diff options
Diffstat (limited to 'crates/ra_assists/src/handlers/apply_demorgan.rs')
-rw-r--r-- | crates/ra_assists/src/handlers/apply_demorgan.rs | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/crates/ra_assists/src/handlers/apply_demorgan.rs b/crates/ra_assists/src/handlers/apply_demorgan.rs new file mode 100644 index 000000000..ba08a8223 --- /dev/null +++ b/crates/ra_assists/src/handlers/apply_demorgan.rs | |||
@@ -0,0 +1,90 @@ | |||
1 | use super::invert_if::invert_boolean_expression; | ||
2 | use ra_syntax::ast::{self, AstNode}; | ||
3 | |||
4 | use crate::{Assist, AssistCtx, AssistId}; | ||
5 | |||
6 | // Assist: apply_demorgan | ||
7 | // | ||
8 | // Apply [De Morgan's law](https://en.wikipedia.org/wiki/De_Morgan%27s_laws). | ||
9 | // This transforms expressions of the form `!l || !r` into `!(l && r)`. | ||
10 | // This also works with `&&`. This assist can only be applied with the cursor | ||
11 | // on either `||` or `&&`, with both operands being a negation of some kind. | ||
12 | // This means something of the form `!x` or `x != y`. | ||
13 | // | ||
14 | // ``` | ||
15 | // fn main() { | ||
16 | // if x != 4 ||<|> !y {} | ||
17 | // } | ||
18 | // ``` | ||
19 | // -> | ||
20 | // ``` | ||
21 | // fn main() { | ||
22 | // if !(x == 4 && y) {} | ||
23 | // } | ||
24 | // ``` | ||
25 | pub(crate) fn apply_demorgan(ctx: AssistCtx) -> Option<Assist> { | ||
26 | let expr = ctx.find_node_at_offset::<ast::BinExpr>()?; | ||
27 | let op = expr.op_kind()?; | ||
28 | let op_range = expr.op_token()?.text_range(); | ||
29 | let opposite_op = opposite_logic_op(op)?; | ||
30 | let cursor_in_range = ctx.frange.range.is_subrange(&op_range); | ||
31 | if !cursor_in_range { | ||
32 | return None; | ||
33 | } | ||
34 | |||
35 | let lhs = expr.lhs()?; | ||
36 | let lhs_range = lhs.syntax().text_range(); | ||
37 | let not_lhs = invert_boolean_expression(lhs); | ||
38 | |||
39 | let rhs = expr.rhs()?; | ||
40 | let rhs_range = rhs.syntax().text_range(); | ||
41 | let not_rhs = invert_boolean_expression(rhs); | ||
42 | |||
43 | ctx.add_assist(AssistId("apply_demorgan"), "Apply De Morgan's law", |edit| { | ||
44 | edit.target(op_range); | ||
45 | edit.replace(op_range, opposite_op); | ||
46 | edit.replace(lhs_range, format!("!({}", not_lhs.syntax().text())); | ||
47 | edit.replace(rhs_range, format!("{})", not_rhs.syntax().text())); | ||
48 | }) | ||
49 | } | ||
50 | |||
51 | // Return the opposite text for a given logical operator, if it makes sense | ||
52 | fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> { | ||
53 | match kind { | ||
54 | ast::BinOp::BooleanOr => Some("&&"), | ||
55 | ast::BinOp::BooleanAnd => Some("||"), | ||
56 | _ => None, | ||
57 | } | ||
58 | } | ||
59 | |||
60 | #[cfg(test)] | ||
61 | mod tests { | ||
62 | use super::*; | ||
63 | |||
64 | use crate::helpers::{check_assist, check_assist_not_applicable}; | ||
65 | |||
66 | #[test] | ||
67 | fn demorgan_turns_and_into_or() { | ||
68 | check_assist(apply_demorgan, "fn f() { !x &&<|> !x }", "fn f() { !(x ||<|> x) }") | ||
69 | } | ||
70 | |||
71 | #[test] | ||
72 | fn demorgan_turns_or_into_and() { | ||
73 | check_assist(apply_demorgan, "fn f() { !x ||<|> !x }", "fn f() { !(x &&<|> x) }") | ||
74 | } | ||
75 | |||
76 | #[test] | ||
77 | fn demorgan_removes_inequality() { | ||
78 | check_assist(apply_demorgan, "fn f() { x != x ||<|> !x }", "fn f() { !(x == x &&<|> x) }") | ||
79 | } | ||
80 | |||
81 | #[test] | ||
82 | fn demorgan_general_case() { | ||
83 | check_assist(apply_demorgan, "fn f() { x ||<|> x }", "fn f() { !(!x &&<|> !x) }") | ||
84 | } | ||
85 | |||
86 | #[test] | ||
87 | fn demorgan_doesnt_apply_with_cursor_not_on_op() { | ||
88 | check_assist_not_applicable(apply_demorgan, "fn f() { <|> !x || !x }") | ||
89 | } | ||
90 | } | ||