
let index = code_body.len();
|
|
code_offsets.index_term(arg, index);
|
|
});
|
|
|
|
code_body.append(&mut clause_code);
|
|
}
|
|
|
|
let mut code = Vec::new();
|
|
|
|
code_offsets.add_indices(&mut code, code_body);
|
|
code
|
|
}
|
|
|
|
pub fn compile_predicate<'b: 'a>(&mut self, clauses: &'b Vec<PredicateClause>) -> Code
|
|
{
|
|
let mut code = Vec::new();
|
|
let split_pred = Self::split_predicate(&clauses);
|
|
let multi_seq = split_pred.len() > 1;
|
|
|
|
for (l, r) in split_pred {
|
|
let mut code_segment = self.compile_pred_subseq(&clauses[l .. r]);
|
|
|
|
if multi_seq {
|
|
let choice = match l {
|
|
0 => ChoiceInstruction::TryMeElse(code_segment.len() + 1),
|
|
_ if r == clauses.len() => ChoiceInstruction::TrustMe,
|
|
_ => ChoiceInstruction::RetryMeElse(code_segment.len() + 1)
|
|
};
|
|
|
|
code.push(Line::Choice(choice));
|
|
}
|
|
|
|
code.append(&mut code_segment);
|
|
}
|
|
|
|
code
|
|
}
|
|
}
|