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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
//
//===----------------------------------------------------------------------===//
internal import _RegexParser
/*
TODO: Specialized data structure for all captures:
- We want to be able to refer to COW prefixes for which
simple appends do not invalidate
- We want a compact save-point representation
TODO: Conjectures:
- We should be able to remove the entire capture history,
lazily recomputing it on-request from the initial stored
save point
- We should be able to keep these flat and simple, lazily
constructing structured types on-request
*/
extension Processor {
struct _StoredCapture {
var range: Range<Position>? = nil
var value: Any? = nil
// An in-progress capture start
var currentCaptureBegin: Position? = nil
fileprivate func _invariantCheck() {
if range == nil {
assert(value == nil)
}
}
// MARK: - IPI
var deconstructed: (range: Range<Position>, value: Any?)? {
guard let r = range else { return nil }
return (r, value)
}
/// Start a new capture. If the previously started one was un-ended,
/// will clear it and restart.
mutating func startCapture(
_ idx: Position
) {
_invariantCheck()
defer { _invariantCheck() }
currentCaptureBegin = idx
}
mutating func endCapture(_ idx: Position) {
_invariantCheck()
defer { _invariantCheck() }
guard let low = currentCaptureBegin else {
fatalError("Invariant violated: ending unstarted capture")
}
range = low..<idx
value = nil // TODO: cleaner IPI around this...
currentCaptureBegin = nil
}
mutating func registerValue(_ value: Any) {
_invariantCheck()
defer { _invariantCheck() }
self.value = value
}
}
}
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