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use std::iter;
use ide_db::{
assists::{AssistId, ExprFillDefaultMode},
ty_filter::TryEnum,
};
use syntax::{
AstNode, T,
ast::{
self,
edit::{AstNodeEdit, IndentLevel},
make,
syntax_factory::SyntaxFactory,
},
};
use crate::assist_context::{AssistContext, Assists};
// Assist: desugar_try_expr_match
//
// Replaces a `try` expression with a `match` expression.
//
// ```
// # //- minicore: try, option
// fn handle() {
// let pat = Some(true)$0?;
// }
// ```
// ->
// ```
// fn handle() {
// let pat = match Some(true) {
// Some(it) => it,
// None => return None,
// };
// }
// ```
// Assist: desugar_try_expr_let_else
//
// Replaces a `try` expression with a `let else` statement.
//
// ```
// # //- minicore: try, option
// fn handle() {
// let pat = Some(true)$0?;
// }
// ```
// ->
// ```
// fn handle() {
// let Some(pat) = Some(true) else {
// return None;
// };
// }
// ```
pub(crate) fn desugar_try_expr(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
let question_tok = ctx.find_token_syntax_at_offset(T![?])?;
let try_expr = question_tok.parent().and_then(ast::TryExpr::cast)?;
let expr = try_expr.expr()?;
let expr_type_info = ctx.sema.type_of_expr(&expr)?;
let try_enum = TryEnum::from_ty(&ctx.sema, &expr_type_info.original)?;
let target = try_expr.syntax().text_range();
acc.add(
AssistId::refactor_rewrite("desugar_try_expr_match"),
"Replace try expression with match",
target,
|edit| {
let sad_pat = match try_enum {
TryEnum::Option => make::path_pat(make::ext::ident_path("None")),
TryEnum::Result => make::tuple_struct_pat(
make::ext::ident_path("Err"),
iter::once(make::path_pat(make::ext::ident_path("err"))),
)
.into(),
};
let sad_expr = match try_enum {
TryEnum::Option => {
make::expr_return(Some(make::expr_path(make::ext::ident_path("None"))))
}
TryEnum::Result => make::expr_return(Some(
make::expr_call(
make::expr_path(make::ext::ident_path("Err")),
make::arg_list(iter::once(make::expr_path(make::ext::ident_path("err")))),
)
.into(),
)),
};
let happy_arm = make::match_arm(
try_enum.happy_pattern(make::ident_pat(false, false, make::name("it")).into()),
None,
make::expr_path(make::ext::ident_path("it")),
);
let sad_arm = make::match_arm(sad_pat, None, sad_expr);
let match_arm_list = make::match_arm_list([happy_arm, sad_arm]);
let expr_match = make::expr_match(expr.clone(), match_arm_list)
.indent(IndentLevel::from_node(try_expr.syntax()));
edit.replace_ast::<ast::Expr>(try_expr.clone().into(), expr_match.into());
},
);
if let Some(let_stmt) = try_expr.syntax().parent().and_then(ast::LetStmt::cast)
&& let_stmt.let_else().is_none()
{
let pat = let_stmt.pat()?;
acc.add(
AssistId::refactor_rewrite("desugar_try_expr_let_else"),
"Replace try expression with let else",
target,
|builder| {
let make = SyntaxFactory::with_mappings();
let mut editor = builder.make_editor(let_stmt.syntax());
let indent_level = IndentLevel::from_node(let_stmt.syntax());
let new_let_stmt = make.let_else_stmt(
try_enum.happy_pattern(pat),
let_stmt.ty(),
expr,
make.block_expr(
iter::once(
make.expr_stmt(
make.expr_return(Some(match try_enum {
TryEnum::Option => make.expr_path(make.ident_path("None")),
TryEnum::Result => make
.expr_call(
make.expr_path(make.ident_path("Err")),
make.arg_list(iter::once(
match ctx.config.expr_fill_default {
ExprFillDefaultMode::Todo => make
.expr_macro(
make.ident_path("todo"),
make.token_tree(
syntax::SyntaxKind::L_PAREN,
[],
),
)
.into(),
ExprFillDefaultMode::Underscore => {
make.expr_underscore().into()
}
ExprFillDefaultMode::Default => make
.expr_macro(
make.ident_path("todo"),
make.token_tree(
syntax::SyntaxKind::L_PAREN,
[],
),
)
.into(),
},
)),
)
.into(),
}))
.indent(indent_level + 1)
.into(),
)
.into(),
),
None,
)
.indent(indent_level),
);
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);
},
);
}
Some(())
}
#[cfg(test)]
mod tests {
use super::*;
use crate::tests::{check_assist, check_assist_by_label, check_assist_not_applicable};
#[test]
fn test_desugar_try_expr_not_applicable() {
check_assist_not_applicable(
desugar_try_expr,
r#"
fn test() {
let pat: u32 = 25$0;
}
"#,
);
}
#[test]
fn test_desugar_try_expr_option() {
check_assist(
desugar_try_expr,
r#"
//- minicore: try, option
fn test() {
let pat = Some(true)$0?;
}
"#,
r#"
fn test() {
let pat = match Some(true) {
Some(it) => it,
None => return None,
};
}
"#,
);
}
#[test]
fn test_desugar_try_expr_result() {
check_assist(
desugar_try_expr,
r#"
//- minicore: try, from, result
fn test() {
let pat = Ok(true)$0?;
}
"#,
r#"
fn test() {
let pat = match Ok(true) {
Ok(it) => it,
Err(err) => return Err(err),
};
}
"#,
);
}
#[test]
fn test_desugar_try_expr_option_let_else() {
check_assist_by_label(
desugar_try_expr,
r#"
//- minicore: try, option
fn test() {
let pat = Some(true)$0?;
}
"#,
r#"
fn test() {
let Some(pat) = Some(true) else {
return None;
};
}
"#,
"Replace try expression with let else",
);
}
#[test]
fn test_desugar_try_expr_result_let_else() {
check_assist_by_label(
desugar_try_expr,
r#"
//- minicore: try, from, result
fn test() {
let pat = Ok(true)$0?;
}
"#,
r#"
fn test() {
let Ok(pat) = Ok(true) else {
return Err(todo!());
};
}
"#,
"Replace try expression with let else",
);
}
}