use std::iter::{self, successors};
use either::Either;
use ide_db::{
defs::NameClass,
syntax_helpers::node_ext::{is_pattern_cond, single_let},
ty_filter::TryEnum,
RootDatabase,
};
use syntax::{
ast::{
self,
edit::{AstNodeEdit, IndentLevel},
make, HasName,
},
AstNode, TextRange, T,
};
use crate::{
utils::{does_nested_pattern, does_pat_match_variant, unwrap_trivial_block},
AssistContext, AssistId, AssistKind, Assists,
};
pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
let available_range = TextRange::new(
if_expr.syntax().text_range().start(),
if_expr.then_branch()?.syntax().text_range().start(),
);
let cursor_in_range = available_range.contains_range(ctx.selection_trimmed());
if !cursor_in_range {
return None;
}
let mut else_block = None;
let if_exprs = successors(Some(if_expr.clone()), |expr| match expr.else_branch()? {
ast::ElseBranch::IfExpr(expr) => Some(expr),
ast::ElseBranch::Block(block) => {
else_block = Some(block);
None
}
});
let scrutinee_to_be_expr = if_expr.condition()?;
let scrutinee_to_be_expr = match single_let(scrutinee_to_be_expr.clone()) {
Some(cond) => cond.expr()?,
None => scrutinee_to_be_expr,
};
let mut pat_seen = false;
let mut cond_bodies = Vec::new();
for if_expr in if_exprs {
let cond = if_expr.condition()?;
let cond = match single_let(cond.clone()) {
Some(let_) => {
let pat = let_.pat()?;
let expr = let_.expr()?;
if scrutinee_to_be_expr.syntax().text() != expr.syntax().text() {
return None;
}
pat_seen = true;
Either::Left(pat)
}
None if is_pattern_cond(cond.clone()) => return None,
None => Either::Right(cond),
};
let body = if_expr.then_branch()?;
cond_bodies.push((cond, body));
}
if !pat_seen && cond_bodies.len() != 1 {
return None;
}
let let_ = if pat_seen { " let" } else { "" };
acc.add(
AssistId("replace_if_let_with_match", AssistKind::RefactorRewrite),
format!("Replace if{let_} with match"),
available_range,
move |edit| {
let match_expr = {
let else_arm = make_else_arm(ctx, else_block, &cond_bodies);
let make_match_arm = |(pat, body): (_, ast::BlockExpr)| {
let body = body.reset_indent().indent(IndentLevel(1));
match pat {
Either::Left(pat) => {
make::match_arm(iter::once(pat), None, unwrap_trivial_block(body))
}
Either::Right(_) if !pat_seen => make::match_arm(
iter::once(make::literal_pat("true").into()),
None,
unwrap_trivial_block(body),
),
Either::Right(expr) => make::match_arm(
iter::once(make::wildcard_pat().into()),
Some(expr),
unwrap_trivial_block(body),
),
}
};
let arms = cond_bodies.into_iter().map(make_match_arm).chain(iter::once(else_arm));
let match_expr = make::expr_match(scrutinee_to_be_expr, make::match_arm_list(arms));
match_expr.indent(IndentLevel::from_node(if_expr.syntax()))
};
let has_preceding_if_expr =
if_expr.syntax().parent().map_or(false, |it| ast::IfExpr::can_cast(it.kind()));
let expr = if has_preceding_if_expr {
make::block_expr(None, Some(match_expr)).into()
} else {
match_expr
};
edit.replace_ast::<ast::Expr>(if_expr.into(), expr);
},
)
}
fn make_else_arm(
ctx: &AssistContext<'_>,
else_block: Option<ast::BlockExpr>,
conditionals: &[(Either<ast::Pat, ast::Expr>, ast::BlockExpr)],
) -> ast::MatchArm {
let (pattern, expr) = if let Some(else_block) = else_block {
let pattern = match conditionals {
[(Either::Right(_), _)] => make::literal_pat("false").into(),
[(Either::Left(pat), _)] => match ctx
.sema
.type_of_pat(pat)
.and_then(|ty| TryEnum::from_ty(&ctx.sema, &ty.adjusted()))
{
Some(it) => {
if does_pat_match_variant(pat, &it.sad_pattern()) {
it.happy_pattern_wildcard()
} else if does_nested_pattern(pat) {
make::wildcard_pat().into()
} else {
it.sad_pattern()
}
}
None => make::wildcard_pat().into(),
},
_ => make::wildcard_pat().into(),
};
(pattern, unwrap_trivial_block(else_block))
} else {
let pattern = match conditionals {
[(Either::Right(_), _)] => make::literal_pat("false").into(),
_ => make::wildcard_pat().into(),
};
(pattern, make::expr_unit())
};
make::match_arm(iter::once(pattern), None, expr)
}
pub(crate) fn replace_match_with_if_let(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
let match_expr: ast::MatchExpr = ctx.find_node_at_offset()?;
let match_arm_list = match_expr.match_arm_list()?;
let available_range = TextRange::new(
match_expr.syntax().text_range().start(),
match_arm_list.syntax().text_range().start(),
);
let cursor_in_range = available_range.contains_range(ctx.selection_trimmed());
if !cursor_in_range {
return None;
}
let mut arms = match_arm_list.arms();
let (first_arm, second_arm) = (arms.next()?, arms.next()?);
if arms.next().is_some() || first_arm.guard().is_some() || second_arm.guard().is_some() {
return None;
}
let (if_let_pat, then_expr, else_expr) = pick_pattern_and_expr_order(
&ctx.sema,
first_arm.pat()?,
second_arm.pat()?,
first_arm.expr()?,
second_arm.expr()?,
)?;
let scrutinee = match_expr.expr()?;
let let_ = match &if_let_pat {
ast::Pat::LiteralPat(p)
if p.literal()
.map(|it| it.token().kind())
.map_or(false, |it| it == T![true] || it == T![false]) =>
{
""
}
_ => " let",
};
let target = match_expr.syntax().text_range();
acc.add(
AssistId("replace_match_with_if_let", AssistKind::RefactorRewrite),
format!("Replace match with if{let_}"),
target,
move |edit| {
fn make_block_expr(expr: ast::Expr) -> ast::BlockExpr {
match expr {
ast::Expr::BlockExpr(block) if block.modifier().is_none() => block,
expr => make::block_expr(iter::empty(), Some(expr)),
}
}
let condition = match if_let_pat {
ast::Pat::LiteralPat(p)
if p.literal().map_or(false, |it| it.token().kind() == T![true]) =>
{
scrutinee
}
ast::Pat::LiteralPat(p)
if p.literal().map_or(false, |it| it.token().kind() == T![false]) =>
{
make::expr_prefix(T![!], scrutinee)
}
_ => make::expr_let(if_let_pat, scrutinee).into(),
};
let then_block = make_block_expr(then_expr.reset_indent());
let else_expr = if is_empty_expr(&else_expr) { None } else { Some(else_expr) };
let if_let_expr = make::expr_if(
condition,
then_block,
else_expr.map(make_block_expr).map(ast::ElseBranch::Block),
)
.indent(IndentLevel::from_node(match_expr.syntax()));
edit.replace_ast::<ast::Expr>(match_expr.into(), if_let_expr);
},
)
}
fn pick_pattern_and_expr_order(
sema: &hir::Semantics<'_, RootDatabase>,
pat: ast::Pat,
pat2: ast::Pat,
expr: ast::Expr,
expr2: ast::Expr,
) -> Option<(ast::Pat, ast::Expr, ast::Expr)> {
let res = match (pat, pat2) {
(ast::Pat::WildcardPat(_), _) => return None,
(pat, ast::Pat::WildcardPat(_)) => (pat, expr, expr2),
(pat, _) if is_empty_expr(&expr2) => (pat, expr, expr2),
(_, pat) if is_empty_expr(&expr) => (pat, expr2, expr),
(pat, pat2) => match (binds_name(sema, &pat), binds_name(sema, &pat2)) {
(true, true) => return None,
(true, false) => (pat, expr, expr2),
(false, true) => (pat2, expr2, expr),
_ if is_sad_pat(sema, &pat) => (pat2, expr2, expr),
(false, false) => (pat, expr, expr2),
},
};
Some(res)
}
fn is_empty_expr(expr: &ast::Expr) -> bool {
match expr {
ast::Expr::BlockExpr(expr) => match expr.stmt_list() {
Some(it) => it.statements().next().is_none() && it.tail_expr().is_none(),
None => true,
},
ast::Expr::TupleExpr(expr) => expr.fields().next().is_none(),
_ => false,
}
}
fn binds_name(sema: &hir::Semantics<'_, RootDatabase>, pat: &ast::Pat) -> bool {
let binds_name_v = |pat| binds_name(sema, &pat);
match pat {
ast::Pat::IdentPat(pat) => !matches!(
pat.name().and_then(|name| NameClass::classify(sema, &name)),
Some(NameClass::ConstReference(_))
),
ast::Pat::MacroPat(_) => true,
ast::Pat::OrPat(pat) => pat.pats().any(binds_name_v),
ast::Pat::SlicePat(pat) => pat.pats().any(binds_name_v),
ast::Pat::TuplePat(it) => it.fields().any(binds_name_v),
ast::Pat::TupleStructPat(it) => it.fields().any(binds_name_v),
ast::Pat::RecordPat(it) => it
.record_pat_field_list()
.map_or(false, |rpfl| rpfl.fields().flat_map(|rpf| rpf.pat()).any(binds_name_v)),
ast::Pat::RefPat(pat) => pat.pat().map_or(false, binds_name_v),
ast::Pat::BoxPat(pat) => pat.pat().map_or(false, binds_name_v),
ast::Pat::ParenPat(pat) => pat.pat().map_or(false, binds_name_v),
_ => false,
}
}
fn is_sad_pat(sema: &hir::Semantics<'_, RootDatabase>, pat: &ast::Pat) -> bool {
sema.type_of_pat(pat)
.and_then(|ty| TryEnum::from_ty(sema, &ty.adjusted()))
.map_or(false, |it| does_pat_match_variant(pat, &it.sad_pattern()))
}
#[cfg(test)]
mod tests {
use super::*;
use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
#[test]
fn test_if_let_with_match_inapplicable_for_simple_ifs() {
check_assist_not_applicable(
replace_if_let_with_match,
r#"
fn main() {
if $0true {} else if false {} else {}
}
"#,
)
}
#[test]
fn test_if_with_match_no_else() {
check_assist(
replace_if_let_with_match,
r#"
pub fn foo(foo: bool) {
if foo$0 {
self.foo();
}
}
"#,
r#"
pub fn foo(foo: bool) {
match foo {
true => {
self.foo();
}
false => (),
}
}
"#,
)
}
#[test]
fn test_if_with_match_with_else() {
check_assist(
replace_if_let_with_match,
r#"
pub fn foo(foo: bool) {
if foo$0 {
self.foo();
} else {
self.bar();
}
}
"#,
r#"
pub fn foo(foo: bool) {
match foo {
true => {
self.foo();
}
false => {
self.bar();
}
}
}
"#,
)
}
#[test]
fn test_if_let_with_match_no_else() {
check_assist(
replace_if_let_with_match,
r#"
impl VariantData {
pub fn foo(&self) {
if $0let VariantData::Struct(..) = *self {
self.foo();
}
}
}
"#,
r#"
impl VariantData {
pub fn foo(&self) {
match *self {
VariantData::Struct(..) => {
self.foo();
}
_ => (),
}
}
}
"#,
)
}
#[test]
fn test_if_let_with_match_available_range_left() {
check_assist_not_applicable(
replace_if_let_with_match,
r#"
impl VariantData {
pub fn foo(&self) {
$0 if let VariantData::Struct(..) = *self {
self.foo();
}
}
}
"#,
)
}
#[test]
fn test_if_let_with_match_available_range_right() {
check_assist_not_applicable(
replace_if_let_with_match,
r#"
impl VariantData {
pub fn foo(&self) {
if let VariantData::Struct(..) = *self {$0
self.foo();
}
}
}
"#,
)
}
#[test]
fn test_if_let_with_match_let_chain() {
check_assist_not_applicable(
replace_if_let_with_match,
r#"
fn main() {
if $0let true = true && let Some(1) = None {}
}
"#,
)
}
#[test]
fn test_if_let_with_match_basic() {
check_assist(
replace_if_let_with_match,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
if $0let VariantData::Struct(..) = *self {
true
} else if let VariantData::Tuple(..) = *self {
false
} else if cond() {
true
} else {
bar(
123
)
}
}
}
"#,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
match *self {
VariantData::Struct(..) => true,
VariantData::Tuple(..) => false,
_ if cond() => true,
_ => {
bar(
123
)
}
}
}
}
"#,
)
}
#[test]
fn test_if_let_with_match_on_tail_if_let() {
check_assist(
replace_if_let_with_match,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
if let VariantData::Struct(..) = *self {
true
} else if let$0 VariantData::Tuple(..) = *self {
false
} else {
false
}
}
}
"#,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
if let VariantData::Struct(..) = *self {
true
} else {
match *self {
VariantData::Tuple(..) => false,
_ => false,
}
}
}
}
"#,
)
}
#[test]
fn special_case_option() {
check_assist(
replace_if_let_with_match,
r#"
//- minicore: option
fn foo(x: Option<i32>) {
$0if let Some(x) = x {
println!("{}", x)
} else {
println!("none")
}
}
"#,
r#"
fn foo(x: Option<i32>) {
match x {
Some(x) => println!("{}", x),
None => println!("none"),
}
}
"#,
);
}
#[test]
fn special_case_inverted_option() {
check_assist(
replace_if_let_with_match,
r#"
//- minicore: option
fn foo(x: Option<i32>) {
$0if let None = x {
println!("none")
} else {
println!("some")
}
}
"#,
r#"
fn foo(x: Option<i32>) {
match x {
None => println!("none"),
Some(_) => println!("some"),
}
}
"#,
);
}
#[test]
fn special_case_result() {
check_assist(
replace_if_let_with_match,
r#"
//- minicore: result
fn foo(x: Result<i32, ()>) {
$0if let Ok(x) = x {
println!("{}", x)
} else {
println!("none")
}
}
"#,
r#"
fn foo(x: Result<i32, ()>) {
match x {
Ok(x) => println!("{}", x),
Err(_) => println!("none"),
}
}
"#,
);
}
#[test]
fn special_case_inverted_result() {
check_assist(
replace_if_let_with_match,
r#"
//- minicore: result
fn foo(x: Result<i32, ()>) {
$0if let Err(x) = x {
println!("{}", x)
} else {
println!("ok")
}
}
"#,
r#"
fn foo(x: Result<i32, ()>) {
match x {
Err(x) => println!("{}", x),
Ok(_) => println!("ok"),
}
}
"#,
);
}
#[test]
fn nested_indent() {
check_assist(
replace_if_let_with_match,
r#"
fn main() {
if true {
$0if let Ok(rel_path) = path.strip_prefix(root_path) {
let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
Some((*id, rel_path))
} else {
None
}
}
}
"#,
r#"
fn main() {
if true {
match path.strip_prefix(root_path) {
Ok(rel_path) => {
let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
Some((*id, rel_path))
}
_ => None,
}
}
}
"#,
)
}
#[test]
fn nested_type() {
check_assist(
replace_if_let_with_match,
r#"
//- minicore: result
fn foo(x: Result<i32, ()>) {
let bar: Result<_, ()> = Ok(Some(1));
$0if let Ok(Some(_)) = bar {
()
} else {
()
}
}
"#,
r#"
fn foo(x: Result<i32, ()>) {
let bar: Result<_, ()> = Ok(Some(1));
match bar {
Ok(Some(_)) => (),
_ => (),
}
}
"#,
);
}
#[test]
fn test_replace_match_with_if_let_unwraps_simple_expressions() {
check_assist(
replace_match_with_if_let,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
$0match *self {
VariantData::Struct(..) => true,
_ => false,
}
}
} "#,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
if let VariantData::Struct(..) = *self {
true
} else {
false
}
}
} "#,
)
}
#[test]
fn test_replace_match_with_if_let_doesnt_unwrap_multiline_expressions() {
check_assist(
replace_match_with_if_let,
r#"
fn foo() {
$0match a {
VariantData::Struct(..) => {
bar(
123
)
}
_ => false,
}
} "#,
r#"
fn foo() {
if let VariantData::Struct(..) = a {
bar(
123
)
} else {
false
}
} "#,
)
}
#[test]
fn replace_match_with_if_let_target() {
check_assist_target(
replace_match_with_if_let,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
$0match *self {
VariantData::Struct(..) => true,
_ => false,
}
}
} "#,
r#"match *self {
VariantData::Struct(..) => true,
_ => false,
}"#,
);
}
#[test]
fn special_case_option_match_to_if_let() {
check_assist(
replace_match_with_if_let,
r#"
//- minicore: option
fn foo(x: Option<i32>) {
$0match x {
Some(x) => println!("{}", x),
None => println!("none"),
}
}
"#,
r#"
fn foo(x: Option<i32>) {
if let Some(x) = x {
println!("{}", x)
} else {
println!("none")
}
}
"#,
);
}
#[test]
fn special_case_result_match_to_if_let() {
check_assist(
replace_match_with_if_let,
r#"
//- minicore: result
fn foo(x: Result<i32, ()>) {
$0match x {
Ok(x) => println!("{}", x),
Err(_) => println!("none"),
}
}
"#,
r#"
fn foo(x: Result<i32, ()>) {
if let Ok(x) = x {
println!("{}", x)
} else {
println!("none")
}
}
"#,
);
}
#[test]
fn nested_indent_match_to_if_let() {
check_assist(
replace_match_with_if_let,
r#"
fn main() {
if true {
$0match path.strip_prefix(root_path) {
Ok(rel_path) => {
let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
Some((*id, rel_path))
}
_ => None,
}
}
}
"#,
r#"
fn main() {
if true {
if let Ok(rel_path) = path.strip_prefix(root_path) {
let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
Some((*id, rel_path))
} else {
None
}
}
}
"#,
)
}
#[test]
fn replace_match_with_if_let_empty_wildcard_expr() {
check_assist(
replace_match_with_if_let,
r#"
fn main() {
$0match path.strip_prefix(root_path) {
Ok(rel_path) => println!("{}", rel_path),
_ => (),
}
}
"#,
r#"
fn main() {
if let Ok(rel_path) = path.strip_prefix(root_path) {
println!("{}", rel_path)
}
}
"#,
)
}
#[test]
fn replace_match_with_if_let_number_body() {
check_assist(
replace_match_with_if_let,
r#"
fn main() {
$0match Ok(()) {
Ok(()) => {},
Err(_) => 0,
}
}
"#,
r#"
fn main() {
if let Err(_) = Ok(()) {
0
}
}
"#,
)
}
#[test]
fn replace_match_with_if_let_exhaustive() {
check_assist(
replace_match_with_if_let,
r#"
fn print_source(def_source: ModuleSource) {
match def_so$0urce {
ModuleSource::SourceFile(..) => { println!("source file"); }
ModuleSource::Module(..) => { println!("module"); }
}
}
"#,
r#"
fn print_source(def_source: ModuleSource) {
if let ModuleSource::SourceFile(..) = def_source { println!("source file"); } else { println!("module"); }
}
"#,
)
}
#[test]
fn replace_match_with_if_let_prefer_name_bind() {
check_assist(
replace_match_with_if_let,
r#"
fn foo() {
match $0Foo(0) {
Foo(_) => (),
Bar(bar) => println!("bar {}", bar),
}
}
"#,
r#"
fn foo() {
if let Bar(bar) = Foo(0) {
println!("bar {}", bar)
}
}
"#,
);
check_assist(
replace_match_with_if_let,
r#"
fn foo() {
match $0Foo(0) {
Bar(bar) => println!("bar {}", bar),
Foo(_) => (),
}
}
"#,
r#"
fn foo() {
if let Bar(bar) = Foo(0) {
println!("bar {}", bar)
}
}
"#,
);
}
#[test]
fn replace_match_with_if_let_prefer_nonempty_body() {
check_assist(
replace_match_with_if_let,
r#"
fn foo() {
match $0Ok(0) {
Ok(value) => {},
Err(err) => eprintln!("{}", err),
}
}
"#,
r#"
fn foo() {
if let Err(err) = Ok(0) {
eprintln!("{}", err)
}
}
"#,
);
check_assist(
replace_match_with_if_let,
r#"
fn foo() {
match $0Ok(0) {
Err(err) => eprintln!("{}", err),
Ok(value) => {},
}
}
"#,
r#"
fn foo() {
if let Err(err) = Ok(0) {
eprintln!("{}", err)
}
}
"#,
);
}
#[test]
fn replace_match_with_if_let_rejects_double_name_bindings() {
check_assist_not_applicable(
replace_match_with_if_let,
r#"
fn foo() {
match $0Foo(0) {
Foo(foo) => println!("bar {}", foo),
Bar(bar) => println!("bar {}", bar),
}
}
"#,
);
}
#[test]
fn test_replace_match_with_if_let_keeps_unsafe_block() {
check_assist(
replace_match_with_if_let,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
$0match *self {
VariantData::Struct(..) => true,
_ => unsafe { unreachable_unchecked() },
}
}
} "#,
r#"
impl VariantData {
pub fn is_struct(&self) -> bool {
if let VariantData::Struct(..) = *self {
true
} else {
unsafe { unreachable_unchecked() }
}
}
} "#,
)
}
#[test]
fn test_replace_match_with_if_let_forces_else() {
check_assist(
replace_match_with_if_let,
r#"
fn main() {
match$0 0 {
0 => (),
_ => code(),
}
}
"#,
r#"
fn main() {
if let 0 = 0 {
()
} else {
code()
}
}
"#,
)
}
#[test]
fn test_replace_match_with_if_bool() {
check_assist(
replace_match_with_if_let,
r#"
fn main() {
match$0 b {
true => (),
_ => code(),
}
}
"#,
r#"
fn main() {
if b {
()
} else {
code()
}
}
"#,
);
check_assist(
replace_match_with_if_let,
r#"
fn main() {
match$0 b {
false => code(),
true => (),
}
}
"#,
r#"
fn main() {
if !b {
code()
}
}
"#,
);
check_assist(
replace_match_with_if_let,
r#"
fn main() {
match$0 b {
false => (),
true => code(),
}
}
"#,
r#"
fn main() {
if b {
code()
}
}
"#,
)
}
}