115 lines
3.9 KiB
Swift
115 lines
3.9 KiB
Swift
import SwiftSyntax
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struct ArrayInitRule: SwiftSyntaxRule, ConfigurationProviderRule, OptInRule {
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var configuration = SeverityConfiguration(.warning)
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init() {}
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static let description = RuleDescription(
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identifier: "array_init",
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name: "Array Init",
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description: "Prefer using `Array(seq)` over `seq.map { $0 }` to convert a sequence into an Array.",
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kind: .lint,
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nonTriggeringExamples: [
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Example("Array(foo)\n"),
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Example("foo.map { $0.0 }\n"),
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Example("foo.map { $1 }\n"),
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Example("foo.map { $0() }\n"),
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Example("foo.map { ((), $0) }\n"),
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Example("foo.map { $0! }\n"),
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Example("foo.map { $0! /* force unwrap */ }\n"),
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Example("foo.something { RouteMapper.map($0) }\n"),
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Example("foo.map { !$0 }\n"),
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Example("foo.map { /* a comment */ !$0 }\n")
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],
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triggeringExamples: [
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Example("foo.↓map({ $0 })\n"),
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Example("foo.↓map { $0 }\n"),
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Example("foo.↓map { return $0 }\n"),
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Example("""
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foo.↓map { elem in
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elem
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}
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"""),
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Example("""
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foo.↓map { elem in
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return elem
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}
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"""),
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Example("""
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foo.↓map { (elem: String) in
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elem
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}
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"""),
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Example("""
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foo.↓map { elem -> String in
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elem
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}
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"""),
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Example("foo.↓map { $0 /* a comment */ }\n"),
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Example("foo.↓map { /* a comment */ $0 }\n")
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]
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)
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func makeVisitor(file: SwiftLintFile) -> ViolationsSyntaxVisitor {
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Visitor(viewMode: .sourceAccurate)
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}
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}
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extension ArrayInitRule {
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private final class Visitor: ViolationsSyntaxVisitor {
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override func visitPost(_ node: FunctionCallExprSyntax) {
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guard let memberAccess = node.calledExpression.as(MemberAccessExprSyntax.self),
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memberAccess.name.text == "map",
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let (closureParam, closureStatement) = node.singleClosure(),
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closureStatement.returnsInput(closureParam)
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else {
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return
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}
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violations.append(memberAccess.name.positionAfterSkippingLeadingTrivia)
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}
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}
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}
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private extension FunctionCallExprSyntax {
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func singleClosure() -> (String?, CodeBlockItemSyntax)? {
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let closure: ClosureExprSyntax
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if let expression = argumentList.onlyElement?.expression.as(ClosureExprSyntax.self) {
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closure = expression
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} else if argumentList.isEmpty, let expression = trailingClosure {
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closure = expression
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} else {
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return nil
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}
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if let closureStatement = closure.statements.onlyElement {
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return (closure.signature?.singleInputParamText(), closureStatement)
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} else {
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return nil
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}
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}
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}
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private extension CodeBlockItemSyntax {
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func returnsInput(_ closureParam: String?) -> Bool {
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let expectedReturnIdentifier = closureParam ?? "$0"
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let identifier = item.as(IdentifierExprSyntax.self) ??
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item.as(ReturnStmtSyntax.self)?.expression?.as(IdentifierExprSyntax.self)
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return identifier?.identifier.text == expectedReturnIdentifier
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}
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}
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private extension ClosureSignatureSyntax {
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func singleInputParamText() -> String? {
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if let list = input?.as(ClosureParamListSyntax.self), list.count == 1 {
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return list.onlyElement?.name.text
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} else if let clause = input?.as(ParameterClauseSyntax.self), clause.parameterList.count == 1,
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clause.parameterList.first?.secondName == nil {
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return clause.parameterList.first?.firstName?.text
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} else {
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return nil
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}
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}
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}
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