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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021-2022 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 PEG.VM {
// TODO: Consumers need a concept of forward progress.
// They can return `nil` and `startIndex`, both which may
// have the same effect for many API, but others might wish
// to differentiate it. We should think through this issue
// and likely make forward progress a more established
// concept.
func consume(_ input: Input) -> Input.Index? {
var core = Core(
instructions, input, enableTracing: enableTracing)
while true {
switch core.state {
case .accept: return core.current.pos
case .fail: return nil
case .processing: core.cycle()
}
}
}
}
extension PEG {
public struct Consumer<Input: Collection> where Input.Element == Element {
var vm: PEG.VM<Input>
public func consume(_ input: Input) -> Input.Index? {
vm.consume(input)
}
}
}
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