50 lines
1.6 KiB
Swift
50 lines
1.6 KiB
Swift
import SwiftSyntax
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struct EmptyStringRule: ConfigurationProviderRule, OptInRule, SwiftSyntaxRule {
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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: "empty_string",
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name: "Empty String",
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description: "Prefer checking `isEmpty` over comparing `string` to an empty string literal",
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kind: .performance,
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nonTriggeringExamples: [
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Example("myString.isEmpty"),
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Example("!myString.isEmpty"),
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Example("\"\"\"\nfoo==\n\"\"\"")
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],
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triggeringExamples: [
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Example(#"myString↓ == """#),
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Example(#"myString↓ != """#),
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Example(#"myString↓=="""#),
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Example(##"myString↓ == #""#"##),
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Example(###"myString↓ == ##""##"###)
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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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private extension EmptyStringRule {
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final class Visitor: ViolationsSyntaxVisitor {
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override func visitPost(_ node: StringLiteralExprSyntax) {
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guard
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// Empty string literal: `""`, `#""#`, etc.
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node.segments.onlyElement?.contentLength == .zero,
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let previousToken = node.previousToken,
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// On the rhs of an `==` or `!=` operator
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previousToken.tokenKind.isEqualityComparison,
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let violationPosition = previousToken.previousToken?.endPositionBeforeTrailingTrivia
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else {
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return
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}
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violations.append(violationPosition)
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}
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}
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}
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