From e8130a90dca048d195603281f72e1af0b4f7ccc6 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Sun, 20 Feb 2022 09:37:32 +0530
Subject: new lint: bool_simplification
TODO: add more patterns to this
---
lib/src/lints.rs | 1 +
lib/src/lints/bool_simplification.rs | 61 ++++++++++++++++++++++++++++++++++++
2 files changed, 62 insertions(+)
create mode 100644 lib/src/lints/bool_simplification.rs
(limited to 'lib/src')
diff --git a/lib/src/lints.rs b/lib/src/lints.rs
index 439fd8f..582cabe 100644
--- a/lib/src/lints.rs
+++ b/lib/src/lints.rs
@@ -18,4 +18,5 @@ lints! {
faster_groupby,
faster_zipattrswith,
deprecated_to_path,
+ bool_simplification,
}
diff --git a/lib/src/lints/bool_simplification.rs b/lib/src/lints/bool_simplification.rs
new file mode 100644
index 0000000..9ccb1f6
--- /dev/null
+++ b/lib/src/lints/bool_simplification.rs
@@ -0,0 +1,61 @@
+use crate::{make, session::SessionInfo, Metadata, Report, Rule, Suggestion};
+
+use if_chain::if_chain;
+use macros::lint;
+use rnix::{
+ types::{BinOp, BinOpKind, Paren, TypedNode, UnaryOp, UnaryOpKind, Wrapper},
+ NodeOrToken, SyntaxElement, SyntaxKind,
+};
+
+/// ## What it does
+/// Checks for boolean expressions that can be simplified.
+///
+/// ## Why is this bad?
+/// Complex booleans affect readibility.
+///
+/// ## Example
+/// ```nix
+/// if !(x == y) then 0 else 1
+/// ```
+///
+/// Use `!=` instead:
+///
+/// ```nix
+/// if x != y then 0 else 1
+/// ```
+#[lint(
+ name = "bool_simplification",
+ note = "This boolean expression can be simplified",
+ code = 18,
+ match_with = SyntaxKind::NODE_UNARY_OP
+)]
+struct BoolSimplification;
+
+impl Rule for BoolSimplification {
+ fn validate(&self, node: &SyntaxElement, _sess: &SessionInfo) -> Option<Report> {
+ if_chain! {
+ if let NodeOrToken::Node(node) = node;
+ if let Some(unary_expr) = UnaryOp::cast(node.clone());
+ if unary_expr.operator() == UnaryOpKind::Invert;
+ if let Some(value_expr) = unary_expr.value();
+ if let Some(paren_expr) = Paren::cast(value_expr.clone());
+ if let Some(inner_expr) = paren_expr.inner();
+ if let Some(bin_expr) = BinOp::cast(inner_expr);
+ if let Some(BinOpKind::Equal) = bin_expr.operator();
+ then {
+ let at = node.text_range();
+ let message = "Try `!=` instead of `!(... == ...)`";
+
+ let lhs = bin_expr.lhs()?;
+ let rhs = bin_expr.rhs()?;
+ let replacement = make::binary(&lhs, "!=", &rhs).node().clone();
+ Some(
+ self.report()
+ .suggest(at, message, Suggestion::new(at, replacement)),
+ )
+ } else {
+ None
+ }
+ }
+ }
+}
--
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