mirror of
https://github.com/OpenEmu/OpenEmuKit.git
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58 lines
2.2 KiB
Swift
58 lines
2.2 KiB
Swift
// Copyright (c) 2022, OpenEmu Team
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// * Neither the name of the OpenEmu Team nor the
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// names of its contributors may be used to endorse or promote products
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// derived from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY OpenEmu Team ''AS IS'' AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL OpenEmu Team BE LIABLE FOR ANY
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// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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import Foundation
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struct PeekableIterator<Base: IteratorProtocol>: IteratorProtocol {
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private var peeked: Base.Element??
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private var iter: Base
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init(_ base: Base) {
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iter = base
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}
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mutating func peek() -> Base.Element? {
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if peeked == nil {
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peeked = iter.next()
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}
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return peeked!
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}
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@discardableResult
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mutating func next() -> Base.Element? {
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if let val = peeked {
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peeked = nil
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return val
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}
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return iter.next()
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}
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}
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extension Sequence {
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func makePeekableIterator() -> PeekableIterator<Self.Iterator> {
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return PeekableIterator(makeIterator())
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}
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}
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