Respect grapheme clusters in the collection_alignment rule (#5173)

Do so by counting characters. Solves (to some extent) the problem of apparent character counts not matching the UTF-8-based offsets returned by SwiftSyntax.
realm · Sep 11, 2023 · 05818b5 · 05818b5
1 parent f05fbf5
commit 05818b5
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -80,6 +80,10 @@
 
 #### Bug Fixes
 
+* Respect grapheme clusters in counting the number of characters in the `collection_alignment` rule.  
+  [kishikawakatsumi](https://github.com/kishikawakatsumi)
+  [#4837](https://github.com/realm/SwiftLint/issues/4837)
+
 * Fix false positive in `control_statement` rule that triggered on conditions
   with trailing closures where parentheses are recommended by the compiler.  
   [SimplyDanny](https://github.com/SimplyDanny)

diff --git a/Source/SwiftLintBuiltInRules/Rules/Style/CollectionAlignmentRule.swift b/Source/SwiftLintBuiltInRules/Rules/Style/CollectionAlignmentRule.swift
@@ -39,7 +39,24 @@ private extension CollectionAlignmentRule {
             let locations = node.map { element in
                 let position = alignColons ? element.colon.positionAfterSkippingLeadingTrivia :
                 element.key.positionAfterSkippingLeadingTrivia
-                return locationConverter.location(for: position)
+                let location = locationConverter.location(for: position)
+
+                let graphemeColumn: Int
+                let graphemeClusters = String(
+                    locationConverter.sourceLines[location.line - 1].utf8.prefix(location.column - 1)
+                )
+                if let graphemeClusters {
+                    graphemeColumn = graphemeClusters.count + 1
+                } else {
+                    graphemeColumn = location.column
+                }
+
+                return SourceLocation(
+                    line: location.line,
+                    column: graphemeColumn,
+                    offset: location.offset,
+                    file: location.file
+                )
             }
             violations.append(contentsOf: validate(keyLocations: locations))
         }
@@ -141,6 +158,10 @@ extension CollectionAlignmentRule {
                       "b"  :2,
                        "c" :      3
                 ]
+                """),
+                Example("""
+                NSAttributedString(string: "…", attributes: [.font: UIFont.systemFont(ofSize: 12, weight: .regular),
+                                                  .foregroundColor: UIColor(white: 0, alpha: 0.2)])
                 """)
             ]
         }
@@ -199,6 +220,10 @@ extension CollectionAlignmentRule {
                                 "lunch": "sandwich",
                                 "dinner": "burger"
                 ]
+                """),
+                Example("""
+                NSAttributedString(string: "…", attributes: [.font: UIFont.systemFont(ofSize: 12, weight: .regular),
+                                                             .foregroundColor: UIColor(white: 0, alpha: 0.2)])
                 """)
             ]
         }