use hir::db::HirDatabase; use ra_syntax::ast::{AstNode, BinExpr, BinOp}; use crate::{Assist, AssistCtx, AssistId}; // Assist: flip_binexpr // // Flips operands of a binary expression. // // ``` // fn main() { // let _ = 90 +<|> 2; // } // ``` // -> // ``` // fn main() { // let _ = 2 + 90; // } // ``` pub(crate) fn flip_binexpr(ctx: AssistCtx) -> Option { let expr = ctx.find_node_at_offset::()?; let lhs = expr.lhs()?.syntax().clone(); let rhs = expr.rhs()?.syntax().clone(); let op_range = expr.op_token()?.text_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_assist(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.text_range(), rhs.text()); edit.replace(rhs.text_range(), lhs.text()); }) } 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 for FlipAction { fn from(op_kind: BinOp) -> Self { match op_kind { kind if kind.is_assignment() => 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_not_applicable, check_assist_target}; #[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::() { None => false, Some(it) => it ==<|> self, } } "#, r#" fn dyn_eq(&self, other: &dyn Diagnostic) -> bool { match other.downcast_ref::() { None => false, Some(it) => self ==<|> it, } } "#, ) } }