use prolog_parser::ast::*;
use prolog::allocator::*;
use prolog::arithmetic::*;
use prolog::clause_types::*;
use prolog::fixtures::*;
use prolog::forms::*;
use prolog::indexing::*;
use prolog::instructions::*;
use prolog::iterators::*;
use prolog::machine::machine_indices::*;
use prolog::targets::*;
use std::cell::Cell;
use std::collections::{HashMap};
use std::rc::Rc;
use std::vec::Vec;
pub struct CodeGenerator<TermMarker> {
flags: MachineFlags,
marker: TermMarker,
var_count: HashMap<Rc<Var>, usize>,
non_counted_bt: bool
}
pub struct ConjunctInfo<'a> {
pub perm_vs: VariableFixtures<'a>,
pub num_of_chunks: usize,
pub has_deep_cut: bool,
}
impl<'a> ConjunctInfo<'a>
{
fn new(perm_vs: VariableFixtures<'a>, num_of_chunks: usize, has_deep_cut: bool) -> Self {
ConjunctInfo { perm_vs, num_of_chunks, has_deep_cut }
}
fn allocates(&self) -> bool {
self.perm_vs.size() > 0 || self.num_of_chunks > 1 || self.has_deep_cut
}
fn perm_vars(&self) -> usize {
self.perm_vs.size() + self.perm_var_offset()
}
fn perm_var_offset(&self) -> usize {
self.has_deep_cut as usize
}
fn mark_unsafe_vars(&self, mut unsafe_var_marker: UnsafeVarMarker, code: &mut Code) {
let right_index = if let &Line::Control(_) = code.last().unwrap() {
code.len() - 2
} else {
code.len() - 1
};
let mut index = right_index;
if let Line::Query(_) = &code[right_index] {
while let Line::Query(_) = &code[index] { if index == 0 {
break;
} else {
index -= 1;
}
}
if let Line::Query(_) = &code[index] {} else {
index += 1;
}
unsafe_var_marker.record_unsafe_vars(&self.perm_vs);
for line in code.iter_mut() {
if let &mut Line::Query(ref mut query_instr) = line {
unsafe_var_marker.mark_safe_vars(query_instr);
}
}
for index in index .. right_index + 1 {
if let &mut Line::Query(ref mut query_instr) = &mut code[index] {
unsafe_var_marker.mark_unsafe_vars(query_instr);
}
}
}
}
}
impl<'a, TermMarker: Allocator<'a>> CodeGenerator<TermMarker>
{
pub fn new(non_counted_bt: bool, flags: MachineFlags) -> Self {
CodeGenerator { marker: Allocator::new(),
var_count: HashMap::new(),
non_counted_bt,
flags }
}
pub fn take_vars(self) -> AllocVarDict {
self.marker.take_bindings()
}
fn update_var_count<Iter: Iterator<Item=TermRef<'a>>>(&mut self, iter: Iter)
{
for term in iter {
if let TermRef::Var(_, _, var) = term {
let entry = self.var_count.entry(var).or_insert(0);
*entry += 1;
}
}
}
fn get_var_count(&self, var: &'a Var) -> usize {
*self.var_count.get(var).unwrap()
}
fn mark_non_callable(&mut self, name: Rc<Var>, arity: usize, term_loc: GenContext,
vr: &'a Cell<VarReg>, code: &mut Code)
-> RegType
{
match self.marker.bindings().get(&name) {
Some(&VarData::Temp(_, t, _)) if t != 0 => RegType::Temp(t),
Some(&VarData::Perm(p)) if p != 0 => RegType::Perm(p),
_ => {
let mut target = Vec::new();
self.marker.reset_arg(arity);
self.marker.mark_var(name, Level::Shallow, vr, term_loc, &mut target);
if !target.is_empty() {
for query_instr in target {
code.push(Line::Query(query_instr));
}
}
vr.get().norm()
}
}
}
fn add_or_increment_void_instr<Target>(target: &mut Vec<Target>)
where Target: CompilationTarget<'a>
{
if let Some(ref mut instr) = target.last_mut() {
if Target::is_void_instr(&*instr) {
Target::incr_void_instr(instr);
return;
}
}
target.push(Target::to_void(1));
}
fn subterm_to_instr<Target>(&mut self,
subterm: &'a Term,
term_loc: GenContext,
is_exposed: bool,
target: &mut Vec<Target>)
where Target: CompilationTarget<'a>
{
match subterm {
&Term::AnonVar if is_exposed =>
self.marker.mark_anon_var(Level::Deep, term_loc, target),
&Term::AnonVar =>
Self::add_or_increment_void_instr(target),
&Term::Cons(ref cell, _, _) | &Term::Clause(ref cell, _, _, _) => {
self.marker.mark_non_var(Level::Deep, term_loc, cell, target);
target.push(Target::clause_arg_to_instr(cell.get()));
},
&Term::Constant(_, ref constant) =>
target.push(Target::constant_subterm(constant.clone())),
&Term::Var(ref cell, ref var) =>
if is_exposed || self.get_var_count(var) > 1 {
self.marker.mark_var(var.clone(), Level::Deep, cell, term_loc, target);
} else {
Self::add_or_increment_void_instr(target);
}
};
}
fn compile_target<Target, Iter>(&mut self, iter: Iter, term_loc: GenContext, is_exposed: bool)
-> Vec<Target>
where Target: CompilationTarget<'a>, Iter: Iterator<Item=TermRef<'a>>
{
let mut target = Vec::new();
for term in iter {
match term {
TermRef::Clause(lvl, cell, ct, terms) => {
self.marker.mark_non_var(lvl, term_loc, cell, &mut target);
target.push(Target::to_structure(ct, terms.len(), cell.get()));
for subterm in terms {
self.subterm_to_instr(subterm.as_ref(), term_loc, is_exposed, &mut target);
}
},
TermRef::Cons(lvl, cell, head, tail) => {
self.marker.mark_non_var(lvl, term_loc, cell, &mut target);
target.push(Target::to_list(lvl, cell.get()));
self.subterm_to_instr(head, term_loc, is_exposed, &mut target);
self.subterm_to_instr(tail, term_loc, is_exposed, &mut target);
},
TermRef::Constant(lvl @ Level::Shallow, cell, constant) => {
self.marker.mark_non_var(lvl, term_loc, cell, &mut target);
target.push(Target::to_constant(lvl, constant.clone(), cell.get()));
},
TermRef::AnonVar(lvl @ Level::Shallow) =>
if let GenContext::Head = term_loc {
self.marker.advance_arg();
} else {
self.marker.mark_anon_var(lvl, term_loc, &mut target);
},
TermRef::Var(lvl @ Level::Shallow, cell, ref var) if var.as_str() == "!" => {
if self.marker.is_unbound(var.clone()) {
if term_loc != GenContext::Head {
self.marker.mark_reserved_var(var.clone(), lvl, cell, term_loc,
&mut target, perm_v!(1), false);
continue;
}
}
self.marker.mark_var(var.clone(), lvl, cell, term_loc, &mut target);
},
TermRef::Var(lvl @ Level::Shallow, cell, var) =>
self.marker.mark_var(var.clone(), lvl, cell, term_loc, &mut target),
_ => {}
};
}
target
}
fn collect_var_data(&mut self, mut iter: ChunkedIterator<'a>) -> ConjunctInfo<'a>
{
let mut vs = VariableFixtures::new();
while let Some((chunk_num, lt_arity, chunked_terms)) = iter.next() {
for (i, chunked_term) in chunked_terms.iter().enumerate() {
let term_loc = match chunked_term {
&ChunkedTerm::HeadClause(..) => GenContext::Head,
&ChunkedTerm::BodyTerm(_) => if i < chunked_terms.len() - 1 {
GenContext::Mid(chunk_num)
} else {
GenContext::Last(chunk_num)
}
};
self.update_var_count(chunked_term.post_order_iter());
vs.mark_vars_in_chunk(chunked_term.post_order_iter(), lt_arity, term_loc);
}
}
let num_of_chunks = iter.chunk_num;
let has_deep_cut = iter.encountered_deep_cut();
vs.populate_restricting_sets();
vs.set_perm_vals(has_deep_cut);
let vs = self.marker.drain_var_data(vs);
ConjunctInfo::new(vs, num_of_chunks, has_deep_cut)
}
fn add_conditional_call(code: &mut Code, qt: &QueryTerm, pvs: usize)
{
match qt {
&QueryTerm::Jump(ref vars) =>
code.push(jmp_call!(vars.len(), 0, pvs)),
&QueryTerm::Clause(_, ref ct, ref terms, true) =>
code.push(call_clause_by_default!(ct.clone(), terms.len(), pvs)),
&QueryTerm::Clause(_, ref ct, ref terms, false) =>
code.push(call_clause!(ct.clone(), terms.len(), pvs)),
_ => {}
}
}
fn lco(code: &mut Code) -> usize
{
let mut dealloc_index = code.len() - 1;
match code.last_mut() {
Some(&mut Line::Control(ref mut ctrl)) =>
match ctrl {
&mut ControlInstruction::CallClause(_, _, _, ref mut last_call, _) =>
*last_call = true,
&mut ControlInstruction::JmpBy(_, _, _, ref mut last_call) =>
*last_call = true,
&mut ControlInstruction::Proceed => {},
_ => dealloc_index += 1
},
Some(&mut Line::Cut(CutInstruction::Cut(_))) =>
dealloc_index += 1,
_ => {}
};
dealloc_index
}
fn compile_inlined(&mut self, ct: &InlinedClauseType, terms: &'a Vec<Box<Term>>,
term_loc: GenContext, code: &mut Code)
-> Result<(), ParserError>
{
match ct {
&InlinedClauseType::CompareNumber(cmp, ..) => {
if let &Term::Var(ref vr, ref name) = terms[0].as_ref() {
self.mark_non_callable(name.clone(), 2, term_loc, vr, code);
}
if let &Term::Var(ref vr, ref name) = terms[1].as_ref() {
self.mark_non_callable(name.clone(), 2, term_loc, vr, code);
}
let (mut lcode, at_1) = self.call_arith_eval(terms[0].as_ref(), 1)?;
let (mut rcode, at_2) = self.call_arith_eval(terms[1].as_ref(), 2)?;
code.append(&mut lcode);
code.append(&mut rcode);
code.push(compare_number_instr!(cmp,
at_1.unwrap_or(interm!(1)),
at_2.unwrap_or(interm!(2))));
},
&InlinedClauseType::IsAtom(..) =>
match terms[0].as_ref() {
&Term::Constant(_, Constant::Char(_))
| &Term::Constant(_, Constant::EmptyList)
| &Term::Constant(_, Constant::Atom(..)) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_atom!(r));
}
_ => {
code.push(fail!());
}
},
&InlinedClauseType::IsAtomic(..) =>
match terms[0].as_ref() {
&Term::AnonVar | &Term::Clause(..) | &Term::Cons(..) => {
code.push(fail!());
},
&Term::Constant(..) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_atomic!(r));
}
},
&InlinedClauseType::IsCompound(..) =>
match terms[0].as_ref() {
&Term::Clause(..) | &Term::Cons(..) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_compound!(r));
},
_ => {
code.push(fail!());
}
},
&InlinedClauseType::IsRational(..) =>
match terms[0].as_ref() {
&Term::Constant(_, Constant::Number(Number::Rational(_))) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_rational!(r));
},
_ => {
code.push(fail!());
}
},
&InlinedClauseType::IsFloat(..) =>
match terms[0].as_ref() {
&Term::Constant(_, Constant::Number(Number::Float(_))) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_float!(r));
},
_ => {
code.push(fail!());
}
},
&InlinedClauseType::IsString(..) =>
match terms[0].as_ref() {
&Term::Constant(_, Constant::String(_)) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_string!(r));
},
_ => {
code.push(fail!());
}
},
&InlinedClauseType::IsNonVar(..) =>
match terms[0].as_ref() {
&Term::AnonVar => {
code.push(fail!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_nonvar!(r));
},
_ => {
code.push(succeed!());
}
},
&InlinedClauseType::IsInteger(..) =>
match terms[0].as_ref() {
&Term::Constant(_, Constant::CharCode(_))
| &Term::Constant(_, Constant::Number(Number::Integer(_))) => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_integer!(r));
},
_ => {
code.push(fail!());
},
},
&InlinedClauseType::IsVar(..) =>
match terms[0].as_ref() {
&Term::Constant(..) | &Term::Clause(..) | &Term::Cons(..) => {
code.push(fail!());
},
&Term::AnonVar => {
code.push(succeed!());
},
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_var!(r));
}
},
&InlinedClauseType::IsPartialString(..) =>
match terms[0].as_ref() {
&Term::Var(ref vr, ref name) => {
let r = self.mark_non_callable(name.clone(), 1, term_loc, vr, code);
code.push(is_partial_string!(r));
},
_ => code.push(fail!())
}
}
Ok(())
}
fn call_arith_eval(&self, term: &'a Term, target_int: usize) -> Result<ArithCont, ArithmeticError>
{
let mut evaluator = ArithmeticEvaluator::new(self.marker.bindings(), target_int);
evaluator.eval(term)
}
fn compile_is_call(&mut self, terms: &'a Vec<Box<Term>>, code: &mut Code,
term_loc: GenContext, use_default_call_policy: bool)
-> Result<(), ParserError>
{
let (mut acode, at) = self.call_arith_eval(terms[1].as_ref(), 1)?;
code.append(&mut acode);
Ok(match terms[0].as_ref() {
&Term::Var(ref vr, ref name) => {
let mut target = vec![];
self.marker.reset_arg(2);
self.marker.mark_var(name.clone(), Level::Shallow, vr,
term_loc, &mut target);
if !target.is_empty() {
code.extend(target.into_iter().map(Line::Query));
}
if use_default_call_policy {
code.push(is_call_by_default!(temp_v!(1), at.unwrap_or(interm!(1))))
} else {
code.push(is_call!(temp_v!(1), at.unwrap_or(interm!(1))))
}
},
&Term::Constant(_, ref c @ Constant::Number(_)) => {
code.push(Line::Query(put_constant!(Level::Shallow, c.clone(), temp_v!(1))));
if use_default_call_policy {
code.push(is_call_by_default!(temp_v!(1), at.unwrap_or(interm!(1))))
} else {
code.push(is_call!(temp_v!(1), at.unwrap_or(interm!(1))))
}
},
_ => code.push(fail!())
})
}
#[inline]
fn compile_unblocked_cut(&mut self, code: &mut Code, cell: &'a Cell<VarReg>)
{
let r = self.marker.get(Rc::new(String::from("!")));
cell.set(VarReg::Norm(r));
code.push(set_cp!(cell.get().norm()));
}
fn compile_get_level_and_unify(&mut self, code: &mut Code, cell: &'a Cell<VarReg>,
var: Rc<Var>, term_loc: GenContext)
{
let mut target = Vec::new();
self.marker.reset_arg(1);
self.marker.mark_var(var, Level::Shallow, cell, term_loc, &mut target);
if !target.is_empty() {
code.extend(target.into_iter().map(|query_instr| Line::Query(query_instr)));
}
code.push(get_level_and_unify!(cell.get().norm()));
}
fn compile_seq(&mut self, iter: ChunkedIterator<'a>, conjunct_info: &ConjunctInfo<'a>,
code: &mut Code, is_exposed: bool)
-> Result<(), ParserError>
{
for (chunk_num, _, terms) in iter.rule_body_iter() {
for (i, term) in terms.iter().enumerate() {
let term_loc = if i + 1 < terms.len() {
GenContext::Mid(chunk_num)
} else {
GenContext::Last(chunk_num)
};
match *term {
&QueryTerm::GetLevelAndUnify(ref cell, ref var) =>
self.compile_get_level_and_unify(code, cell, var.clone(), term_loc),
&QueryTerm::UnblockedCut(ref cell) =>
self.compile_unblocked_cut(code, cell),
&QueryTerm::BlockedCut =>
code.push(if chunk_num == 0 {
Line::Cut(CutInstruction::NeckCut)
} else {
Line::Cut(CutInstruction::Cut(perm_v!(1)))
}),
&QueryTerm::Clause(_, ClauseType::BuiltIn(BuiltInClauseType::Is(..)),
ref terms, use_default_call_policy)
=> self.compile_is_call(terms, code, term_loc, use_default_call_policy)?,
&QueryTerm::Clause(_, ClauseType::Inlined(ref ct), ref terms, _)
=> self.compile_inlined(ct, terms, term_loc, code)?,
_ => {
let num_perm_vars = if chunk_num == 0 {
conjunct_info.perm_vars()
} else {
conjunct_info.perm_vs.vars_above_threshold(i + 1)
};
self.compile_query_line(term, term_loc, code, num_perm_vars, is_exposed);
},
}
}
self.marker.reset_contents();
}
Ok(())
}
fn compile_seq_prelude(&mut self, conjunct_info: &ConjunctInfo, body: &mut Code)
{
if conjunct_info.allocates() {
let perm_vars = conjunct_info.perm_vars();
body.push(Line::Control(ControlInstruction::Allocate(perm_vars)));
if conjunct_info.has_deep_cut {
body.push(Line::Cut(CutInstruction::GetLevel(perm_v!(1))));
}
}
}
fn compile_cleanup(code: &mut Code, conjunct_info: &ConjunctInfo, toc: &'a QueryTerm)
{
match toc {
&QueryTerm::BlockedCut | &QueryTerm::UnblockedCut(..) => code.push(proceed!()),
&QueryTerm::Clause(_, ClauseType::Inlined(..), ..) => code.push(proceed!()),
_ => {}
};
let dealloc_index = Self::lco(code);
if conjunct_info.allocates() {
code.insert(dealloc_index, Line::Control(ControlInstruction::Deallocate));
}
}
pub fn compile_rule<'b: 'a>(&mut self, rule: &'b Rule) -> Result<Code, ParserError>
{
let iter = ChunkedIterator::from_rule(rule);
let conjunct_info = self.collect_var_data(iter);
let &Rule { head: (_, ref args, ref p1), ref clauses } = rule;
let mut code = Vec::new();
self.marker.reset_at_head(args);
self.compile_seq_prelude(&conjunct_info, &mut code);
let iter = FactIterator::from_rule_head_clause(args);
let mut fact = self.compile_target(iter, GenContext::Head, false);
let mut unsafe_var_marker = UnsafeVarMarker::new();
if !fact.is_empty() {
unsafe_var_marker = self.mark_unsafe_fact_vars(&mut fact);
for fact_instr in fact {
code.push(Line::Fact(fact_instr));
}
}
let iter = ChunkedIterator::from_rule_body(p1, clauses);
try!(self.compile_seq(iter, &conjunct_info, &mut code, false));
if conjunct_info.allocates() {
conjunct_info.mark_unsafe_vars(unsafe_var_marker, &mut code);
}
Self::compile_cleanup(&mut code, &conjunct_info, clauses.last().unwrap_or(p1));
Ok(code)
}
fn mark_unsafe_fact_vars(&self, fact: &mut CompiledFact) -> UnsafeVarMarker
{
let mut unsafe_vars = HashMap::new();
for var_status in self.marker.bindings().values() {
unsafe_vars.insert(var_status.as_reg_type(), false);
}
for fact_instr in fact.iter_mut() {
match fact_instr {
&mut FactInstruction::UnifyValue(reg) =>
if let Some(found) = unsafe_vars.get_mut(®) {
if !*found {
*found = true;
*fact_instr = FactInstruction::UnifyLocalValue(reg);
}
},
&mut FactInstruction::UnifyVariable(reg) =>
if let Some(found) = unsafe_vars.get_mut(®) {
*found = true;
},
_ => {}
};
}
UnsafeVarMarker { unsafe_vars }
}
pub fn compile_fact<'b: 'a>(&mut self, term: &'b Term) -> Code
{
self.update_var_count(post_order_iter(term));
let mut vs = VariableFixtures::new();
vs.mark_vars_in_chunk(post_order_iter(term), term.arity(), GenContext::Head);
vs.populate_restricting_sets();
self.marker.drain_var_data(vs);
let mut code = Vec::new();
if let &Term::Clause(_, _, ref args, _) = term {
self.marker.reset_at_head(args);
let iter = FactInstruction::iter(term);
let mut compiled_fact = self.compile_target(iter, GenContext::Head, false);
self.mark_unsafe_fact_vars(&mut compiled_fact);
if !compiled_fact.is_empty() {
for fact_instr in compiled_fact {
code.push(Line::Fact(fact_instr));
}
}
}
code.push(proceed!());
code
}
fn compile_query_line(&mut self, term: &'a QueryTerm, term_loc: GenContext,
code: &mut Code, num_perm_vars_left: usize, is_exposed: bool)
{
self.marker.reset_arg(term.arity());
let iter = query_term_post_order_iter(term);
let query = self.compile_target(iter, term_loc, is_exposed);
if !query.is_empty() {
for query_instr in query {
code.push(Line::Query(query_instr));
}
}
Self::add_conditional_call(code, term, num_perm_vars_left);
}
pub fn compile_query(&mut self, query: &'a Vec<QueryTerm>) -> Result<Code, ParserError>
{
let iter = ChunkedIterator::from_term_sequence(query);
let conjunct_info = self.collect_var_data(iter);
let mut code = Vec::new();
self.compile_seq_prelude(&conjunct_info, &mut code);
let iter = ChunkedIterator::from_term_sequence(query);
try!(self.compile_seq(iter, &conjunct_info, &mut code, true));
if conjunct_info.allocates() {
conjunct_info.mark_unsafe_vars(UnsafeVarMarker::new(), &mut code);
}
if let Some(query_term) = query.last() {
Self::compile_cleanup(&mut code, &conjunct_info, query_term);
}
Ok(code)
}
fn split_predicate(clauses: &Vec<PredicateClause>) -> Vec<(usize, usize)>
{
let mut subseqs = Vec::new();
let mut left_index = 0;
for (right_index, clause) in clauses.iter().enumerate() {
match clause.first_arg() {
Some(&Term::Var(_, _)) | Some(&Term::AnonVar) => {
if left_index < right_index {
subseqs.push((left_index, right_index));
}
subseqs.push((right_index, right_index + 1));
left_index = right_index + 1;
},
_ => {}
}
}
if left_index < clauses.len() {
subseqs.push((left_index, clauses.len()));
}
subseqs
}
fn trust_me(&self) -> ChoiceInstruction {
if self.non_counted_bt {
ChoiceInstruction::DefaultTrustMe
} else {
ChoiceInstruction::TrustMe
}
}
fn retry_me_else(&self, offset: usize) -> ChoiceInstruction {
if self.non_counted_bt {
ChoiceInstruction::DefaultRetryMeElse(offset)
} else {
ChoiceInstruction::RetryMeElse(offset)
}
}
fn compile_pred_subseq<'b: 'a>(&mut self, clauses: &'b [PredicateClause])
-> Result<Code, ParserError>
{
let mut code_body = Vec::new();
let mut code_offsets = CodeOffsets::new(self.flags);
let num_clauses = clauses.len();
for (i, clause) in clauses.iter().enumerate() {
self.marker.reset();
let mut clause_code = match clause {
&PredicateClause::Fact(ref fact) =>
self.compile_fact(fact),
&PredicateClause::Rule(ref rule) =>
try!(self.compile_rule(rule))
};
if num_clauses > 1 {
let choice = match i {
0 => ChoiceInstruction::TryMeElse(clause_code.len() + 1),
_ if i == num_clauses - 1 => self.trust_me(),
_ => self.retry_me_else(clause_code.len() + 1)
};
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);
Ok(code)
}
pub fn compile_predicate<'b: 'a>(&mut self, clauses: &'b Vec<PredicateClause>)
-> Result<Code, ParserError>
{
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 = try!(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() => self.trust_me(),
_ => self.retry_me_else(code_segment.len() + 1)
};
code.push(Line::Choice(choice));
}
code.append(&mut code_segment);
}
Ok(code)
}
}