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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2022 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
extension BitArray: Codable {
/// Encodes this bit array into the given encoder.
///
/// Bit arrays are encoded as an unkeyed container of `UInt64` values,
/// representing the total number of bits in the array, followed by
/// UInt64-sized pieces of the underlying bitmap.
///
/// - Parameter encoder: The encoder to write data to.
public func encode(to encoder: Encoder) throws {
var container = encoder.unkeyedContainer()
try container.encode(UInt64(truncatingIfNeeded: _count))
try _storage._encodeAsUInt64(to: &container)
}
/// Creates a new bit array by decoding from the given decoder.
///
/// Bit arrays are encoded as an unkeyed container of `UInt64` values,
/// representing the total number of bits in the array, followed by
/// UInt64-sized pieces of the underlying bitmap.
///
/// - Parameter decoder: The decoder to read data from.
public init(from decoder: Decoder) throws {
var container = try decoder.unkeyedContainer()
guard let count = UInt(exactly: try container.decode(UInt64.self)) else {
let context = DecodingError.Context(
codingPath: container.codingPath,
debugDescription: "Bit Array too long")
throw DecodingError.dataCorrupted(context)
}
var words = try [_Word](
_fromUInt64: &container,
reservingCount: container.count.map { Swift.max(1, $0) - 1 })
if _Word.capacity < UInt64.bitWidth,
count <= (words.count - 1) * _Word.capacity
{
let last = words.removeLast()
guard last.isEmpty else {
let context = DecodingError.Context(
codingPath: container.codingPath,
debugDescription: "Unexpected bits after end")
throw DecodingError.dataCorrupted(context)
}
}
guard
count <= words.count * _Word.capacity,
count > (words.count - 1) * _Word.capacity
else {
let context = DecodingError.Context(
codingPath: container.codingPath,
debugDescription: "Decoded words don't match expected count")
throw DecodingError.dataCorrupted(context)
}
let bit = _BitPosition(count).bit
if bit > 0, !words.last!.subtracting(_Word(upTo: bit)).isEmpty {
let context = DecodingError.Context(
codingPath: container.codingPath,
debugDescription: "Unexpected bits after end")
throw DecodingError.dataCorrupted(context)
}
self.init(_storage: words, count: count)
}
}
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