rust/crates/ide_assists/src/handlers/pull_assignment_up.rs
2021-05-16 14:18:49 +03:00

511 lines
10 KiB
Rust

use syntax::{
ast::{self, make},
ted, AstNode,
};
use crate::{
assist_context::{AssistContext, Assists},
AssistId, AssistKind,
};
// Assist: pull_assignment_up
//
// Extracts variable assignment to outside an if or match statement.
//
// ```
// fn main() {
// let mut foo = 6;
//
// if true {
// $0foo = 5;
// } else {
// foo = 4;
// }
// }
// ```
// ->
// ```
// fn main() {
// let mut foo = 6;
//
// foo = if true {
// 5
// } else {
// 4
// };
// }
// ```
pub(crate) fn pull_assignment_up(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
let assign_expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
let op_kind = assign_expr.op_kind()?;
if op_kind != ast::BinOp::Assignment {
cov_mark::hit!(test_cant_pull_non_assignments);
return None;
}
let mut collector = AssignmentsCollector {
sema: &ctx.sema,
common_lhs: assign_expr.lhs()?,
assignments: Vec::new(),
};
let tgt: ast::Expr = if let Some(if_expr) = ctx.find_node_at_offset::<ast::IfExpr>() {
collector.collect_if(&if_expr)?;
if_expr.into()
} else if let Some(match_expr) = ctx.find_node_at_offset::<ast::MatchExpr>() {
collector.collect_match(&match_expr)?;
match_expr.into()
} else {
return None;
};
if let Some(parent) = tgt.syntax().parent() {
if matches!(parent.kind(), syntax::SyntaxKind::BIN_EXPR | syntax::SyntaxKind::LET_STMT) {
return None;
}
}
acc.add(
AssistId("pull_assignment_up", AssistKind::RefactorExtract),
"Pull assignment up",
tgt.syntax().text_range(),
move |edit| {
let assignments: Vec<_> = collector
.assignments
.into_iter()
.map(|(stmt, rhs)| (edit.make_mut(stmt), rhs.clone_for_update()))
.collect();
let tgt = edit.make_mut(tgt);
for (stmt, rhs) in assignments {
let mut stmt = stmt.syntax().clone();
if let Some(parent) = stmt.parent() {
if ast::ExprStmt::cast(parent.clone()).is_some() {
stmt = parent.clone();
}
}
ted::replace(stmt, rhs.syntax());
}
let assign_expr = make::expr_assignment(collector.common_lhs, tgt.clone());
let assign_stmt = make::expr_stmt(assign_expr);
ted::replace(tgt.syntax(), assign_stmt.syntax().clone_for_update());
},
)
}
struct AssignmentsCollector<'a> {
sema: &'a hir::Semantics<'a, ide_db::RootDatabase>,
common_lhs: ast::Expr,
assignments: Vec<(ast::BinExpr, ast::Expr)>,
}
impl<'a> AssignmentsCollector<'a> {
fn collect_match(&mut self, match_expr: &ast::MatchExpr) -> Option<()> {
for arm in match_expr.match_arm_list()?.arms() {
match arm.expr()? {
ast::Expr::BlockExpr(block) => self.collect_block(&block)?,
ast::Expr::BinExpr(expr) => self.collect_expr(&expr)?,
_ => return None,
}
}
Some(())
}
fn collect_if(&mut self, if_expr: &ast::IfExpr) -> Option<()> {
let then_branch = if_expr.then_branch()?;
self.collect_block(&then_branch)?;
match if_expr.else_branch()? {
ast::ElseBranch::Block(block) => self.collect_block(&block),
ast::ElseBranch::IfExpr(expr) => {
cov_mark::hit!(test_pull_assignment_up_chained_if);
self.collect_if(&expr)
}
}
}
fn collect_block(&mut self, block: &ast::BlockExpr) -> Option<()> {
let last_expr = block.tail_expr().or_else(|| {
if let ast::Stmt::ExprStmt(stmt) = block.statements().last()? {
stmt.expr()
} else {
None
}
})?;
if let ast::Expr::BinExpr(expr) = last_expr {
return self.collect_expr(&expr);
}
None
}
fn collect_expr(&mut self, expr: &ast::BinExpr) -> Option<()> {
if expr.op_kind()? == ast::BinOp::Assignment
&& is_equivalent(self.sema, &expr.lhs()?, &self.common_lhs)
{
self.assignments.push((expr.clone(), expr.rhs()?));
return Some(());
}
None
}
}
fn is_equivalent(
sema: &hir::Semantics<ide_db::RootDatabase>,
expr0: &ast::Expr,
expr1: &ast::Expr,
) -> bool {
match (expr0, expr1) {
(ast::Expr::FieldExpr(field_expr0), ast::Expr::FieldExpr(field_expr1)) => {
cov_mark::hit!(test_pull_assignment_up_field_assignment);
sema.resolve_field(field_expr0) == sema.resolve_field(field_expr1)
}
(ast::Expr::PathExpr(path0), ast::Expr::PathExpr(path1)) => {
let path0 = path0.path();
let path1 = path1.path();
if let (Some(path0), Some(path1)) = (path0, path1) {
sema.resolve_path(&path0) == sema.resolve_path(&path1)
} else {
false
}
}
(ast::Expr::PrefixExpr(prefix0), ast::Expr::PrefixExpr(prefix1))
if prefix0.op_kind() == Some(ast::PrefixOp::Deref)
&& prefix1.op_kind() == Some(ast::PrefixOp::Deref) =>
{
cov_mark::hit!(test_pull_assignment_up_deref);
if let (Some(prefix0), Some(prefix1)) = (prefix0.expr(), prefix1.expr()) {
is_equivalent(sema, &prefix0, &prefix1)
} else {
false
}
}
_ => false,
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::tests::{check_assist, check_assist_not_applicable};
#[test]
fn test_pull_assignment_up_if() {
check_assist(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
if true {
$0a = 2;
} else {
a = 3;
}
}"#,
r#"
fn foo() {
let mut a = 1;
a = if true {
2
} else {
3
};
}"#,
);
}
#[test]
fn test_pull_assignment_up_match() {
check_assist(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
match 1 {
1 => {
$0a = 2;
},
2 => {
a = 3;
},
3 => {
a = 4;
}
}
}"#,
r#"
fn foo() {
let mut a = 1;
a = match 1 {
1 => {
2
},
2 => {
3
},
3 => {
4
}
};
}"#,
);
}
#[test]
fn test_pull_assignment_up_assignment_expressions() {
check_assist(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
match 1 {
1 => { $0a = 2; },
2 => a = 3,
3 => {
a = 4
}
}
}"#,
r#"
fn foo() {
let mut a = 1;
a = match 1 {
1 => { 2 },
2 => 3,
3 => {
4
}
};
}"#,
);
}
#[test]
fn test_pull_assignment_up_not_last_not_applicable() {
check_assist_not_applicable(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
if true {
$0a = 2;
b = a;
} else {
a = 3;
}
}"#,
)
}
#[test]
fn test_pull_assignment_up_chained_if() {
cov_mark::check!(test_pull_assignment_up_chained_if);
check_assist(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
if true {
$0a = 2;
} else if false {
a = 3;
} else {
a = 4;
}
}"#,
r#"
fn foo() {
let mut a = 1;
a = if true {
2
} else if false {
3
} else {
4
};
}"#,
);
}
#[test]
fn test_pull_assignment_up_retains_stmts() {
check_assist(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
if true {
let b = 2;
$0a = 2;
} else {
let b = 3;
a = 3;
}
}"#,
r#"
fn foo() {
let mut a = 1;
a = if true {
let b = 2;
2
} else {
let b = 3;
3
};
}"#,
)
}
#[test]
fn pull_assignment_up_let_stmt_not_applicable() {
check_assist_not_applicable(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
let b = if true {
$0a = 2
} else {
a = 3
};
}"#,
)
}
#[test]
fn pull_assignment_up_if_missing_assigment_not_applicable() {
check_assist_not_applicable(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
if true {
$0a = 2;
} else {}
}"#,
)
}
#[test]
fn pull_assignment_up_match_missing_assigment_not_applicable() {
check_assist_not_applicable(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
match 1 {
1 => {
$0a = 2;
},
2 => {
a = 3;
},
3 => {},
}
}"#,
)
}
#[test]
fn test_pull_assignment_up_field_assignment() {
cov_mark::check!(test_pull_assignment_up_field_assignment);
check_assist(
pull_assignment_up,
r#"
struct A(usize);
fn foo() {
let mut a = A(1);
if true {
$0a.0 = 2;
} else {
a.0 = 3;
}
}"#,
r#"
struct A(usize);
fn foo() {
let mut a = A(1);
a.0 = if true {
2
} else {
3
};
}"#,
)
}
#[test]
fn test_pull_assignment_up_deref() {
cov_mark::check!(test_pull_assignment_up_deref);
check_assist(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
let b = &mut a;
if true {
$0*b = 2;
} else {
*b = 3;
}
}
"#,
r#"
fn foo() {
let mut a = 1;
let b = &mut a;
*b = if true {
2
} else {
3
};
}
"#,
)
}
#[test]
fn test_cant_pull_non_assignments() {
cov_mark::check!(test_cant_pull_non_assignments);
check_assist_not_applicable(
pull_assignment_up,
r#"
fn foo() {
let mut a = 1;
let b = &mut a;
if true {
$0*b + 2;
} else {
*b + 3;
}
}
"#,
)
}
}