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refactor: migrate let_else_to_match to editor #19542

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Merged
Veykril merged 1 commit into from
Apr 28, 2025
Merged

refactor: migrate let_else_to_match to editor #19542

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4 changes: 2 additions & 2 deletions crates/ide-assists/src/handlers/add_missing_match_arms.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -493,8 +493,8 @@ fn build_pat(
hir::StructKind::Record => {
let fields = fields
.into_iter()
.map(|f| make.name_ref(f.name(db).as_str()))
.map(|name_ref| make.record_pat_field_shorthand(name_ref));
.map(|f| make.ident_pat(false, false, make.name(f.name(db).as_str())))
.map(|ident| make.record_pat_field_shorthand(ident.into()));
let fields = make.record_pat_field_list(fields, None);
make.record_pat_with_fields(path, fields).into()
}
Expand Down
299 changes: 175 additions & 124 deletions crates/ide-assists/src/handlers/convert_let_else_to_match.rs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
use hir::Semantics;
use ide_db::RootDatabase;
use syntax::T;
use syntax::ast::RangeItem;
use syntax::ast::{AstNode, HasName, LetStmt, Name, Pat, edit::AstNodeEdit};
use syntax::ast::edit::IndentLevel;
use syntax::ast::edit_in_place::Indent;
use syntax::ast::syntax_factory::SyntaxFactory;
use syntax::ast::{self, AstNode, HasName, LetStmt, Pat};

use crate::{AssistContext, AssistId, Assists};

Expand All @@ -25,155 +26,205 @@ use crate::{AssistContext, AssistId, Assists};
// }
// ```
pub(crate) fn convert_let_else_to_match(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
// should focus on else token to trigger
// Should focus on the `else` token to trigger
let let_stmt = ctx
.find_token_syntax_at_offset(T![else])
.and_then(|it| it.parent()?.parent())
.or_else(|| ctx.find_token_syntax_at_offset(T![let])?.parent())?;
let let_stmt = LetStmt::cast(let_stmt)?;
let let_else_block = let_stmt.let_else()?.block_expr()?;
let let_init = let_stmt.initializer()?;
let else_block = let_stmt.let_else()?.block_expr()?;
let else_expr = if else_block.statements().next().is_none() {
else_block.tail_expr()?
} else {
else_block.into()
};
let init = let_stmt.initializer()?;
// Ignore let stmt with type annotation
if let_stmt.ty().is_some() {
// don't support let with type annotation
return None;
}
let pat = let_stmt.pat()?;
let mut binders = Vec::new();
binders_in_pat(&mut binders, &pat, &ctx.sema)?;

let target = let_stmt.syntax().text_range();
let make = SyntaxFactory::with_mappings();
let mut idents = Vec::default();
let pat_without_mut = remove_mut_and_collect_idents(&make, &pat, &mut idents)?;
let bindings = idents
.into_iter()
.filter_map(|ref pat| {
// Identifiers which resolve to constants are not bindings
if ctx.sema.resolve_bind_pat_to_const(pat).is_none() {
Some((pat.name()?, pat.ref_token().is_none() && pat.mut_token().is_some()))
} else {
None
}
})
.collect::<Vec<_>>();

acc.add(
AssistId::refactor_rewrite("convert_let_else_to_match"),
"Convert let-else to let and match",
target,
|edit| {
let indent_level = let_stmt.indent_level().0 as usize;
let indent = " ".repeat(indent_level);
let indent1 = " ".repeat(indent_level + 1);
if bindings.is_empty() {
"Convert let-else to match"
} else {
"Convert let-else to let and match"
},
let_stmt.syntax().text_range(),
|builder| {
let mut editor = builder.make_editor(let_stmt.syntax());

let binders_str = binders_to_str(&binders, false);
let binders_str_mut = binders_to_str(&binders, true);
let binding_paths = bindings
.iter()
.map(|(name, _)| make.expr_path(make.ident_path(&name.to_string())))
.collect::<Vec<_>>();

let init_expr = let_init.syntax().text();
let mut pat_no_mut = pat.syntax().text().to_string();
// remove the mut from the pattern
for (b, ismut) in binders.iter() {
if *ismut {
pat_no_mut = pat_no_mut.replace(&format!("mut {b}"), &b.to_string());
}
}
let binding_arm = make.match_arm(
pat_without_mut,
None,
// There are three possible cases:
//
// - No bindings: `None => {}`
// - Single binding: `Some(it) => it`
// - Multiple bindings: `Foo::Bar { a, b, .. } => (a, b)`
match binding_paths.len() {
0 => make.expr_empty_block().into(),

let only_expr = let_else_block.statements().next().is_none();
let branch2 = match &let_else_block.tail_expr() {
Some(tail) if only_expr => format!("{tail},"),
_ => let_else_block.syntax().text().to_string(),
};
let replace = if binders.is_empty() {
format!(
"match {init_expr} {{
{indent1}{pat_no_mut} => {binders_str}
{indent1}_ => {branch2}
{indent}}}"
)
1 => binding_paths[0].clone(),
_ => make.expr_tuple(binding_paths).into(),
},
);
let else_arm = make.match_arm(make.wildcard_pat().into(), None, else_expr);
let match_ = make.expr_match(init, make.match_arm_list([binding_arm, else_arm]));
match_.reindent_to(IndentLevel::from_node(let_stmt.syntax()));

if bindings.is_empty() {
editor.replace(let_stmt.syntax(), match_.syntax());
} else {
format!(
"let {binders_str_mut} = match {init_expr} {{
{indent1}{pat_no_mut} => {binders_str},
{indent1}_ => {branch2}
{indent}}};"
)
};
edit.replace(target, replace);
let ident_pats = bindings
.into_iter()
.map(|(name, is_mut)| make.ident_pat(false, is_mut, name).into())
.collect::<Vec<Pat>>();
let new_let_stmt = make.let_stmt(
if ident_pats.len() == 1 {
ident_pats[0].clone()
} else {
make.tuple_pat(ident_pats).into()
},
None,
Some(match_.into()),
);
editor.replace(let_stmt.syntax(), new_let_stmt.syntax());
}

editor.add_mappings(make.finish_with_mappings());
builder.add_file_edits(ctx.vfs_file_id(), editor);
},
)
}

/// Gets a list of binders in a pattern, and whether they are mut.
fn binders_in_pat(
acc: &mut Vec<(Name, bool)>,
pat: &Pat,
sem: &Semantics<'_, RootDatabase>,
) -> Option<()> {
use Pat::*;
match pat {
IdentPat(p) => {
let ident = p.name()?;
let ismut = p.ref_token().is_none() && p.mut_token().is_some();
// check for const reference
if sem.resolve_bind_pat_to_const(p).is_none() {
acc.push((ident, ismut));
}
fn remove_mut_and_collect_idents(
make: &SyntaxFactory,
pat: &ast::Pat,
acc: &mut Vec<ast::IdentPat>,
) -> Option<ast::Pat> {
Some(match pat {
ast::Pat::IdentPat(p) => {
acc.push(p.clone());
let non_mut_pat = make.ident_pat(
p.ref_token().is_some(),
p.ref_token().is_some() && p.mut_token().is_some(),
p.name()?,
);
if let Some(inner) = p.pat() {
binders_in_pat(acc, &inner, sem)?;
}
Some(())
}
BoxPat(p) => p.pat().and_then(|p| binders_in_pat(acc, &p, sem)),
RestPat(_) | LiteralPat(_) | PathPat(_) | WildcardPat(_) | ConstBlockPat(_) => Some(()),
OrPat(p) => {
for p in p.pats() {
binders_in_pat(acc, &p, sem)?;
non_mut_pat.set_pat(remove_mut_and_collect_idents(make, &inner, acc));
}
Some(())
non_mut_pat.into()
}
ParenPat(p) => p.pat().and_then(|p| binders_in_pat(acc, &p, sem)),
RangePat(p) => {
if let Some(st) = p.start() {
binders_in_pat(acc, &st, sem)?
}
if let Some(ed) = p.end() {
binders_in_pat(acc, &ed, sem)?
}
Some(())
}
RecordPat(p) => {
for f in p.record_pat_field_list()?.fields() {
let pat = f.pat()?;
binders_in_pat(acc, &pat, sem)?;
}
Some(())
ast::Pat::BoxPat(p) => {
make.box_pat(remove_mut_and_collect_idents(make, &p.pat()?, acc)?).into()
}
RefPat(p) => p.pat().and_then(|p| binders_in_pat(acc, &p, sem)),
SlicePat(p) => {
for p in p.pats() {
binders_in_pat(acc, &p, sem)?;
}
Some(())
}
TuplePat(p) => {
for p in p.fields() {
binders_in_pat(acc, &p, sem)?;
}
Some(())
ast::Pat::OrPat(p) => make
.or_pat(
p.pats()
.map(|pat| remove_mut_and_collect_idents(make, &pat, acc))
.collect::<Option<Vec<_>>>()?,
p.leading_pipe().is_some(),
)
.into(),
ast::Pat::ParenPat(p) => {
make.paren_pat(remove_mut_and_collect_idents(make, &p.pat()?, acc)?).into()
}
TupleStructPat(p) => {
for p in p.fields() {
binders_in_pat(acc, &p, sem)?;
ast::Pat::RangePat(p) => make
.range_pat(
if let Some(start) = p.start() {
Some(remove_mut_and_collect_idents(make, &start, acc)?)
} else {
None
},
if let Some(end) = p.end() {
Some(remove_mut_and_collect_idents(make, &end, acc)?)
} else {
None
},
)
.into(),
ast::Pat::RecordPat(p) => make
.record_pat_with_fields(
p.path()?,
make.record_pat_field_list(
p.record_pat_field_list()?
.fields()
.map(|field| {
remove_mut_and_collect_idents(make, &field.pat()?, acc).map(|pat| {
if let Some(name_ref) = field.name_ref() {
make.record_pat_field(name_ref, pat)
} else {
make.record_pat_field_shorthand(pat)
}
})
})
.collect::<Option<Vec<_>>>()?,
p.record_pat_field_list()?.rest_pat(),
),
)
.into(),
ast::Pat::RefPat(p) => {
let inner = p.pat()?;
if let ast::Pat::IdentPat(ident) = inner {
acc.push(ident);
p.clone_for_update().into()
} else {
make.ref_pat(remove_mut_and_collect_idents(make, &inner, acc)?).into()
}
Some(())
}
ast::Pat::SlicePat(p) => make
.slice_pat(
p.pats()
.map(|pat| remove_mut_and_collect_idents(make, &pat, acc))
.collect::<Option<Vec<_>>>()?,
)
.into(),
ast::Pat::TuplePat(p) => make
.tuple_pat(
p.fields()
.map(|field| remove_mut_and_collect_idents(make, &field, acc))
.collect::<Option<Vec<_>>>()?,
)
.into(),
ast::Pat::TupleStructPat(p) => make
.tuple_struct_pat(
p.path()?,
p.fields()
.map(|field| remove_mut_and_collect_idents(make, &field, acc))
.collect::<Option<Vec<_>>>()?,
)
.into(),
ast::Pat::RestPat(_)
| ast::Pat::LiteralPat(_)
| ast::Pat::PathPat(_)
| ast::Pat::WildcardPat(_)
| ast::Pat::ConstBlockPat(_) => pat.clone(),
// don't support macro pat yet
MacroPat(_) => None,
}
}

fn binders_to_str(binders: &[(Name, bool)], addmut: bool) -> String {
let vars = binders
.iter()
.map(
|(ident, ismut)| {
if *ismut && addmut { format!("mut {ident}") } else { ident.to_string() }
},
)
.collect::<Vec<_>>()
.join(", ");
if binders.is_empty() {
String::from("{}")
} else if binders.len() == 1 {
vars
} else {
format!("({vars})")
}
ast::Pat::MacroPat(_) => return None,
})
}

#[cfg(test)]
Expand Down
4 changes: 3 additions & 1 deletion crates/ide-assists/src/handlers/destructure_struct_binding.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -196,7 +196,9 @@ fn destructure_pat(
let fields = field_names.iter().map(|(old_name, new_name)| {
// Use shorthand syntax if possible
if old_name == new_name && !is_mut {
make.record_pat_field_shorthand(make.name_ref(old_name))
make.record_pat_field_shorthand(
make.ident_pat(false, false, make.name(old_name)).into(),
)
} else {
make.record_pat_field(
make.name_ref(old_name),
Expand Down
7 changes: 6 additions & 1 deletion crates/ide-assists/src/handlers/expand_rest_pattern.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,12 @@ fn expand_record_rest_pattern(
let new_field_list = make.record_pat_field_list(old_field_list.fields(), None);
for (f, _) in missing_fields.iter() {
let field = make.record_pat_field_shorthand(
make.name_ref(&f.name(ctx.sema.db).display_no_db(edition).to_smolstr()),
make.ident_pat(
false,
false,
make.name(&f.name(ctx.sema.db).display_no_db(edition).to_smolstr()),
)
.into(),
);
new_field_list.add_field(field);
}
Expand Down
10 changes: 8 additions & 2 deletions crates/ide-assists/src/handlers/unmerge_match_arm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,8 +53,14 @@ pub(crate) fn unmerge_match_arm(acc: &mut Assists, ctx: &AssistContext<'_>) -> O
|edit| {
let pats_after = pipe_token
.siblings_with_tokens(Direction::Next)
.filter_map(|it| ast::Pat::cast(it.into_node()?));
let new_pat = make::or_pat(pats_after, or_pat.leading_pipe().is_some());
.filter_map(|it| ast::Pat::cast(it.into_node()?))
.collect::<Vec<_>>();
// It is guaranteed that `pats_after` has at least one element
let new_pat = if pats_after.len() == 1 {
pats_after[0].clone()
} else {
make::or_pat(pats_after, or_pat.leading_pipe().is_some()).into()
};
let new_match_arm =
make::match_arm(new_pat, match_arm.guard(), match_arm_body).clone_for_update();

Expand Down
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