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Collection: Added [safe:] and [safePosition:] subscripts for `i…
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…...`, `...i`, `..<i`
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@orchetect
orchetect committed Nov 30, 2021
1 parent 52fac34 commit 96ac061
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Showing 2 changed files with 781 additions and 355 deletions.
289 changes: 187 additions & 102 deletions Sources/OTCore/Extensions/Swift/Collections.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ extension Collection where Self: RangeReplaceableCollection,

}

// MARK: - Safe subscripts
// MARK: - [safe:]

// MutableCollection:
// (inherits from Sequence, Collection)
Expand Down Expand Up @@ -116,6 +116,152 @@ extension MutableCollection where Element : OptionalType {

}

// Collection:
// (inherits from Sequence)
// (conformance on Array, ArraySlice, ContiguousArray, Dictionary, Set, Range, ClosedRange, KeyValuePairs, CollectionOfOne, EmptyCollection, etc.)
// (does not conform on NSArray, NSDictionary, etc.)
extension Collection {

/// **OTCore:**
/// Access collection indexes safely.
///
/// Get: if index does not exist (out-of-bounds), `nil` is returned.
///
/// Set: if index does not exist, set fails silently and the value is not stored.
///
/// Example:
///
/// let arr = [1, 2, 3]
/// arr[safe: 0] // Optional(1)
/// arr[safe: 3] // nil
///
/// // for slice, index numbers are preserved like native subscript
/// let arrSlice = [1, 2, 3].suffix(2)
/// arrSlice[safe: 0] // nil
/// arrSlice[safe: 1] // Optional(2)
/// arrSlice[safe: 2] // Optional(3)
/// arrSlice[safe: 3] // nil
///
@_disfavoredOverload
@inlinable public subscript(safe index: Index) -> Element? {

indices.contains(index) ? self[index] : nil

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index does not exist (out-of-bounds), `defaultValue` is returned.
@_disfavoredOverload
@inlinable public subscript(
safe index: Index,
default defaultValue: @autoclosure () -> Element
) -> Element {

indices.contains(index) ? self[index] : defaultValue()

}

}

extension Collection where Index == Int {

/// **OTCore:**
/// Access collection indexes safely.
///
/// Get: if index does not exist (out-of-bounds), `nil` is returned.
///
/// Set: if index does not exist, set fails silently and the value is not stored.
///
/// Example:
///
/// let arr = [1, 2, 3]
/// arr[safe: 0] // Optional(1)
/// arr[safe: 3] // nil
///
/// // for slice, index numbers are preserved like native subscript
/// let arrSlice = [1, 2, 3].suffix(2)
/// arrSlice[safe: 0] // nil
/// arrSlice[safe: 1] // Optional(2)
/// arrSlice[safe: 2] // Optional(3)
/// arrSlice[safe: 3] // nil
///
@inlinable public subscript(safe index: Int) -> Element? {

indices.contains(index) ? self[index] : nil

}

}

// MARK: - [safe: Range]

extension Collection {

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: ClosedRange<Index>) -> SubSequence? {

guard range.lowerBound >= startIndex,
range.upperBound < endIndex else { return nil }

return self[range.lowerBound...range.upperBound]

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: Range<Index>) -> SubSequence? {

guard range.lowerBound >= startIndex,
range.upperBound <= endIndex else { return nil }

return self[range.lowerBound..<range.upperBound]

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: PartialRangeFrom<Index>) -> SubSequence? {

guard range.lowerBound >= startIndex,
range.lowerBound <= endIndex else { return nil }

return self[range.lowerBound...]

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: PartialRangeThrough<Index>) -> SubSequence? {

guard range.upperBound >= startIndex,
range.upperBound < endIndex else { return nil }

return self[...range.upperBound]

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: PartialRangeUpTo<Index>) -> SubSequence? {

guard range.upperBound >= startIndex,
range.upperBound <= endIndex else { return nil }

return self[..<range.upperBound]

}

}

// MARK: - [safePosition:]

extension MutableCollection {

/// **OTCore:**
Expand Down Expand Up @@ -207,82 +353,8 @@ extension MutableCollection where Element : OptionalType {

}

// Collection:
// (inherits from Sequence)
// (conformance on Array, ArraySlice, ContiguousArray, Dictionary, Set, Range, ClosedRange, KeyValuePairs, CollectionOfOne, EmptyCollection, etc.)
// (does not conform on NSArray, NSDictionary, etc.)
extension Collection {

/// **OTCore:**
/// Access collection indexes safely.
///
/// Get: if index does not exist (out-of-bounds), `nil` is returned.
///
/// Set: if index does not exist, set fails silently and the value is not stored.
///
/// Example:
///
/// let arr = [1, 2, 3]
/// arr[safe: 0] // Optional(1)
/// arr[safe: 3] // nil
///
/// // for slice, index numbers are preserved like native subscript
/// let arrSlice = [1, 2, 3].suffix(2)
/// arrSlice[safe: 0] // nil
/// arrSlice[safe: 1] // Optional(2)
/// arrSlice[safe: 2] // Optional(3)
/// arrSlice[safe: 3] // nil
///
@_disfavoredOverload
@inlinable public subscript(safe index: Index) -> Element? {

indices.contains(index) ? self[index] : nil

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index does not exist (out-of-bounds), `defaultValue` is returned.
@_disfavoredOverload
@inlinable public subscript(
safe index: Index,
default defaultValue: @autoclosure () -> Element
) -> Element {

indices.contains(index) ? self[index] : defaultValue()

}

}

extension Collection where Index == Int {

/// **OTCore:**
/// Access collection indexes safely.
///
/// Get: if index does not exist (out-of-bounds), `nil` is returned.
///
/// Set: if index does not exist, set fails silently and the value is not stored.
///
/// Example:
///
/// let arr = [1, 2, 3]
/// arr[safe: 0] // Optional(1)
/// arr[safe: 3] // nil
///
/// // for slice, index numbers are preserved like native subscript
/// let arrSlice = [1, 2, 3].suffix(2)
/// arrSlice[safe: 0] // nil
/// arrSlice[safe: 1] // Optional(2)
/// arrSlice[safe: 2] // Optional(3)
/// arrSlice[safe: 3] // nil
///
@inlinable public subscript(safe index: Int) -> Element? {

indices.contains(index) ? self[index] : nil

}

/// **OTCore:**
/// Access collection indexes safely, referenced by position offset `0..<count`. (Same as `[position: Int]` but returns `nil` if out-of-bounds.
///
Expand Down Expand Up @@ -365,33 +437,7 @@ extension Collection where Index == Int {

}

extension Collection {

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: ClosedRange<Index>) -> SubSequence? {

guard range.lowerBound >= startIndex,
range.upperBound < endIndex else { return nil }

return self[range.lowerBound...range.upperBound]

}

/// **OTCore:**
/// Access collection indexes safely.
/// If index range is not fully contained within the collection's indices, `nil` is returned.
@inlinable public subscript(safe range: Range<Index>) -> SubSequence? {

guard range.lowerBound >= startIndex,
range.upperBound <= endIndex else { return nil }

return self[range.lowerBound..<range.upperBound]

}

}
// MARK: - [safePosition: Range]

extension Collection where Index == Int {

Expand Down Expand Up @@ -423,6 +469,45 @@ extension Collection where Index == Int {

}

/// **OTCore:**
/// Access collection indexes safely, referenced by position offset `0..<count`. (Same as `[Int]` but if position range is not fully contained within the collection's element position offsets, `nil` is returned.
@inlinable public subscript(safePosition range: PartialRangeFrom<Int>) -> SubSequence? {

let fromIndex = index(startIndex, offsetBy: range.lowerBound)

guard fromIndex >= startIndex,
fromIndex <= endIndex else { return nil }

return self[fromIndex...]

}

/// **OTCore:**
/// Access collection indexes safely, referenced by position offset `0..<count`. (Same as `[Int]` but if position range is not fully contained within the collection's element position offsets, `nil` is returned.
@inlinable public subscript(safePosition range: PartialRangeThrough<Int>) -> SubSequence? {

let toIndex = index(startIndex, offsetBy: range.upperBound)

guard toIndex >= startIndex,
toIndex < endIndex else { return nil }

return self[...toIndex]

}

/// **OTCore:**
/// Access collection indexes safely, referenced by position offset `0..<count`. (Same as `[Int]` but if position range is not fully contained within the collection's element position offsets, `nil` is returned.
@inlinable public subscript(safePosition range: PartialRangeUpTo<Int>) -> SubSequence? {

let toIndex = index(startIndex, offsetBy: range.upperBound)

guard toIndex >= startIndex,
toIndex <= endIndex else { return nil }

return self[..<toIndex]

}

}


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