swift-ascii

ASCII validation, case conversion, line-ending normalization, and decimal serialization for Swift strings, characters, and integers, built on the INCITS 4-1986 (US-ASCII) specification.

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Key Features

• Validated String construction — String(ascii:) builds a string from bytes or ASCII.Code values and returns nil when any byte falls outside the 7-bit range (0x00–0x7F), instead of decoding it to a replacement character.
• ASCII-only case conversion — string.ascii.uppercased() / .lowercased() fold the letters A–Z / a–z and leave every non-ASCII scalar untouched.
• Line-ending normalization — normalized(to:) rewrites mixed LF, CR, and CRLF endings to one consistent style.
• 7-bit ASCII predicate — string.ascii.isAllASCII reports whether a string contains only US-ASCII characters.
• Decimal integer serialization — Int, Int64, UInt, and UInt64 serialize to their ASCII decimal byte representation through Binary.Serializable.
• INCITS 4-1986 grounding — classification, case, and format-effector behavior follow the US-ASCII specification.

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Quick Start

import ASCII

// Reject non-ASCII on construction instead of decoding it to replacement characters.
let greeting = String(ascii: [104, 101, 108, 108, 111])  // "hello"
let rejected = String(ascii: [0xFF])                     // nil — 0xFF is not 7-bit ASCII

// Test whether a string is pure 7-bit ASCII.
let pure = "hello".ascii.isAllASCII   // true
let mixed = "café".ascii.isAllASCII   // false

// Fold only ASCII letters; non-ASCII scalars pass through unchanged.
let shout = "HELLO🌍".ascii.lowercased()  // "hello🌍"

// Normalize mixed CR / LF / CRLF line endings to a single style.
let body = "line1\nline2\r\nline3".normalized(to: .crlf)
// "line1\r\nline2\r\nline3"

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Installation

dependencies: [
    .package(url: "https://github.com/swift-foundations/swift-ascii.git", branch: "main")
]

.target(
    name: "YourTarget",
    dependencies: [
        .product(name: "ASCII", package: "swift-ascii")
    ]
)

Requires Swift 6.3.1. The ASCII product supports Windows as a host platform; the repository's universal CI includes its required Windows build-and-test leg. Package.swift declares minimum deployment versions for Apple platforms: macOS 26, iOS 26, tvOS 26, watchOS 26, and visionOS 26.

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Community

Discussion thread will be created at first public release.

License

Apache 2.0. See LICENSE.