[PATCH v2] userdiff: add support for Swift
- From
Shlok Kulshreshtha <diy2903@gmail.com>
- Date
- Jul 21, 2026, 06:57 UTC
- Message-ID
- <20260721065736.8747-1-diy2903@gmail.com>
- In-Reply-To
- <20260717140232.6722-1-diy2903@gmail.com>
Add a built-in userdiff driver for the Swift programming language so that diff hunk headers and word diffs work out of the box for ".swift" files.
The funcname pattern is built for Swift's own declaration grammar: an optional run of attributes ("@objc", "@available(iOS 13, *)", ...), followed by an optional run of lowercase modifiers ("public", "static", "final", ...), followed by a declaration keyword (func, class, struct, enum, protocol, extension, actor, init, deinit, subscript). The keyword is followed by a boundary that allows whitespace, "(" (init/subscript), "?" or "!" (failable init), or "<" (generics), while still acting as a word boundary so e.g. "initialize(" does not match.
The word regex recognizes Swift identifiers, hexadecimal, octal, binary, integer and floating-point literals, and the language's operators.
Signed-off-by: Shlok Kulshreshtha <diy2903@gmail.com> --- v2, addressing Johannes Sixt's review of v1 (<2a3a73c5-5e90-44a3-bf6a-6e98ce5e5a59@kdbg.org>). Changes since v1:
- t4018/swift-{init,failable-init,generic-subscript}: "RIGHT" now
appears only once, on the declaration line, so the expected header is
unambiguous.
- word regex: dropped the redundant "?" after the single-character
operator class. Single characters are already covered by the
"|[^[:space:]]" fallback that the PATTERNS macro appends, so only the
two-character forms need to be spelled out.(A couple of Hannes's other suggestions I kept as-is; I have explained the reasoning in a reply to his review.)
Some coverage evidence beyond the t4018 fixtures:
- Grammar: a test over every declaration form in Swift's grammar summary (26 forms -- func/class/struct/enum/protocol/extension/actor, init incl. "init?"/"init!"/generic, deinit, subscript incl. generic, operator methods, stacked modifiers, inline attributes with and without arguments, "where" clauses, multi-line signatures) -- all 26 resolve to the correct declaration.
- Corpus: run over the last 200 commits touching *.swift in seven
stylistically different projects (Alamofire, apple/
swift-argument-parser, vapor, Kingfisher, RxSwift, SnapKit,
pointfreeco/swift-composable-architecture): of 20454 hunks, 15310
produced a header and 15296 (99.9%) named a real declaration. The
empty-header hunks are changes with no enclosing declaration (file
comment blocks, imports, Package.swift, top-level code); sampling
found no change inside a declaration that failed to get a header.
The handful of non-declaration headers are the selective-import form
("import class Foundation.Bundle"), which reads "import" as a
modifier; rare and low-harm, and I can exclude it in a follow-up if
preferred.Documentation/gitattributes.adoc | 2 ++ t/t4018/swift-actor | 5 +++++ t/t4018/swift-attribute-with-args | 7 +++++++ t/t4018/swift-class | 5 +++++ t/t4018/swift-enum | 5 +++++ t/t4018/swift-extension | 5 +++++ t/t4018/swift-failable-init | 7 +++++++ t/t4018/swift-func | 5 +++++ t/t4018/swift-generic-subscript | 7 +++++++ t/t4018/swift-init | 7 +++++++ t/t4018/swift-inline-attribute | 7 +++++++ t/t4018/swift-modifiers | 4 ++++ t/t4018/swift-protocol | 5 +++++ t/t4018/swift-struct | 5 +++++ userdiff.c | 10 ++++++++++ 15 files changed, 86 insertions(+) create mode 100644 t/t4018/swift-actor create mode 100644 t/t4018/swift-attribute-with-args create mode 100644 t/t4018/swift-class create mode 100644 t/t4018/swift-enum create mode 100644 t/t4018/swift-extension create mode 100644 t/t4018/swift-failable-init create mode 100644 t/t4018/swift-func create mode 100644 t/t4018/swift-generic-subscript create mode 100644 t/t4018/swift-init create mode 100644 t/t4018/swift-inline-attribute create mode 100644 t/t4018/swift-modifiers create mode 100644 t/t4018/swift-protocol create mode 100644 t/t4018/swift-struct
diff --git a/Documentation/gitattributes.adoc b/Documentation/gitattributes.adoc index bd76167a45..9fea75f96f 100644 --- a/Documentation/gitattributes.adoc +++ b/Documentation/gitattributes.adoc @@ -914,6 +914,8 @@ patterns are available: - `scheme` suitable for source code in most Lisp dialects, including Scheme, Emacs Lisp, Common Lisp, and Clojure. +- `swift` suitable for source code in the Swift language. + - `tex` suitable for source code for LaTeX documents. diff --git a/t/t4018/swift-actor b/t/t4018/swift-actor new file mode 100644 index 0000000000..e4852f40a7 --- /dev/null +++ b/t/t4018/swift-actor @@ -0,0 +1,5 @@ +actor RIGHT { + let a = 1 + // a comment + let b = ChangeMe +} diff --git a/t/t4018/swift-attribute-with-args b/t/t4018/swift-attribute-with-args new file mode 100644 index 0000000000..22b1ee32f1 --- /dev/null +++ b/t/t4018/swift-attribute-with-args @@ -0,0 +1,7 @@ +struct View { + @available(iOS 13, *) public func RIGHT() { + let a = 1 + // a comment + print(ChangeMe) + } +} diff --git a/t/t4018/swift-class b/t/t4018/swift-class new file mode 100644 index 0000000000..c3a9336027 --- /dev/null +++ b/t/t4018/swift-class @@ -0,0 +1,5 @@ +class RIGHT { + let a = 1 + // a comment + let b = ChangeMe +} diff --git a/t/t4018/swift-enum b/t/t4018/swift-enum new file mode 100644 index 0000000000..0a84302993 --- /dev/null +++ b/t/t4018/swift-enum @@ -0,0 +1,5 @@ +enum RIGHT { + case first + // a comment + case ChangeMe +} diff --git a/t/t4018/swift-extension b/t/t4018/swift-extension new file mode 100644 index 0000000000..cbc18ab6ef --- /dev/null +++ b/t/t4018/swift-extension @@ -0,0 +1,5 @@ +extension RIGHT { + static let a = 1 + // a comment + static let b = ChangeMe +} diff --git a/t/t4018/swift-failable-init b/t/t4018/swift-failable-init new file mode 100644 index 0000000000..4bbd6217c9 --- /dev/null +++ b/t/t4018/swift-failable-init @@ -0,0 +1,7 @@ +class Bar { + init?(RIGHT: Int) { + let x = 0 + // a comment + print(ChangeMe) + } +} diff --git a/t/t4018/swift-func b/t/t4018/swift-func new file mode 100644 index 0000000000..1fecae0911 --- /dev/null +++ b/t/t4018/swift-func @@ -0,0 +1,5 @@ +func RIGHT(x: Int) -> Int { + let y = x + // a comment + return ChangeMe +} diff --git a/t/t4018/swift-generic-subscript b/t/t4018/swift-generic-subscript new file mode 100644 index 0000000000..423cb58941 --- /dev/null +++ b/t/t4018/swift-generic-subscript @@ -0,0 +1,7 @@ +struct Container { + subscript<RIGHT>(index: Int) -> Int { + let a = 0 + // a comment + return ChangeMe + } +} diff --git a/t/t4018/swift-init b/t/t4018/swift-init new file mode 100644 index 0000000000..dc7a298f38 --- /dev/null +++ b/t/t4018/swift-init @@ -0,0 +1,7 @@ +class Foo { + init(RIGHT: Int) { + let x = 0 + // a comment + print(ChangeMe) + } +} diff --git a/t/t4018/swift-inline-attribute b/t/t4018/swift-inline-attribute new file mode 100644 index 0000000000..2374c4b603 --- /dev/null +++ b/t/t4018/swift-inline-attribute @@ -0,0 +1,7 @@ +class Service { + @objc func RIGHT() { + let path = "/api" + // a comment + log(ChangeMe) + } +} diff --git a/t/t4018/swift-modifiers b/t/t4018/swift-modifiers new file mode 100644 index 0000000000..9d80685a78 --- /dev/null +++ b/t/t4018/swift-modifiers @@ -0,0 +1,4 @@ +public static func RIGHT() -> Int { + // a comment + return ChangeMe +} diff --git a/t/t4018/swift-protocol b/t/t4018/swift-protocol new file mode 100644 index 0000000000..07c39ec2a3 --- /dev/null +++ b/t/t4018/swift-protocol @@ -0,0 +1,5 @@ +protocol RIGHT { + var first: Int { get } + // a comment + var second: ChangeMe { get } +} diff --git a/t/t4018/swift-struct b/t/t4018/swift-struct new file mode 100644 index 0000000000..e399ed7759 --- /dev/null +++ b/t/t4018/swift-struct @@ -0,0 +1,5 @@ +struct RIGHT { + let a = 1 + // a comment + let b = ChangeMe +} diff --git a/userdiff.c b/userdiff.c index b5412e6bc3..7129bf1482 100644 --- a/userdiff.c +++ b/userdiff.c @@ -362,6 +362,16 @@ PATTERNS("scheme", "\\|([^|\\\\]|\\\\.)*\\|" /* All other words should be delimited by spaces or parentheses. */ "|([^][)(}{ \t])+"), +PATTERNS("swift", + "^[ \t]*((@[A-Za-z_][A-Za-z0-9_]*(\\([^()]*\\))?[ \t]+)*([a-z]+[ \t]+)*(func|init|deinit|subscript|class|struct|enum|protocol|extension|actor)[ \t(?!<].*)$", + /* -- */ + "[a-zA-Z_][a-zA-Z0-9_]*" + /* hexadecimal, octal, and binary literals */ + "|0[xX][0-9a-fA-F_]+|0[oO][0-7_]+|0[bB][01_]+" + /* integers and floating-point numbers */ + "|[0-9][0-9_]*([.][0-9_]+)?([eE][-+]?[0-9]+)?" + /* unary and binary operators */ + "|[-+*/%<>=!&|^~?]=|&&|\\|\\||<<=?|>>=?|\\?\\?|\\.\\.[.<]|->"), PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$", "\\\\[a-zA-Z@]+|\\\\.|([a-zA-Z0-9]|[^\x01-\x7f])+"), { .name = "default", .binary = -1 }, Range-diff against v1: 1: 1e7e199355 ! 1: af48611565 userdiff: add support for Swift @@ t/t4018/swift-failable-init (new) @@ +class Bar { + init?(RIGHT: Int) { -+ let value = RIGHT ++ let x = 0 + // a comment + print(ChangeMe) + } @@ t/t4018/swift-func (new) ## t/t4018/swift-generic-subscript (new) ## @@ +struct Container { -+ subscript<RIGHT>(index: RIGHT) -> Int { ++ subscript<RIGHT>(index: Int) -> Int { + let a = 0 + // a comment + return ChangeMe @@ t/t4018/swift-init (new) @@ +class Foo { + init(RIGHT: Int) { -+ let value = RIGHT ++ let x = 0 + // a comment + print(ChangeMe) + } @@ userdiff.c: PATTERNS("scheme", + /* integers and floating-point numbers */ + "|[0-9][0-9_]*([.][0-9_]+)?([eE][-+]?[0-9]+)?" + /* unary and binary operators */ -+ "|[-+*/%<>=!&|^~?]=?|&&|\\|\\||<<=?|>>=?|\\?\\?|\\.\\.[.<]|->"), ++ "|[-+*/%<>=!&|^~?]=|&&|\\|\\||<<=?|>>=?|\\?\\?|\\.\\.[.<]|->"), PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$", "\\\\[a-zA-Z@]+|\\\\.|([a-zA-Z0-9]|[^\x01-\x7f])+"), { .name = "default", .binary = -1 },
-- 2.52.0