Mihaela Mihaljevic
83e6e27d12
Group @testable imports at the bottom, per public/rules-swift's swiftformat. A behavior-preserving import-ordering reformat across 252 files (mostly tests). --trailingclosures was deliberately not adopted (cosmetic, and swiftformat flags it as caution-worthy).
53 lines
2.4 KiB
Swift
53 lines
2.4 KiB
Swift
import Testing
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@testable import PureXML
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/// Guards the content-model NFA builder against occurrence-explosion (#129).
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/// The per-particle unroll cap bounds one repetition, but nested high-`maxOccurs`
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/// particles multiply: the XSTS msMeta Particles set drove the builder to 8 GB
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/// and OOM-killed the suite. A total state ceiling caps the whole automaton,
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/// degrading further repetition to star. This locks that ceiling in: the
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/// pathological model must build, stay bounded, and still match without
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/// crashing, while ordinary models are untouched.
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@Suite("Content NFA state budget")
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struct ContentNFAStateBudgetTests {
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private func element(_ name: String, min: Int, max: Int?) -> PureXML.Schema.Particle {
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.init(minOccurs: min, maxOccurs: max, term: .element(name: .init(name), type: nil, typeName: nil))
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}
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/// A sequence repeated `min` times, each repeat holding an element repeated
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/// `min` times: naively `min * min` automaton states.
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private func nested(min: Int) -> PureXML.Schema.Particle {
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let inner = element("a", min: min, max: min)
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return .init(
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minOccurs: min,
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maxOccurs: min,
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term: .group(.init(compositor: .sequence, particles: [inner])),
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)
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}
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@Test("A nested occurrence explosion stays bounded instead of exhausting memory")
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func test_nestedExplosionBounded() {
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// 16384 * 16384 ~ 2.7e8 states without a total cap; the ceiling is 2^20.
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let nfa = PureXML.Schema.ContentNFABuilder.build(nested(min: 16384))
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// Bounded to the ceiling plus at most one in-flight term expansion,
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// far below the naive product that previously allocated until death.
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#expect(nfa.states.count < 1_500_000)
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// The degraded automaton must still answer queries without crashing.
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let names = Array(repeating: PureXML.Model.QualifiedName("a"), count: 32)
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_ = nfa.matchesWhole(names)
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}
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@Test("Ordinary content models are unaffected by the ceiling")
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func test_ordinaryModelUnchanged() {
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let particle = PureXML.Schema.Particle(
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minOccurs: 1,
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maxOccurs: nil,
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term: .group(.init(compositor: .sequence, particles: [element("a", min: 1, max: 1)])),
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)
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let nfa = PureXML.Schema.ContentNFABuilder.build(particle)
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#expect(nfa.states.count < 64)
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#expect(nfa.matchesWhole([.init("a"), .init("a"), .init("a")]))
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#expect(!nfa.matchesWhole([.init("b")]))
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}
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}
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