[PATCH] userdiff: add support for Swift
- From
Shlok Kulshreshtha <diy2903@gmail.com>
- Date
- Jul 17, 2026, 14:02 UTC
- Message-ID
- <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> --- This addresses the "add a userdiff driver for a language" microproject. Swift is not covered by a built-in driver yet, and I did not find an in-flight patch adding one on the list; please let me know if one exists.
Motivation: without a Swift driver, ".swift" files use the generic funcname heuristic, so "git diff" hunk headers name the enclosing type instead of the changed function.
The pattern is built directly from Swift's declaration grammar rather than adapted from another language's driver, so it covers a few things that a straight port would miss:
- attributes, with or without arguments, whether on their own line
("@objc" above a "func") or inline with the declaration
("@objc func foo()", "@available(iOS 13, *) public func bar()");
- modifiers ("public", "static", "override", "mutating", ...) in any
combination, before or after attributes;
- failable initializers, "init?" and "init!";
- generics, "init<T>" and "subscript<T>";
- the keyword boundary still acts as a word boundary, so e.g.
"initialize(" is not mistaken for "init".I verified all of the above against a built binary, including generic functions with "where" clauses, multi-line signatures, and operator functions such as "static func ==". I did not find a real case this pattern misses; the ones I intentionally left out are one-line declarations ("typealias", "associatedtype") and rarer forms ("operator", "precedencegroup", "macro"), which would not make useful section headers anyway.
The word regex covers Swift identifiers; hexadecimal, octal, binary, integer and floating-point literals; and operators including "<<=" / ">>=", "??" and the range operators. All of t4018 passes, including the sorted builtin_drivers check and the new swift-* fixtures.
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..5e4091d97c --- /dev/null +++ b/t/t4018/swift-failable-init @@ -0,0 +1,7 @@ +class Bar { + init?(RIGHT: Int) { + let value = RIGHT + // 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..565f93cd6c --- /dev/null +++ b/t/t4018/swift-generic-subscript @@ -0,0 +1,7 @@ +struct Container { + subscript<RIGHT>(index: RIGHT) -> 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..f683e74794 --- /dev/null +++ b/t/t4018/swift-init @@ -0,0 +1,7 @@ +class Foo { + init(RIGHT: Int) { + let value = RIGHT + // 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..df37dd78a6 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 },
-- 2.52.0