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Avoid unnecessarily allocating an array when initializing String from a sequence of bytes #4813

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Merged
parkera merged 1 commit into from
Jan 4, 2024
Merged

Avoid unnecessarily allocating an array when initializing String from a sequence of bytes #4813

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19 changes: 14 additions & 5 deletions Darwin/Foundation-swiftoverlay/NSStringAPI.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -208,14 +208,23 @@ extension String {
/// - encoding: The encoding to use to interpret `bytes`.
public init?<S: Sequence>(bytes: __shared S, encoding: Encoding)
where S.Iterator.Element == UInt8 {
let byteArray = Array(bytes)
if encoding == .utf8,
let str = byteArray.withUnsafeBufferPointer({ String._tryFromUTF8($0) })
{
self = str
if encoding == .utf8 {
if let str = bytes.withContiguousStorageIfAvailable({ String._tryFromUTF8($0) }) {
guard let str else {
return nil
}
self = str
} else {
let byteArray = Array(bytes)
guard let str = byteArray.withUnsafeBufferPointer({ String._tryFromUTF8($0) }) else {
return nil
}
self = str
}
return
}

let byteArray = Array(bytes)
if let ns = NSString(
bytes: byteArray, length: byteArray.count, encoding: encoding.rawValue) {
self = String._unconditionallyBridgeFromObjectiveC(ns)
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19 changes: 14 additions & 5 deletions Sources/Foundation/NSStringAPI.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -256,14 +256,23 @@ extension String {
/// - encoding: The encoding to use to interpret `bytes`.
public init?<S: Sequence>(bytes: __shared S, encoding: Encoding)
where S.Iterator.Element == UInt8 {
let byteArray = Array(bytes)
if encoding == .utf8,
let str = byteArray.withUnsafeBufferPointer({ String._tryFromUTF8($0) })
{
self = str
if encoding == .utf8 {
if let str = bytes.withContiguousStorageIfAvailable({ String._tryFromUTF8($0) }) {
guard let str else {
return nil
}
self = str
} else {
let byteArray = Array(bytes)
guard let str = byteArray.withUnsafeBufferPointer({ String._tryFromUTF8($0) }) else {
return nil
}
self = str
}
return
}

let byteArray = Array(bytes)
if let ns = NSString(
bytes: byteArray, length: byteArray.count, encoding: encoding.rawValue) {
self = String._unconditionallyBridgeFromObjectiveC(ns)
Expand Down