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use crate::{
Binder1,
Comp,
Literal,
Val,
VName,
Gen,
Sig,
};
use std::collections::HashMap;
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum DemandVal {
Positive,
Negative(VName),
Both(VName),
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DemandSet(HashMap<VName, DemandVal>);
impl DemandSet {
pub fn empty() -> Self { DemandSet(HashMap::new()) }
pub fn get(&self, x: &VName) -> Option<DemandVal> {
match self.0.get(x) {
Some(y) => Some(y.clone()),
None => None,
}
}
pub fn add_positive(&mut self, x: &VName) {
match self.0.get(x) {
Some(DemandVal::Both(_y)) => {},
Some(DemandVal::Positive) => {},
Some(DemandVal::Negative(y)) => {
self.0.insert(x.clone(),DemandVal::Both(y.clone()));
}
None => {
self.0.insert(x.clone(),DemandVal::Positive);
}
}
}
/// First VName arg is the demanded name, second is the what the
/// negation should be named as. The returned value is what the
/// negation has already been named as, if any.
pub fn add_negative(&mut self, x: &VName, y: &VName) -> VName {
match self.0.get(x) {
Some(DemandVal::Both(y2)) => y2.clone(),
Some(DemandVal::Negative(y2)) => y2.clone(),
Some(DemandVal::Positive) => {
self.0.insert(x.clone(),DemandVal::Both(y.clone()));
y.clone()
}
None => {
self.0.insert(x.clone(),DemandVal::Negative(y.clone()));
y.clone()
}
}
}
/// Adds a negative demand for the given VName. If a negative
/// demand already exists, add return the negative version's
/// name. If not, generate a unique name for the negative version
/// and return it.
pub fn add_negative_gen(&mut self, x: &VName, gen: &mut Gen) -> VName {
match self.0.get(x) {
Some(DemandVal::Both(x2)) => x2.clone(),
Some(DemandVal::Negative(x2)) => x2.clone(),
Some(DemandVal::Positive) => {
let x2 = gen.next();
self.0.insert(x.clone(), DemandVal::Both(x2.clone()));
x2
}
None => {
let x2 = gen.next();
self.0.insert(x.clone(), DemandVal::Negative(x2.clone()));
x2
}
}
}
}
impl Binder1 {
fn neg_normal_form_r(&self, sig: &Sig, dem: &mut DemandSet, gen: &mut Gen) -> Self {
match self {
Self::Eq(pos, vs1, vs2) => {
for v in vs1 {
v.demand_positive(dem);
}
for v in vs2 {
v.demand_positive(dem);
}
Self::Eq(*pos, vs1.clone(), vs2.clone())
}
Self::LogQuantifier(q, xs, m) => {
let m2 = m.neg_normal_form_r(sig, dem, gen);
Self::LogQuantifier(*q, xs.clone(), Box::new(m2))
}
Self::LogOpN(op, vs) => {
// Demand all of the args
for v in vs {
v.demand_positive(dem);
}
// let mut vs2 = Vec::new();
// for v in vs {
// match v {
// Val::Var(n) => {
// dem.add_positive(n);
// vs2.push(Val::Var(n.clone()));
// }
// Val::Literal(l) => {
// vs2.push(Val::Literal(l.clone()));
// },
// // I'm worried about the demand-set here, but
// // normalization itself for the body of a
// // thunk is not necessary, since it will be
// // normalized later when it is forced.
// //
// // Val::Thunk(m) => {
// // let v2 = Val::Thunk(Box::new(
// // m.neg_normal_form_r(dem,gen)
// // ));
// // vs2.push(v2);
// // }
// Val::Thunk(m) => {
// vs2.push(Val::Thunk(m.clone()));
// }
// }
// }
Self::LogOpN(op.clone(), vs.clone())
}
_ => todo!("neg_normal_form_r for {:?}", self),
}
}
}
impl Comp {
/// Convert a computation into normal form. This may require the
/// creation of new variables, so we require a Gen.
pub fn neg_normal_form(self, sig: &Sig, gen: &mut Gen) -> Self {
self.neg_normal_form_r(sig, &mut DemandSet::empty(), gen)
}
fn neg_normal_form_r(&self, sig: &Sig, dem: &mut DemandSet, gen: &mut Gen) -> Self {
match self {
Self::Return(vs) => {
for v in vs {
match v {
Val::Var(x,_) => { dem.add_positive(x); }
_ => {},
}
}
Self::Return(vs.clone())
}
Self::Bind1(Binder1::LogNot(v), x, m) => {
let m2 = m.neg_normal_form_r(sig,dem,gen);
match dem.get(x) {
None => m2,
Some(DemandVal::Positive) => {
// Get the negative version of the value,
// recording a negative demand if it's a
// variable.
let v_neg = v.demand_negative(dem,gen);
// Replace x's with the negative value.
m2.substitute(x, &v_neg)
}
Some(DemandVal::Negative(y1)) => {
// Record a positive demand for the value (if
// it's a variable).
v.demand_positive(dem);
// Replace y1's with the (positive) value. The
// positive x (negative value) is not
// demanded, so there are no x's in m2 to
// replace with anything.
m2.substitute(&y1, v)
}
Some(DemandVal::Both(y1)) => {
v.demand_positive(dem);
let v_neg = v.demand_negative(dem,gen);
m2
.substitute(&y1,v)
.substitute(x,&v_neg)
}
}
}
Self::Bind1(b, x, m) => {
let m2 = m.neg_normal_form_r(sig,dem,gen);
match dem.get(x) {
None => {
// println!("{:?} was not demanded by {:?}", x, m2);
m2
}
Some(DemandVal::Positive) => {
let b2p = b.neg_normal_form_r(sig,dem,gen);
Self::Bind1(b2p, x.clone(), Box::new(m2))
}
Some(DemandVal::Negative(y)) => {
let b2n = b.negate(sig,dem,gen).neg_normal_form_r(sig,dem,gen);
Self::Bind1(b2n, y.clone(), Box::new(m2))
}
Some(DemandVal::Both(y)) => {
let b2p = b.neg_normal_form_r(sig,dem,gen);
let b2n = b.negate(sig,dem,gen).neg_normal_form_r(sig,dem,gen);
Self::Bind1(b2p, x.clone(), Box::new(
Self::Bind1(b2n, y.clone(), Box::new(m2))
))
}
}
}
Self::BindN(b, ps, m) => {
Self::BindN(
b.clone(),
ps.clone(),
Box::new(m.neg_normal_form_r(sig,dem,gen)),
)
}
Self::Ite(cond, then_b, else_b) => {
cond.demand_positive(dem);
Self::ite(
cond.clone(),
then_b.neg_normal_form_r(sig,dem,gen),
else_b.neg_normal_form_r(sig,dem,gen),
)
}
Self::Apply(_m, _targs, _vs) => {
panic!(
"Apply should be gone before neg_normal_form_r: {:?}",
self,
)
}
_ => todo!("neg_normal_form_r for {:?}", self),
}
}
}
impl Val {
/// Record positive demand if the value is a Var. Note that
/// nothing gets demanded inside of Thunks.
pub fn demand_positive(&self, dem: &mut DemandSet) {
match self {
Self::Var(x, _) => {
dem.add_positive(x);
}
Self::Tuple(vs) => {
for v in vs {
v.demand_positive(dem);
}
}
_ => {},
}
}
/// Generate the negation of the value, recording a negative
/// demand if it's a Var.
pub fn demand_negative(
&self,
dem: &mut DemandSet,
gen: &mut Gen
) -> Self {
match self {
Self::Var(x, types) => {
let x2 = dem.add_negative_gen(&x,gen);
Self::Var(x2, types.clone())
}
Self::Literal(Literal::LogTrue) =>
Self::Literal(Literal::LogFalse),
Self::Literal(Literal::LogFalse) =>
Self::Literal(Literal::LogTrue),
_ => panic!("Can't demand (negative) non-prop value {:?}", self),
}
}
}