nac3_sca/nac3core/src/inference_core.rs

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2021-01-04 14:52:50 +08:00
use crate::context::InferenceContext;
use crate::typedef::{TypeEnum::*, *};
use std::collections::HashMap;
fn find_subst(
ctx: &InferenceContext,
valuation: &Option<(VariableId, Type)>,
sub: &mut HashMap<VariableId, Type>,
mut a: Type,
mut b: Type,
) -> Result<(), String> {
// TODO: fix error messages later
if let TypeVariable(id) = a.as_ref() {
if let Some((assumption_id, t)) = valuation {
if assumption_id == id {
a = t.clone();
}
}
}
let mut substituted = false;
if let TypeVariable(id) = b.as_ref() {
if let Some(c) = sub.get(&id) {
b = c.clone();
substituted = true;
}
}
match (a.as_ref(), b.as_ref()) {
(BotType, _) => Ok(()),
(TypeVariable(id_a), TypeVariable(id_b)) => {
if substituted {
return if id_a == id_b {
Ok(())
} else {
Err("different variables".to_string())
};
}
let v_a = ctx.get_variable_def(*id_a);
let v_b = ctx.get_variable_def(*id_b);
if !v_b.bound.is_empty() {
if v_a.bound.is_empty() {
return Err("unbounded a".to_string());
} else {
let diff: Vec<_> = v_a
.bound
.iter()
.filter(|x| !v_b.bound.contains(x))
.collect();
if !diff.is_empty() {
return Err("different domain".to_string());
}
}
}
sub.insert(*id_b, a.clone());
Ok(())
}
(TypeVariable(id_a), _) => {
let v_a = ctx.get_variable_def(*id_a);
if v_a.bound.len() == 1 && v_a.bound[0].as_ref() == b.as_ref() {
Ok(())
} else {
Err("different domain".to_string())
}
}
(_, TypeVariable(id_b)) => {
let v_b = ctx.get_variable_def(*id_b);
if v_b.bound.is_empty() || v_b.bound.contains(&a) {
sub.insert(*id_b, a.clone());
Ok(())
} else {
Err("different domain".to_string())
}
}
(_, VirtualClassType(id_b)) => {
let mut parents;
match a.as_ref() {
ClassType(id_a) => {
parents = [*id_a].to_vec();
}
VirtualClassType(id_a) => {
parents = [*id_a].to_vec();
}
_ => {
return Err("cannot substitute non-class type into virtual class".to_string());
}
};
while !parents.is_empty() {
if *id_b == parents[0] {
return Ok(());
}
let c = ctx.get_class_def(parents.remove(0));
parents.extend_from_slice(&c.parents);
}
Err("not subtype".to_string())
}
(ParametricType(id_a, param_a), ParametricType(id_b, param_b)) => {
if id_a != id_b || param_a.len() != param_b.len() {
Err("different parametric types".to_string())
} else {
for (x, y) in param_a.iter().zip(param_b.iter()) {
find_subst(ctx, valuation, sub, x.clone(), y.clone())?;
}
Ok(())
}
}
(_, _) => {
if a == b {
Ok(())
} else {
Err("not equal".to_string())
}
}
}
}
fn resolve_call_rec(
ctx: &InferenceContext,
valuation: &Option<(VariableId, Type)>,
obj: Option<Type>,
func: &str,
args: &[Type],
) -> Result<Option<Type>, String> {
let mut subst = obj
.as_ref()
.map(|v| v.get_subst(ctx))
.unwrap_or_else(HashMap::new);
let fun = match &obj {
Some(obj) => {
let base = match obj.as_ref() {
TypeVariable(id) => {
let v = ctx.get_variable_def(*id);
if v.bound.is_empty() {
return Err("unbounded type var".to_string());
}
let results: Result<Vec<_>, String> = v
.bound
.iter()
.map(|ins| {
resolve_call_rec(
ctx,
&Some((*id, ins.clone())),
Some(ins.clone()),
func,
args.clone(),
)
})
.collect();
let results = results?;
if results.iter().all(|v| v == &results[0]) {
return Ok(results[0].clone());
}
let mut results = results.iter().zip(v.bound.iter()).map(|(r, ins)| {
r.as_ref()
.map(|v| v.inv_subst(&[(ins.clone(), obj.clone())]))
});
let first = results.next().unwrap();
if results.all(|v| v == first) {
return Ok(first);
} else {
return Err("divergent type after substitution".to_string());
}
}
PrimitiveType(id) => &ctx.get_primitive_def(*id),
ClassType(id) | VirtualClassType(id) => &ctx.get_class_def(*id).base,
ParametricType(id, _) => &ctx.get_parametric_def(*id).base,
_ => return Err("not supported".to_string()),
};
base.methods.get(func)
}
None => ctx.get_fn_def(func),
}
.ok_or_else(|| "no such function".to_string())?;
if args.len() != fun.args.len() {
return Err("incorrect parameter number".to_string());
}
for (a, b) in args.iter().zip(fun.args.iter()) {
find_subst(ctx, valuation, &mut subst, a.clone(), b.clone())?;
}
let result = fun.result.as_ref().map(|v| v.subst(&subst));
Ok(result.map(|result| {
if let SelfType = result {
obj.unwrap()
} else {
result.into()
}
}))
}
pub fn resolve_call(
ctx: &InferenceContext,
obj: Option<Type>,
func: &str,
args: &[Type],
) -> Result<Option<Type>, String> {
resolve_call_rec(ctx, &None, obj, func, args)
}