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can for list .. as

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Folkert 2022-12-31 16:00:40 +01:00
parent 905341d849
commit 2e27746413
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1 changed files with 66 additions and 27 deletions
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93
crates/compiler/can/src/pattern.rs
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@ -186,18 +186,18 @@ pub struct ListPatterns {
/// [ .., A, B ] -> patterns = [A, B], rest = 0
/// [ A, .., B ] -> patterns = [A, B], rest = 1
/// [ A, B, .. ] -> patterns = [A, B], rest = 2
pub opt_rest: Option<usize>,
pub opt_rest: Option<(usize, Option<Symbol>)>,
}
impl ListPatterns {
/// Is this list pattern the trivially-exhaustive pattern `[..]`?
fn surely_exhaustive(&self) -> bool {
self.patterns.is_empty() && matches!(self.opt_rest, Some(0))
self.patterns.is_empty() && matches!(self.opt_rest, Some((0, _)))
}
pub fn arity(&self) -> ListArity {
match self.opt_rest {
Some(i) => {
Some((i, _)) => {
let before = i;
let after = self.patterns.len() - before;
ListArity::Slice(before, after)
@ -293,6 +293,43 @@ pub fn canonicalize_def_header_pattern<'a>(
#[derive(PartialEq, Eq, Clone, Copy)]
pub struct PermitShadows(pub bool);
fn canonicalize_pattern_symbol<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
output: &mut Output,
region: Region,
permit_shadows: PermitShadows,
name: &str,
) -> Result<Symbol, Pattern> {
match scope.introduce_str(name, region) {
Ok(symbol) => {
output.references.insert_bound(symbol);
Ok(symbol)
}
Err((shadowed_symbol, shadow, new_symbol)) => {
if permit_shadows.0 {
output.references.insert_bound(shadowed_symbol.value);
Ok(shadowed_symbol.value)
} else {
env.problem(Problem::RuntimeError(RuntimeError::Shadowing {
original_region: shadowed_symbol.region,
shadow: shadow.clone(),
kind: ShadowKind::Variable,
}));
output.references.insert_bound(new_symbol);
Err(Pattern::Shadowed(
shadowed_symbol.region,
shadow,
new_symbol,
))
}
}
}
}
#[allow(clippy::too_many_arguments)]
pub fn canonicalize_pattern<'a>(
env: &mut Env<'a>,
@ -308,29 +345,12 @@ pub fn canonicalize_pattern<'a>(
use PatternType::*;
let can_pattern = match pattern {
Identifier(name) => match scope.introduce_str(name, region) {
Ok(symbol) => {
output.references.insert_bound(symbol);
Pattern::Identifier(symbol)
Identifier(name) => {
match canonicalize_pattern_symbol(env, scope, output, region, permit_shadows, name) {
Ok(symbol) => Pattern::Identifier(symbol),
Err(pattern) => pattern,
}
Err((shadowed_symbol, shadow, new_symbol)) => {
if permit_shadows.0 {
output.references.insert_bound(shadowed_symbol.value);
Pattern::Identifier(shadowed_symbol.value)
} else {
env.problem(Problem::RuntimeError(RuntimeError::Shadowing {
original_region: shadowed_symbol.region,
shadow: shadow.clone(),
kind: ShadowKind::Variable,
}));
output.references.insert_bound(new_symbol);
Pattern::Shadowed(shadowed_symbol.region, shadow, new_symbol)
}
}
},
}
Tag(name) => {
// Canonicalize the tag's name.
Pattern::AppliedTag {
@ -688,14 +708,33 @@ pub fn canonicalize_pattern<'a>(
let list_var = var_store.fresh();
let mut rest_index = None;
let mut rest_name = None;
let mut can_pats = Vec::with_capacity(patterns.len());
let mut opt_erroneous = None;
for (i, loc_pattern) in patterns.iter().enumerate() {
match &loc_pattern.value {
ListRest(_opt_pattern_as) => match rest_index {
ListRest(opt_pattern_as) => match rest_index {
None => {
rest_index = Some(i);
if let Some((_, pattern_as)) = opt_pattern_as {
match canonicalize_pattern_symbol(
env,
scope,
output,
region,
permit_shadows,
pattern_as.identifier.value,
) {
Ok(symbol) => {
rest_name = Some(symbol);
}
Err(pattern) => {
opt_erroneous = Some(pattern);
}
}
}
}
Some(_) => {
env.problem(Problem::MultipleListRestPattern {
@ -731,7 +770,7 @@ pub fn canonicalize_pattern<'a>(
elem_var,
patterns: ListPatterns {
patterns: can_pats,
opt_rest: rest_index,
opt_rest: rest_index.map(|i| (i, rest_name)),
},
})
}