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Reuse the executor in firstMatch #489

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Reuse the executor in firstMatch #489

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1c50722
Reuse executor in firstMatch
rctcwyvrn Jun 15, 2022
218bd33
Reuse processor
rctcwyvrn Jun 15, 2022
b559197
Add register resetting
rctcwyvrn Jun 15, 2022
7aa82fd
Clear arrays in place
rctcwyvrn Jun 15, 2022
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17 changes: 8 additions & 9 deletions Sources/_StringProcessing/Engine/Processor.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ struct Processor<
typealias Element = Input.Element

let input: Input
var bounds: Range<Position>
let bounds: Range<Position>
let matchMode: MatchMode
var currentPosition: Position

Expand Down Expand Up @@ -95,19 +95,18 @@ extension Processor {
assert(currentPosition <= end)
}

mutating func reset(newBounds: Range<Position>)
mutating func reset(newPosition: Position)
{
self.bounds = newBounds

self.controller = Controller(pc: 0)
self.currentPosition = bounds.lowerBound
self.currentPosition = newPosition

self.registers.reset(bounds.upperBound)
self.storedCaptures = self.storedCaptures.map {_ in .init()}
for idx in storedCaptures.indices {
storedCaptures[idx] = .init()
}

self.cycleCount = 0
self.savePoints = []
self.callStack = []
self.savePoints.removeAll(keepingCapacity: true)
self.callStack.removeAll(keepingCapacity: true)
self.state = .inProgress
self.failureReason = nil
}
Expand Down
24 changes: 14 additions & 10 deletions Sources/_StringProcessing/Engine/Registers.swift
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Expand Up @@ -162,17 +162,21 @@ extension Processor.Registers {
mutating func reset(_ sentinel: Input.Index) {
// note: Is there any issue with the program transform functions holding
// state and not getting reset here? Do we care?
self.bools = Array(repeating: false, count: info.bools)
self.ints = Array(repeating: 0, count: info.ints)
self.floats = Array(repeating: 0, count: info.floats)
self.positions = Array(repeating: sentinel, count: info.positions)
self.values = Array(
repeating: SentinelValue(), count: info.values)
func clear<T>(_ xs: inout [T], _ v: T) {
for idx in xs.indices {
xs[idx] = v
}
}
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Or as an extension on MutableCollection. @natecook1000 does such an algorithm exist?

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We could try these out here before adding them to swift-algorithms:

extension MutableCollection {
  mutating func setAll(to element: Element) {
    self.withEach { $0 = element }
  }
  
  mutating func withEach(_ body: (inout Element) throws -> Void) rethrows {
    var i = startIndex
    while i < endIndex {
      try body(&self[i])
      formIndex(after: &i)
    }
  }
}

// usage:
self.bools.setAll(to: false)

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Also considering an underscore them so that no one accidentally ships it 😅


self.instructionAddresses = Array(repeating: 0, count: info.instructionAddresses)
self.classStackAddresses = Array(repeating: 0, count: info.classStackAddresses)
self.positionStackAddresses = Array(repeating: 0, count: info.positionStackAddresses)
self.savePointAddresses = Array(repeating: 0, count: info.savePointAddresses)
clear(&self.bools, false)
clear(&self.ints, 0)
clear(&self.floats, 0)
clear(&self.positions, sentinel)
clear(&self.values, SentinelValue())
clear(&self.instructionAddresses, 0)
clear(&self.classStackAddresses, 0)
clear(&self.positionStackAddresses, 0)
clear(&self.savePointAddresses, 0)
}
}

Expand Down
15 changes: 10 additions & 5 deletions Sources/_StringProcessing/Executor.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ struct Executor {
) throws -> Regex<Output>.Match? {
var cpu = engine.makeProcessor(
input: input, bounds: inputRange, matchMode: mode)
return try consume(input, &cpu)
return try consume(input, &cpu, startingFrom: inputRange.lowerBound)
}

@available(SwiftStdlib 5.7, *)
Expand All @@ -43,7 +43,11 @@ struct Executor {
input: input, bounds: inputRange, matchMode: mode)

while true {
if let m: Regex<Output>.Match = try consume(input, &cpu) {
if let m: Regex<Output>.Match = try consume(
input,
&cpu,
startingFrom: low
Comment on lines +47 to +49
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Suggested change
input,
&cpu,
startingFrom: low
input, &cpu, startingFrom: low

) {
return m
}

Expand All @@ -54,14 +58,15 @@ struct Executor {
input.unicodeScalars.formIndex(after: &low)
}

cpu.reset(newBounds: low..<high)
cpu.reset(newPosition: low)
}
}

@available(SwiftStdlib 5.7, *)
func consume<Output>(
_ input: String,
_ cpu: inout Processor<String>
_ cpu: inout Processor<String>,
startingFrom startIdx: String.Index
) throws -> Regex<Output>.Match? {
guard let endIdx = cpu.consume() else {
if let e = cpu.failureReason {
Expand All @@ -75,7 +80,7 @@ struct Executor {
referencedCaptureOffsets: engine.program.referencedCaptureOffsets,
namedCaptureOffsets: engine.program.namedCaptureOffsets)

let range = cpu.bounds.lowerBound..<endIdx
let range = startIdx..<endIdx
let caps = engine.program.captureList.createElements(capList, input)

// FIXME: This is a workaround for not tracking (or
Expand Down