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improve and clean up StringXxxx (note a couple compile errors remain in dependent files)

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This commit is contained in:
Shawn Erickson
2016-03-08 15:04:45 -08:00
parent 80670a2b24
commit 7a84232a06
4 changed files with 78 additions and 49 deletions
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60
stdlib/public/core/StringUTF16.swift
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@@ -18,7 +18,7 @@ extension String {
CustomDebugStringConvertible {
/// A position in a string's collection of UTF-16 code units.
public struct Index {
public struct Index : Comparable {
// Foundation needs access to these fields so it can expose
// random access
public // SPI(Foundation)
@@ -27,6 +27,8 @@ extension String {
public let _offset: Int
}
public typealias IndexDistance = Int
/// The position of the first code unit if the `String` is
/// non-empty; identical to `endIndex` otherwise.
public var startIndex: Index {
@@ -45,24 +47,28 @@ extension String {
// TODO: swift-3-indexing-model - add docs
@warn_unused_result
public func next(i: Index) -> Index {
// FIXME: swift-3-indexing-model: range check i?
return Index(_offset: i._offset.advanced(by: 1))
}
// TODO: swift-3-indexing-model - add docs
@warn_unused_result
public func previous(i: Index) -> Index {
// FIXME: swift-3-indexing-model: range check i?
return Index(_offset: i._offset.advanced(by: -1))
}
// TODO: swift-3-indexing-model - add docs
@warn_unused_result
public func advance(i: Index, by n: Int) -> Index {
public func advance(i: Index, by n: IndexDistance) -> Index {
// FIXME: swift-3-indexing-model: range check i?
return Index(_offset: i._offset.advanced(by: n))
}
// TODO: swift-3-indexing-model - add docs
@warn_unused_result
public func advance(i: Index, by n: Int, limit: Index) -> Index {
public func advance(i: Index, by n: IndexDistance, limit: Index) -> Index {
// FIXME: swift-3-indexing-model: range check i?
let d = i._offset.distance(to: limit._offset)
if d == 0 || (d > 0 ? d <= n : d >= n) {
return limit
@@ -72,7 +78,8 @@ extension String {
// TODO: swift-3-indexing-model - add docs
@warn_unused_result
public func distance(from start: Index, to end: Index) -> Int {
public func distance(from start: Index, to end: Index) -> IndexDistance {
// FIXME: swift-3-indexing-model: range check start and end?
return start._offset.distance(to: end._offset)
}
@@ -206,24 +213,8 @@ extension String {
public typealias UTF16Index = UTF16View.Index
}
// Conformance to RandomAccessIndex intentionally only appears
// when Foundation is loaded
extension String.UTF16View.Index {
public typealias Distance = Int
@warn_unused_result
public func successor() -> String.UTF16View.Index {
return String.UTF16View.Index(
_offset: _unsafePlus(_offset, 1))
}
@warn_unused_result
public func predecessor() -> String.UTF16View.Index {
return String.UTF16View.Index(
_offset: _unsafeMinus(_offset, 1))
}
}
// FIXME: swift-3-indexing-model: add complete set of forwards for Comparable
// assuming String.UTF8View.Index continues to exist
@warn_unused_result
public func == (
lhs: String.UTF16View.Index, rhs: String.UTF16View.Index
@@ -231,8 +222,6 @@ public func == (
return lhs._offset == rhs._offset
}
extension String.UTF16View.Index : Comparable, Equatable {}
@warn_unused_result
public func < (
lhs: String.UTF16View.Index, rhs: String.UTF16View.Index
@@ -240,29 +229,6 @@ public func < (
return lhs._offset < rhs._offset
}
// We can do some things more efficiently, even if we don't promise to
// by conforming to RandomAccessIndex.
extension String.UTF16View.Index {
@warn_unused_result
public func distance(to end: String.UTF16View.Index)
-> String.UTF16View.Index.Distance {
return self._offset.distance(to: end._offset)
}
@warn_unused_result
public func advanced(by n: Distance) -> String.UTF16View.Index {
return String.UTF16View.Index(_offset: self._offset.advanced(by: n))
}
@warn_unused_result
public func advanced(by n: Distance, limit: String.UTF16View.Index)
-> String.UTF16View.Index {
return String.UTF16View.Index(
_offset: self._offset.advanced(by: n, limit: limit._offset))
}
}
// Index conversions
extension String.UTF16View.Index {
/// Construct the position in `utf16` that corresponds exactly to