Migrate no_fallthrough_only rule to SwiftSyntax (realm#4266)

vexonius · Oct 3, 2022 · f37ea8a · f37ea8a
1 parent ac91f7b
commit f37ea8a
Showing 1 changed file with 25 additions and 72 deletions.
diff --git a/Source/SwiftLintFramework/Rules/Idiomatic/NoFallthroughOnlyRule.swift b/Source/SwiftLintFramework/Rules/Idiomatic/NoFallthroughOnlyRule.swift
@@ -1,7 +1,6 @@
-import Foundation
-import SourceKittenFramework
+import SwiftSyntax
 
-public struct NoFallthroughOnlyRule: ASTRule, ConfigurationProviderRule {
+public struct NoFallthroughOnlyRule: SwiftSyntaxRule, ConfigurationProviderRule {
     public var configuration = SeverityConfiguration(.warning)
 
     public init() {}
@@ -15,82 +14,36 @@ public struct NoFallthroughOnlyRule: ASTRule, ConfigurationProviderRule {
         triggeringExamples: NoFallthroughOnlyRuleExamples.triggeringExamples
     )
 
-    public func validate(file: SwiftLintFile,
-                         kind: StatementKind,
-                         dictionary: SourceKittenDictionary) -> [StyleViolation] {
-        guard kind == .case,
-            let byteRange = dictionary.byteRange,
-            case let contents = file.stringView,
-            let range = contents.byteRangeToNSRange(byteRange),
-            let colonLocation = findCaseColon(text: file.stringView.nsString, range: range)
-        else {
-            return []
-        }
+    public func makeVisitor(file: SwiftLintFile) -> ViolationsSyntaxVisitor? {
+        Visitor(viewMode: .sourceAccurate)
+    }
+}
 
-        let caseBodyRange = NSRange(location: colonLocation,
-                                    length: range.length + range.location - colonLocation)
-        let nonCommentCaseBody = file.match(pattern: "\\w+", range: caseBodyRange).filter { _, syntaxKinds in
-            return !Set(syntaxKinds).subtracting(SyntaxKind.commentKinds).isEmpty
-        }
+private extension NoFallthroughOnlyRule {
+    final class Visitor: SyntaxVisitor, ViolationsSyntaxVisitor {
+        private(set) var violationPositions: [AbsolutePosition] = []
 
-        guard nonCommentCaseBody.count == 1 else {
-            return []
-        }
+        override func visitPost(_ node: SwitchCaseListSyntax) {
+            let cases = node.compactMap { $0.as(SwitchCaseSyntax.self) }
 
-        let nsRange = nonCommentCaseBody[0].0
-        if contents.substring(with: nsRange) == "fallthrough" && nonCommentCaseBody[0].1 == [.keyword] &&
-            !isNextTokenUnknownAttribute(afterOffset: byteRange.upperBound, file: file) {
-            return [StyleViolation(ruleDescription: Self.description,
-                                   severity: configuration.severity,
-                                   location: Location(file: file, characterOffset: nsRange.location))]
-        }
+            let violations = cases.enumerated()
+                .compactMap { index, element -> AbsolutePosition? in
+                    guard element.statements.count == 1,
+                          let fallthroughStmt = element.statements.first?.item.as(FallthroughStmtSyntax.self) else {
+                        return nil
+                    }
 
-        return []
-    }
+                    if case let nextCaseIndex = cases.index(after: index),
+                       nextCaseIndex < cases.endIndex,
+                       case let nextCase = cases[nextCaseIndex],
+                       nextCase.unknownAttr != nil {
+                        return nil
+                    }
 
-    private func isNextTokenUnknownAttribute(afterOffset offset: ByteCount, file: SwiftLintFile) -> Bool {
-        let nextNonCommentToken = file.syntaxMap.tokens
-            .first { token in
-                guard let kind = token.kind, !kind.isCommentLike else {
-                    return false
+                    return fallthroughStmt.positionAfterSkippingLeadingTrivia
                 }
-                return token.offset > offset
-            }
-
-        return nextNonCommentToken?.kind == .attributeID &&
-            nextNonCommentToken.flatMap(file.contents(for:)) == "@unknown"
-    }
-
-    // Find the first colon that exists outside of all enclosing delimiters
-    private func findCaseColon(text: NSString, range: NSRange) -> Int? {
-        var nParen = 0
-        var nBrace = 0
-        var nBrack = 0
-        for index in range.location..<(range.location + range.length) {
-            let char = text.substring(with: NSRange(location: index, length: 1))
-            if char == "(" {
-                nParen += 1
-            }
-            if char == ")" {
-                nParen -= 1
-            }
-            if char == "[" {
-                nBrack += 1
-            }
-            if char == "]" {
-                nBrack -= 1
-            }
-            if char == "{" {
-                nBrace += 1
-            }
-            if char == "}" {
-                nBrace -= 1
-            }
 
-            if nParen == 0 && nBrack == 0 && nBrace == 0 && char == ":" {
-                return index
-            }
+            violationPositions.append(contentsOf: violations)
         }
-        return nil
     }
 }