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|
use crate::r#type::{Type, TypeError, Type::*, TypeError::*, PatFail::*, util::*};
use crate::sexp::{SExp, SExp::*, SLeaf::*, util::*};
use std::collections::{HashMap, HashSet};
use std::iter;
impl SExp {
/// Checks if this expression matches the given type,
/// returns all variable names bound by a respective case.
///
/// TODO? Nil / empty list
pub fn matches_type(
&self,
ty: &Type
) -> Result<Vec<(String, Type)>, TypeError> {
let mut checks = HashSet::new();
let res = self.clone()
.matches_type_ctx(ty.clone(), HashMap::new())?;
for (k, _) in res.clone() {
if !checks.insert(k.clone()) {
return Err(InvalidPattern(RepeatedVariable(k, self.clone())));
}
}
Ok(res)
}
fn matches_type_ctx(
self,
ty: Type,
ctx: HashMap<String, Type>
) -> Result<Vec<(String, Type)>, TypeError> {
println!("checking if {} matches pattern {}", &ty, &self);
match (self, ty) {
(a, b) if a.infer_list_type(ctx.clone()) == Ok(b.clone()) =>
Ok(ctx.into_iter().collect()),
(a, b) if a.infer_type(ctx.clone()) == Ok(b.clone()) =>
Ok(ctx.into_iter().collect()),
(Atom(Var(name)), t) =>
Ok(ctx.into_iter()
.chain(iter::once((name, t)))
.collect()),
(exp, VecOf(ty)) => {
let mut res: Vec<(String, Type)> =
ctx.clone().into_iter().collect();
let mut exps = exp.clone().parts();
// TODO: Nil or empty exp
let restpat = exps.remove(exps.len() - 1);
for exp in exps {
for et in exp.matches_type_ctx(*ty.clone(), ctx.clone())? {
res.push(et);
}
}
match restpat {
Atom(RestPat(name)) => {
res.push((name, vecof(ty)));
Ok(res)
},
t => {
for et in t.matches_type_ctx(*ty.clone(), ctx.clone())? {
res.push(et);
}
Ok(res)
}
}
},
(SCons(e1, e2), List(typelist)) => {
let explist = scons(e1.clone(), e2.clone()).parts();
let mut res: Vec<(String, Type)> =
ctx.clone().into_iter().collect();
if explist.len() == typelist.len() {
for (exp, ty) in explist.into_iter().zip(typelist) {
for (e, t) in exp.matches_type_ctx(ty, ctx.clone())? {
res.push((e, t));
}
}
Ok(res)
} else {
match explist.last().cloned() {
Some(Atom(RestPat(name))) => {
for (exp, ty) in explist.clone()
.into_iter()
.rev().skip(1).rev()
.zip(typelist.clone())
{
for (e, t) in exp.matches_type_ctx(ty, ctx.clone())? {
res.push((e, t));
}
}
res.push((
name,
List(typelist
.into_iter()
.skip(explist.len() - 1)
.collect())
));
Ok(res)
},
_ => Err(InvalidPattern(TypeMismatch {
pattern: scons(e1.clone(), e2.clone()),
expected: List(typelist),
found: scons(e1, e2).infer_list_type(ctx)?,
})),
}
}
},
(e, t) => {
let found_ty = e.infer_list_type(ctx)?;
Err(InvalidPattern(TypeMismatch {
pattern: e,
expected: t,
found: found_ty
}))
},
}
}
}
#[cfg(test)]
mod tests {
use crate::sexp::{SExp::*, SLeaf::*, util::*};
use crate::r#type::{Type::*, util::*, TypeError::*, PatFail::*};
#[test]
fn test_type_atoms() {
assert_eq!(Atom(Int(1)).matches_type(&Integer), Ok(vec![]));
assert_eq!(Atom(True).matches_type(&Boolean), Ok(vec![]));
assert_eq!(Atom(Ty(Integer)).matches_type(&TypeLit), Ok(vec![]));
assert_eq!(Atom(Nil).matches_type(&NilType), Ok(vec![]));
}
#[test]
fn test_vector_match() {
assert_eq!(
scons(1, scons(2, Nil))
.matches_type(&List(vec![VecType, vecof(Integer)])),
Ok(vec![])
);
assert_eq!(
scons(var("a"), scons(var("b"), Nil))
.matches_type(&List(vec![VecType, vecof(Integer)])),
Ok(vec![
("a".to_string(), Integer),
("b".to_string(), Integer)
])
);
assert_eq!(
scons(var("a"), scons(RestPat("b".to_string()), Nil))
.matches_type(&List(vec![VecType, vecof(Integer)])),
Ok(vec![
("a".to_string(), Integer),
("b".to_string(), List(vec![VecType, vecof(Integer)]))
])
);
}
#[test]
fn test_list_match() {
assert_eq!(
scons(1, scons(2, Nil))
.matches_type(&List(vec![QuoteTy, List(vec![Integer, Integer])])),
Ok(vec![])
);
assert_eq!(
scons(var("a"), scons(var("b"), Nil))
.matches_type(&List(vec![QuoteTy, List(vec![Integer, Integer])])),
Ok(vec![
("a".to_string(), Integer),
("b".to_string(), Integer)
])
);
assert_eq!(
scons(var("a"), scons(RestPat("b".to_string()), Nil))
.matches_type(&List(vec![QuoteTy, List(vec![Integer, Integer, Integer])])),
Ok(vec![
("a".to_string(), Integer),
("b".to_string(), List(vec![QuoteTy, List(vec![Integer, Integer])]))
])
);
}
#[test]
fn test_mismatch_match() {
assert_eq!(
scons(1, scons(2, Nil))
.matches_type(&List(vec![QuoteTy, List(vec![Integer])])),
Err(InvalidPattern(TypeMismatch {
pattern: scons(1, scons(2, Nil)),
expected: List(vec![QuoteTy, List(vec![Integer])]),
found: List(vec![QuoteTy, List(vec![Integer, Integer])])
}))
);
}
#[test]
fn test_simple_wildcard_match() {
assert_eq!(
var("x").matches_type(&List(vec![QuoteTy, List(vec![Integer, Integer])])),
Ok(vec![("x".to_string(), List(vec![QuoteTy, List(vec![Integer, Integer])]))])
);
}
#[test]
fn test_invalid_pattern_match() {
assert_eq!(
scons(var("x"), scons(var("x"), Nil))
.matches_type(&List(vec![QuoteTy, List(vec![Integer, Integer])])),
Err(InvalidPattern(RepeatedVariable(
"x".to_string(),
scons(var("x"), scons(var("x"), Nil))
)))
);
}
#[test]
fn test_nil_match() {
assert_eq!(
Atom(Nil).matches_type(&List(vec![VecType, vecof(Boolean)])),
Ok(vec![])
);
assert_eq!(
Atom(Nil).matches_type(&List(vec![QuoteTy, List(vec![])])),
Ok(vec![])
);
}
}
|
