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simplify handling of optional fields

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Folkert 2020-11-24 20:57:10 +01:00
parent 9c7514c449
commit 517f8f4a4a
1 changed files with 79 additions and 102 deletions
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181
compiler/mono/src/ir.rs
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@ -5374,8 +5374,8 @@ pub fn from_can_pattern<'a>(
// sorted fields based on the destruct
let mut mono_destructs = Vec::with_capacity_in(destructs.len(), env.arena);
let mut destructs = destructs.clone();
destructs.sort_by(|a, b| a.value.label.cmp(&b.value.label));
let destructs_by_label = env.arena.alloc(MutMap::default());
destructs_by_label.extend(destructs.iter().map(|x| (&x.value.label, x)));
let mut field_layouts = Vec::with_capacity_in(sorted_fields.len(), env.arena);
@ -5387,119 +5387,96 @@ pub fn from_can_pattern<'a>(
// in the source the field is not matche in the source language.
//
// Optional fields somewhat complicate the matter here
let mut it1 = sorted_fields.into_iter();
let mut opt_sorted = it1.next();
let mut it2 = destructs.iter();
let mut opt_destruct = it2.next();
for (label, variable, res_layout) in sorted_fields.into_iter() {
match res_layout {
Ok(field_layout) => {
// the field is non-optional according to the type
loop {
match (opt_sorted, opt_destruct) {
(Some((label, variable, Ok(field_layout))), Some(destruct)) => {
if destruct.value.label == label {
mono_destructs.push(from_can_record_destruct(
env,
layout_cache,
&destruct.value,
field_layout.clone(),
));
opt_sorted = it1.next();
opt_destruct = it2.next();
} else {
// insert underscore pattern
mono_destructs.push(RecordDestruct {
label: label.clone(),
symbol: env.unique_symbol(),
variable,
layout: field_layout.clone(),
typ: DestructType::Guard(Pattern::Underscore),
});
opt_sorted = it1.next();
match destructs_by_label.remove(&label) {
Some(destruct) => {
// this field is destructured by the pattern
mono_destructs.push(from_can_record_destruct(
env,
layout_cache,
&destruct.value,
field_layout.clone(),
));
}
None => {
// this field is not destructured by the pattern
// put in an underscore
mono_destructs.push(RecordDestruct {
label: label.clone(),
symbol: env.unique_symbol(),
variable,
layout: field_layout.clone(),
typ: DestructType::Guard(Pattern::Underscore),
});
}
}
// the layout of this field is part of the layout of the record
field_layouts.push(field_layout);
}
(Some((label, variable, Err(field_layout))), Some(destruct)) => {
if destruct.value.label == label {
opt_destruct = it2.next();
mono_destructs.push(RecordDestruct {
label: destruct.value.label.clone(),
symbol: destruct.value.symbol,
layout: field_layout,
variable,
typ: match &destruct.value.typ {
roc_can::pattern::DestructType::Optional(_, loc_expr) => {
// if we reach this stage, the optional field is not present
// so use the default
DestructType::Optional(loc_expr.value.clone())
}
_ => unreachable!(
"only optional destructs can be optional fields"
),
},
});
}
opt_sorted = it1.next();
}
(Some((label, variable, Err(field_layout))), None) => {
// the remainder of the fields (from the type) is not matched on in
// this pattern; to fill it out, we put underscores
mono_destructs.push(RecordDestruct {
label: label.clone(),
symbol: env.unique_symbol(),
variable,
layout: field_layout.clone(),
typ: DestructType::Guard(Pattern::Underscore),
});
opt_sorted = it1.next();
}
(Some((label, variable, Ok(field_layout))), None) => {
// the remainder of the fields (from the type) is not matched on in
// this pattern; to fill it out, we put underscores
mono_destructs.push(RecordDestruct {
label: label.clone(),
symbol: env.unique_symbol(),
variable,
layout: field_layout.clone(),
typ: DestructType::Guard(Pattern::Underscore),
});
field_layouts.push(field_layout);
opt_sorted = it1.next();
}
(None, Some(destruct)) => {
// destruct is not in the type, but is in the pattern
// it must be an optional field, and we will use the default
match &destruct.value.typ {
roc_can::pattern::DestructType::Optional(field_var, loc_expr) => {
let field_layout = layout_cache
.from_var(env.arena, *field_var, env.subs)
.unwrap_or_else(|err| {
panic!("TODO turn fn_var into a RuntimeError {:?}", err)
});
Err(field_layout) => {
// the field is optional according to the type
match destructs_by_label.remove(&label) {
Some(destruct) => {
// this field is destructured by the pattern
mono_destructs.push(RecordDestruct {
label: destruct.value.label.clone(),
symbol: destruct.value.symbol,
variable: destruct.value.var,
layout: field_layout,
typ: DestructType::Optional(loc_expr.value.clone()),
})
variable,
typ: match &destruct.value.typ {
roc_can::pattern::DestructType::Optional(_, loc_expr) => {
// if we reach this stage, the optional field is not present
// so use the default
DestructType::Optional(loc_expr.value.clone())
}
_ => unreachable!(
"only optional destructs can be optional fields"
),
},
});
}
None => {
// this field is not destructured by the pattern
// put in an underscore
mono_destructs.push(RecordDestruct {
label: label.clone(),
symbol: env.unique_symbol(),
variable,
layout: field_layout.clone(),
typ: DestructType::Guard(Pattern::Underscore),
});
}
_ => unreachable!("only optional destructs can be optional fields"),
}
}
}
}
opt_sorted = None;
opt_destruct = it2.next();
}
(None, None) => {
break;
for (_, destruct) in destructs_by_label.drain() {
// this destruct is not in the type, but is in the pattern
// it must be an optional field, and we will use the default
match &destruct.value.typ {
roc_can::pattern::DestructType::Optional(field_var, loc_expr) => {
let field_layout = layout_cache
.from_var(env.arena, *field_var, env.subs)
.unwrap_or_else(|err| {
panic!("TODO turn fn_var into a RuntimeError {:?}", err)
});
mono_destructs.push(RecordDestruct {
label: destruct.value.label.clone(),
symbol: destruct.value.symbol,
variable: destruct.value.var,
layout: field_layout,
typ: DestructType::Optional(loc_expr.value.clone()),
})
}
_ => unreachable!("only optional destructs can be optional fields"),
}
}