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[cxx-interop] Add CxxStack protocol for std::stack ergonomics.
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11 files changed

+216
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‎include/swift/AST/KnownProtocols.def

+1
Original file line numberDiff line numberDiff line change
@@ -137,6 +137,7 @@ PROTOCOL(CxxSet)
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PROTOCOL(CxxRandomAccessCollection)
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PROTOCOL(CxxMutableRandomAccessCollection)
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PROTOCOL(CxxSequence)
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PROTOCOL(CxxStack)
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PROTOCOL(CxxUniqueSet)
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PROTOCOL(CxxVector)
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PROTOCOL(CxxSpan)

‎lib/AST/ASTContext.cpp

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@@ -1475,6 +1475,7 @@ ProtocolDecl *ASTContext::getProtocol(KnownProtocolKind kind) const {
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case KnownProtocolKind::CxxMutableRandomAccessCollection:
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case KnownProtocolKind::CxxSet:
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case KnownProtocolKind::CxxSequence:
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case KnownProtocolKind::CxxStack:
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case KnownProtocolKind::CxxUniqueSet:
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case KnownProtocolKind::CxxVector:
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case KnownProtocolKind::CxxSpan:

‎lib/ClangImporter/ClangDerivedConformances.cpp

+39
Original file line numberDiff line numberDiff line change
@@ -865,6 +865,45 @@ void swift::conformToCxxSequenceIfNeeded(
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}
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}
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868+
void swift::conformToCxxStackIfNeeded(
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ClangImporter::Implementation &impl, NominalTypeDecl *decl,
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const clang::CXXRecordDecl *clangDecl) {
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PrettyStackTraceDecl trace("conforming to CxxStack", decl);
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assert(decl);
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assert(clangDecl);
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ASTContext &ctx = decl->getASTContext();
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if (!isStdDecl(clangDecl, {"stack"}))
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return;
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auto valueType = lookupDirectSingleWithoutExtensions<TypeAliasDecl>(
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decl, ctx.getIdentifier("value_type"));
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auto sizeType = lookupDirectSingleWithoutExtensions<TypeAliasDecl>(
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decl, ctx.getIdentifier("size_type"));
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if (!valueType ||!sizeType)
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return;
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impl.addSynthesizedTypealias(decl, ctx.Id_Element,
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valueType->getUnderlyingType());
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impl.addSynthesizedTypealias(decl, ctx.getIdentifier("Size"),
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sizeType->getUnderlyingType());
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ProtocolDecl *cxxInputIteratorProto =
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ctx.getProtocol(KnownProtocolKind::UnsafeCxxInputIterator);
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if (!cxxInputIteratorProto)
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return;
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auto rawReferenceType = lookupDirectSingleWithoutExtensions<TypeAliasDecl>(
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decl, ctx.getIdentifier("const_reference"));
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if (!rawReferenceType)
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return;
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auto rawReferenceTy = rawReferenceType->getUnderlyingType();
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if (!checkConformance(rawReferenceTy, cxxInputIteratorProto))
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return;
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impl.addSynthesizedTypealias(decl, ctx.getIdentifier("RawReference"), rawReferenceTy);
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impl.addSynthesizedProtocolAttrs(decl, {KnownProtocolKind::CxxStack});
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}
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static bool isStdSetType(const clang::CXXRecordDecl *clangDecl) {
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return isStdDecl(clangDecl, {"set", "unordered_set", "multiset"});
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}

‎lib/ClangImporter/ClangDerivedConformances.h

+6
Original file line numberDiff line numberDiff line change
@@ -46,6 +46,12 @@ void conformToCxxSequenceIfNeeded(ClangImporter::Implementation &impl,
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NominalTypeDecl *decl,
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const clang::CXXRecordDecl *clangDecl);
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/// If the decl is an instantiation of C++ `std::stack`,
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/// synthesize a conformance to CxxStack, which is defined in the Cxx module.
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void conformToCxxStackIfNeeded(ClangImporter::Implementation &impl,
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NominalTypeDecl *decl,
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const clang::CXXRecordDecl *clangDecl);
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/// If the decl is an instantiation of C++ `std::set`, `std::unordered_set` or
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/// `std::multiset`, synthesize a conformance to CxxSet, which is defined in the
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/// Cxx module.

‎lib/ClangImporter/ImportDecl.cpp

+1
Original file line numberDiff line numberDiff line change
@@ -3156,6 +3156,7 @@ namespace {
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conformToCxxVectorIfNeeded(Impl, nominalDecl, decl);
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conformToCxxFunctionIfNeeded(Impl, nominalDecl, decl);
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conformToCxxSpanIfNeeded(Impl, nominalDecl, decl);
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conformToCxxStackIfNeeded(Impl, nominalDecl, decl);
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}
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}
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‎lib/IRGen/GenMeta.cpp

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Original file line numberDiff line numberDiff line change
@@ -7128,6 +7128,7 @@ SpecialProtocol irgen::getSpecialProtocolID(ProtocolDecl *P) {
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case KnownProtocolKind::CxxMutableRandomAccessCollection:
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case KnownProtocolKind::CxxSet:
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case KnownProtocolKind::CxxSequence:
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case KnownProtocolKind::CxxStack:
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case KnownProtocolKind::CxxUniqueSet:
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case KnownProtocolKind::CxxVector:
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case KnownProtocolKind::CxxSpan:

‎stdlib/public/Cxx/CMakeLists.txt

+1
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@@ -15,6 +15,7 @@ add_swift_target_library(swiftCxx STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY
1515
CxxSet.swift
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CxxRandomAccessCollection.swift
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CxxSequence.swift
18+
CxxStack.swift
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CxxVector.swift
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CxxSpan.swift
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UnsafeCxxIterators.swift

‎stdlib/public/Cxx/CxxStack.swift

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@@ -0,0 +1,59 @@
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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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/// A C++ type that represents a stack.
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///
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/// C++ standard library types `std::stack` conforms to this protocol.
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public protocol CxxStack<Element> {
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associatedtype Element
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associatedtype Size: BinaryInteger
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associatedtype RawReference: UnsafeCxxInputIterator
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where RawReference.Pointee == Element
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/// Do not implement this function manually in Swift.
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func empty() -> Bool
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/// Do not implement this function manually in Swift.
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func size() -> Size
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/// Do not implement this function manually in Swift.
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func __topUnsafe() -> RawReference
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/// Do not implement this function manually in Swift.
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mutating func pop()
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/// Do not implement this function manually in Swift.
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mutating func push(_ element: Element)
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}
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public extension CxxStack {
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@inlinable var count: Int { Int(self.size()) }
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@inlinable var isEmpty: Bool { self.empty() }
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@inlinable
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func top() -> Element? {
43+
if self.empty() {
44+
return nil
45+
}
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return self.__topUnsafe().pointee
47+
}
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@inlinable
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@discardableResult
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mutating func safePop() -> Element? {
52+
if self.empty() {
53+
return nil
54+
}
55+
let result: Element = self.__topUnsafe().pointee
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self.pop()
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return result
58+
}
59+
}

‎test/Interop/Cxx/stdlib/Inputs/module.modulemap

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@@ -52,6 +52,12 @@ module StdStringView {
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export *
5353
}
5454

55+
module StdStack {
56+
header "std-stack.h"
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requires cplusplus
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export *
59+
}
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5561
module StdPair {
5662
header "std-pair.h"
5763
requires cplusplus

‎test/Interop/Cxx/stdlib/Inputs/std-stack.h

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@@ -0,0 +1,21 @@
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#ifndef TEST_INTEROP_CXX_STDLIB_INPUTS_STD_STACK_H
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#define TEST_INTEROP_CXX_STDLIB_INPUTS_STD_STACK_H
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#include <stack>
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6+
using StackOfInt = std::stack<int>;
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StackOfInt initStackOfCInt() {
9+
StackOfInt s;
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s.push(1);
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s.push(2);
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s.push(3);
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return s;
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}
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StackOfInt initEmptyStackOfCInt() {
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StackOfInt s;
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return s;
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}
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#endif // TEST_INTEROP_CXX_STDLIB_INPUTS_STD_STACK_H

‎test/Interop/Cxx/stdlib/use-std-stack.swift

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@@ -0,0 +1,80 @@
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// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=swift-6)
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// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=upcoming-swift)
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// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=upcoming-swift -Xcc -std=c++14)
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// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=upcoming-swift -Xcc -std=c++17)
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// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=upcoming-swift -Xcc -std=c++20)
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// Also test this with a bridging header instead of the StdSet module.
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// RUN: %empty-directory(%t2)
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// RUN: cp %S/Inputs/std-stack.h %t2/std-stack-bridging-header.h
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// RUN: %target-run-simple-swift(-D BRIDGING_HEADER -import-objc-header %t2/std-stack-bridging-header.h -cxx-interoperability-mode=swift-6)
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// RUN: %target-run-simple-swift(-D BRIDGING_HEADER -import-objc-header %t2/std-stack-bridging-header.h -cxx-interoperability-mode=upcoming-swift)
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// REQUIRES: executable_test
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//
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// Enable this everywhere once we have a solution for modularizing other C++ stdlibs: rdar://87654514
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// REQUIRES: OS=macosx || OS=linux-gnu
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18+
import StdlibUnittest
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#if !BRIDGING_HEADER
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import StdStack
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#endif
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import CxxStdlib
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var StdStackTestSuite = TestSuite("StdStack")
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StdStackTestSuite.test("stack count") {
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let s1 = initStackOfCInt()
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expectEqual(s1.count, 3)
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let s2 = initEmptyStackOfCInt()
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expectEqual(s2.count, 0)
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}
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StdStackTestSuite.test("stack isEmpty") {
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let s1 = initStackOfCInt()
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expectFalse(s1.isEmpty)
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let s2 = initEmptyStackOfCInt()
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expectTrue(s2.isEmpty)
40+
}
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StdStackTestSuite.test("stack top") {
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let s1 = initStackOfCInt()
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expectEqual(s1.top(), 3)
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let s2 = initEmptyStackOfCInt()
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expectNil(s2.top())
48+
}
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50+
StdStackTestSuite.test("stack push") {
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var s1 = initStackOfCInt()
52+
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s1.push(4)
54+
expectEqual(s1.top(), 4)
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expectEqual(s1.count, 4)
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s1.safePop()
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expectEqual(s1.top(), 3)
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expectEqual(s1.count, 3)
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var s2 = initEmptyStackOfCInt()
61+
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s2.push(4)
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expectEqual(s2.top(), 4)
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expectEqual(s2.count, 1)
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}
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StdStackTestSuite.test("stack safePop") {
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var s1 = initStackOfCInt()
69+
70+
expectEqual(s1.safePop(), 3)
71+
expectEqual(s1.safePop(), 2)
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expectEqual(s1.safePop(), 1)
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expectNil(s1.safePop())
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expectTrue(s1.isEmpty)
75+
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var s2 = initEmptyStackOfCInt()
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expectNil(s2.safePop())
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}
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runAllTests()

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