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clean up tag pattern match conversion

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This commit is contained in:
Folkert 2020-03-23 17:12:44 +01:00
parent a7b5768c47
commit b9613fcdc5
4 changed files with 121 additions and 139 deletions
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125
compiler/mono/src/expr.rs
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@ -842,7 +842,7 @@ fn store_pattern<'a>(
}
Underscore => {
// Since _ is never read, it's safe to reassign it.
stored.push((Symbol::UNDERSCORE, layout, Expr::Load(outer_symbol)))
// stored.push((Symbol::UNDERSCORE, layout, Expr::Load(outer_symbol)))
}
IntLiteral(_) | FloatLiteral(_) | EnumLiteral { .. } | BitLiteral(_) => {}
AppliedTag {
@ -1335,57 +1335,87 @@ fn from_can_pattern<'a>(
arguments,
..
} => {
let mut fields = std::vec::Vec::new();
use crate::layout::UnionVariant::*;
match roc_types::pretty_print::chase_ext_tag_union(env.subs, *whole_var, &mut fields) {
Ok(()) | Err((_, Content::FlexVar(_))) => {}
Err(content) => panic!("invalid content in ext_var: {:?}", content),
}
let variant =
crate::layout::union_sorted_tags(env.arena, *whole_var, env.subs, env.pointer_size);
fields.sort();
let tag_id = fields
.iter()
.position(|(key, _)| key == tag_name)
.expect("tag must be in its own type");
let enum_size = fields.len();
let mut ctors = std::vec::Vec::with_capacity(fields.len());
for (tag_name, args) in &fields {
ctors.push(Ctor {
name: tag_name.clone(),
arity: args.len(),
})
}
let union = crate::pattern::Union {
alternatives: ctors,
};
let fields_map: MutMap<_, _> = fields.into_iter().collect();
match crate::layout::layout_from_tag_union(
env.arena,
&fields_map,
env.subs,
env.pointer_size,
) {
Ok(Layout::Builtin(Builtin::Bool)) => Pattern::BitLiteral(tag_id != 0),
Ok(Layout::Builtin(Builtin::Byte)) => Pattern::EnumLiteral {
tag_id: tag_id as u8,
enum_size: enum_size as u8,
match variant {
Never => unreachable!("there is no pattern of type `[]`"),
Unit => Pattern::EnumLiteral {
tag_id: 0,
enum_size: 1,
},
Ok(layout) => {
let mut mono_args = Vec::with_capacity_in(arguments.len(), env.arena);
for (pat_var, loc_pat) in arguments {
let layout =
Layout::from_var(env.arena, *pat_var, env.subs, env.pointer_size)
.unwrap_or_else(|err| {
panic!("TODO turn pat_var into a RuntimeError {:?}", err)
});
BoolUnion { ttrue, .. } => Pattern::BitLiteral(tag_name == &ttrue),
ByteUnion(tag_names) => {
let tag_id = tag_names
.iter()
.position(|key| key == tag_name)
.expect("tag must be in its own type");
mono_args.push((from_can_pattern(env, &loc_pat.value), layout));
Pattern::EnumLiteral {
tag_id: tag_id as u8,
enum_size: tag_names.len() as u8,
}
}
Unwrapped(field_layouts) => {
let union = crate::pattern::Union {
alternatives: vec![Ctor {
name: tag_name.clone(),
arity: field_layouts.len(),
}],
};
let mut mono_args = Vec::with_capacity_in(arguments.len(), env.arena);
for ((_, loc_pat), layout) in arguments.iter().zip(field_layouts.iter()) {
mono_args.push((from_can_pattern(env, &loc_pat.value), layout.clone()));
}
let layout = Layout::Struct(field_layouts.into_bump_slice());
Pattern::AppliedTag {
tag_name: tag_name.clone(),
tag_id: 0,
arguments: mono_args,
union,
layout,
}
}
Wrapped(tags) => {
let mut ctors = std::vec::Vec::with_capacity(tags.len());
for (tag_name, args) in &tags {
ctors.push(Ctor {
name: tag_name.clone(),
// don't include tag discriminant in arity
arity: args.len() - 1,
})
}
let union = crate::pattern::Union {
alternatives: ctors,
};
let (tag_id, (_, argument_layouts)) = tags
.iter()
.enumerate()
.find(|(_, (key, _))| key == tag_name)
.expect("tag must be in its own type");
let mut mono_args = Vec::with_capacity_in(arguments.len(), env.arena);
// disregard the tag discriminant layout
let it = argument_layouts[1..].iter();
for ((_, loc_pat), layout) in arguments.iter().zip(it) {
mono_args.push((from_can_pattern(env, &loc_pat.value), layout.clone()));
}
let mut layouts: Vec<&'a [Layout<'a>]> =
Vec::with_capacity_in(tags.len(), env.arena);
for (_, arg_layouts) in tags.into_iter() {
layouts.push(arg_layouts);
}
let layout = Layout::Union(layouts.into_bump_slice());
Pattern::AppliedTag {
tag_name: tag_name.clone(),
@ -1395,7 +1425,6 @@ fn from_can_pattern<'a>(
layout,
}
}
Err(()) => panic!("Invalid layout"),
}
}