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[cxx-interop] Add conversions between std::u16string and Swift.String #61695

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Merged
merged 1 commit into from
Oct 24, 2022
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[cxx-interop] Add conversions between std::u16string and Swift.String #61695

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29 changes: 29 additions & 0 deletions stdlib/public/Cxx/std/String.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,8 @@
//
//===----------------------------------------------------------------------===//

// MARK: Initializing C++ string from a Swift String

extension std.string {
public init(_ string: String) {
self.init()
Expand All @@ -19,12 +21,31 @@ extension std.string {
}
}

extension std.u16string {
public init(_ string: String) {
self.init()
for char in string.utf16 {
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I will optimize this in a follow-up patch.

self.push_back(char)
}
}
}

// MARK: Initializing C++ string from a Swift String literal

extension std.string: ExpressibleByStringLiteral {
public init(stringLiteral value: String) {
self.init(value)
}
}

extension std.u16string: ExpressibleByStringLiteral {
public init(stringLiteral value: String) {
self.init(value)
}
}

// MARK: Initializing Swift String from a C++ string

extension String {
public init(cxxString: std.string) {
let buffer = UnsafeBufferPointer<CChar>(
Expand All @@ -35,4 +56,12 @@ extension String {
}
withExtendedLifetime(cxxString) {}
}

public init(cxxU16String: std.u16string) {
let buffer = UnsafeBufferPointer<UInt16>(
start: cxxU16String.__dataUnsafe(),
count: cxxU16String.size())
self = String(decoding: buffer, as: UTF16.self)
withExtendedLifetime(cxxU16String) {}
}
}
30 changes: 30 additions & 0 deletions test/Interop/Cxx/stdlib/overlay/std-string-overlay.swift
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Expand Up @@ -37,6 +37,36 @@ StdStringOverlayTestSuite.test("std::string <=> Swift.String") {
expectEqual(swift6, "xyz\0abc")
}

StdStringOverlayTestSuite.test("std::u16string <=> Swift.String") {
let cxx1 = std.u16string()
let swift1 = String(cxxU16String: cxx1)
expectEqual(swift1, "")

let cxx2 = std.u16string("something123")
expectEqual(cxx2.size(), 12)
let swift2 = String(cxxU16String: cxx2)
expectEqual(swift2, "something123")

let cxx3: std.u16string = "literal"
expectEqual(cxx3.size(), 7)

let cxx4: std.u16string = "тест"
expectEqual(cxx4.size(), 4)
let swift4 = String(cxxU16String: cxx4)
expectEqual(swift4, "тест")

// Emojis are represented by more than one CWideChar.
let cxx5: std.u16string = "emoji_🤖"
expectEqual(cxx5.size(), 8)
let swift5 = String(cxxU16String: cxx5)
expectEqual(swift5, "emoji_🤖")

let cxx6 = std.u16string("xyz\0abc")
expectEqual(cxx6.size(), 7)
let swift6 = String(cxxU16String: cxx6)
expectEqual(swift6, "xyz\0abc")
}

extension std.string.const_iterator: UnsafeCxxInputIterator {
// This func should not be required.
public static func ==(lhs: std.string.const_iterator,
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