fix enum_variant_names linting on all caps enum variants

src/enum_variants.rs

@@ -6,6 +6,7 @@ use syntax::ast::*;
 use syntax::parse::token::InternedString;
 
 use utils::span_help_and_lint;
+use utils::{camel_case_from, camel_case_until};
 
 /// **What it does:** Warns on enum variants that are prefixed or suffixed by the same characters
 ///
@@ -31,48 +32,63 @@ fn var2str(var: &Variant) -> InternedString {
     var.node.name.name.as_str()
 }
 
-fn partial_match(left: &str, right: &str) -> usize {
-    left.chars().zip(right.chars()).take_while(|&(l, r)| l == r).count()
+/*
+FIXME: waiting for https://github.com/rust-lang/rust/pull/31700
+fn partial_match(pre: &str, name: &str) -> usize {
+    // skip(1) to ensure that the prefix never takes the whole variant name
+    pre.chars().zip(name.chars().rev().skip(1).rev()).take_while(|&(l, r)| l == r).count()
 }
 
-fn partial_rmatch(left: &str, right: &str) -> usize {
-    left.chars().rev().zip(right.chars().rev()).take_while(|&(l, r)| l == r).count()
+fn partial_rmatch(post: &str, name: &str) -> usize {
+    // skip(1) to ensure that the postfix never takes the whole variant name
+    post.chars().rev().zip(name.chars().skip(1).rev()).take_while(|&(l, r)| l == r).count()
+}*/
+
+fn partial_match(pre: &str, name: &str) -> usize {
+    let mut name_iter = name.chars();
+    let _ = name_iter.next_back(); // make sure the name is never fully matched
+    pre.chars().zip(name_iter).take_while(|&(l, r)| l == r).count()
+}
+
+fn partial_rmatch(post: &str, name: &str) -> usize {
+    let mut name_iter = name.chars();
+    let _ = name_iter.next(); // make sure the name is never fully matched
+    post.chars().rev().zip(name_iter.rev()).take_while(|&(l, r)| l == r).count()
 }
 
 impl EarlyLintPass for EnumVariantNames {
+    // FIXME: #600
+    #[allow(while_let_on_iterator)]
     fn check_item(&mut self, cx: &EarlyContext, item: &Item) {
         if let ItemKind::Enum(ref def, _) = item.node {
             if def.variants.len() < 2 {
                 return;
             }
             let first = var2str(&def.variants[0]);
-            let mut pre = first.to_string();
-            let mut post = pre.clone();
-            for var in &def.variants[1..] {
+            let mut pre = &first[..camel_case_until(&*first)];
+            let mut post = &first[camel_case_from(&*first)..];
+            for var in &def.variants {
                 let name = var2str(var);
+
                 let pre_match = partial_match(&pre, &name);
-                let post_match = partial_rmatch(&post, &name);
-                pre.truncate(pre_match);
-                let post_end = post.len() - post_match;
-                post.drain(..post_end);
-            }
-            if let Some(c) = first[pre.len()..].chars().next() {
-                if !c.is_uppercase() {
-                    // non camel case prefix
-                    pre.clear()
-                }
-            }
-            if let Some(c) = first[..(first.len() - post.len())].chars().rev().next() {
-                if let Some(c1) = post.chars().next() {
-                    if !c.is_lowercase() || !c1.is_uppercase() {
-                        // non camel case postfix
-                        post.clear()
+                pre = &pre[..pre_match];
+                let pre_camel = camel_case_until(&pre);
+                pre = &pre[..pre_camel];
+                while let Some((next, last)) = name[pre.len()..].chars().zip(pre.chars().rev()).next() {
+                    if next.is_lowercase() {
+                        let last = pre.len() - last.len_utf8();
+                        let last_camel = camel_case_until(&pre[..last]);
+                        pre = &pre[..last_camel];
+                    } else {
+                        break;
                     }
                 }
-            }
-            if pre == "_" {
-                // don't lint on underscores which are meant to allow dead code
-                pre.clear();
+
+                let post_match = partial_rmatch(&post, &name);
+                let post_end = post.len() - post_match;
+                post = &post[post_end..];
+                let post_camel = camel_case_from(&post);
+                post = &post[post_camel..];
             }
             let (what, value) = if !pre.is_empty() {
                 ("pre", pre)

src/utils/mod.rs

@@ -607,3 +607,65 @@ pub fn is_expn_of(cx: &LateContext, mut span: Span, name: &str) -> Option<Span>
         }
     }
 }
+
+/// Returns index of character after first CamelCase component of `s`
+pub fn camel_case_until(s: &str) -> usize {
+    let mut iter = s.char_indices();
+    if let Some((_, first)) = iter.next() {
+        if !first.is_uppercase() {
+            return 0;
+        }
+    } else {
+        return 0;
+    }
+    let mut up = true;
+    let mut last_i = 0;
+    for (i, c) in iter {
+        if up {
+            if c.is_lowercase() {
+                up = false;
+            } else {
+                return last_i;
+            }
+        } else if c.is_uppercase() {
+            up = true;
+            last_i = i;
+        } else if !c.is_lowercase() {
+            return i;
+        }
+    }
+    if up {
+        last_i
+    } else {
+        s.len()
+    }
+}
+
+/// Returns index of last CamelCase component of `s`.
+pub fn camel_case_from(s: &str) -> usize {
+    let mut iter = s.char_indices().rev();
+    if let Some((_, first)) = iter.next() {
+        if !first.is_lowercase() {
+            return s.len();
+        }
+    } else {
+        return s.len();
+    }
+    let mut down = true;
+    let mut last_i = s.len();
+    for (i, c) in iter {
+        if down {
+            if c.is_uppercase() {
+                down = false;
+                last_i = i;
+            } else if !c.is_lowercase() {
+                return last_i;
+            }
+        } else if c.is_lowercase() {
+            down = true;
+        } else {
+            return last_i;
+        }
+    }
+    last_i
+}

tests/camel_case.rs

@@ -0,0 +1,51 @@
+#[allow(plugin_as_library)]
+extern crate clippy;
+
+use clippy::utils::{camel_case_from, camel_case_until};
+
+#[test]
+fn from_full() {
+    assert_eq!(camel_case_from("AbcDef"), 0);
+    assert_eq!(camel_case_from("Abc"), 0);
+}
+
+#[test]
+fn from_partial() {
+    assert_eq!(camel_case_from("abcDef"), 3);
+    assert_eq!(camel_case_from("aDbc"), 1);
+}
+
+#[test]
+fn from_not() {
+    assert_eq!(camel_case_from("AbcDef_"), 7);
+    assert_eq!(camel_case_from("AbcDD"), 5);
+}
+
+#[test]
+fn from_caps() {
+    assert_eq!(camel_case_from("ABCD"), 4);
+}
+
+#[test]
+fn until_full() {
+    assert_eq!(camel_case_until("AbcDef"), 6);
+    assert_eq!(camel_case_until("Abc"), 3);
+}
+
+#[test]
+fn until_not() {
+    assert_eq!(camel_case_until("abcDef"), 0);
+    assert_eq!(camel_case_until("aDbc"), 0);
+}
+
+#[test]
+fn until_partial() {
+    assert_eq!(camel_case_until("AbcDef_"), 6);
+    assert_eq!(camel_case_until("CallTypeC"), 8);
+    assert_eq!(camel_case_until("AbcDD"), 3);
+}
+
+#[test]
+fn until_caps() {
+    assert_eq!(camel_case_until("ABCD"), 0);
+}

tests/compile-fail/enum_variants.rs

@@ -0,0 +1,71 @@
+#![feature(plugin, non_ascii_idents)]
+#![plugin(clippy)]
+#![deny(clippy)]
+
+enum FakeCallType {
+    CALL, CREATE
+}
+
+enum FakeCallType2 {
+    CALL, CREATELL
+}
+
+enum Foo {
+    cFoo, cBar,
+}
+
+enum BadCallType { //~ ERROR: All variants have the same prefix: `CallType`
+    CallTypeCall,
+    CallTypeCreate,
+    CallTypeDestroy,
+}
+
+enum TwoCallType { //~ ERROR: All variants have the same prefix: `CallType`
+    CallTypeCall,
+    CallTypeCreate,
+}
+
+enum Consts { //~ ERROR: All variants have the same prefix: `Constant`
+    ConstantInt,
+    ConstantCake,
+    ConstantLie,
+}
+
+enum Two { //~ ERROR: All variants have the same prefix: `Constant`
+    ConstantInt,
+    ConstantInfer,
+}
+
+enum Something {
+    CCall,
+    CCreate,
+    CCryogenize,
+}
+
+enum Seal {
+    With,
+    Without,
+}
+
+enum Seall {
+    With,
+    WithOut,
+    Withbroken,
+}
+
+enum Sealll {
+    With,
+    WithOut,
+}
+
+enum Seallll { //~ ERROR: All variants have the same prefix: `With`
+    WithOutCake,
+    WithOut,
+}
+
+enum NonCaps { //~ ERROR: All variants have the same prefix: `Prefix`
+    Prefix的,
+    PrefixCake,
+}
+
+fn main() {}