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GitHub - apple/swift-syntax: SwiftPM package for SwiftSyntax library.

 5 years ago
source link: https://github.com/apple/swift-syntax
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README.md

SwiftSyntax

SwiftSyntax is a set of Swift bindings for the libSyntax library. It allows for Swift tools to parse, inspect, generate, and transform Swift source code.

Note: SwiftSyntax is still in development, and the API is not guaranteed to be stable. It's subject to change without warning.

Usage

Add this repository to the Package.swift manifest of your project:

import PackageDescription

let package = Package(
  name: "MyTool",
  dependencies: [
    .package(url: "https://github.com/apple/swift-syntax.git", .branch("<#Specify Release tag#>")),
  ],
  targets: [
    .target(name: "MyTool", dependencies: ["SwiftSyntax"]),
  ]
)

Replace <#Specify Release tag#> by the version of SwiftSyntax that you want to use. Tags will be created for every release of the compiler in the form swift-4.2-RELEASE and for every nightly build in the form swift-4.2-DEVELOPMENT-SNAPSHOT-2018-08-25-a.

Then, import SwiftSyntax in your Swift code.

Example

This is a program that adds 1 to every integer literal in a Swift file.

import SwiftSyntax
import Foundation

/// AddOneToIntegerLiterals will visit each token in the Syntax tree, and
/// (if it is an integer literal token) add 1 to the integer and return the
/// new integer literal token.
class AddOneToIntegerLiterals: SyntaxRewriter {
  override func visit(_ token: TokenSyntax) -> Syntax {
    // Only transform integer literals.
    guard case .integerLiteral(let text) = token.tokenKind else {
      return token
    }

    // Remove underscores from the original text.
    let integerText = String(text.filter { ("0"..."9").contains($0) })

    // Parse out the integer.
    let int = Int(integerText)!

    // Return a new integer literal token with `int + 1` as its text.
    return token.withKind(.integerLiteral("\(int + 1)"))
  }
}

let file = CommandLine.arguments[1]
let url = URL(fileURLWithPath: file)
let sourceFile = try SourceFileSyntax.parse(url)
let incremented = AddOneToIntegerLiterals().visit(sourceFile)
print(incremented)

This example turns this:

let x = 2
let y = 3_000

into:

let x = 3
let y = 3001

report

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