Use tree-based structure matching instead of loop

Author: relaxcn

clippy_lints/src/methods/ip_constant.rs

@@ -8,16 +8,6 @@ use rustc_span::sym;
 
 use super::IP_CONSTANT;
 
-static IPV4V6_CONSTANTS: &[(&[u128], &str)] = &[
-    // Ipv4
-    (&[127, 0, 0, 1], "LOCALHOST"),
-    (&[255, 255, 255, 255], "BROADCAST"),
-    (&[0, 0, 0, 0], "UNSPECIFIED"),
-    // Ipv6
-    (&[0, 0, 0, 0, 0, 0, 0, 1], "LOCALHOST"),
-    (&[0, 0, 0, 0, 0, 0, 0, 0], "UNSPECIFIED"),
-];
-
 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, func: &Expr<'_>, args: &[Expr<'_>]) {
     if let ExprKind::Path(QPath::TypeRelative(
         Ty {
@@ -30,7 +20,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, func: &Expr<'_>, args
         && let Some(func_def_id) = func_path.res.opt_def_id()
         && (cx.tcx.is_diagnostic_item(sym::Ipv4Addr, func_def_id)
             || cx.tcx.is_diagnostic_item(sym::Ipv6Addr, func_def_id))
-        && let Some(constant_name) = is_ipv4v6_constants(cx, args)
+        && let Some(constant_name) = is_ipaddr_constants(cx, args)
     {
         let sugg_snip = format!(
             "{}::{}",
@@ -50,7 +40,63 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, func: &Expr<'_>, args
     }
 }
 
-fn is_ipv4v6_constants(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<&'static str> {
+struct Node {
+    children: &'static [(u128, Node)],
+    constant_name: Option<&'static str>,
+}
+
+impl Node {
+    const fn new(children: &'static [(u128, Node)], constant_name: Option<&'static str>) -> Self {
+        Self {
+            children,
+            constant_name,
+        }
+    }
+
+    const fn leaf(constant_name: &'static str) -> Self {
+        Self {
+            children: &[],
+            constant_name: Some(constant_name),
+        }
+    }
+}
+
+// Tree structure for IP constants
+#[rustfmt::skip]
+static IPADDR_CONSTANTS_TREE: Node = Node::new(&[
+    (127, Node::new(&[
+        (0, Node::new(&[
+            (0, Node::new(&[
+                (1, Node::leaf("LOCALHOST")) // IPv4 127.0.0.1
+            ], None))
+        ], None))
+    ], None)),
+    (255, Node::new(&[
+        (255, Node::new(&[
+            (255, Node::new(&[
+                (255, Node::leaf("BROADCAST")) // IPv4 255.255.255.255
+            ], None))
+        ], None))
+    ], None)),
+    (0, Node::new(&[
+        (0, Node::new(&[
+            (0, Node::new(&[
+                (0, Node::new(&[
+                    (0, Node::new(&[
+                        (0, Node::new(&[
+                            (0, Node::new(&[
+                                (0, Node::leaf("UNSPECIFIED")), // IPv6 ::
+                                (1, Node::leaf("LOCALHOST"))    // IPv6 ::1
+                            ], None))
+                        ], None))
+                    ], None))
+                ], Some("UNSPECIFIED"))) // IPv4 0.0.0.0
+            ], None))
+        ], None))
+    ], None)),
+], None);
+
+fn is_ipaddr_constants(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<&'static str> {
     if args.len() != 4 && args.len() != 8 {
         return None;
     }
@@ -64,12 +110,15 @@ fn is_ipv4v6_constants(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<&'stat
             return None;
         }
     }
-    // Check against known IP constants
-    for (pattern, name) in IPV4V6_CONSTANTS {
-        if pattern.len() == constants.len() && pattern.iter().eq(constants.iter()) {
-            return Some(name);
+
+    let mut current_node = &IPADDR_CONSTANTS_TREE;
+    for value in constants {
+        if let Some((_, next_node)) = current_node.children.iter().find(|(val, _)| *val == value) {
+            current_node = next_node;
+        } else {
+            return None; // Early termination on mismatch
         }
     }
 
-    None
+    current_node.constant_name
 }

tests/ui/ip_constant.fixed

@@ -102,11 +102,17 @@ fn macro_test() {
     // no lint
 }
 
+include!("ip_constant_included.rs");
+
+fn external_constant_test() {
+    use std::net::{Ipv4Addr, Ipv6Addr};
+
+    let _ = Ipv4Addr::LOCALHOST;
+    //~^ ip_constant
+
+    let _ = Ipv6Addr::LOCALHOST;
+}
+
 fn main() {
-    literal_test1();
-    literal_test2();
-    literal_test3();
-    const_test1();
-    const_test2();
-    macro_test();
+    // UI Test
 }

tests/ui/ip_constant.rs

@@ -122,11 +122,27 @@ fn macro_test() {
     // no lint
 }
 
+include!("ip_constant_included.rs");
+
+fn external_constant_test() {
+    use std::net::{Ipv4Addr, Ipv6Addr};
+
+    let _ = Ipv4Addr::new(EXTERNAL_CONST_U8_127, 0, 0, 1);
+    //~^ ip_constant
+
+    let _ = Ipv6Addr::new(
+        //~^ ip_constant
+        EXTERNAL_CONST_U16_0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        1,
+    );
+}
+
 fn main() {
-    literal_test1();
-    literal_test2();
-    literal_test3();
-    const_test1();
-    const_test2();
-    macro_test();
+    // UI Test
 }

tests/ui/ip_constant.stderr

@@ -165,5 +165,24 @@ error: use `Ipv6Addr::LOCALHOST` instead
 LL |     let _ = Ipv6Addr::new(0 + 0, 0, 0, 0, 0, { 2 - 1 - CONST_U16_1 }, 0, 1);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Ipv6Addr::LOCALHOST`
 
-error: aborting due to 25 previous errors
+error: use `Ipv4Addr::LOCALHOST` instead
+  --> tests/ui/ip_constant.rs:130:13
+   |
+LL |     let _ = Ipv4Addr::new(EXTERNAL_CONST_U8_127, 0, 0, 1);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Ipv4Addr::LOCALHOST`
+
+error: use `Ipv6Addr::LOCALHOST` instead
+  --> tests/ui/ip_constant.rs:133:13
+   |
+LL |       let _ = Ipv6Addr::new(
+   |  _____________^
+LL | |
+LL | |         EXTERNAL_CONST_U16_0,
+LL | |         0,
+...  |
+LL | |         1,
+LL | |     );
+   | |_____^ help: try: `Ipv6Addr::LOCALHOST`
+
+error: aborting due to 27 previous errors
 

tests/ui/ip_constant_included.rs

@@ -0,0 +1,5 @@
+//@only-target: NOWAY
+
+const EXTERNAL_CONST_U8_127: u8 = 127;
+
+const EXTERNAL_CONST_U16_0: u16 = 0;