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|
//! FIXME: write short doc here
use crate::{Assist, AssistCtx, AssistId, TextRange, TextUnit};
use hir::db::HirDatabase;
use ra_syntax::ast::{AstNode, MatchArm};
pub(crate) fn merge_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
let current_arm = ctx.node_at_offset::<MatchArm>()?;
// We check if the following match arm matches this one. We could, but don't,
// compare to the previous match arm as well.
let next = current_arm.syntax().next_sibling();
let next_arm = MatchArm::cast(next?)?;
// Don't try to handle arms with guards for now - can add support for this later
if current_arm.guard().is_some() || next_arm.guard().is_some() {
return None;
}
let current_expr = current_arm.expr()?;
let next_expr = next_arm.expr()?;
// Check for match arm equality by comparing lengths and then string contents
if current_expr.syntax().text_range().len() != next_expr.syntax().text_range().len() {
return None;
}
if current_expr.syntax().text() != next_expr.syntax().text() {
return None;
}
let cursor_to_end = current_arm.syntax().text_range().end() - ctx.frange.range.start();
ctx.add_action(AssistId("merge_match_arms"), "merge match arms", |edit| {
fn contains_placeholder(a: &MatchArm) -> bool {
a.pats().any(|x| match x {
ra_syntax::ast::Pat::PlaceholderPat(..) => true,
_ => false,
})
}
let pats = if contains_placeholder(¤t_arm) || contains_placeholder(&next_arm) {
"_".into()
} else {
let ps: Vec<String> = current_arm
.pats()
.map(|x| x.syntax().to_string())
.chain(next_arm.pats().map(|x| x.syntax().to_string()))
.collect();
ps.join(" | ")
};
let arm = format!("{} => {}", pats, current_expr.syntax().text());
let offset = TextUnit::from_usize(arm.len()) - cursor_to_end;
let start = current_arm.syntax().text_range().start();
let end = next_arm.syntax().text_range().end();
edit.target(current_arm.syntax().text_range());
edit.replace(TextRange::from_to(start, end), arm);
edit.set_cursor(start + offset);
});
ctx.build()
}
#[cfg(test)]
mod tests {
use super::merge_match_arms;
use crate::helpers::{check_assist, check_assist_not_applicable};
#[test]
fn merge_match_arms_single_patterns() {
check_assist(
merge_match_arms,
r#"
#[derive(Debug)]
enum X { A, B, C }
fn main() {
let x = X::A;
let y = match x {
X::A => { 1i32<|> }
X::B => { 1i32 }
X::C => { 2i32 }
}
}
"#,
r#"
#[derive(Debug)]
enum X { A, B, C }
fn main() {
let x = X::A;
let y = match x {
X::A | X::B => { 1i32<|> }
X::C => { 2i32 }
}
}
"#,
);
}
#[test]
fn merge_match_arms_multiple_patterns() {
check_assist(
merge_match_arms,
r#"
#[derive(Debug)]
enum X { A, B, C, D, E }
fn main() {
let x = X::A;
let y = match x {
X::A | X::B => {<|> 1i32 },
X::C | X::D => { 1i32 },
X::E => { 2i32 },
}
}
"#,
r#"
#[derive(Debug)]
enum X { A, B, C, D, E }
fn main() {
let x = X::A;
let y = match x {
X::A | X::B | X::C | X::D => {<|> 1i32 },
X::E => { 2i32 },
}
}
"#,
);
}
#[test]
fn merge_match_arms_placeholder_pattern() {
check_assist(
merge_match_arms,
r#"
#[derive(Debug)]
enum X { A, B, C, D, E }
fn main() {
let x = X::A;
let y = match x {
X::A => { 1i32 },
X::B => { 2i<|>32 },
_ => { 2i32 }
}
}
"#,
r#"
#[derive(Debug)]
enum X { A, B, C, D, E }
fn main() {
let x = X::A;
let y = match x {
X::A => { 1i32 },
_ => { 2i<|>32 }
}
}
"#,
);
}
#[test]
fn merge_match_arms_rejects_guards() {
check_assist_not_applicable(
merge_match_arms,
r#"
#[derive(Debug)]
enum X {
A(i32),
B,
C
}
fn main() {
let x = X::A;
let y = match x {
X::A(a) if a > 5 => { <|>1i32 },
X::B => { 1i32 },
X::C => { 2i32 }
}
}
"#,
);
}
}
|
