roc/crates/compiler/can/src/desugar.rs
2025-01-08 17:04:28 -08:00

1731 lines
62 KiB
Rust

#![allow(clippy::manual_map)]
use crate::env::Env;
use crate::scope::Scope;
use bumpalo::collections::Vec;
use roc_error_macros::internal_error;
use roc_module::called_via::BinOp::{DoubleQuestion, 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, Defs, ModuleImportParams, Pattern, ResultTryKind, StrLiteral,
StrSegment, ValueDef, WhenBranch,
};
use roc_problem::can::Problem;
use roc_region::all::{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!
/// Desugar a single binary operation.
///
/// When using this function, don't desugar `left` and `right` before calling so that
/// we can properly desugar `|> try` expressions!
fn new_op_call_expr<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
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 {
// Rewrite the Pizza operator into an Apply
Pizza => {
// Allow `left |> try (optional)` to desugar to `try left (optional)`
let right_without_spaces = without_spaces(&right.value);
match right_without_spaces {
Try => {
let desugared_left = desugar_expr(env, scope, left);
return Loc::at(
region,
Expr::LowLevelTry(desugared_left, ResultTryKind::KeywordPrefix),
);
}
PncApply(&Loc { value: Try, .. }, arguments) => {
let try_fn = desugar_expr(env, scope, arguments.items.first().unwrap());
let mut args = Vec::with_capacity_in(arguments.len(), env.arena);
args.push(desugar_expr(env, scope, left));
args.extend(
arguments
.iter()
.skip(1)
.map(|a| desugar_expr(env, scope, a)),
);
return Loc::at(
region,
Expr::LowLevelTry(
env.arena.alloc(Loc::at(
region,
Expr::Apply(try_fn, args.into_bump_slice(), CalledVia::Try),
)),
ResultTryKind::KeywordPrefix,
),
);
}
Apply(&Loc { value: Try, .. }, arguments, _called_via) => {
let try_fn = desugar_expr(env, scope, arguments.first().unwrap());
let mut args = Vec::with_capacity_in(arguments.len(), env.arena);
args.push(desugar_expr(env, scope, left));
args.extend(
arguments
.iter()
.skip(1)
.map(|a| desugar_expr(env, scope, a)),
);
return Loc::at(
region,
Expr::LowLevelTry(
env.arena.alloc(Loc::at(
region,
Expr::Apply(try_fn, args.into_bump_slice(), CalledVia::Try),
)),
ResultTryKind::KeywordPrefix,
),
);
}
TrySuffix(fn_expr) => {
let loc_fn = env.arena.alloc(Loc::at(right.region, **fn_expr));
let function = desugar_expr(env, scope, loc_fn);
return Loc::at(
region,
LowLevelTry(
env.arena.alloc(Loc::at(
region,
Expr::Apply(
function,
env.arena.alloc([desugar_expr(env, scope, left)]),
CalledVia::Try,
),
)),
ResultTryKind::OperatorSuffix,
),
);
}
PncApply(
&Loc {
value: TrySuffix(fn_expr),
region: fn_region,
},
loc_args,
) => {
let loc_fn = env.arena.alloc(Loc::at(fn_region, *fn_expr));
let function = desugar_expr(env, scope, loc_fn);
let mut desugared_args = Vec::with_capacity_in(loc_args.len() + 1, env.arena);
desugared_args.push(desugar_expr(env, scope, left));
for loc_arg in loc_args.items {
desugared_args.push(desugar_expr(env, scope, loc_arg));
}
return Loc::at(
region,
LowLevelTry(
env.arena.alloc(Loc::at(
region,
Expr::Apply(
function,
desugared_args.into_bump_slice(),
CalledVia::Try,
),
)),
ResultTryKind::OperatorSuffix,
),
);
}
Apply(
&Loc {
value: TrySuffix(fn_expr),
region: fn_region,
},
loc_args,
_called_via,
) => {
let loc_fn = env.arena.alloc(Loc::at(fn_region, *fn_expr));
let function = desugar_expr(env, scope, loc_fn);
let mut desugared_args = Vec::with_capacity_in(loc_args.len() + 1, env.arena);
desugared_args.push(desugar_expr(env, scope, left));
for loc_arg in &loc_args[..] {
desugared_args.push(desugar_expr(env, scope, loc_arg));
}
return Loc::at(
region,
LowLevelTry(
env.arena.alloc(Loc::at(
region,
Expr::Apply(
function,
desugared_args.into_bump_slice(),
CalledVia::Try,
),
)),
ResultTryKind::OperatorSuffix,
),
);
}
_ => {}
}
let left = desugar_expr(env, scope, left);
let right = desugar_expr(env, scope, right);
match right.value {
Apply(function, arguments, _called_via) => {
let mut args = Vec::with_capacity_in(1 + arguments.len(), env.arena);
args.push(left);
args.extend(arguments.iter());
let args = args.into_bump_slice();
Apply(function, args, CalledVia::BinOp(Pizza))
}
PncApply(function, arguments) => {
let mut args = Vec::with_capacity_in(1 + arguments.len(), env.arena);
args.push(left);
args.extend(arguments.iter());
let args = args.into_bump_slice();
Apply(function, args, CalledVia::BinOp(Pizza))
}
Dbg => *desugar_dbg_expr(env, scope, left, region),
_ => {
// e.g. `1 |> (if b then (\a -> a) else (\c -> c))`
Apply(right, env.arena.alloc([left]), CalledVia::BinOp(Pizza))
}
}
}
DoubleQuestion => {
let left = desugar_expr(env, scope, left);
let right = desugar_expr(env, scope, right);
let mut branches = Vec::with_capacity_in(2, env.arena);
let mut branch_1_patts = Vec::with_capacity_in(1, env.arena);
let mut branch_1_patts_args = Vec::with_capacity_in(1, env.arena);
let success_var = env.arena.alloc_str(
format!(
"success_BRANCH1_{}_{}",
left.region.start().offset,
left.region.end().offset
)
.as_str(),
);
branch_1_patts_args.push(Loc::at(
left.region,
Pattern::Identifier { ident: success_var },
));
let branch_1_tag: &Loc<Pattern<'a>> =
env.arena.alloc(Loc::at(left.region, Pattern::Tag("Ok")));
branch_1_patts.push(Loc::at(
left.region,
Pattern::PncApply(
branch_1_tag,
Collection::with_items(branch_1_patts_args.into_bump_slice()),
),
));
let branch_one: &WhenBranch<'_> = env.arena.alloc(WhenBranch {
patterns: branch_1_patts.into_bump_slice(),
value: Loc::at(
left.region,
Expr::Var {
module_name: "",
ident: success_var,
},
),
guard: None,
});
branches.push(branch_one);
let mut branch_2_patts = Vec::with_capacity_in(1, env.arena);
let mut branch_2_patts_args = Vec::with_capacity_in(1, env.arena);
branch_2_patts_args.push(Loc::at(right.region, Pattern::Underscore("")));
let branch_2_tag: &Loc<Pattern<'a>> =
env.arena.alloc(Loc::at(left.region, Pattern::Tag("Err")));
branch_2_patts.push(Loc::at(
right.region,
Pattern::PncApply(
branch_2_tag,
Collection::with_items(branch_2_patts_args.into_bump_slice()),
),
));
let branch_two: &WhenBranch<'_> = env.arena.alloc(WhenBranch {
patterns: branch_2_patts.into_bump_slice(),
value: *right,
guard: None,
});
branches.push(branch_two);
When(left, branches.into_bump_slice())
}
binop => {
let left = desugar_expr(env, scope, left);
let right = desugar_expr(env, scope, right);
// 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 = env.arena.alloc([left, right]);
let loc_expr = env.arena.alloc(Loc {
value: Expr::Var { module_name, ident },
region: loc_op.region,
});
Apply(loc_expr, args, CalledVia::BinOp(binop))
}
};
Loc { region, value }
}
fn without_spaces<'a>(expr: &'a Expr<'a>) -> &'a Expr<'a> {
match expr {
Expr::SpaceBefore(inner, _) | Expr::SpaceAfter(inner, _) => without_spaces(inner),
_ => expr,
}
}
fn desugar_value_def<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
def: &'a ValueDef<'a>,
) -> ValueDef<'a> {
use ValueDef::*;
match def {
Body(loc_pattern, loc_expr) => Body(
desugar_loc_pattern(env, scope, loc_pattern),
desugar_expr(env, scope, loc_expr),
),
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(env, scope, body_pattern),
body_expr: desugar_expr(env, scope, body_expr),
},
Dbg {
condition,
preceding_comment,
} => {
let desugared_condition = &*env.arena.alloc(desugar_expr(env, scope, condition));
Dbg {
condition: desugared_condition,
preceding_comment: *preceding_comment,
}
}
Expect {
condition,
preceding_comment,
} => {
let desugared_condition = &*env.arena.alloc(desugar_expr(env, scope, condition));
Expect {
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(env, scope, *params)),
});
ModuleImport(roc_parse::ast::ModuleImport {
before_name,
name: *name,
params: desugared_params,
alias: *alias,
exposed: *exposed,
})
}
IngestedFileImport(_) => *def,
StmtAfterExpr => internal_error!(
"StmtAfterExpression is only created during desugaring, so it shouldn't exist here."
),
Stmt(stmt_expr) => Stmt(desugar_expr(env, scope, stmt_expr)),
}
}
pub fn desugar_defs_node_values<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
defs: &mut roc_parse::ast::Defs<'a>,
) {
for value_def in defs.value_defs.iter_mut() {
*value_def = desugar_value_def(env, scope, env.arena.alloc(*value_def));
}
}
/// 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>(
env: &mut Env<'a>,
scope: &mut Scope,
loc_expr: &'a Loc<Expr<'a>>,
) -> &'a Loc<Expr<'a>> {
match &loc_expr.value {
Float(..)
| Num(..)
| NonBase10Int { .. }
| SingleQuote(_)
| Var { .. }
| AccessorFunction(_)
| Underscore { .. }
| MalformedIdent(_, _)
| PrecedenceConflict { .. }
| EmptyRecordBuilder(_)
| SingleFieldRecordBuilder(_)
| OptionalFieldInRecordBuilder { .. }
| Tag(_)
| OpaqueRef(_)
| Crash
| Try => 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(env, scope, segments)));
env.arena.alloc(Loc { region, value })
}
StrLiteral::Block(lines) => {
let region = loc_expr.region;
let mut new_lines = Vec::with_capacity_in(lines.len(), env.arena);
for segments in lines.iter() {
new_lines.push(desugar_str_segments(env, scope, segments));
}
let value = Str(StrLiteral::Block(new_lines.into_bump_slice()));
env.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(env, scope, env.arena.alloc(loc_sub_expr)).value,
paths,
);
env.arena.alloc(Loc { region, value })
}
TrySuffix(sub_expr) => {
let intermediate = env.arena.alloc(Loc::at(loc_expr.region, **sub_expr));
let new_sub_loc_expr = desugar_expr(env, scope, intermediate);
env.arena.alloc(Loc::at(
loc_expr.region,
LowLevelTry(new_sub_loc_expr, ResultTryKind::OperatorSuffix),
))
}
RecordAccess(sub_expr, paths) => {
let region = loc_expr.region;
let loc_sub_expr = Loc {
region,
value: **sub_expr,
};
let value = RecordAccess(
&desugar_expr(env, scope, env.arena.alloc(loc_sub_expr)).value,
paths,
);
env.arena.alloc(Loc { region, value })
}
List(items) => {
let mut new_items = Vec::with_capacity_in(items.len(), env.arena);
for item in items.iter() {
new_items.push(desugar_expr(env, scope, item));
}
let new_items = new_items.into_bump_slice();
let value: Expr<'a> = List(items.replace_items(new_items));
env.arena.alloc(Loc {
region: loc_expr.region,
value,
})
}
Record(fields) => {
let fields = desugar_field_collection(env, scope, *fields);
env.arena.alloc(Loc {
region: loc_expr.region,
value: Record(fields),
})
}
Tuple(fields) => {
let mut allocated = Vec::with_capacity_in(fields.len(), env.arena);
for field in fields.iter() {
let expr = desugar_expr(env, scope, field);
allocated.push(expr);
}
let fields = fields.replace_items(allocated.into_bump_slice());
env.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(env, scope, update);
let mut allocated = Vec::with_capacity_in(fields.len(), env.arena);
for field in fields.iter() {
let value = desugar_field(env, scope, &field.value);
allocated.push(Loc {
value,
region: field.region,
});
}
let new_fields = fields.replace_items(allocated.into_bump_slice());
env.arena.alloc(Loc {
region: loc_expr.region,
value: RecordUpdate {
update: new_update,
fields: new_fields,
},
})
}
RecordUpdater(field_name) => {
let region = loc_expr.region;
let closure_body = RecordUpdate {
update: env.arena.alloc(Loc {
region,
value: Expr::Var {
module_name: "",
ident: "#record_updater_record",
},
}),
fields: Collection::with_items(
Vec::from_iter_in(
[Loc::at(
region,
AssignedField::RequiredValue(
Loc::at(region, field_name),
&[],
&*env.arena.alloc(Loc {
region,
value: Expr::Var {
module_name: "",
ident: "#record_updater_field",
},
}),
),
)],
env.arena,
)
.into_bump_slice(),
),
};
env.arena.alloc(Loc {
region,
value: Closure(
env.arena.alloc_slice_copy(&[
Loc::at(
region,
Pattern::Identifier {
ident: "#record_updater_record",
},
),
Loc::at(
region,
Pattern::Identifier {
ident: "#record_updater_field",
},
),
]),
env.arena.alloc(Loc::at(region, closure_body)),
),
})
}
Closure(loc_patterns, loc_ret) => env.arena.alloc(Loc {
region: loc_expr.region,
value: Closure(
desugar_loc_patterns(env, scope, loc_patterns),
desugar_expr(env, scope, loc_ret),
),
}),
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(env, scope, mapper);
if fields.is_empty() {
return env.arena.alloc(Loc {
value: EmptyRecordBuilder(loc_expr),
region: loc_expr.region,
});
} else if fields.len() == 1 {
return env.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(), env.arena);
for field in fields.items {
let desugared_field = desugar_field(env, scope, &field.value);
let (name, value, ignored) = match desugared_field {
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,
&*env.arena.alloc(Loc {
region: loc_name.region,
value: Expr::Var {
module_name: "",
ident: loc_name.value,
},
}),
false,
),
AssignedField::OptionalValue(loc_name, _, loc_val) => {
return env.arena.alloc(Loc {
region: loc_expr.region,
value: OptionalFieldInRecordBuilder(env.arena.alloc(loc_name), loc_val),
});
}
AssignedField::SpaceBefore(_, _) | AssignedField::SpaceAfter(_, _) => {
unreachable!("Should have been desugared in `desugar_field`")
}
};
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: env.arena.alloc_str(&format!("#{}", name.value)),
}
},
};
let combiner_closure_in_region = |region| {
let closure_body = Tuple(Collection::with_items(
Vec::from_iter_in(
[
&*env.arena.alloc(Loc::at(
region,
Expr::Var {
module_name: "",
ident: "#record_builder_closure_arg_a",
},
)),
&*env.arena.alloc(Loc::at(
region,
Expr::Var {
module_name: "",
ident: "#record_builder_closure_arg_b",
},
)),
],
env.arena,
)
.into_bump_slice(),
));
env.arena.alloc(Loc::at(
region,
Closure(
env.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",
},
),
]),
env.arena.alloc(Loc::at(region, closure_body)),
),
))
};
let closure_args = {
if field_data.len() == 2 {
env.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(
env.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(env.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);
}
env.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,
&[],
env.arena.alloc(Loc::at(
field.name.region,
Expr::Var {
module_name: "",
ident: env
.arena
.alloc_str(&format!("#{}", field.name.value)),
},
)),
),
)
}),
env.arena,
)
.into_bump_slice(),
));
let record_combiner_closure = env.arena.alloc(Loc {
region: loc_expr.region,
value: Closure(
closure_args,
env.arena.alloc(Loc::at(loc_expr.region, record_val)),
),
});
if field_data.len() == 2 {
return env.arena.alloc(Loc {
region: loc_expr.region,
value: Apply(
new_mapper,
env.arena.alloc_slice_copy(&[
field_data[0].value,
field_data[1].value,
record_combiner_closure,
]),
CalledVia::RecordBuilder,
),
});
}
let mut inner_combined = env.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,
env.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 = env.arena.alloc(Loc {
region: Region::span_across(
&field_data[index].value.region,
&inner_combined.region,
),
value: Apply(
new_mapper,
env.arena.alloc_slice_copy(&[
field_data[index].value,
inner_combined,
combiner_closure_in_region(loc_expr.region),
]),
CalledVia::RecordBuilder,
),
});
}
env.arena.alloc(Loc {
region: loc_expr.region,
value: Apply(
new_mapper,
env.arena.alloc_slice_copy(&[
field_data[0].value,
inner_combined,
record_combiner_closure,
]),
CalledVia::RecordBuilder,
),
})
}
BinOps(lefts, right) => desugar_bin_ops(env, scope, loc_expr.region, lefts, right),
Defs(defs, loc_ret) => {
let mut defs = (*defs).clone();
desugar_defs_node_values(env, scope, &mut defs);
let loc_ret = desugar_expr(env, scope, loc_ret);
env.arena.alloc(Loc::at(
loc_expr.region,
Defs(env.arena.alloc(defs), loc_ret),
))
}
Apply(Loc { value: Dbg, .. }, loc_args, _called_via) => {
debug_assert!(!loc_args.is_empty());
if loc_args.len() > 1 {
let args_region = Region::span_across(
&loc_args.first().unwrap().region,
&loc_args.last().unwrap().region,
);
env.problem(Problem::OverAppliedDbg {
region: args_region,
});
env.arena.alloc(Loc {
value: *desugar_invalid_dbg_expr(env, scope, loc_expr.region),
region: loc_expr.region,
})
} else {
let desugared_arg = desugar_expr(env, scope, loc_args.first().unwrap());
env.arena.alloc(Loc {
value: *desugar_dbg_expr(env, scope, desugared_arg, loc_expr.region),
region: loc_expr.region,
})
}
}
Apply(
Loc {
value: Try,
region: _,
},
loc_args,
_called_via,
) => {
let result_expr = if loc_args.len() == 1 {
desugar_expr(env, scope, loc_args[0])
} else {
let function = desugar_expr(env, scope, loc_args.first().unwrap());
let mut desugared_args = Vec::with_capacity_in(loc_args.len() - 1, env.arena);
for loc_arg in &loc_args[1..] {
desugared_args.push(desugar_expr(env, scope, loc_arg));
}
let args_region =
Region::span_across(&loc_args[0].region, &loc_args[loc_args.len() - 1].region);
env.arena.alloc(Loc::at(
args_region,
Expr::Apply(function, desugared_args.into_bump_slice(), CalledVia::Try),
))
};
env.arena.alloc(Loc::at(
loc_expr.region,
Expr::LowLevelTry(result_expr, ResultTryKind::KeywordPrefix),
))
}
Apply(
Loc {
value: TrySuffix(fn_expr),
region: fn_region,
},
loc_args,
_called_via,
) => {
let loc_fn = env.arena.alloc(Loc::at(*fn_region, **fn_expr));
let function = desugar_expr(env, scope, loc_fn);
let mut desugared_args = Vec::with_capacity_in(loc_args.len(), env.arena);
for loc_arg in &loc_args[..] {
desugared_args.push(desugar_expr(env, scope, loc_arg));
}
let args_region =
Region::span_across(&loc_args[0].region, &loc_args[loc_args.len() - 1].region);
let result_expr = env.arena.alloc(Loc::at(
args_region,
Expr::Apply(function, desugared_args.into_bump_slice(), CalledVia::Try),
));
env.arena.alloc(Loc::at(
loc_expr.region,
Expr::LowLevelTry(result_expr, ResultTryKind::OperatorSuffix),
))
}
Apply(loc_fn, loc_args, called_via) => {
let mut desugared_args = Vec::with_capacity_in(loc_args.len(), env.arena);
for loc_arg in loc_args.iter() {
let mut current = loc_arg.value;
let arg = loop {
match current {
SpaceBefore(expr, _) | SpaceAfter(expr, _) => {
current = *expr;
}
_ => break loc_arg,
}
};
desugared_args.push(desugar_expr(env, scope, arg));
}
let desugared_args = desugared_args.into_bump_slice();
env.arena.alloc(Loc {
value: Apply(
desugar_expr(env, scope, loc_fn),
desugared_args,
*called_via,
),
region: loc_expr.region,
})
}
PncApply(Loc { value: Dbg, .. }, loc_args) => {
if loc_args.is_empty() {
env.problem(Problem::UnappliedDbg {
region: loc_expr.region,
});
env.arena.alloc(Loc {
value: *desugar_invalid_dbg_expr(env, scope, loc_expr.region),
region: loc_expr.region,
})
} else if loc_args.len() > 1 {
let args_region = Region::span_across(
&loc_args.items.first().unwrap().region,
&loc_args.items.last().unwrap().region,
);
env.problem(Problem::OverAppliedDbg {
region: args_region,
});
env.arena.alloc(Loc {
value: *desugar_invalid_dbg_expr(env, scope, loc_expr.region),
region: loc_expr.region,
})
} else {
let desugared_arg = desugar_expr(env, scope, loc_args.items.first().unwrap());
env.arena.alloc(Loc {
value: *desugar_dbg_expr(env, scope, desugared_arg, loc_expr.region),
region: loc_expr.region,
})
}
}
PncApply(
Loc {
value: Try,
region: _,
},
loc_args,
) => {
let result_expr = if loc_args.len() == 1 {
desugar_expr(env, scope, loc_args.items[0])
} else {
let function = desugar_expr(env, scope, loc_args.items.first().unwrap());
let mut desugared_args = Vec::with_capacity_in(loc_args.len() - 1, env.arena);
for loc_arg in &loc_args.items[1..] {
desugared_args.push(desugar_expr(env, scope, loc_arg));
}
let args_region = Region::span_across(
&loc_args.items[0].region,
&loc_args.items[loc_args.items.len() - 1].region,
);
env.arena.alloc(Loc::at(
args_region,
Expr::Apply(function, desugared_args.into_bump_slice(), CalledVia::Try),
))
};
env.arena.alloc(Loc::at(
loc_expr.region,
Expr::LowLevelTry(result_expr, ResultTryKind::KeywordPrefix),
))
}
PncApply(loc_fn, loc_args) => {
let mut desugared_args = Vec::with_capacity_in(loc_args.len(), env.arena);
for loc_arg in loc_args.iter() {
let mut current = loc_arg.value;
let arg = loop {
match current {
SpaceBefore(expr, _) | SpaceAfter(expr, _) => {
current = *expr;
}
_ => break loc_arg,
}
};
desugared_args.push(desugar_expr(env, scope, arg));
}
let desugared_args = Collection::with_items(desugared_args.into_bump_slice());
env.arena.alloc(Loc {
value: PncApply(desugar_expr(env, scope, loc_fn), desugared_args),
region: loc_expr.region,
})
}
When(loc_cond_expr, branches) => {
let loc_desugared_cond = &*env.arena.alloc(desugar_expr(env, scope, loc_cond_expr));
let mut desugared_branches = Vec::with_capacity_in(branches.len(), env.arena);
for branch in branches.iter() {
let desugared_expr = desugar_expr(env, scope, &branch.value);
let desugared_patterns = desugar_loc_patterns(env, scope, branch.patterns);
let desugared_guard = if let Some(guard) = &branch.guard {
Some(*desugar_expr(env, scope, guard))
} else {
None
};
desugared_branches.push(&*env.arena.alloc(WhenBranch {
patterns: desugared_patterns,
value: *desugared_expr,
guard: desugared_guard,
}));
}
let desugared_branches = desugared_branches.into_bump_slice();
env.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 = env.arena.alloc(Loc { region, value });
let desugared_args = env.arena.alloc([desugar_expr(env, scope, loc_arg)]);
env.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(
env,
scope,
env.arena.alloc(Loc {
value: **expr,
region: loc_expr.region,
}),
)
}
ParensAround(expr) => {
let desugared = desugar_expr(
env,
scope,
env.arena.alloc(Loc {
value: **expr,
region: loc_expr.region,
}),
);
env.arena.alloc(Loc {
value: ParensAround(&desugared.value),
region: loc_expr.region,
})
}
If {
if_thens,
final_else,
indented_else,
} => {
// If does not get desugared into `when` so we can give more targeted error messages during type checking.
let desugared_final_else = &*env.arena.alloc(desugar_expr(env, scope, final_else));
let mut desugared_if_thens = Vec::with_capacity_in(if_thens.len(), env.arena);
for (condition, then_branch) in if_thens.iter() {
let desugared_condition = *desugar_expr(env, scope, condition);
let desugared_then_branch = *desugar_expr(env, scope, then_branch);
desugared_if_thens.push((desugared_condition, desugared_then_branch));
}
env.arena.alloc(Loc {
value: If {
if_thens: desugared_if_thens.into_bump_slice(),
final_else: desugared_final_else,
indented_else: *indented_else,
},
region: loc_expr.region,
})
}
Dbg => {
// Allow naked dbg, necessary for piping values into dbg with the `Pizza` binop
loc_expr
}
DbgStmt {
first: condition,
extra_args,
continuation,
} => {
let desugared_condition = &*env.arena.alloc(desugar_expr(env, scope, condition));
let desugared_continuation = &*env.arena.alloc(desugar_expr(env, scope, continuation));
if let Some(last) = extra_args.last() {
let args_region = Region::span_across(&condition.region, &last.region);
env.problem(Problem::OverAppliedDbg {
region: args_region,
});
}
env.arena.alloc(Loc {
value: *desugar_dbg_stmt(env, desugared_condition, desugared_continuation),
region: loc_expr.region,
})
}
Return(return_value, after_return) => {
let desugared_return_value = &*env.arena.alloc(desugar_expr(env, scope, return_value));
env.arena.alloc(Loc {
// Do not desugar after_return since it isn't run anyway
value: Return(desugared_return_value, *after_return),
region: loc_expr.region,
})
}
// note these only exist after desugaring
LowLevelDbg(_, _, _) | LowLevelTry(_, _) => loc_expr,
}
}
fn desugar_str_segments<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
segments: &'a [StrSegment<'a>],
) -> &'a [StrSegment<'a>] {
let mut allocated = Vec::with_capacity_in(segments.len(), env.arena);
for segment in segments.iter() {
allocated.push(match segment {
StrSegment::Plaintext(_) | StrSegment::Unicode(_) | StrSegment::EscapedChar(_) => {
*segment
}
StrSegment::Interpolated(loc_expr) => {
let loc_desugared = desugar_expr(
env,
scope,
env.arena.alloc(Loc {
region: loc_expr.region,
value: *loc_expr.value,
}),
);
StrSegment::Interpolated(Loc {
region: loc_desugared.region,
value: env.arena.alloc(loc_desugared.value),
})
}
});
}
allocated.into_bump_slice()
}
fn desugar_field_collection<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
fields: Collection<'a, Loc<AssignedField<'a, Expr<'a>>>>,
) -> Collection<'a, Loc<AssignedField<'a, Expr<'a>>>> {
let mut allocated = Vec::with_capacity_in(fields.len(), env.arena);
for field in fields.iter() {
let value = desugar_field(env, scope, &field.value);
allocated.push(Loc::at(field.region, value));
}
fields.replace_items(allocated.into_bump_slice())
}
fn desugar_field<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
field: &'a AssignedField<'a, Expr<'a>>,
) -> 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(env, scope, loc_expr),
),
OptionalValue(loc_str, spaces, loc_expr) => OptionalValue(
Loc {
value: loc_str.value,
region: loc_str.region,
},
spaces,
desugar_expr(env, scope, loc_expr),
),
IgnoredValue(loc_str, spaces, loc_expr) => IgnoredValue(
Loc {
value: loc_str.value,
region: loc_str.region,
},
spaces,
desugar_expr(env, scope, loc_expr),
),
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(env, scope, env.arena.alloc(loc_expr)),
)
}
SpaceBefore(field, _spaces) => desugar_field(env, scope, field),
SpaceAfter(field, _spaces) => desugar_field(env, scope, field),
}
}
fn desugar_loc_patterns<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
loc_patterns: &'a [Loc<Pattern<'a>>],
) -> &'a [Loc<Pattern<'a>>] {
let mut allocated = Vec::with_capacity_in(loc_patterns.len(), env.arena);
for loc_pattern in loc_patterns.iter() {
allocated.push(Loc {
region: loc_pattern.region,
value: desugar_pattern(env, scope, loc_pattern.value),
});
}
allocated.into_bump_slice()
}
fn desugar_loc_pattern<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
loc_pattern: &'a Loc<Pattern<'a>>,
) -> &'a Loc<Pattern<'a>> {
env.arena.alloc(Loc {
region: loc_pattern.region,
value: desugar_pattern(env, scope, loc_pattern.value),
})
}
fn desugar_pattern<'a>(env: &mut Env<'a>, scope: &mut Scope, pattern: Pattern<'a>) -> 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 mut desugared_arg_patterns = Vec::with_capacity_in(arg_patterns.len(), env.arena);
for arg_pattern in arg_patterns.iter() {
desugared_arg_patterns.push(Loc {
region: arg_pattern.region,
value: desugar_pattern(env, scope, arg_pattern.value),
});
}
Apply(tag, desugared_arg_patterns.into_bump_slice())
}
PncApply(tag, arg_patterns) => {
// Skip desugaring the tag, it should either be a Tag or OpaqueRef
let mut desugared_arg_patterns = Vec::with_capacity_in(arg_patterns.len(), env.arena);
for arg_pattern in arg_patterns.iter() {
desugared_arg_patterns.push(Loc {
region: arg_pattern.region,
value: desugar_pattern(env, scope, arg_pattern.value),
});
}
PncApply(
tag,
Collection::with_items(desugared_arg_patterns.into_bump_slice()),
)
}
RecordDestructure(field_patterns) => {
RecordDestructure(desugar_record_destructures(env, scope, field_patterns))
}
RequiredField(name, field_pattern) => {
RequiredField(name, desugar_loc_pattern(env, scope, field_pattern))
}
OptionalField(name, expr) => OptionalField(name, desugar_expr(env, scope, expr)),
Tuple(patterns) => {
let mut allocated = Vec::with_capacity_in(patterns.len(), env.arena);
for pattern in patterns.iter() {
let value = desugar_pattern(env, scope, pattern.value);
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(), env.arena);
for pattern in patterns.iter() {
let value = desugar_pattern(env, scope, pattern.value);
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(env, scope, sub_pattern), symbol),
SpaceBefore(sub_pattern, _spaces) => desugar_pattern(env, scope, *sub_pattern),
SpaceAfter(sub_pattern, _spaces) => desugar_pattern(env, scope, *sub_pattern),
}
}
pub fn desugar_record_destructures<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
field_patterns: Collection<'a, Loc<Pattern<'a>>>,
) -> Collection<'a, Loc<Pattern<'a>>> {
let mut allocated = Vec::with_capacity_in(field_patterns.len(), env.arena);
for field_pattern in field_patterns.iter() {
let value = desugar_pattern(env, scope, field_pattern.value);
allocated.push(Loc {
value,
region: field_pattern.region,
});
}
field_patterns.replace_items(allocated.into_bump_slice())
}
/// Desugars a `dbg expr` expression into a statement block that prints and returns the
/// value produced by `expr`. Essentially:
/// (
/// tmpVar = expr
/// LowLevelDbg (Inspect.to_str tmpVar)
/// tmpVar
/// )
fn desugar_dbg_expr<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
expr: &'a Loc<Expr<'a>>,
outer_region: Region,
) -> &'a Expr<'a> {
let region = expr.region;
// tmpVar = expr
let ident = env.arena.alloc(scope.gen_unique_symbol_name().to_string());
let value_def = ValueDef::Body(
env.arena.alloc(Loc {
value: Pattern::Identifier { ident },
region,
}),
expr,
);
let defs = env.arena.alloc(Defs::default());
defs.push_value_def(value_def, region, &[], &[]);
// tmpVar
let tmp_var = env.arena.alloc(Loc {
value: Var {
module_name: "",
ident,
},
region,
});
// LowLevelDbg
let dbg_stmt = env.arena.alloc(Loc {
value: *desugar_dbg_stmt(env, tmp_var, tmp_var),
region: outer_region,
});
env.arena.alloc(Defs(defs, dbg_stmt))
}
/// Build a desugared `dbg {}` expression to act as a placeholder when the AST
/// is invalid.
pub fn desugar_invalid_dbg_expr<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
outer_region: Region,
) -> &'a Expr<'a> {
let placeholder_expr = env.arena.alloc(Loc {
value: Record(Collection::empty()),
region: outer_region,
});
desugar_dbg_expr(env, scope, placeholder_expr, outer_region)
}
/// Desugars a `dbg x` statement into essentially `Inspect.to_str x |> LowLevelDbg`
fn desugar_dbg_stmt<'a>(
env: &mut Env<'a>,
condition: &'a Loc<Expr<'a>>,
continuation: &'a Loc<Expr<'a>>,
) -> &'a Expr<'a> {
let region = condition.region;
let inspect_fn = Var {
module_name: ModuleName::INSPECT,
ident: "to_str",
};
let loc_inspect_fn_var = env.arena.alloc(Loc {
value: inspect_fn,
region,
});
let inspect_args = &*env.arena.alloc([condition]);
let dbg_str = env.arena.alloc(Loc {
value: Apply(loc_inspect_fn_var, inspect_args, CalledVia::Space),
region,
});
let line_col = env.line_info().convert_pos(region.start());
let dbg_src = env
.src
.split_at(region.start().offset as usize)
.1
.split_at((region.end().offset - region.start().offset) as usize)
.0;
let module_path_str = env.module_path.to_string_lossy();
// |> LowLevelDbg
env.arena.alloc(LowLevelDbg(
env.arena.alloc((
&*env
.arena
.alloc_str(&format!("{}:{}", module_path_str, line_col.line + 1)),
&*env.arena.alloc_str(dbg_src),
)),
dbg_str,
continuation,
))
}
// 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, "div_trunc"),
Percent => (ModuleName::NUM, "rem"),
Plus => (ModuleName::NUM, "add"),
Minus => (ModuleName::NUM, "sub"),
Equals => (ModuleName::BOOL, "is_eq"),
NotEquals => (ModuleName::BOOL, "is_not_eq"),
LessThan => (ModuleName::NUM, "is_lt"),
GreaterThan => (ModuleName::NUM, "is_gt"),
LessThanOrEq => (ModuleName::NUM, "is_lte"),
GreaterThanOrEq => (ModuleName::NUM, "is_gte"),
And => (ModuleName::BOOL, "and"),
Or => (ModuleName::BOOL, "or"),
Pizza => unreachable!("Cannot desugar the |> operator"),
DoubleQuestion => unreachable!("Cannot desugar the ?? operator"),
}
}
fn desugar_bin_ops<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
whole_region: Region,
lefts: &'a [(Loc<Expr<'_>>, Loc<BinOp>)],
right: &'a Loc<Expr<'_>>,
) -> &'a Loc<Expr<'a>> {
let mut arg_stack: Vec<&'a Loc<Expr>> = Vec::with_capacity_in(lefts.len() + 1, env.arena);
let mut op_stack: Vec<Loc<BinOp>> = Vec::with_capacity_in(lefts.len(), env.arena);
for (loc_expr, loc_op) in lefts {
arg_stack.push(loc_expr);
match run_binop_step(
env,
scope,
whole_region,
&mut arg_stack,
&mut op_stack,
*loc_op,
) {
Err(problem) => return problem,
Ok(()) => continue,
}
}
let mut expr = right;
for (left, loc_op) in arg_stack.into_iter().zip(op_stack.into_iter()).rev() {
expr = env
.arena
.alloc(new_op_call_expr(env, scope, left, loc_op, expr));
}
expr
}
enum Step<'a> {
Error(&'a Loc<Expr<'a>>),
Push(Loc<BinOp>),
Skip,
}
fn run_binop_step<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
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(env, scope, whole_region, arg_stack, op_stack, next_op) {
Error(problem) => Err(problem),
Push(loc_op) => run_binop_step(env, scope, whole_region, arg_stack, op_stack, loc_op),
Skip => Ok(()),
}
}
fn binop_step<'a>(
env: &mut Env<'a>,
scope: &mut Scope,
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(
env.arena
.alloc(new_op_call_expr(env, scope, 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(
env.arena
.alloc(new_op_call_expr(env, scope, 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 = env
.arena
.alloc(new_op_call_expr(env, scope, 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: env.arena.alloc(broken_expr),
};
let value = Expr::PrecedenceConflict(env.arena.alloc(data));
Step::Error(env.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
}
}
}