feat(swift): modernise syntax highlighting

- added better numeric literal support (hex, binary, octal, floats with underscores)
- expanded keyword list with async/await, actor, protocol, and other modern Swift keywords
- expanded type list including standard library types and SIMD types
- added compilation directive support (#if, #available, etc.)
- added discard literal (_) highlighting
- updated attributes list with modern Swift modifiers
- added support for escaped identifiers using backticks

Signed-Off-By: Paal Øye-Strømme <paal.o.eye@gmail.com>

Author: paaloeye

rc/filetype/swift.kak

@@ -35,6 +35,10 @@ provide-module swift %§
 add-highlighter shared/swift regions
 add-highlighter shared/swift/code default-region group
 
+add-highlighter shared/swift/comment region /\* \*/ group
+add-highlighter shared/swift/line_comment region // $ ref swift/comment
+add-highlighter shared/swift/comment/ fill comment
+
 add-highlighter shared/swift/string_multiline region %{(?<!')"""} %{(?<!\\)(\\\\)*"""} regions
 add-highlighter shared/swift/string_multiline/base default-region fill string
 add-highlighter shared/swift/string_multiline/interpolation region -recurse \( \Q\( \) fill meta
@@ -43,19 +47,54 @@ add-highlighter shared/swift/string region %{(?<!')"} %{(?<!\\)(\\\\)*"} regions
 add-highlighter shared/swift/string/base default-region fill string
 add-highlighter shared/swift/string/interpolation region -recurse \( \Q\( \) fill meta
 
-add-highlighter shared/swift/comment region /\* \*/ group
-add-highlighter shared/swift/line_comment region // $ ref swift/comment
+# backticked identifiers
+add-highlighter shared/swift/backtick_identifier region ` ` fill meta
 
-add-highlighter shared/swift/comment/ fill comment
+# discard literal
+add-highlighter shared/swift/code/ regex "\b_\b" 0:comment
 
-add-highlighter shared/swift/code/ regex %{\b(true|false|nil)\b|\b-?(?!\$)\d+[fdiu]?|'((\\.)?|[^'\\])'} 0:value
-add-highlighter shared/swift/code/ regex "\b(let|var|while|in|for|if|guard|else|do|switch|case|default|break|continue|return|try|catch|throw|new|delete|and|or|not|operator|explicit|func|import|return|init|deinit|get|set)\b" 0:keyword
+# values
+add-highlighter shared/swift/code/ regex \b(?:true|false|nil)\b 0:value
+add-highlighter shared/swift/code/ regex \b(?:self|super)\b 0:value
+
+# Numeric literals with underscores, hex, binary, octal, floats (plus/minus are not painted, matching Xcode)
+#   - Decimal with underscores: 1_000_000, 3.141_592_653_59
+#   - Hexadecimal: 0xFF, 0x1A_2B, 0xDEAD_BEEF
+#   - Hex floats: 0xF.8p2, +0x1_A.F_Fp3
+#   - Binary: 0b1010, 0b1111_0000
+#   - Octal: 0o17, +0o7_7_7, 0o7_7_7
+#   - Decimal floats: 6.28, 1.5e10, +1.5e-5, 1.5E+10
+#   - Negative numbers: -42, -3.14
+#
+# Pattern breakdown:
+#   [-+]?  # optional plus or minus
+#   (?:
+#     0x[0-9a-fA-F][_0-9a-fA-F]*            # hex integer/float start
+#        (?:\.[0-9a-fA-F][_0-9a-fA-F]*)?    # optional hex fraction
+#        (?:[pP][+-]?[0-9][_0-9]*)?         # optional binary exponent
+#     |0o[0-7][_0-7]*                       # octal
+#     |0b[01][_01]*                         # binary
+#     |[0-9][_0-9]*                         # decimal integer/float start
+#        (?:\.[0-9][_0-9]*)?                # optional decimal fraction
+#        (?:[eE][+-]?[0-9][_0-9]*)?         # optional decimal exponent
+#   )
+#
+add-highlighter shared/swift/code/ regex \b[+-]?(?:0x[0-9a-fA-F][_0-9a-fA-F]*(?:\.[0-9a-fA-F][_0-9a-fA-F]*)?(?:[pP][+-]?[0-9][_0-9]*)?|0o[0-7][_0-7]*|0b[01][_01]*|[0-9][_0-9]*(?:\.[0-9][_0-9]*)?(?:[eE][+-]?[0-9][_0-9]*)?)\b 0:value
+
+# keywords
+add-highlighter shared/swift/code/ regex "\b(let|var|while|in|for|if|guard|else|do|switch|case|default|break|continue|return|try|catch|throw|operator|func|import|init|deinit|get|set|defer|repeat|fallthrough|async|await|throws|rethrows|inout|where|is|subscript|macro|protocol|typealias|actor|class|struct|enum|extension|some|any|associatedtype|distributed|isolated|nonisolated|consuming|borrowing|borrow|move|discard|sending|nonsending)\b" 0:keyword
 add-highlighter shared/swift/code/ regex "\bas\b[!?]?" 0:keyword
 add-highlighter shared/swift/code/ regex "(\$[0-9])\b" 0:keyword
-add-highlighter shared/swift/code/ regex "\b(const|mutable|auto|namespace|inline|static|volatile|class|struct|enum|union|extension|open|public|protected|private|fileprivate|internal|typedef|virtual|friend|extern|typename|override|final|required|convenience|dynamic)\b" 0:attribute
 
-add-highlighter shared/swift/code/ regex "\b(self|nil|id|super)\b" 0:value
-add-highlighter shared/swift/code/ regex "\b(Bool|String|UInt|UInt16|UInt32|UInt64|UInt8)\b" 0:type
+# types
+add-highlighter shared/swift/code/ regex "[\[]?\b(Bool|String|Character|Int|Int8|Int16|Int32|Int64|Int128|UInt|UInt8|UInt16|UInt32|UInt64|UInt128|Float|Float16|Float32|Float64|Float80|Double|Void|Never|Any|AnyObject|AnyClass|Optional|Array|Dictionary|Set|Range|ClosedRange|PartialRangeFrom|PartialRangeThrough|PartialRangeUpTo|Result|Error|Equatable|Hashable|Comparable|Codable|Encodable|Decodable|Sendable|CaseIterable|CodingKey|Task|TaskGroup|AsyncStream|AsyncThrowingStream|GlobalActor|UnsafePointer|UnsafeMutablePointer|UnsafeRawPointer|UnsafeMutableRawPointer|UnsafeBufferPointer|UnsafeMutableBufferPointer|UnsafeRawBufferPointer|UnsafeMutableRawBufferPointer|Unmanaged|AutoreleasingUnsafeMutablePointer|SIMD|SIMD2|SIMD3|SIMD4|SIMD8|SIMD16|SIMD32|SIMD64|SIMDMask|SIMDScalar|SIMDStorage)\b[\]]?[!?]?" 0:type
+
+# compilation directives
+add-highlighter shared/swift/code/ regex "#(if|elseif|else|endif|available|unavailable|warning|error|sourceLocation|file|fileID|filePath|line|column|function|dsohandle|selector|keyPath|colorLiteral|imageLiteral|fileLiteral)\b" 0:meta
+add-highlighter shared/swift/code/ regex "\b(canImport|os|arch|swift|compiler|targetEnvironment)[\s\(]+\b" 1:meta
+
+# attributes
+add-highlighter shared/swift/code/ regex "\b(inline|static|open|public|private|fileprivate|internal|package|override|final|required|convenience|dynamic|lazy|mutating|nonmutating|indirect|weak|unowned|didSet|willSet)\b" 0:attribute
 add-highlighter shared/swift/code/ regex "\b(IBAction|IBOutlet)\b" 0:attribute
 add-highlighter shared/swift/code/ regex "@\w+\b" 0:attribute