Fix false positives in array_init rule with prefix operators

Fixes realm#1877
sjavora · Mar 9, 2019 · fc76d89 · fc76d89
1 parent 91e3964
commit fc76d89
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -22,6 +22,10 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#2159](https://github.com/realm/SwiftLint/issues/2159)
 
+* Fix false positives on `array_init` rule when using prefix operators.  
+  [Marcelo Fabri](https://github.com/marcelofabri)
+  [#1877](https://github.com/realm/SwiftLint/issues/1877)
+
 ## 0.30.0: A New Washer and Dryer Set
 
 #### Breaking

diff --git a/Rules.md b/Rules.md
@@ -276,6 +276,16 @@ foo.something { RouteMapper.map($0) }
 
 ```
 
+```swift
+foo.map { !$0 }
+
+```
+
+```swift
+foo.map { /* a comment */ !$0 }
+
+```
+
 </details>
 <details>
 <summary>Triggering Examples</summary>
@@ -328,6 +338,11 @@ foo.something { RouteMapper.map($0) }
 
 ```
 
+```swift
+↓foo.map { /* a comment */ $0 }
+
+```
+
 </details>
 
 

diff --git a/Source/SwiftLintFramework/Rules/Lint/ArrayInitRule.swift b/Source/SwiftLintFramework/Rules/Lint/ArrayInitRule.swift
@@ -19,7 +19,9 @@ public struct ArrayInitRule: ASTRule, ConfigurationProviderRule, OptInRule, Auto
             "foo.map { ((), $0) }\n",
             "foo.map { $0! }\n",
             "foo.map { $0! /* force unwrap */ }\n",
-            "foo.something { RouteMapper.map($0) }\n"
+            "foo.something { RouteMapper.map($0) }\n",
+            "foo.map { !$0 }\n",
+            "foo.map { /* a comment */ !$0 }\n"
         ],
         triggeringExamples: [
             "↓foo.map({ $0 })\n",
@@ -37,7 +39,8 @@ public struct ArrayInitRule: ASTRule, ConfigurationProviderRule, OptInRule, Auto
             "↓foo.map { elem -> String in\n" +
             "   elem\n" +
             "}\n",
-            "↓foo.map { $0 /* a comment */ }\n"
+            "↓foo.map { $0 /* a comment */ }\n",
+            "↓foo.map { /* a comment */ $0 }\n"
         ]
     )
 
@@ -68,7 +71,8 @@ public struct ArrayInitRule: ASTRule, ConfigurationProviderRule, OptInRule, Auto
             isParameterStyleViolation(file: file, dictionary: dictionary, tokens: tokens),
             let lastToken = tokens.last,
             case let bodyEndPosition = bodyOffset + bodyLength,
-            !containsTrailingContent(lastToken: lastToken, bodyEndPosition: bodyEndPosition, file: file) else {
+            !containsTrailingContent(lastToken: lastToken, bodyEndPosition: bodyEndPosition, file: file),
+            !containsLeadingContent(tokens: tokens, bodyStartPosition: bodyOffset, file: file) else {
                 return []
         }
 
@@ -98,10 +102,38 @@ public struct ArrayInitRule: ASTRule, ConfigurationProviderRule, OptInRule, Auto
                                          file: File) -> Bool {
         let lastTokenEnd = lastToken.offset + lastToken.length
         let remainingLength = bodyEndPosition - lastTokenEnd
-        let nsstring = file.contents.bridge()
         let remainingRange = NSRange(location: lastTokenEnd, length: remainingLength)
-        let remainingTokens = file.syntaxMap.tokens(inByteRange: remainingRange)
-        let ranges = NSMutableIndexSet(indexesIn: remainingRange)
+        return containsContent(inByteRange: remainingRange, file: file)
+    }
+
+    private func containsLeadingContent(tokens: [SyntaxToken],
+                                        bodyStartPosition: Int,
+                                        file: File) -> Bool {
+        let inTokenPosition = tokens.firstIndex(where: { token in
+            SyntaxKind(rawValue: token.type) == .keyword && file.contents(for: token) == "in"
+        })
+
+        let firstToken: SyntaxToken
+        let start: Int
+        if let position = inTokenPosition {
+            let index = tokens.index(after: position)
+            firstToken = tokens[index]
+            let inToken = tokens[position]
+            start = inToken.offset + inToken.length
+        } else {
+            firstToken = tokens[0]
+            start = bodyStartPosition
+        }
+
+        let length = firstToken.offset - start
+        let remainingRange = NSRange(location: start, length: length)
+        return containsContent(inByteRange: remainingRange, file: file)
+    }
+
+    private func containsContent(inByteRange byteRange: NSRange, file: File) -> Bool {
+        let nsstring = file.contents.bridge()
+        let remainingTokens = file.syntaxMap.tokens(inByteRange: byteRange)
+        let ranges = NSMutableIndexSet(indexesIn: byteRange)
 
         for token in remainingTokens {
             ranges.remove(in: NSRange(location: token.offset, length: token.length))