1052: Flip binary expression assist r=matklad a=marcogroppo

Adds an assist that can flip these binary comparison operators: `==`, `!=`, `>`, `>=`, `<`, `<=`.

This is a small extension to the 'flip ==' assist.
In theory we could easily flip ANY binary expression, but I'm not sure it would be a good idea (IMHO we should try not to change the meaning of the expression).

Does it make sense?

Co-authored-by: Marco Groppo <marco.groppo@gmail.com>
This commit is contained in:
bors[bot] 2019-03-27 05:40:18 +00:00
commit de8f72aad9
3 changed files with 143 additions and 88 deletions

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@ -0,0 +1,141 @@
use hir::db::HirDatabase;
use ra_syntax::ast::{AstNode, BinExpr, BinOp};
use crate::{AssistCtx, Assist, AssistId};
/// Flip binary expression assist.
pub(crate) fn flip_binexpr(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
let expr = ctx.node_at_offset::<BinExpr>()?;
let lhs = expr.lhs()?.syntax();
let rhs = expr.rhs()?.syntax();
let op_range = expr.op()?.range();
// The assist should be applied only if the cursor is on the operator
let cursor_in_range = ctx.frange.range.is_subrange(&op_range);
if !cursor_in_range {
return None;
}
let action: FlipAction = expr.op_kind()?.into();
// The assist should not be applied for certain operators
if let FlipAction::DontFlip = action {
return None;
}
ctx.add_action(AssistId("flip_binexpr"), "flip binary expression", |edit| {
edit.target(op_range);
if let FlipAction::FlipAndReplaceOp(new_op) = action {
edit.replace(op_range, new_op);
}
edit.replace(lhs.range(), rhs.text());
edit.replace(rhs.range(), lhs.text());
});
ctx.build()
}
enum FlipAction {
// Flip the expression
Flip,
// Flip the expression and replace the operator with this string
FlipAndReplaceOp(&'static str),
// Do not flip the expression
DontFlip,
}
impl From<BinOp> for FlipAction {
fn from(op_kind: BinOp) -> Self {
match op_kind {
BinOp::Assignment => FlipAction::DontFlip,
BinOp::AddAssign => FlipAction::DontFlip,
BinOp::DivAssign => FlipAction::DontFlip,
BinOp::MulAssign => FlipAction::DontFlip,
BinOp::RemAssign => FlipAction::DontFlip,
BinOp::ShrAssign => FlipAction::DontFlip,
BinOp::ShlAssign => FlipAction::DontFlip,
BinOp::SubAssign => FlipAction::DontFlip,
BinOp::BitOrAssign => FlipAction::DontFlip,
BinOp::BitAndAssign => FlipAction::DontFlip,
BinOp::BitXorAssign => FlipAction::DontFlip,
BinOp::GreaterTest => FlipAction::FlipAndReplaceOp("<"),
BinOp::GreaterEqualTest => FlipAction::FlipAndReplaceOp("<="),
BinOp::LesserTest => FlipAction::FlipAndReplaceOp(">"),
BinOp::LesserEqualTest => FlipAction::FlipAndReplaceOp(">="),
_ => FlipAction::Flip,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::helpers::{ check_assist, check_assist_target, check_assist_not_applicable };
#[test]
fn flip_binexpr_target_is_the_op() {
check_assist_target(flip_binexpr, "fn f() { let res = 1 ==<|> 2; }", "==")
}
#[test]
fn flip_binexpr_not_applicable_for_assignment() {
check_assist_not_applicable(flip_binexpr, "fn f() { let mut _x = 1; _x +=<|> 2 }")
}
#[test]
fn flip_binexpr_works_for_eq() {
check_assist(
flip_binexpr,
"fn f() { let res = 1 ==<|> 2; }",
"fn f() { let res = 2 ==<|> 1; }",
)
}
#[test]
fn flip_binexpr_works_for_gt() {
check_assist(
flip_binexpr,
"fn f() { let res = 1 ><|> 2; }",
"fn f() { let res = 2 <<|> 1; }",
)
}
#[test]
fn flip_binexpr_works_for_lteq() {
check_assist(
flip_binexpr,
"fn f() { let res = 1 <=<|> 2; }",
"fn f() { let res = 2 >=<|> 1; }",
)
}
#[test]
fn flip_binexpr_works_for_complex_expr() {
check_assist(
flip_binexpr,
"fn f() { let res = (1 + 1) ==<|> (2 + 2); }",
"fn f() { let res = (2 + 2) ==<|> (1 + 1); }",
)
}
#[test]
fn flip_binexpr_works_inside_match() {
check_assist(
flip_binexpr,
r#"
fn dyn_eq(&self, other: &dyn Diagnostic) -> bool {
match other.downcast_ref::<Self>() {
None => false,
Some(it) => it ==<|> self,
}
}
"#,
r#"
fn dyn_eq(&self, other: &dyn Diagnostic) -> bool {
match other.downcast_ref::<Self>() {
None => false,
Some(it) => self ==<|> it,
}
}
"#,
)
}
}

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@ -1,86 +0,0 @@
use hir::db::HirDatabase;
use ra_syntax::ast::{AstNode, BinExpr, BinOp};
use crate::{AssistCtx, Assist, AssistId};
pub(crate) fn flip_eq_operands(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
let expr = ctx.node_at_offset::<BinExpr>()?;
let lhs = expr.lhs()?.syntax();
let rhs = expr.rhs()?.syntax();
let op_range = expr.op()?.range();
let cursor_in_range = ctx.frange.range.is_subrange(&op_range);
let allowed_ops = [BinOp::EqualityTest, BinOp::NegatedEqualityTest];
let expr_op = expr.op_kind()?;
if !cursor_in_range || !allowed_ops.iter().any(|o| *o == expr_op) {
return None;
}
ctx.add_action(AssistId("flip_eq_operands"), "flip equality operands", |edit| {
edit.target(op_range);
edit.replace(lhs.range(), rhs.text());
edit.replace(rhs.range(), lhs.text());
});
ctx.build()
}
#[cfg(test)]
mod tests {
use super::*;
use crate::helpers::{check_assist, check_assist_target};
#[test]
fn flip_eq_operands_for_simple_stmt() {
check_assist(
flip_eq_operands,
"fn f() { let res = 1 ==<|> 2; }",
"fn f() { let res = 2 ==<|> 1; }",
)
}
#[test]
fn flip_neq_operands_for_simple_stmt() {
check_assist(
flip_eq_operands,
"fn f() { let res = 1 !=<|> 2; }",
"fn f() { let res = 2 !=<|> 1; }",
)
}
#[test]
fn flip_eq_operands_for_complex_stmt() {
check_assist(
flip_eq_operands,
"fn f() { let res = (1 + 1) ==<|> (2 + 2); }",
"fn f() { let res = (2 + 2) ==<|> (1 + 1); }",
)
}
#[test]
fn flip_eq_operands_in_match_expr() {
check_assist(
flip_eq_operands,
r#"
fn dyn_eq(&self, other: &dyn Diagnostic) -> bool {
match other.downcast_ref::<Self>() {
None => false,
Some(it) => it ==<|> self,
}
}
"#,
r#"
fn dyn_eq(&self, other: &dyn Diagnostic) -> bool {
match other.downcast_ref::<Self>() {
None => false,
Some(it) => self ==<|> it,
}
}
"#,
)
}
#[test]
fn flip_eq_operands_target() {
check_assist_target(flip_eq_operands, "fn f() { let res = 1 ==<|> 2; }", "==")
}
}

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@ -88,7 +88,7 @@ where
mod add_derive;
mod add_impl;
mod flip_comma;
mod flip_eq_operands;
mod flip_binexpr;
mod change_visibility;
mod fill_match_arms;
mod fill_struct_fields;
@ -108,7 +108,7 @@ fn all_assists<DB: HirDatabase>() -> &'static [fn(AssistCtx<DB>) -> Option<Assis
fill_match_arms::fill_match_arms,
fill_struct_fields::fill_struct_fields,
flip_comma::flip_comma,
flip_eq_operands::flip_eq_operands,
flip_binexpr::flip_binexpr,
introduce_variable::introduce_variable,
replace_if_let_with_match::replace_if_let_with_match,
split_import::split_import,