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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Async Algorithms open source project
//
// Copyright (c) 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 AsyncSequenceValidationDiagram {
struct Failure: Error, Equatable { }
enum ParseFailure: Error, CustomStringConvertible, SourceFailure {
case stepInGroup(String, String.Index, SourceLocation)
case nestedGroup(String, String.Index, SourceLocation)
case unbalancedNesting(String, String.Index, SourceLocation)
var location: SourceLocation {
switch self {
case .stepInGroup(_, _, let location): return location
case .nestedGroup(_, _, let location): return location
case .unbalancedNesting(_, _, let location): return location
}
}
var description: String {
switch self {
case .stepInGroup:
return "validation diagram step symbol in group"
case .nestedGroup:
return "validation diagram nested grouping"
case .unbalancedNesting:
return "validation diagram unbalanced grouping"
}
}
}
enum Event {
case value(String, String.Index)
case failure(Error, String.Index)
case finish(String.Index)
case delayNext(String.Index)
case cancel(String.Index)
var results: [Result<String?, Error>] {
switch self {
case .value(let value, _): return [.success(value)]
case .failure(let failure, _): return [.failure(failure)]
case .finish: return [.success(nil)]
case .delayNext: return []
case .cancel: return []
}
}
var index: String.Index {
switch self {
case .value(_, let index): return index
case .failure(_, let index): return index
case .finish(let index): return index
case .delayNext(let index): return index
case .cancel(let index): return index
}
}
static func parse<Theme: AsyncSequenceValidationTheme>(_ dsl: String, theme: Theme, location: SourceLocation) throws -> [(Clock.Instant, Event)] {
var emissions = [(Clock.Instant, Event)]()
var when = Clock.Instant(when: .steps(0))
var string: String?
var grouping = 0
for index in dsl.indices {
let ch = dsl[index]
switch theme.token(dsl[index], inValue: string != nil) {
case .step:
if string == nil {
if grouping == 0 {
when = when.advanced(by: .steps(1))
} else {
throw ParseFailure.stepInGroup(dsl, index, location)
}
} else {
string?.append(ch)
}
case .error:
if string == nil {
if grouping == 0 {
when = when.advanced(by: .steps(1))
}
emissions.append((when, .failure(Failure(), index)))
} else {
string?.append(ch)
}
case .finish:
if string == nil {
if grouping == 0 {
when = when.advanced(by: .steps(1))
}
emissions.append((when, .finish(index)))
} else {
string?.append(ch)
}
case .cancel:
if string == nil {
if grouping == 0 {
when = when.advanced(by: .steps(1))
}
emissions.append((when, .cancel(index)))
} else {
string?.append(ch)
}
case .delayNext:
if string == nil {
if grouping == 0 {
when = when.advanced(by: .steps(1))
}
emissions.append((when, .delayNext(index)))
} else {
string?.append(ch)
}
case .beginValue:
string = ""
case .endValue:
if let value = string {
string = nil
if grouping == 0 {
when = when.advanced(by: .steps(1))
}
emissions.append((when, .value(value, index)))
}
case .beginGroup:
if grouping == 0 {
when = when.advanced(by: .steps(1))
} else {
throw ParseFailure.nestedGroup(dsl, index, location)
}
grouping += 1
case .endGroup:
grouping -= 1
if grouping < 0 {
throw ParseFailure.unbalancedNesting(dsl, index, location)
}
case .skip:
string?.append(ch)
continue
case .value(let str):
if string == nil {
if grouping == 0 {
when = when.advanced(by: .steps(1))
}
emissions.append((when, .value(String(ch), index)))
} else {
string?.append(str)
}
}
}
if grouping != 0 {
throw ParseFailure.unbalancedNesting(dsl, dsl.endIndex, location)
}
return emissions
}
}
}
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