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SwiftSyntaxೖ
2019/04/19 @Mobile Act KYOTO #1
Yutaro Muta @yutailang0119
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• Yutaro Muta @yutailang0119
• Hatena Co., Ltd. @Kyoto
• Conference Staff
• builderscon 2017, 2018
• try! Swift Tokyo 2019, 2020?
• and more
Who am I ?
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Goal
• SwiftSyntaxΛ͏͖͔͚ͬʹͳΔ
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apple/swift-syntax
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apple/swift-syntax
• https://github.com/apple/swift-syntax
> 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.
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libSyntax vs SwiftSyntax
• libSyntax
• SwiftίϯύΠϥͰ࠾༻
• APISwift ͱ C++Λࠞࡏͯ͠ఏڙ
• SwiftSyntax
• libSyntaxͷSwiftϥούʔ
• SwiftPackageManagerͰ༻Ͱ͖Δ
• ։ൃஈ֊
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Some Example Users
• Swift AST Explorer: a Swift AST visualizer.
• Swift Stress Tester: a test driver for sourcekitd and Swift evolution.
• SwiftRewriter: a Swift code formatter.
• SwiftPack: a tool for automatically embedding Swift library source.
• Periphery: a tool to detect unused code.
• BartyCrouch: a tool to incrementally update strings files to help App localization.
• Muter: Automated mutation testing for Swift
• Swift Variable Injector: a tool to replace string literals with environment variables values.
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Some Example Users
• Swift AST Explorer: a Swift AST visualizer.
• Swift Stress Tester: a test driver for sourcekitd and Swift evolution.
• SwiftRewriter: a Swift code formatter.
• SwiftPack: a tool for automatically embedding Swift library source.
• Periphery: a tool to detect unused code.
• BartyCrouch: a tool to incrementally update strings files to help App localization.
• Muter: Automated mutation testing for Swift
• Swift Variable Injector: a tool to replace string literals with environment variables values.
SwiftͷASTΛѻ͏্Ͱඞਢ!!!
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͓
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͓: UIColor
• UIColor.init(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat)
• ײతʹͲΜͳ৭ͳͷ͔͕Θ͔ΓͮΒ͍
• HexColor (16ਐτϦϓϨοτ) ͰऔΓѻ͍͍ͨ
=> HexColorͰॳظԽ͢Δϝιουʹॻ͖͑Δ
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UIColor.init(hex string: String, alpha: CGFloat)
https://gist.github.com/yutailang0119/bef7cbe591ba6f76318219ba8bb69946
extension UIColor {
convenience init(hex string: String, alpha: CGFloat) {
let hex = string.replacingOccurrences(of: "#", with: "")
let scanner = Scanner(string: hex)
var color: UInt32 = 0
if scanner.scanHexInt32(&color) {
let r = CGFloat((color & 0xFF0000) >> 16) / 255.0
let g = CGFloat((color & 0x00FF00) >> 8) / 255.0
let b = CGFloat(color & 0x0000FF) / 255.0
self.init(red: r, green: g, blue: b, alpha: alpha)
} else {
self.init(white: 1.0, alpha: 1)
}
}
}
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yutailang0119/swift-color-detector
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Demo
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0. SwiftSyntaxͷґଘ
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Package.swift
// swift-tools-version:5.0
// The swift-tools-version declares the minimum version of Swift required to build this package.
import PackageDescription
let package = Package(
name: "swift-color-detector",
products: [
.executable(name:"swift-color-detector", targets: ["swift-color-detector"]),
.library(name: "SwiftColorDetectKit", targets: ["SwiftColorDetectKit"]),
],
dependencies: [
.package(url: "https://github.com/apple/swift-syntax.git", from: Version(0, 50000, 0)),
...
],
targets: [
.target(name: "swift-color-detector", dependencies: ["SwiftColorDetectKit", ...]),
.target(name: "SwiftColorDetectKit", dependencies: ["SwiftSyntax", ...]),
.testTarget(name: "SwiftColorDetectKitTests", dependencies: ["SwiftColorDetectKit"]),
]
)
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1. UIColor.init(red: _,
green: _,
blue: _,
alpha: _)
ͷಛఆ
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1.1 UIColor.initͷಛఆ
func isUIColorInitializer(of node: FunctionCallExprSyntax) -> Bool {
return
(node.calledExpression.description == "UIColor"&& node.leftParen != nil)
||
node.calledExpression.description == "UIColor.init"
}
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1.1 UIColor.initͷಛఆ
func isUIColorInitializer(of node: FunctionCallExprSyntax) -> Bool {
return
(node.calledExpression.description == "UIColor"&& node.leftParen != nil)
||
node.calledExpression.description == "UIColor.init"
}
ਫ਼Λ্͛Δ͘ɺݕূத
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1.2 Label red, green, blue, alphaͷಛఆ
func detectRGBColor(from node: FunctionCallExprSyntax) -> RGBColor? {
guard isUIColorInitializer(of: node) else {
return nil
}
var red, green, blue, alpha: CGFloat?
node.argumentList.forEach { argumentSyntax in
guard let label = argumentSyntax.label else {
return
}
switch label.text {
case "red":
red = CGFloat(expression: argumentSyntax.expression)
case "green":
green = CGFloat(expression: argumentSyntax.expression)
case "blue":
blue = CGFloat(expression: argumentSyntax.expression)
case "alpha":
alpha = CGFloat(expression: argumentSyntax.expression)
default:
break
}
}
guard let rgbColor = RGBColor(red: red, green: green, blue: blue, alpha: alpha) else {
return nil
}
return rgbColor
}
}
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2. UIColor.init(hex string: String,
alpha: CGFloat)
ͷॻ͖͑
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2.1ҾϦετΛΈཱͯΔ
import SwiftSyntax
var hexInitializerArgumentListSyntax: FunctionCallArgumentListSyntax {
let space = Trivia.init(arrayLiteral: TriviaPiece.spaces(1))
let colon = SyntaxFactory.makeIdentifier(":").withTrailingTrivia(space)
let hexArgument = FunctionCallArgumentSyntax { builder in
let label = SyntaxFactory.makeIdentifier("hex")
let value = SyntaxFactory.makeStringLiteral("\"\(hex)\"")
let expression = SyntaxFactory.makeStringLiteralExpr(stringLiteral: value)
let trailingComma = SyntaxFactory.makeIdentifier(",").withTrailingTrivia(space)
builder.useLabel(label)
builder.useColon(colon)
builder.useExpression(expression)
builder.useTrailingComma(trailingComma)
}
let alphaArgument = FunctionCallArgumentSyntax { builder in
let label = SyntaxFactory.makeIdentifier("alpha")
let value = SyntaxFactory.makeFloatingLiteral("\(alpha)")
let expression = SyntaxFactory.makeFloatLiteralExpr(floatingDigits: value)
builder.useLabel(label)
builder.useColon(colon)
builder.useExpression(expression)
}
let argumentList = SyntaxFactory.makeFunctionCallArgumentList([hexArgument, alphaArgument])
return argumentList // hex: \"#8C0000\", alpha: 1.0
}
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2.2 UIColor.initΛॻ͖͑Δ
import SwiftSyntax
class RGBColorSyntaxRewriter: SyntaxRewriter {
override func visit(_ node: FunctionCallExprSyntax) -> ExprSyntax {
guard let rgbColor = detectRGBColor(from: node) else {
return node
}
let colorInitializerSyntax =
node.withArgumentList(rgbColor.hexInitializerArgumentListSyntax)
// UIColor(hex: "#8C0000", alpha: 1.0)
return colorInitializerSyntax
}
}
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3. ࣮ߦ
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࣮ߦ
import SwiftSyntax
public func rewrite() throws {
let sourceFile = try SyntaxTreeParser.parse(path)
let rewriter = RGBColorSyntaxRewriter(filePath: path)
let syntax = rewriter.visit(sourceFile)
// ϑΝΠϧͷॻ͖͑
try syntax.description.write(to: path, atomically: true, encoding: .utf8)
}
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ޙҰͭҰͭͷϑΝΠϧʹ
࣮ߦ͍͚ͯͩ͘͠
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One more thing...
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yutailang0119/FileScanKit
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yutailang0119/FileScanKit
• ࢦఆύεҎԼͷϑΝΠϧύεΛཏతʹऔಘ͢ΔͨΊͷSwift͚Library
• Support
• Recursion
• all
• depth limit
• File extension
• Ignore paths
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&OKPZ4XJGU4ZOUBYMJGF
5IBOLT
w NVUBZVUBSP!HNBJMDPN
w IUUQTUXJUUFSDPNZVUBJMBOH
w IUUQTHJUIVCDPNZVUBJMBOH