rust/crates/ide_assists/src/handlers/extract_variable.rs

863 lines
17 KiB
Rust

use stdx::format_to;
use syntax::{
ast::{self, AstNode},
SyntaxKind::{
BLOCK_EXPR, BREAK_EXPR, CLOSURE_EXPR, COMMENT, LOOP_EXPR, MATCH_ARM, MATCH_GUARD,
PATH_EXPR, RETURN_EXPR,
},
SyntaxNode,
};
use crate::{utils::suggest_name, AssistContext, AssistId, AssistKind, Assists};
// Assist: extract_variable
//
// Extracts subexpression into a variable.
//
// ```
// fn main() {
// $0(1 + 2)$0 * 4;
// }
// ```
// ->
// ```
// fn main() {
// let $0var_name = (1 + 2);
// var_name * 4;
// }
// ```
pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
if ctx.frange.range.is_empty() {
return None;
}
let node = ctx.covering_element();
if node.kind() == COMMENT {
cov_mark::hit!(extract_var_in_comment_is_not_applicable);
return None;
}
let to_extract = node
.ancestors()
.take_while(|it| it.text_range().contains_range(ctx.frange.range))
.find_map(valid_target_expr)?;
if let Some(ty_info) = ctx.sema.type_of_expr(&to_extract) {
if ty_info.adjusted().is_unit() {
return None;
}
}
let anchor = Anchor::from(&to_extract)?;
let indent = anchor.syntax().prev_sibling_or_token()?.as_token()?.clone();
let target = to_extract.syntax().text_range();
acc.add(
AssistId("extract_variable", AssistKind::RefactorExtract),
"Extract into variable",
target,
move |edit| {
let field_shorthand =
match to_extract.syntax().parent().and_then(ast::RecordExprField::cast) {
Some(field) => field.name_ref(),
None => None,
};
let mut buf = String::new();
let var_name = match &field_shorthand {
Some(it) => it.to_string(),
None => suggest_name::for_variable(&to_extract, &ctx.sema),
};
let expr_range = match &field_shorthand {
Some(it) => it.syntax().text_range().cover(to_extract.syntax().text_range()),
None => to_extract.syntax().text_range(),
};
if let Anchor::WrapInBlock(_) = anchor {
format_to!(buf, "{{ let {} = ", var_name);
} else {
format_to!(buf, "let {} = ", var_name);
};
format_to!(buf, "{}", to_extract.syntax());
if let Anchor::Replace(stmt) = anchor {
cov_mark::hit!(test_extract_var_expr_stmt);
if stmt.semicolon_token().is_none() {
buf.push_str(";");
}
match ctx.config.snippet_cap {
Some(cap) => {
let snip = buf
.replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
edit.replace_snippet(cap, expr_range, snip)
}
None => edit.replace(expr_range, buf),
}
return;
}
buf.push_str(";");
// We want to maintain the indent level,
// but we do not want to duplicate possible
// extra newlines in the indent block
let text = indent.text();
if text.starts_with('\n') {
buf.push('\n');
buf.push_str(text.trim_start_matches('\n'));
} else {
buf.push_str(text);
}
edit.replace(expr_range, var_name.clone());
let offset = anchor.syntax().text_range().start();
match ctx.config.snippet_cap {
Some(cap) => {
let snip =
buf.replace(&format!("let {}", var_name), &format!("let $0{}", var_name));
edit.insert_snippet(cap, offset, snip)
}
None => edit.insert(offset, buf),
}
if let Anchor::WrapInBlock(_) = anchor {
edit.insert(anchor.syntax().text_range().end(), " }");
}
},
)
}
/// Check whether the node is a valid expression which can be extracted to a variable.
/// In general that's true for any expression, but in some cases that would produce invalid code.
fn valid_target_expr(node: SyntaxNode) -> Option<ast::Expr> {
match node.kind() {
PATH_EXPR | LOOP_EXPR => None,
BREAK_EXPR => ast::BreakExpr::cast(node).and_then(|e| e.expr()),
RETURN_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()),
BLOCK_EXPR => {
ast::BlockExpr::cast(node).filter(|it| it.is_standalone()).map(ast::Expr::from)
}
_ => ast::Expr::cast(node),
}
}
enum Anchor {
Before(SyntaxNode),
Replace(ast::ExprStmt),
WrapInBlock(SyntaxNode),
}
impl Anchor {
fn from(to_extract: &ast::Expr) -> Option<Anchor> {
to_extract.syntax().ancestors().take_while(|it| !ast::Item::can_cast(it.kind())).find_map(
|node| {
if let Some(expr) =
node.parent().and_then(ast::BlockExpr::cast).and_then(|it| it.tail_expr())
{
if expr.syntax() == &node {
cov_mark::hit!(test_extract_var_last_expr);
return Some(Anchor::Before(node));
}
}
if let Some(parent) = node.parent() {
if parent.kind() == CLOSURE_EXPR {
cov_mark::hit!(test_extract_var_in_closure_no_block);
return Some(Anchor::WrapInBlock(node));
}
if parent.kind() == MATCH_ARM {
if node.kind() == MATCH_GUARD {
cov_mark::hit!(test_extract_var_in_match_guard);
} else {
cov_mark::hit!(test_extract_var_in_match_arm_no_block);
return Some(Anchor::WrapInBlock(node));
}
}
}
if let Some(stmt) = ast::Stmt::cast(node.clone()) {
if let ast::Stmt::ExprStmt(stmt) = stmt {
if stmt.expr().as_ref() == Some(to_extract) {
return Some(Anchor::Replace(stmt));
}
}
return Some(Anchor::Before(node));
}
None
},
)
}
fn syntax(&self) -> &SyntaxNode {
match self {
Anchor::Before(it) | Anchor::WrapInBlock(it) => it,
Anchor::Replace(stmt) => stmt.syntax(),
}
}
}
#[cfg(test)]
mod tests {
use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
use super::*;
#[test]
fn test_extract_var_simple() {
check_assist(
extract_variable,
r#"
fn foo() {
foo($01 + 1$0);
}"#,
r#"
fn foo() {
let $0var_name = 1 + 1;
foo(var_name);
}"#,
);
}
#[test]
fn extract_var_in_comment_is_not_applicable() {
cov_mark::check!(extract_var_in_comment_is_not_applicable);
check_assist_not_applicable(extract_variable, "fn main() { 1 + /* $0comment$0 */ 1; }");
}
#[test]
fn test_extract_var_expr_stmt() {
cov_mark::check!(test_extract_var_expr_stmt);
check_assist(
extract_variable,
r#"
fn foo() {
$01 + 1$0;
}"#,
r#"
fn foo() {
let $0var_name = 1 + 1;
}"#,
);
check_assist(
extract_variable,
"
fn foo() {
$0{ let x = 0; x }$0
something_else();
}",
"
fn foo() {
let $0var_name = { let x = 0; x };
something_else();
}",
);
}
#[test]
fn test_extract_var_part_of_expr_stmt() {
check_assist(
extract_variable,
"
fn foo() {
$01$0 + 1;
}",
"
fn foo() {
let $0var_name = 1;
var_name + 1;
}",
);
}
#[test]
fn test_extract_var_last_expr() {
cov_mark::check!(test_extract_var_last_expr);
check_assist(
extract_variable,
r#"
fn foo() {
bar($01 + 1$0)
}
"#,
r#"
fn foo() {
let $0var_name = 1 + 1;
bar(var_name)
}
"#,
);
check_assist(
extract_variable,
r#"
fn foo() -> i32 {
$0bar(1 + 1)$0
}
fn bar(i: i32) -> i32 {
i
}
"#,
r#"
fn foo() -> i32 {
let $0bar = bar(1 + 1);
bar
}
fn bar(i: i32) -> i32 {
i
}
"#,
)
}
#[test]
fn test_extract_var_in_match_arm_no_block() {
cov_mark::check!(test_extract_var_in_match_arm_no_block);
check_assist(
extract_variable,
r#"
fn main() {
let x = true;
let tuple = match x {
true => ($02 + 2$0, true)
_ => (0, false)
};
}
"#,
r#"
fn main() {
let x = true;
let tuple = match x {
true => { let $0var_name = 2 + 2; (var_name, true) }
_ => (0, false)
};
}
"#,
);
}
#[test]
fn test_extract_var_in_match_arm_with_block() {
check_assist(
extract_variable,
r#"
fn main() {
let x = true;
let tuple = match x {
true => {
let y = 1;
($02 + y$0, true)
}
_ => (0, false)
};
}
"#,
r#"
fn main() {
let x = true;
let tuple = match x {
true => {
let y = 1;
let $0var_name = 2 + y;
(var_name, true)
}
_ => (0, false)
};
}
"#,
);
}
#[test]
fn test_extract_var_in_match_guard() {
cov_mark::check!(test_extract_var_in_match_guard);
check_assist(
extract_variable,
r#"
fn main() {
match () {
() if $010 > 0$0 => 1
_ => 2
};
}
"#,
r#"
fn main() {
let $0var_name = 10 > 0;
match () {
() if var_name => 1
_ => 2
};
}
"#,
);
}
#[test]
fn test_extract_var_in_closure_no_block() {
cov_mark::check!(test_extract_var_in_closure_no_block);
check_assist(
extract_variable,
r#"
fn main() {
let lambda = |x: u32| $0x * 2$0;
}
"#,
r#"
fn main() {
let lambda = |x: u32| { let $0var_name = x * 2; var_name };
}
"#,
);
}
#[test]
fn test_extract_var_in_closure_with_block() {
check_assist(
extract_variable,
r#"
fn main() {
let lambda = |x: u32| { $0x * 2$0 };
}
"#,
r#"
fn main() {
let lambda = |x: u32| { let $0var_name = x * 2; var_name };
}
"#,
);
}
#[test]
fn test_extract_var_path_simple() {
check_assist(
extract_variable,
"
fn main() {
let o = $0Some(true)$0;
}
",
"
fn main() {
let $0var_name = Some(true);
let o = var_name;
}
",
);
}
#[test]
fn test_extract_var_path_method() {
check_assist(
extract_variable,
"
fn main() {
let v = $0bar.foo()$0;
}
",
"
fn main() {
let $0foo = bar.foo();
let v = foo;
}
",
);
}
#[test]
fn test_extract_var_return() {
check_assist(
extract_variable,
"
fn foo() -> u32 {
$0return 2 + 2$0;
}
",
"
fn foo() -> u32 {
let $0var_name = 2 + 2;
return var_name;
}
",
);
}
#[test]
fn test_extract_var_does_not_add_extra_whitespace() {
check_assist(
extract_variable,
"
fn foo() -> u32 {
$0return 2 + 2$0;
}
",
"
fn foo() -> u32 {
let $0var_name = 2 + 2;
return var_name;
}
",
);
check_assist(
extract_variable,
"
fn foo() -> u32 {
$0return 2 + 2$0;
}
",
"
fn foo() -> u32 {
let $0var_name = 2 + 2;
return var_name;
}
",
);
check_assist(
extract_variable,
"
fn foo() -> u32 {
let foo = 1;
// bar
$0return 2 + 2$0;
}
",
"
fn foo() -> u32 {
let foo = 1;
// bar
let $0var_name = 2 + 2;
return var_name;
}
",
);
}
#[test]
fn test_extract_var_break() {
check_assist(
extract_variable,
"
fn main() {
let result = loop {
$0break 2 + 2$0;
};
}
",
"
fn main() {
let result = loop {
let $0var_name = 2 + 2;
break var_name;
};
}
",
);
}
#[test]
fn test_extract_var_for_cast() {
check_assist(
extract_variable,
"
fn main() {
let v = $00f32 as u32$0;
}
",
"
fn main() {
let $0var_name = 0f32 as u32;
let v = var_name;
}
",
);
}
#[test]
fn extract_var_field_shorthand() {
check_assist(
extract_variable,
r#"
struct S {
foo: i32
}
fn main() {
S { foo: $01 + 1$0 }
}
"#,
r#"
struct S {
foo: i32
}
fn main() {
let $0foo = 1 + 1;
S { foo }
}
"#,
)
}
#[test]
fn extract_var_name_from_type() {
check_assist(
extract_variable,
r#"
struct Test(i32);
fn foo() -> Test {
$0{ Test(10) }$0
}
"#,
r#"
struct Test(i32);
fn foo() -> Test {
let $0test = { Test(10) };
test
}
"#,
)
}
#[test]
fn extract_var_name_from_parameter() {
check_assist(
extract_variable,
r#"
fn bar(test: u32, size: u32)
fn foo() {
bar(1, $01+1$0);
}
"#,
r#"
fn bar(test: u32, size: u32)
fn foo() {
let $0size = 1+1;
bar(1, size);
}
"#,
)
}
#[test]
fn extract_var_parameter_name_has_precedence_over_type() {
check_assist(
extract_variable,
r#"
struct TextSize(u32);
fn bar(test: u32, size: TextSize)
fn foo() {
bar(1, $0{ TextSize(1+1) }$0);
}
"#,
r#"
struct TextSize(u32);
fn bar(test: u32, size: TextSize)
fn foo() {
let $0size = { TextSize(1+1) };
bar(1, size);
}
"#,
)
}
#[test]
fn extract_var_name_from_function() {
check_assist(
extract_variable,
r#"
fn is_required(test: u32, size: u32) -> bool
fn foo() -> bool {
$0is_required(1, 2)$0
}
"#,
r#"
fn is_required(test: u32, size: u32) -> bool
fn foo() -> bool {
let $0is_required = is_required(1, 2);
is_required
}
"#,
)
}
#[test]
fn extract_var_name_from_method() {
check_assist(
extract_variable,
r#"
struct S;
impl S {
fn bar(&self, n: u32) -> u32 { n }
}
fn foo() -> u32 {
$0S.bar(1)$0
}
"#,
r#"
struct S;
impl S {
fn bar(&self, n: u32) -> u32 { n }
}
fn foo() -> u32 {
let $0bar = S.bar(1);
bar
}
"#,
)
}
#[test]
fn extract_var_name_from_method_param() {
check_assist(
extract_variable,
r#"
struct S;
impl S {
fn bar(&self, n: u32, size: u32) { n }
}
fn foo() {
S.bar($01 + 1$0, 2)
}
"#,
r#"
struct S;
impl S {
fn bar(&self, n: u32, size: u32) { n }
}
fn foo() {
let $0n = 1 + 1;
S.bar(n, 2)
}
"#,
)
}
#[test]
fn extract_var_name_from_ufcs_method_param() {
check_assist(
extract_variable,
r#"
struct S;
impl S {
fn bar(&self, n: u32, size: u32) { n }
}
fn foo() {
S::bar(&S, $01 + 1$0, 2)
}
"#,
r#"
struct S;
impl S {
fn bar(&self, n: u32, size: u32) { n }
}
fn foo() {
let $0n = 1 + 1;
S::bar(&S, n, 2)
}
"#,
)
}
#[test]
fn extract_var_parameter_name_has_precedence_over_function() {
check_assist(
extract_variable,
r#"
fn bar(test: u32, size: u32)
fn foo() {
bar(1, $0symbol_size(1, 2)$0);
}
"#,
r#"
fn bar(test: u32, size: u32)
fn foo() {
let $0size = symbol_size(1, 2);
bar(1, size);
}
"#,
)
}
#[test]
fn test_extract_var_for_return_not_applicable() {
check_assist_not_applicable(extract_variable, "fn foo() { $0return$0; } ");
}
#[test]
fn test_extract_var_for_break_not_applicable() {
check_assist_not_applicable(extract_variable, "fn main() { loop { $0break$0; }; }");
}
#[test]
fn test_extract_var_unit_expr_not_applicable() {
check_assist_not_applicable(
extract_variable,
r#"
fn foo() {
let mut i = 3;
$0if i >= 0 {
i += 1;
} else {
i -= 1;
}$0
}"#,
);
}
// FIXME: This is not quite correct, but good enough(tm) for the sorting heuristic
#[test]
fn extract_var_target() {
check_assist_target(extract_variable, "fn foo() -> u32 { $0return 2 + 2$0; }", "2 + 2");
check_assist_target(
extract_variable,
"
fn main() {
let x = true;
let tuple = match x {
true => ($02 + 2$0, true)
_ => (0, false)
};
}
",
"2 + 2",
);
}
#[test]
fn extract_var_no_block_body() {
check_assist_not_applicable(
extract_variable,
r"
const X: usize = $0100$0;
",
);
}
}