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authorAkshay <[email protected]>2021-10-08 17:17:07 +0100
committerAkshay <[email protected]>2021-10-08 17:17:07 +0100
commitc6ea58410cb6145cf2791f0ae0d1918cf0d5bc62 (patch)
treeead9b264a346e41198d8fbf3ec84eccf27f59af7 /lib/src
parentdf6d9dc1c390d86b378c103ec03dc75af2474d10 (diff)
new lint: eta_reduction
Diffstat (limited to 'lib/src')
-rw-r--r--lib/src/lints.rs1
-rw-r--r--lib/src/lints/eta_reduction.rs51
2 files changed, 52 insertions, 0 deletions
diff --git a/lib/src/lints.rs b/lib/src/lints.rs
index 7da4933..868cd26 100644
--- a/lib/src/lints.rs
+++ b/lib/src/lints.rs
@@ -7,4 +7,5 @@ lint_map! {
7 manual_inherit_from, 7 manual_inherit_from,
8 legacy_let_syntax, 8 legacy_let_syntax,
9 collapsible_let_in, 9 collapsible_let_in,
10 eta_reduction,
10} 11}
diff --git a/lib/src/lints/eta_reduction.rs b/lib/src/lints/eta_reduction.rs
new file mode 100644
index 0000000..8c34205
--- /dev/null
+++ b/lib/src/lints/eta_reduction.rs
@@ -0,0 +1,51 @@
1use crate::{Lint, Metadata, Report, Rule, Suggestion};
2
3use if_chain::if_chain;
4use macros::lint;
5use rnix::{
6 types::{Lambda, Ident, Apply, TypedNode, TokenWrapper},
7 NodeOrToken, SyntaxElement, SyntaxKind,
8};
9
10#[lint(
11 name = "eta reduction",
12 note = "This function expression is eta reducible",
13 code = 7,
14 match_with = SyntaxKind::NODE_LAMBDA
15)]
16struct EtaReduction;
17
18impl Rule for EtaReduction {
19 fn validate(&self, node: &SyntaxElement) -> Option<Report> {
20 if_chain! {
21 if let NodeOrToken::Node(node) = node;
22 if let Some(lambda_expr) = Lambda::cast(node.clone());
23
24 if let Some(arg_node) = lambda_expr.arg();
25 if let Some(arg) = Ident::cast(arg_node);
26
27 if let Some(body_node) = lambda_expr.body();
28 if let Some(body) = Apply::cast(body_node);
29
30 if let Some(value_node) = body.value();
31 if let Some(value) = Ident::cast(value_node);
32
33 if arg.as_str() == value.as_str() ;
34
35 then {
36 let at = node.text_range();
37 let replacement = body.lambda()?;
38 let message =
39 format!(
40 "Found eta-reduction: `{}`",
41 replacement.text().to_string()
42 );
43 Some(Self::report().suggest(at, message, Suggestion::new(at, replacement)))
44 } else {
45 None
46 }
47 }
48 }
49}
50
51