roc/crates/compiler/can/src/desugar.rs
2024-08-07 18:55:33 -03:00

1556 lines
55 KiB
Rust

#![allow(clippy::manual_map)]
use crate::suffixed::{apply_task_await, unwrap_suffixed_expression, EUnwrapped};
use bumpalo::collections::Vec;
use bumpalo::Bump;
use roc_error_macros::internal_error;
use roc_module::called_via::BinOp::Pizza;
use roc_module::called_via::{BinOp, CalledVia};
use roc_module::ident::ModuleName;
use roc_parse::ast::Expr::{self, *};
use roc_parse::ast::{
AssignedField, Collection, ModuleImportParams, OldRecordBuilderField, Pattern, StrLiteral,
StrSegment, TypeAnnotation, ValueDef, WhenBranch,
};
use roc_region::all::{LineInfo, Loc, Region};
// BinOp precedence logic adapted from Gluon by Markus Westerlind
// https://github.com/gluon-lang/gluon - license information can be found in
// the LEGAL_DETAILS file in the root directory of this distribution.
//
// Thank you, Markus!
fn new_op_call_expr<'a>(
arena: &'a Bump,
left: &'a Loc<Expr<'a>>,
loc_op: Loc<BinOp>,
right: &'a Loc<Expr<'a>>,
) -> Loc<Expr<'a>> {
let region = Region::span_across(&left.region, &right.region);
let value = match loc_op.value {
Pizza => {
// Rewrite the Pizza operator into an Apply
match &right.value {
Apply(function, arguments, _called_via) => {
let mut args = Vec::with_capacity_in(1 + arguments.len(), arena);
args.push(left);
args.extend(arguments.iter());
let args = args.into_bump_slice();
Apply(function, args, CalledVia::BinOp(Pizza))
}
_ => {
// e.g. `1 |> (if b then (\a -> a) else (\c -> c))`
Apply(right, arena.alloc([left]), CalledVia::BinOp(Pizza))
}
}
}
binop => {
// This is a normal binary operator like (+), so desugar it
// into the appropriate function call.
let (module_name, ident) = binop_to_function(binop);
let args = arena.alloc([left, right]);
let loc_expr = arena.alloc(Loc {
value: Expr::Var { module_name, ident },
region: loc_op.region,
});
Apply(loc_expr, args, CalledVia::BinOp(binop))
}
};
Loc { region, value }
}
fn desugar_value_def<'a>(
arena: &'a Bump,
def: &'a ValueDef<'a>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> ValueDef<'a> {
use ValueDef::*;
match def {
Body(loc_pattern, loc_expr) => Body(
desugar_loc_pattern(arena, loc_pattern, src, line_info, module_path),
desugar_expr(arena, loc_expr, src, line_info, module_path),
),
ann @ Annotation(_, _) => *ann,
AnnotatedBody {
ann_pattern,
ann_type,
lines_between,
body_pattern,
body_expr,
} => AnnotatedBody {
ann_pattern,
ann_type,
lines_between,
body_pattern: desugar_loc_pattern(arena, body_pattern, src, line_info, module_path),
body_expr: desugar_expr(arena, body_expr, src, line_info, module_path),
},
Dbg {
condition,
preceding_comment,
} => {
let desugared_condition =
&*arena.alloc(desugar_expr(arena, condition, src, line_info, module_path));
Dbg {
condition: desugared_condition,
preceding_comment: *preceding_comment,
}
}
Expect {
condition,
preceding_comment,
} => {
let desugared_condition =
&*arena.alloc(desugar_expr(arena, condition, src, line_info, module_path));
Expect {
condition: desugared_condition,
preceding_comment: *preceding_comment,
}
}
ExpectFx {
condition,
preceding_comment,
} => {
let desugared_condition =
&*arena.alloc(desugar_expr(arena, condition, src, line_info, module_path));
ExpectFx {
condition: desugared_condition,
preceding_comment: *preceding_comment,
}
}
ModuleImport(roc_parse::ast::ModuleImport {
before_name,
name,
params,
alias,
exposed,
}) => {
let desugared_params =
params.map(|ModuleImportParams { before, params }| ModuleImportParams {
before,
params: params.map(|params| {
desugar_field_collection(arena, *params, src, line_info, module_path)
}),
});
ModuleImport(roc_parse::ast::ModuleImport {
before_name,
name: *name,
params: desugared_params,
alias: *alias,
exposed: *exposed,
})
}
IngestedFileImport(_) => *def,
Stmt(stmt_expr) => {
// desugar `stmt_expr!` to
// _ : {}
// _ = stmt_expr!
let region = stmt_expr.region;
let new_pat = arena.alloc(Loc::at(region, Pattern::Underscore("#!stmt")));
ValueDef::AnnotatedBody {
ann_pattern: new_pat,
ann_type: arena.alloc(Loc::at(
region,
TypeAnnotation::Record {
fields: Collection::empty(),
ext: None,
},
)),
lines_between: &[],
body_pattern: new_pat,
body_expr: desugar_expr(arena, stmt_expr, src, line_info, module_path),
}
}
}
}
pub fn desugar_defs_node_values<'a>(
arena: &'a Bump,
defs: &mut roc_parse::ast::Defs<'a>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
top_level_def: bool,
) {
for value_def in defs.value_defs.iter_mut() {
*value_def = desugar_value_def(arena, arena.alloc(*value_def), src, line_info, module_path);
}
// `desugar_defs_node_values` is called recursively in `desugar_expr`
// and we only want to unwrap suffixed nodes if they are a top level def.
//
// check here first so we only unwrap the expressions once, and after they have
// been desugared
if top_level_def {
for value_def in defs.value_defs.iter_mut() {
*value_def = desugar_value_def_suffixed(arena, *value_def);
}
}
}
/// For each top-level ValueDef in our module, we will unwrap any suffixed
/// expressions
///
/// e.g. `say! "hi"` desugars to `Task.await (say "hi") \{} -> ...`
pub fn desugar_value_def_suffixed<'a>(arena: &'a Bump, value_def: ValueDef<'a>) -> ValueDef<'a> {
use ValueDef::*;
match value_def {
Body(loc_pattern, loc_expr) => {
// note called_from_def is passed as `false` as this is a top_level_def
match unwrap_suffixed_expression(arena, loc_expr, None) {
Ok(new_expr) => Body(loc_pattern, new_expr),
Err(EUnwrapped::UnwrappedSubExpr {
sub_arg,
sub_pat,
sub_new,
}) => desugar_value_def_suffixed(
arena,
Body(
loc_pattern,
apply_task_await(arena, loc_expr.region, sub_arg, sub_pat, sub_new, None),
),
),
Err(..) => Body(
loc_pattern,
arena.alloc(Loc::at(loc_expr.region, MalformedSuffixed(loc_expr))),
),
}
}
ann @ Annotation(_, _) => ann,
AnnotatedBody {
ann_pattern,
ann_type,
lines_between,
body_pattern,
body_expr,
} => {
// note called_from_def is passed as `false` as this is a top_level_def
match unwrap_suffixed_expression(arena, body_expr, None) {
Ok(new_expr) => AnnotatedBody {
ann_pattern,
ann_type,
lines_between,
body_pattern,
body_expr: new_expr,
},
Err(EUnwrapped::UnwrappedSubExpr {
sub_arg,
sub_pat,
sub_new,
}) => desugar_value_def_suffixed(
arena,
AnnotatedBody {
ann_pattern,
ann_type,
lines_between,
body_pattern,
body_expr: apply_task_await(
arena,
body_expr.region,
sub_arg,
sub_pat,
sub_new,
Some((ann_pattern, ann_type)),
),
},
),
Err(..) => AnnotatedBody {
ann_pattern,
ann_type,
lines_between,
body_pattern,
body_expr: arena.alloc(Loc::at(body_expr.region, MalformedSuffixed(body_expr))),
},
}
}
// TODO support desugaring of Dbg, Expect, and ExpectFx
Dbg { .. } | Expect { .. } | ExpectFx { .. } => value_def,
ModuleImport { .. } | IngestedFileImport(_) => value_def,
Stmt(..) => {
internal_error!(
"this should have been desugared into a Body(..) before this call in desugar_expr"
)
}
}
}
/// Reorder the expression tree based on operator precedence and associativity rules,
/// then replace the BinOp nodes with Apply nodes. Also drop SpaceBefore and SpaceAfter nodes.
pub fn desugar_expr<'a>(
arena: &'a Bump,
loc_expr: &'a Loc<Expr<'a>>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> &'a Loc<Expr<'a>> {
match &loc_expr.value {
Float(..)
| Num(..)
| NonBase10Int { .. }
| SingleQuote(_)
| AccessorFunction(_)
| Var { .. }
| Underscore { .. }
| MalformedIdent(_, _)
| MalformedClosure
| MalformedSuffixed(..)
| PrecedenceConflict { .. }
| MultipleOldRecordBuilders(_)
| UnappliedOldRecordBuilder(_)
| EmptyRecordBuilder(_)
| SingleFieldRecordBuilder(_)
| OptionalFieldInRecordBuilder { .. }
| Tag(_)
| OpaqueRef(_)
| Crash => loc_expr,
Str(str_literal) => match str_literal {
StrLiteral::PlainLine(_) => loc_expr,
StrLiteral::Line(segments) => {
let region = loc_expr.region;
let value = Str(StrLiteral::Line(desugar_str_segments(
arena,
segments,
src,
line_info,
module_path,
)));
arena.alloc(Loc { region, value })
}
StrLiteral::Block(lines) => {
let region = loc_expr.region;
let new_lines = Vec::from_iter_in(
lines.iter().map(|segments| {
desugar_str_segments(arena, segments, src, line_info, module_path)
}),
arena,
);
let value = Str(StrLiteral::Block(new_lines.into_bump_slice()));
arena.alloc(Loc { region, value })
}
},
TupleAccess(sub_expr, paths) => {
let region = loc_expr.region;
let loc_sub_expr = Loc {
region,
value: **sub_expr,
};
let value = TupleAccess(
&desugar_expr(
arena,
arena.alloc(loc_sub_expr),
src,
line_info,
module_path,
)
.value,
paths,
);
arena.alloc(Loc { region, value })
}
// desugar the sub_expression, but leave the TaskAwaitBang as this will
// be unwrapped later in desugar_value_def_suffixed
TaskAwaitBang(sub_expr) => {
let intermediate = arena.alloc(Loc::at(loc_expr.region, **sub_expr));
let new_sub_loc_expr = desugar_expr(arena, intermediate, src, line_info, module_path);
let new_sub_expr = arena.alloc(new_sub_loc_expr.value);
arena.alloc(Loc::at(loc_expr.region, TaskAwaitBang(new_sub_expr)))
}
RecordAccess(sub_expr, paths) => {
let region = loc_expr.region;
let loc_sub_expr = Loc {
region,
value: **sub_expr,
};
let value = RecordAccess(
&desugar_expr(
arena,
arena.alloc(loc_sub_expr),
src,
line_info,
module_path,
)
.value,
paths,
);
arena.alloc(Loc { region, value })
}
List(items) => {
let mut new_items = Vec::with_capacity_in(items.len(), arena);
for item in items.iter() {
new_items.push(desugar_expr(arena, item, src, line_info, module_path));
}
let new_items = new_items.into_bump_slice();
let value: Expr<'a> = List(items.replace_items(new_items));
arena.alloc(Loc {
region: loc_expr.region,
value,
})
}
Record(fields) => {
let fields = desugar_field_collection(arena, *fields, src, line_info, module_path);
arena.alloc(Loc {
region: loc_expr.region,
value: Record(fields),
})
}
Tuple(fields) => {
let mut allocated = Vec::with_capacity_in(fields.len(), arena);
for field in fields.iter() {
let expr = desugar_expr(arena, field, src, line_info, module_path);
allocated.push(expr);
}
let fields = fields.replace_items(allocated.into_bump_slice());
arena.alloc(Loc {
region: loc_expr.region,
value: Tuple(fields),
})
}
RecordUpdate { fields, update } => {
// NOTE the `update` field is always a `Var { .. }`, we only desugar it to get rid of
// any spaces before/after
let new_update = desugar_expr(arena, update, src, line_info, module_path);
let mut allocated = Vec::with_capacity_in(fields.len(), arena);
for field in fields.iter() {
let value = desugar_field(arena, &field.value, src, line_info, module_path);
allocated.push(Loc {
value,
region: field.region,
});
}
let new_fields = fields.replace_items(allocated.into_bump_slice());
arena.alloc(Loc {
region: loc_expr.region,
value: RecordUpdate {
update: new_update,
fields: new_fields,
},
})
}
Closure(loc_patterns, loc_ret) => arena.alloc(Loc {
region: loc_expr.region,
value: Closure(
desugar_loc_patterns(arena, loc_patterns, src, line_info, module_path),
desugar_expr(arena, loc_ret, src, line_info, module_path),
),
}),
Backpassing(loc_patterns, loc_body, loc_ret) => {
// loc_patterns <- loc_body
//
// loc_ret
// first desugar the body, because it may contain |>
let desugared_body = desugar_expr(arena, loc_body, src, line_info, module_path);
let desugared_ret = desugar_expr(arena, loc_ret, src, line_info, module_path);
let desugared_loc_patterns =
desugar_loc_patterns(arena, loc_patterns, src, line_info, module_path);
let closure = Expr::Closure(desugared_loc_patterns, desugared_ret);
let loc_closure = Loc::at(loc_expr.region, closure);
match &desugared_body.value {
Expr::Apply(function, arguments, called_via) => {
let mut new_arguments: Vec<'a, &'a Loc<Expr<'a>>> =
Vec::with_capacity_in(arguments.len() + 1, arena);
new_arguments.extend(arguments.iter());
new_arguments.push(arena.alloc(loc_closure));
let call = Expr::Apply(function, new_arguments.into_bump_slice(), *called_via);
let loc_call = Loc::at(loc_expr.region, call);
arena.alloc(loc_call)
}
_ => {
// e.g. `x <- (if b then (\a -> a) else (\c -> c))`
let call = Expr::Apply(
desugared_body,
arena.alloc([&*arena.alloc(loc_closure)]),
CalledVia::Space,
);
let loc_call = Loc::at(loc_expr.region, call);
arena.alloc(loc_call)
}
}
}
OldRecordBuilder(_) => arena.alloc(Loc {
value: UnappliedOldRecordBuilder(loc_expr),
region: loc_expr.region,
}),
RecordBuilder { mapper, fields } => {
// NOTE the `mapper` is always a `Var { .. }`, we only desugar it to get rid of
// any spaces before/after
let new_mapper = desugar_expr(arena, mapper, src, line_info, module_path);
if fields.is_empty() {
return arena.alloc(Loc {
value: EmptyRecordBuilder(loc_expr),
region: loc_expr.region,
});
} else if fields.len() == 1 {
return arena.alloc(Loc {
value: SingleFieldRecordBuilder(loc_expr),
region: loc_expr.region,
});
}
struct FieldData<'d> {
name: Loc<&'d str>,
value: &'d Loc<Expr<'d>>,
ignored: bool,
}
let mut field_data = Vec::with_capacity_in(fields.len(), arena);
for field in fields.items {
let (name, value, ignored) =
match desugar_field(arena, &field.value, src, line_info, module_path) {
AssignedField::RequiredValue(loc_name, _, loc_val) => {
(loc_name, loc_val, false)
}
AssignedField::IgnoredValue(loc_name, _, loc_val) => {
(loc_name, loc_val, true)
}
AssignedField::LabelOnly(loc_name) => (
loc_name,
&*arena.alloc(Loc {
region: loc_name.region,
value: Expr::Var {
module_name: "",
ident: loc_name.value,
},
}),
false,
),
AssignedField::OptionalValue(loc_name, _, loc_val) => {
return arena.alloc(Loc {
region: loc_expr.region,
value: OptionalFieldInRecordBuilder(arena.alloc(loc_name), loc_val),
});
}
AssignedField::SpaceBefore(_, _) | AssignedField::SpaceAfter(_, _) => {
unreachable!("Should have been desugared in `desugar_field`")
}
AssignedField::Malformed(_name) => continue,
};
field_data.push(FieldData {
name,
value,
ignored,
});
}
let closure_arg_from_field =
|FieldData {
name,
value: _,
ignored,
}: &FieldData<'a>| Loc {
region: name.region,
value: if *ignored {
Pattern::Underscore(name.value)
} else {
Pattern::Identifier {
ident: arena.alloc_str(&format!("#{}", name.value)),
}
},
};
let combiner_closure_in_region = |region| {
let closure_body = Tuple(Collection::with_items(
Vec::from_iter_in(
[
&*arena.alloc(Loc::at(
region,
Expr::Var {
module_name: "",
ident: "#record_builder_closure_arg_a",
},
)),
&*arena.alloc(Loc::at(
region,
Expr::Var {
module_name: "",
ident: "#record_builder_closure_arg_b",
},
)),
],
arena,
)
.into_bump_slice(),
));
arena.alloc(Loc::at(
region,
Closure(
arena.alloc_slice_copy(&[
Loc::at(
region,
Pattern::Identifier {
ident: "#record_builder_closure_arg_a",
},
),
Loc::at(
region,
Pattern::Identifier {
ident: "#record_builder_closure_arg_b",
},
),
]),
arena.alloc(Loc::at(region, closure_body)),
),
))
};
let closure_args = {
if field_data.len() == 2 {
arena.alloc_slice_copy(&[
closure_arg_from_field(&field_data[0]),
closure_arg_from_field(&field_data[1]),
])
} else {
let second_to_last_arg =
closure_arg_from_field(&field_data[field_data.len() - 2]);
let last_arg = closure_arg_from_field(&field_data[field_data.len() - 1]);
let mut second_arg = Pattern::Tuple(Collection::with_items(
arena.alloc_slice_copy(&[second_to_last_arg, last_arg]),
));
let mut second_arg_region =
Region::span_across(&second_to_last_arg.region, &last_arg.region);
for index in (1..(field_data.len() - 2)).rev() {
second_arg =
Pattern::Tuple(Collection::with_items(arena.alloc_slice_copy(&[
closure_arg_from_field(&field_data[index]),
Loc::at(second_arg_region, second_arg),
])));
second_arg_region =
Region::span_across(&field_data[index].name.region, &second_arg_region);
}
arena.alloc_slice_copy(&[
closure_arg_from_field(&field_data[0]),
Loc::at(second_arg_region, second_arg),
])
}
};
let record_val = Record(Collection::with_items(
Vec::from_iter_in(
field_data
.iter()
.filter(|field| !field.ignored)
.map(|field| {
Loc::at(
field.name.region,
AssignedField::RequiredValue(
field.name,
&[],
arena.alloc(Loc::at(
field.name.region,
Expr::Var {
module_name: "",
ident: arena
.alloc_str(&format!("#{}", field.name.value)),
},
)),
),
)
}),
arena,
)
.into_bump_slice(),
));
let record_combiner_closure = arena.alloc(Loc {
region: loc_expr.region,
value: Closure(
closure_args,
arena.alloc(Loc::at(loc_expr.region, record_val)),
),
});
if field_data.len() == 2 {
return arena.alloc(Loc {
region: loc_expr.region,
value: Apply(
new_mapper,
arena.alloc_slice_copy(&[
field_data[0].value,
field_data[1].value,
record_combiner_closure,
]),
CalledVia::RecordBuilder,
),
});
}
let mut inner_combined = arena.alloc(Loc {
region: Region::span_across(
&field_data[field_data.len() - 2].value.region,
&field_data[field_data.len() - 1].value.region,
),
value: Apply(
new_mapper,
arena.alloc_slice_copy(&[
field_data[field_data.len() - 2].value,
field_data[field_data.len() - 1].value,
combiner_closure_in_region(loc_expr.region),
]),
CalledVia::RecordBuilder,
),
});
for index in (1..(field_data.len() - 2)).rev() {
inner_combined = arena.alloc(Loc {
region: Region::span_across(
&field_data[index].value.region,
&inner_combined.region,
),
value: Apply(
new_mapper,
arena.alloc_slice_copy(&[
field_data[index].value,
inner_combined,
combiner_closure_in_region(loc_expr.region),
]),
CalledVia::RecordBuilder,
),
});
}
arena.alloc(Loc {
region: loc_expr.region,
value: Apply(
new_mapper,
arena.alloc_slice_copy(&[
field_data[0].value,
inner_combined,
record_combiner_closure,
]),
CalledVia::RecordBuilder,
),
})
}
BinOps(lefts, right) => desugar_bin_ops(
arena,
loc_expr.region,
lefts,
right,
src,
line_info,
module_path,
),
Defs(defs, loc_ret) => {
let mut defs = (*defs).clone();
desugar_defs_node_values(arena, &mut defs, src, line_info, module_path, false);
let loc_ret = desugar_expr(arena, loc_ret, src, line_info, module_path);
arena.alloc(Loc::at(loc_expr.region, Defs(arena.alloc(defs), loc_ret)))
}
Apply(loc_fn, loc_args, called_via) => {
let mut desugared_args = Vec::with_capacity_in(loc_args.len(), arena);
let mut builder_apply_exprs = None;
for loc_arg in loc_args.iter() {
let mut current = loc_arg.value;
let arg = loop {
match current {
OldRecordBuilder(fields) => {
if builder_apply_exprs.is_some() {
return arena.alloc(Loc {
value: MultipleOldRecordBuilders(loc_expr),
region: loc_expr.region,
});
}
let builder_arg = old_record_builder_arg(arena, loc_arg.region, fields);
builder_apply_exprs = Some(builder_arg.apply_exprs);
break builder_arg.closure;
}
SpaceBefore(expr, _) | SpaceAfter(expr, _) => {
current = *expr;
}
_ => break loc_arg,
}
};
desugared_args.push(desugar_expr(arena, arg, src, line_info, module_path));
}
let desugared_args = desugared_args.into_bump_slice();
let mut apply: &Loc<Expr> = arena.alloc(Loc {
value: Apply(
desugar_expr(arena, loc_fn, src, line_info, module_path),
desugared_args,
*called_via,
),
region: loc_expr.region,
});
match builder_apply_exprs {
None => {}
Some(apply_exprs) => {
for expr in apply_exprs {
let desugared_expr = desugar_expr(arena, expr, src, line_info, module_path);
let args = std::slice::from_ref(arena.alloc(apply));
apply = arena.alloc(Loc {
value: Apply(desugared_expr, args, CalledVia::OldRecordBuilder),
region: loc_expr.region,
});
}
}
}
apply
}
When(loc_cond_expr, branches) => {
let loc_desugared_cond = &*arena.alloc(desugar_expr(
arena,
loc_cond_expr,
src,
line_info,
module_path,
));
let mut desugared_branches = Vec::with_capacity_in(branches.len(), arena);
for branch in branches.iter() {
let desugared_expr =
desugar_expr(arena, &branch.value, src, line_info, module_path);
let desugared_patterns =
desugar_loc_patterns(arena, branch.patterns, src, line_info, module_path);
let desugared_guard = if let Some(guard) = &branch.guard {
Some(*desugar_expr(arena, guard, src, line_info, module_path))
} else {
None
};
desugared_branches.push(&*arena.alloc(WhenBranch {
patterns: desugared_patterns,
value: *desugared_expr,
guard: desugared_guard,
}));
}
let desugared_branches = desugared_branches.into_bump_slice();
arena.alloc(Loc {
value: When(loc_desugared_cond, desugared_branches),
region: loc_expr.region,
})
}
UnaryOp(loc_arg, loc_op) => {
use roc_module::called_via::UnaryOp::*;
let region = loc_op.region;
let op = loc_op.value;
// TODO desugar this in canonicalization instead, so we can work
// in terms of integers exclusively and not need to create strings
// which canonicalization then needs to look up, check if they're exposed, etc
let value = match op {
Negate => Var {
module_name: ModuleName::NUM,
ident: "neg",
},
Not => Var {
module_name: ModuleName::BOOL,
ident: "not",
},
};
let loc_fn_var = arena.alloc(Loc { region, value });
let desugared_args =
arena.alloc([desugar_expr(arena, loc_arg, src, line_info, module_path)]);
arena.alloc(Loc {
value: Apply(loc_fn_var, desugared_args, CalledVia::UnaryOp(op)),
region: loc_expr.region,
})
}
SpaceBefore(expr, _) | SpaceAfter(expr, _) => {
// Since we've already begun canonicalization, spaces and parens
// are no longer needed and should be dropped.
desugar_expr(
arena,
arena.alloc(Loc {
value: **expr,
region: loc_expr.region,
}),
src,
line_info,
module_path,
)
}
ParensAround(expr) => {
let desugared = desugar_expr(
arena,
arena.alloc(Loc {
value: **expr,
region: loc_expr.region,
}),
src,
line_info,
module_path,
);
arena.alloc(Loc {
value: ParensAround(&desugared.value),
region: loc_expr.region,
})
}
If(if_thens, final_else_branch) => {
// If does not get desugared into `when` so we can give more targeted error messages during type checking.
let desugared_final_else = &*arena.alloc(desugar_expr(
arena,
final_else_branch,
src,
line_info,
module_path,
));
let mut desugared_if_thens = Vec::with_capacity_in(if_thens.len(), arena);
for (condition, then_branch) in if_thens.iter() {
desugared_if_thens.push((
*desugar_expr(arena, condition, src, line_info, module_path),
*desugar_expr(arena, then_branch, src, line_info, module_path),
));
}
arena.alloc(Loc {
value: If(desugared_if_thens.into_bump_slice(), desugared_final_else),
region: loc_expr.region,
})
}
Expect(condition, continuation) => {
let desugared_condition =
&*arena.alloc(desugar_expr(arena, condition, src, line_info, module_path));
let desugared_continuation = &*arena.alloc(desugar_expr(
arena,
continuation,
src,
line_info,
module_path,
));
arena.alloc(Loc {
value: Expect(desugared_condition, desugared_continuation),
region: loc_expr.region,
})
}
Dbg(condition, continuation) => {
// Desugars a `dbg x` statement into essentially
// Inspect.toStr x |> LowLevelDbg
let desugared_continuation = &*arena.alloc(desugar_expr(
arena,
continuation,
src,
line_info,
module_path,
));
let region = condition.region;
// Inspect.toStr x
let inspect_fn = Var {
module_name: ModuleName::INSPECT,
ident: "toStr",
};
let loc_inspect_fn_var = arena.alloc(Loc {
value: inspect_fn,
region,
});
let desugared_inspect_args =
arena.alloc([desugar_expr(arena, condition, src, line_info, module_path)]);
let dbg_str = arena.alloc(Loc {
value: Apply(loc_inspect_fn_var, desugared_inspect_args, CalledVia::Space),
region,
});
// line_info is an option so that we can lazily calculate it.
// That way it there are no `dbg` statements, we never pay the cast of scanning the source an extra time.
if line_info.is_none() {
*line_info = Some(LineInfo::new(src));
}
let line_col = line_info.as_ref().unwrap().convert_pos(region.start());
let dbg_src = src
.split_at(region.start().offset as usize)
.1
.split_at((region.end().offset - region.start().offset) as usize)
.0;
// |> LowLevelDbg
arena.alloc(Loc {
value: LowLevelDbg(
arena.alloc((
&*arena.alloc_str(&format!("{}:{}", module_path, line_col.line + 1)),
&*arena.alloc_str(dbg_src),
)),
dbg_str,
desugared_continuation,
),
region: loc_expr.region,
})
}
// note this only exists after desugaring
LowLevelDbg(_, _, _) => loc_expr,
}
}
fn desugar_str_segments<'a>(
arena: &'a Bump,
segments: &'a [StrSegment<'a>],
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> &'a [StrSegment<'a>] {
Vec::from_iter_in(
segments.iter().map(|segment| match segment {
StrSegment::Plaintext(_) | StrSegment::Unicode(_) | StrSegment::EscapedChar(_) => {
*segment
}
StrSegment::DeprecatedInterpolated(loc_expr) => {
let loc_desugared = desugar_expr(
arena,
arena.alloc(Loc {
region: loc_expr.region,
value: *loc_expr.value,
}),
src,
line_info,
module_path,
);
StrSegment::DeprecatedInterpolated(Loc {
region: loc_desugared.region,
value: arena.alloc(loc_desugared.value),
})
}
StrSegment::Interpolated(loc_expr) => {
let loc_desugared = desugar_expr(
arena,
arena.alloc(Loc {
region: loc_expr.region,
value: *loc_expr.value,
}),
src,
line_info,
module_path,
);
StrSegment::Interpolated(Loc {
region: loc_desugared.region,
value: arena.alloc(loc_desugared.value),
})
}
}),
arena,
)
.into_bump_slice()
}
fn desugar_field_collection<'a>(
arena: &'a Bump,
fields: Collection<'a, Loc<AssignedField<'a, Expr<'a>>>>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> Collection<'a, Loc<AssignedField<'a, Expr<'a>>>> {
let mut allocated = Vec::with_capacity_in(fields.len(), arena);
for field in fields.iter() {
let value = desugar_field(arena, &field.value, src, line_info, module_path);
allocated.push(Loc::at(field.region, value));
}
fields.replace_items(allocated.into_bump_slice())
}
fn desugar_field<'a>(
arena: &'a Bump,
field: &'a AssignedField<'a, Expr<'a>>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> AssignedField<'a, Expr<'a>> {
use roc_parse::ast::AssignedField::*;
match field {
RequiredValue(loc_str, spaces, loc_expr) => RequiredValue(
Loc {
value: loc_str.value,
region: loc_str.region,
},
spaces,
desugar_expr(arena, loc_expr, src, line_info, module_path),
),
OptionalValue(loc_str, spaces, loc_expr) => OptionalValue(
Loc {
value: loc_str.value,
region: loc_str.region,
},
spaces,
desugar_expr(arena, loc_expr, src, line_info, module_path),
),
IgnoredValue(loc_str, spaces, loc_expr) => IgnoredValue(
Loc {
value: loc_str.value,
region: loc_str.region,
},
spaces,
desugar_expr(arena, loc_expr, src, line_info, module_path),
),
LabelOnly(loc_str) => {
// Desugar { x } into { x: x }
let loc_expr = Loc {
value: Var {
module_name: "",
ident: loc_str.value,
},
region: loc_str.region,
};
RequiredValue(
Loc {
value: loc_str.value,
region: loc_str.region,
},
&[],
desugar_expr(arena, arena.alloc(loc_expr), src, line_info, module_path),
)
}
SpaceBefore(field, _spaces) => desugar_field(arena, field, src, line_info, module_path),
SpaceAfter(field, _spaces) => desugar_field(arena, field, src, line_info, module_path),
Malformed(string) => Malformed(string),
}
}
fn desugar_loc_patterns<'a>(
arena: &'a Bump,
loc_patterns: &'a [Loc<Pattern<'a>>],
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> &'a [Loc<Pattern<'a>>] {
Vec::from_iter_in(
loc_patterns.iter().map(|loc_pattern| Loc {
region: loc_pattern.region,
value: desugar_pattern(arena, loc_pattern.value, src, line_info, module_path),
}),
arena,
)
.into_bump_slice()
}
fn desugar_loc_pattern<'a>(
arena: &'a Bump,
loc_pattern: &'a Loc<Pattern<'a>>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> &'a Loc<Pattern<'a>> {
arena.alloc(Loc {
region: loc_pattern.region,
value: desugar_pattern(arena, loc_pattern.value, src, line_info, module_path),
})
}
fn desugar_pattern<'a>(
arena: &'a Bump,
pattern: Pattern<'a>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> Pattern<'a> {
use roc_parse::ast::Pattern::*;
match pattern {
Identifier { .. }
| Tag(_)
| OpaqueRef(_)
| NumLiteral(_)
| NonBase10Literal { .. }
| FloatLiteral(_)
| StrLiteral(_)
| Underscore(_)
| SingleQuote(_)
| ListRest(_)
| Malformed(_)
| MalformedIdent(_, _)
| QualifiedIdentifier { .. } => pattern,
Apply(tag, arg_patterns) => {
// Skip desugaring the tag, it should either be a Tag or OpaqueRef
let desugared_arg_patterns = Vec::from_iter_in(
arg_patterns.iter().map(|arg_pattern| Loc {
region: arg_pattern.region,
value: desugar_pattern(arena, arg_pattern.value, src, line_info, module_path),
}),
arena,
)
.into_bump_slice();
Apply(tag, desugared_arg_patterns)
}
RecordDestructure(field_patterns) => {
let mut allocated = Vec::with_capacity_in(field_patterns.len(), arena);
for field_pattern in field_patterns.iter() {
let value =
desugar_pattern(arena, field_pattern.value, src, line_info, module_path);
allocated.push(Loc {
value,
region: field_pattern.region,
});
}
let field_patterns = field_patterns.replace_items(allocated.into_bump_slice());
RecordDestructure(field_patterns)
}
RequiredField(name, field_pattern) => RequiredField(
name,
desugar_loc_pattern(arena, field_pattern, src, line_info, module_path),
),
OptionalField(name, expr) => {
OptionalField(name, desugar_expr(arena, expr, src, line_info, module_path))
}
Tuple(patterns) => {
let mut allocated = Vec::with_capacity_in(patterns.len(), arena);
for pattern in patterns.iter() {
let value = desugar_pattern(arena, pattern.value, src, line_info, module_path);
allocated.push(Loc {
value,
region: pattern.region,
});
}
let patterns = patterns.replace_items(allocated.into_bump_slice());
Tuple(patterns)
}
List(patterns) => {
let mut allocated = Vec::with_capacity_in(patterns.len(), arena);
for pattern in patterns.iter() {
let value = desugar_pattern(arena, pattern.value, src, line_info, module_path);
allocated.push(Loc {
value,
region: pattern.region,
});
}
let patterns = patterns.replace_items(allocated.into_bump_slice());
List(patterns)
}
As(sub_pattern, symbol) => As(
desugar_loc_pattern(arena, sub_pattern, src, line_info, module_path),
symbol,
),
SpaceBefore(sub_pattern, _spaces) => {
desugar_pattern(arena, *sub_pattern, src, line_info, module_path)
}
SpaceAfter(sub_pattern, _spaces) => {
desugar_pattern(arena, *sub_pattern, src, line_info, module_path)
}
}
}
struct OldRecordBuilderArg<'a> {
closure: &'a Loc<Expr<'a>>,
apply_exprs: Vec<'a, &'a Loc<Expr<'a>>>,
}
fn old_record_builder_arg<'a>(
arena: &'a Bump,
region: Region,
fields: Collection<'a, Loc<OldRecordBuilderField<'a>>>,
) -> OldRecordBuilderArg<'a> {
let mut record_fields = Vec::with_capacity_in(fields.len(), arena);
let mut apply_exprs = Vec::with_capacity_in(fields.len(), arena);
let mut apply_field_names = Vec::with_capacity_in(fields.len(), arena);
// Build the record that the closure will return and gather apply expressions
for field in fields.iter() {
let mut current = field.value;
let new_field = loop {
match current {
OldRecordBuilderField::Value(label, spaces, expr) => {
break AssignedField::RequiredValue(label, spaces, expr)
}
OldRecordBuilderField::ApplyValue(label, _, _, expr) => {
apply_field_names.push(label);
apply_exprs.push(expr);
let var = arena.alloc(Loc {
region: label.region,
value: Expr::Var {
module_name: "",
ident: arena.alloc("#".to_owned() + label.value),
},
});
break AssignedField::RequiredValue(label, &[], var);
}
OldRecordBuilderField::LabelOnly(label) => break AssignedField::LabelOnly(label),
OldRecordBuilderField::SpaceBefore(sub_field, _) => {
current = *sub_field;
}
OldRecordBuilderField::SpaceAfter(sub_field, _) => {
current = *sub_field;
}
OldRecordBuilderField::Malformed(malformed) => {
break AssignedField::Malformed(malformed)
}
}
};
record_fields.push(Loc {
value: new_field,
region: field.region,
});
}
let record_fields = fields.replace_items(record_fields.into_bump_slice());
let mut body = arena.alloc(Loc {
value: Record(record_fields),
region,
});
// Construct the builder's closure
//
// { x: #x, y: #y, z: 3 }
// \#y -> { x: #x, y: #y, z: 3 }
// \#x -> \#y -> { x: #x, y: #y, z: 3 }
for label in apply_field_names.iter().rev() {
let name = arena.alloc("#".to_owned() + label.value);
let ident = roc_parse::ast::Pattern::Identifier { ident: name };
let arg_pattern = arena.alloc(Loc {
value: ident,
region: label.region,
});
body = arena.alloc(Loc {
value: Closure(std::slice::from_ref(arg_pattern), body),
region,
});
}
OldRecordBuilderArg {
closure: body,
apply_exprs,
}
}
// TODO move this desugaring to canonicalization, so we can use Symbols instead of strings
#[inline(always)]
fn binop_to_function(binop: BinOp) -> (&'static str, &'static str) {
use self::BinOp::*;
match binop {
Caret => (ModuleName::NUM, "pow"),
Star => (ModuleName::NUM, "mul"),
Slash => (ModuleName::NUM, "div"),
DoubleSlash => (ModuleName::NUM, "divTrunc"),
Percent => (ModuleName::NUM, "rem"),
Plus => (ModuleName::NUM, "add"),
Minus => (ModuleName::NUM, "sub"),
Equals => (ModuleName::BOOL, "isEq"),
NotEquals => (ModuleName::BOOL, "isNotEq"),
LessThan => (ModuleName::NUM, "isLt"),
GreaterThan => (ModuleName::NUM, "isGt"),
LessThanOrEq => (ModuleName::NUM, "isLte"),
GreaterThanOrEq => (ModuleName::NUM, "isGte"),
And => (ModuleName::BOOL, "and"),
Or => (ModuleName::BOOL, "or"),
Pizza => unreachable!("Cannot desugar the |> operator"),
}
}
fn desugar_bin_ops<'a>(
arena: &'a Bump,
whole_region: Region,
lefts: &'a [(Loc<Expr<'_>>, Loc<BinOp>)],
right: &'a Loc<Expr<'_>>,
src: &'a str,
line_info: &mut Option<LineInfo>,
module_path: &str,
) -> &'a Loc<Expr<'a>> {
let mut arg_stack: Vec<&'a Loc<Expr>> = Vec::with_capacity_in(lefts.len() + 1, arena);
let mut op_stack: Vec<Loc<BinOp>> = Vec::with_capacity_in(lefts.len(), arena);
for (loc_expr, loc_op) in lefts {
arg_stack.push(desugar_expr(arena, loc_expr, src, line_info, module_path));
match run_binop_step(arena, whole_region, &mut arg_stack, &mut op_stack, *loc_op) {
Err(problem) => return problem,
Ok(()) => continue,
}
}
let mut expr = desugar_expr(arena, right, src, line_info, module_path);
for (left, loc_op) in arg_stack.into_iter().zip(op_stack.into_iter()).rev() {
expr = arena.alloc(new_op_call_expr(arena, left, loc_op, expr));
}
expr
}
enum Step<'a> {
Error(&'a Loc<Expr<'a>>),
Push(Loc<BinOp>),
Skip,
}
fn run_binop_step<'a>(
arena: &'a Bump,
whole_region: Region,
arg_stack: &mut Vec<&'a Loc<Expr<'a>>>,
op_stack: &mut Vec<Loc<BinOp>>,
next_op: Loc<BinOp>,
) -> Result<(), &'a Loc<Expr<'a>>> {
use Step::*;
match binop_step(arena, whole_region, arg_stack, op_stack, next_op) {
Error(problem) => Err(problem),
Push(loc_op) => run_binop_step(arena, whole_region, arg_stack, op_stack, loc_op),
Skip => Ok(()),
}
}
fn binop_step<'a>(
arena: &'a Bump,
whole_region: Region,
arg_stack: &mut Vec<&'a Loc<Expr<'a>>>,
op_stack: &mut Vec<Loc<BinOp>>,
next_op: Loc<BinOp>,
) -> Step<'a> {
use roc_module::called_via::Associativity::*;
use std::cmp::Ordering;
match op_stack.pop() {
Some(stack_op) => {
match next_op.value.cmp(&stack_op.value) {
Ordering::Less => {
// Inline
let right = arg_stack.pop().unwrap();
let left = arg_stack.pop().unwrap();
arg_stack.push(arena.alloc(new_op_call_expr(arena, left, stack_op, right)));
Step::Push(next_op)
}
Ordering::Greater => {
// Swap
op_stack.push(stack_op);
op_stack.push(next_op);
Step::Skip
}
Ordering::Equal => {
match (
next_op.value.associativity(),
stack_op.value.associativity(),
) {
(LeftAssociative, LeftAssociative) => {
// Inline
let right = arg_stack.pop().unwrap();
let left = arg_stack.pop().unwrap();
arg_stack
.push(arena.alloc(new_op_call_expr(arena, left, stack_op, right)));
Step::Push(next_op)
}
(RightAssociative, RightAssociative) => {
// Swap
op_stack.push(stack_op);
op_stack.push(next_op);
Step::Skip
}
(NonAssociative, NonAssociative) => {
// Both operators were non-associative, e.g. (True == False == False).
// We should tell the author to disambiguate by grouping them with parens.
let bad_op = next_op;
let right = arg_stack.pop().unwrap();
let left = arg_stack.pop().unwrap();
let broken_expr =
arena.alloc(new_op_call_expr(arena, left, stack_op, right));
let region = broken_expr.region;
let data = roc_parse::ast::PrecedenceConflict {
whole_region,
binop1_position: stack_op.region.start(),
binop1: stack_op.value,
binop2_position: bad_op.region.start(),
binop2: bad_op.value,
expr: arena.alloc(broken_expr),
};
let value = Expr::PrecedenceConflict(arena.alloc(data));
Step::Error(arena.alloc(Loc { region, value }))
}
_ => {
// The operators had the same precedence but different associativity.
//
// In many languages, this case can happen due to (for example) <| and |> having the same
// precedence but different associativity. Languages which support custom operators with
// (e.g. Haskell) can potentially have arbitrarily many of these cases.
//
// By design, Roc neither allows custom operators nor has any built-in operators with
// the same precedence and different associativity, so this should never happen!
internal_error!("BinOps had the same associativity, but different precedence. This should never happen!");
}
}
}
}
}
None => {
op_stack.push(next_op);
Step::Skip
}
}
}