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[checker][pattern-matching] Take context by reference #1118

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merged 2 commits into from
Oct 29, 2023
Merged

[checker][pattern-matching] Take context by reference #1118

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d7109fe
[checker][pattern-matching] Add `nothing` as a convenience factory fu…
SamChou19815 Oct 28, 2023
72cd10d
[checker][pattern-matching] Take context by reference
SamChou19815 Oct 28, 2023
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43 changes: 32 additions & 11 deletions crates/samlang-core/src/checker/pattern_matching.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,10 @@ impl AbstractPatternNode {
}))
}

pub(super) fn nothing() -> Self {
Self(Rc::new(AbstractPatternNodeInner::Or(Vec::with_capacity(0))))
}

pub(super) fn or(possibilities: Vec<AbstractPatternNode>) -> Self {
Self(Rc::new(AbstractPatternNodeInner::Or(possibilities)))
}
Expand All @@ -61,24 +65,31 @@ struct PatternMatrix(Vec<PatternVector>);

pub(super) trait PatternMatchingContext {
fn is_variant_signature_complete(
&self,
module_reference: ModuleReference,
class_name: PStr,
variant_name: &[PStr],
) -> bool;
}

pub(super) fn is_additional_pattern_useful<CX: PatternMatchingContext>(
cx: &CX,
existing_patterns: &[AbstractPatternNode],
pattern: AbstractPatternNode,
) -> bool {
useful_internal::<CX>(
useful_internal(
cx,
&PatternMatrix(existing_patterns.iter().map(|p| PatternVector(one(p.clone()))).collect_vec()),
PatternVector(one(pattern)),
)
}

/// http://moscova.inria.fr/~maranget/papers/warn/warn.pdf
fn useful_internal<CX: PatternMatchingContext>(p: &PatternMatrix, q: PatternVector) -> bool {
fn useful_internal<CX: PatternMatchingContext>(
cx: &CX,
p: &PatternMatrix,
q: PatternVector,
) -> bool {
if p.0.is_empty() {
return true;
}
Expand All @@ -88,7 +99,8 @@ fn useful_internal<CX: PatternMatchingContext>(p: &PatternMatrix, q: PatternVect
match q_first.0.as_ref() {
AbstractPatternNodeInner::StructLike { variant, elements: rs } => {
let rs_len = rs.len();
useful_internal::<CX>(
useful_internal(
cx,
&convert_into_specialized_matrix(p, *variant, rs_len),
PatternVector(rs.clone().append(q_rest)),
)
Expand All @@ -108,13 +120,14 @@ fn useful_internal<CX: PatternMatchingContext>(p: &PatternMatrix, q: PatternVect
}
}
}
if is_signature_complete::<CX>(&root_constructors) {
if is_signature_complete(cx, &root_constructors) {
for (variant, rs_len) in root_constructors {
let mut new_q = q_rest.clone();
for _ in 0..rs_len {
new_q = cons(AbstractPatternNode::wildcard(), new_q);
}
if useful_internal::<CX>(
if useful_internal(
cx,
&convert_into_specialized_matrix(p, variant, rs_len),
PatternVector(new_q),
) {
Expand All @@ -139,12 +152,12 @@ fn useful_internal<CX: PatternMatchingContext>(p: &PatternMatrix, q: PatternVect
}
}
}
useful_internal::<CX>(&PatternMatrix(default_matrix_rows), PatternVector(q_rest))
useful_internal(cx, &PatternMatrix(default_matrix_rows), PatternVector(q_rest))
}
}
AbstractPatternNodeInner::Or(possibilities) => possibilities
.iter()
.any(|r| useful_internal::<CX>(p, PatternVector(cons(r.clone(), q_rest.clone())))),
.any(|r| useful_internal(cx, p, PatternVector(cons(r.clone(), q_rest.clone())))),
}
}

Expand Down Expand Up @@ -200,6 +213,7 @@ fn convert_into_specialized_matrix(
}

fn is_signature_complete<CX: PatternMatchingContext>(
cx: &CX,
root_constructors: &HashMap<Option<VariantPatternConstructor>, usize>,
) -> bool {
if root_constructors.contains_key(&None) {
Expand All @@ -217,7 +231,7 @@ fn is_signature_complete<CX: PatternMatchingContext>(
assert!(variants_grouped.len() == 1);
let ((mod_ref, class_name), variants) =
variants_grouped.pop().expect("Already checked it's non-empty.");
CX::is_variant_signature_complete(mod_ref, class_name, &variants)
cx.is_variant_signature_complete(mod_ref, class_name, &variants)
}

#[cfg(test)]
Expand Down Expand Up @@ -283,6 +297,7 @@ mod tests {

impl PatternMatchingContext for MockingPatternMatchingContext {
fn is_variant_signature_complete(
&self,
_module_reference: ModuleReference,
class_name: PStr,
variant_name: &[PStr],
Expand All @@ -304,7 +319,8 @@ mod tests {
}

fn useful(matrix: &[&[P]], vector: &[P]) -> bool {
super::useful_internal::<MockingPatternMatchingContext>(
super::useful_internal(
&MockingPatternMatchingContext,
&super::PatternMatrix(
matrix.iter().map(|r| super::PatternVector(super::list(r.to_vec()))).collect(),
),
Expand All @@ -317,7 +333,7 @@ mod tests {
assert!(!format!("{:?}", OPTION_NONE).is_empty());
assert!(!format!("{:?}", P::wildcard()).is_empty());
assert_eq!(LETTERS, LETTERS_A.clone().class_name);
assert!(!MockingPatternMatchingContext::is_variant_signature_complete(
assert!(!MockingPatternMatchingContext.is_variant_signature_complete(
ModuleReference::ROOT,
PStr::PANIC,
&[],
Expand Down Expand Up @@ -405,6 +421,10 @@ mod tests {
&[&[P::enum_(OPTION_NONE), P::wildcard()], &[P::wildcard(), P::enum_(OPTION_NONE)],],
&[P::variant(OPTION_SOME, vec![P::wildcard()]), P::variant(OPTION_SOME, vec![P::wildcard()])]
));
assert!(!useful(
&[&[P::enum_(OPTION_NONE), P::wildcard()], &[P::wildcard(), P::enum_(OPTION_NONE)],],
&[P::nothing()]
));
assert!(!useful(
&[
&[P::enum_(OPTION_NONE), P::wildcard()],
Expand Down Expand Up @@ -440,7 +460,8 @@ mod tests {
P::variant(OPTION_SOME, vec![P::wildcard()])
])]
));
assert!(!super::is_additional_pattern_useful::<MockingPatternMatchingContext>(
assert!(!super::is_additional_pattern_useful(
&MockingPatternMatchingContext,
&[
P::tuple(vec![P::enum_(OPTION_NONE), P::wildcard()]),
P::tuple(vec![P::wildcard(), P::enum_(OPTION_NONE)]),
Expand Down