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Commit58a48e1

Browse files
gdziadkiewiczKevinRansom
authored andcommitted
Add TryExactlyOne for array, list and seq. (dotnet#5804)
1 parent5ae8597 commit58a48e1

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12 files changed

+134
-7
lines changed

12 files changed

+134
-7
lines changed

‎src/fsharp/FSharp.Core/array.fs‎

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Original file line numberDiff line numberDiff line change
@@ -1243,6 +1243,12 @@ namespace Microsoft.FSharp.Collections
12431243
elif array.Length=0then invalidArg"array" LanguagePrimitives.ErrorStrings.InputSequenceEmptyString
12441244
else invalidArg"array"(SR.GetString(SR.inputSequenceTooLong))
12451245

1246+
[<CompiledName("TryExactlyOne")>]
1247+
lettryExactlyOne(array:'T[])=
1248+
checkNonNull"array" array
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if array.Length=1then Some array.[0]
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else None
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lettransposeArrays(array:'T[][])=
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letlen= array.Length
12481254
if len=0then Microsoft.FSharp.Primitives.Basics.Array.zeroCreateUnchecked0else

‎src/fsharp/FSharp.Core/array.fsi‎

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Original file line numberDiff line numberDiff line change
@@ -243,6 +243,16 @@ namespace Microsoft.FSharp.Collections
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[<CompiledName("ExactlyOne")>]
244244
val exactlyOne:array:'T[]-> 'T
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///<summary>Returns the only element of the array or <c>None</c> if array is empty or contains more than one element.</summary>
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///
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///<param name="array">The input array.</param>
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///
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///<returns>The only element of the array or None.</returns>
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///
252+
///<exception cref="System.ArgumentNullException">Thrown when the input array is null.</exception>
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[<CompiledName("TryExactlyOne")>]
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val tryExactlyOne:array:'T[]-> 'T option
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246256
///<summary>Returns a new list with the distinct elements of the input array which do not appear in the itemsToExclude sequence,
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///using generic hash and equality comparisons to compare values.</summary>
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///

‎src/fsharp/FSharp.Core/list.fs‎

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Original file line numberDiff line numberDiff line change
@@ -671,6 +671,12 @@ namespace Microsoft.FSharp.Collections
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|[]-> invalidArg"source" LanguagePrimitives.ErrorStrings.InputSequenceEmptyString
672672
|_-> invalidArg"source"(SR.GetString(SR.inputSequenceTooLong))
673673

674+
[<CompiledName("TryExactlyOne")>]
675+
lettryExactlyOne(list:list<_>)=
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match listwith
677+
|[x]-> Some x
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|_-> None
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674680
[<CompiledName("Transpose")>]
675681
lettranspose(lists:seq<'Tlist>)=
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checkNonNull"lists" lists

‎src/fsharp/FSharp.Core/list.fsi‎

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Original file line numberDiff line numberDiff line change
@@ -172,6 +172,14 @@ namespace Microsoft.FSharp.Collections
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[<CompiledName("ExactlyOne")>]
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val exactlyOne:list:'T list-> 'T
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///<summary>Returns the only element of the list or <c>None</c> if it is empty or contains more than one element.</summary>
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///
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///<param name="list">The input list.</param>
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///
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///<returns>The only element of the list or None.</returns>
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[<CompiledName("TryExactlyOne")>]
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val tryExactlyOne:list:'T list-> 'T option
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///<summary>Tests if any element of the list satisfies the given predicate.</summary>
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///
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///<remarks>The predicate is applied to the elements of the input list. If any application

‎src/fsharp/FSharp.Core/seq.fs‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1421,6 +1421,19 @@ namespace Microsoft.FSharp.Collections
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else
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invalidArg"source" LanguagePrimitives.ErrorStrings.InputSequenceEmptyString
14231423

1424+
[<CompiledName("TryExactlyOne")>]
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lettryExactlyOne(source:seq<_>)=
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checkNonNull"source" source
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use e= source.GetEnumerator()
1428+
if e.MoveNext()then
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letv= e.Current
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if e.MoveNext()then
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None
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else
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Some v
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else
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None
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[<CompiledName("Reverse")>]
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letrev source=
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checkNonNull"source" source

‎src/fsharp/FSharp.Core/seq.fsi‎

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Original file line numberDiff line numberDiff line change
@@ -558,6 +558,16 @@ namespace Microsoft.FSharp.Collections
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[<CompiledName("ExactlyOne")>]
559559
val exactlyOne:source:seq<'T>-> 'T
560560

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///<summary>Returns the only element of the sequence or <c>None</c> if sequence is empty or contains more than one element.</summary>
562+
///
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///<param name="source">The input sequence.</param>
564+
///
565+
///<returns>The only element of the sequence or None.</returns>
566+
///
567+
///<exception cref="System.ArgumentNullException">Thrown when the input sequence is null.</exception>
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[<CompiledName("TryExactlyOne")>]
569+
val tryExactlyOne:source:seq<'T>-> 'T option
570+
561571
///<summary>Returns true if the sequence contains no elements,false otherwise.</summary>
562572
///
563573
///<param name="source">The input sequence.</param>

‎tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule.fs‎

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Original file line numberDiff line numberDiff line change
@@ -1186,6 +1186,24 @@ type ArrayModule() =
11861186
memberthis.``exactlyOne should fail on arrays with more than one element``()=
11871187
CheckThrowsArgumentException(fun()-> Array.exactlyOne[|"1";"2"|]|> ignore)
11881188

1189+
[<Test>]
1190+
memberthis.``tryExactlyOne should return the element from singleton arrays``()=
1191+
Assert.AreEqual(Some1, Array.tryExactlyOne[|1|])
1192+
Assert.AreEqual(Some"2", Array.tryExactlyOne[|"2"|])
1193+
()
1194+
1195+
[<Test>]
1196+
memberthis.``tryExactlyOne should return None on empty array``()=
1197+
Assert.AreEqual(None, Array.tryExactlyOne[||])
1198+
1199+
[<Test>]
1200+
memberthis.``tryExactlyOne should return None for arrays with more than one element``()=
1201+
Assert.AreEqual(None, Array.tryExactlyOne[|"1";"2"|])
1202+
1203+
[<Test>]
1204+
memberthis.``tryExactlyOne should fail on null array``()=
1205+
CheckThrowsArgumentNullException(fun()-> Array.tryExactlyOnenull|> ignore)
1206+
11891207
[<Test>]
11901208
memberthis.GroupBy()=
11911209
letfuncInt x= x%5

‎tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/CollectionModulesConsistency.fs‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -200,6 +200,18 @@ let ``exactlyOne is consistent`` () =
200200
smallerSizeCheck exactlyOne<string>
201201
smallerSizeCheck exactlyOne<NormalFloat>
202202

203+
lettryExactlyOne<'awhen'a:comparison>(xs:'a[])=
204+
lets= runAndCheckErrorType(fun()-> xs|> Seq.tryExactlyOne)
205+
letl= runAndCheckErrorType(fun()-> xs|> List.ofArray|> List.tryExactlyOne)
206+
leta= runAndCheckErrorType(fun()-> xs|> Array.tryExactlyOne)
207+
consistency"tryExactlyOne" s l a
208+
209+
[<Test>]
210+
let``tryExactlyOne is consistent``()=
211+
smallerSizeCheck tryExactlyOne<int>
212+
smallerSizeCheck tryExactlyOne<string>
213+
smallerSizeCheck tryExactlyOne<NormalFloat>
214+
203215
letexcept<'awhen'a:equality>(xs:'a[])(itemsToExclude:'a[])=
204216
lets= xs|> Seq.except itemsToExclude|> Seq.toArray
205217
letl= xs|> List.ofArray|> List.except itemsToExclude|> List.toArray

‎tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -808,6 +808,20 @@ type ListModule() =
808808
memberthis.``exactlyOne should fail on lists with more than one element``()=
809809
CheckThrowsArgumentException(fun()-> List.exactlyOne["1";"2"]|> ignore)
810810

811+
[<Test>]
812+
memberthis.``tryExactlyOne should return the element from singleton lists``()=
813+
Assert.AreEqual(Some1, List.tryExactlyOne[1])
814+
Assert.AreEqual(Some"2", List.tryExactlyOne["2"])
815+
()
816+
817+
[<Test>]
818+
memberthis.``tryExactlyOne should return None for empty list``()=
819+
Assert.AreEqual(None, List.tryExactlyOne[])
820+
821+
[<Test>]
822+
memberthis.``tryExactlyOne should return None for lists with more than one element``()=
823+
Assert.AreEqual(None, List.tryExactlyOne["1";"2"])
824+
811825
[<Test>]
812826
memberthis.TryHead()=
813827
// integer List

‎tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/SeqModule2.fs‎

Lines changed: 31 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -139,17 +139,41 @@ type SeqModule2() =
139139
// Empty Seq
140140
letemptySeq= Seq.empty
141141
CheckThrowsArgumentException(fun()-> Seq.exactlyOne emptySeq)
142-
142+
143143
// non-singleton Seq
144+
letnonSingletonSeq=[0..1]
145+
CheckThrowsArgumentException(fun()-> Seq.exactlyOne nonSingletonSeq|> ignore)
146+
147+
// null Seq
148+
letnullSeq:seq<'a>=null
149+
CheckThrowsArgumentNullException(fun()-> Seq.exactlyOne nullSeq)
150+
()
151+
152+
[<Test>]
153+
memberthis.TryExactlyOne()=
154+
letIntSeq=
155+
seq{for iin7..7do
156+
yield i}
157+
158+
Assert.AreEqual(Some7, Seq.tryExactlyOne IntSeq)
159+
160+
// string Seq
161+
letstrSeq= seq["second"]
162+
Assert.AreEqual(Some"second", Seq.tryExactlyOne strSeq)
163+
164+
// Empty Seq
144165
letemptySeq= Seq.empty
145-
CheckThrowsArgumentException(fun()-> Seq.exactlyOne[0..1]|> ignore)
146-
166+
Assert.AreEqual(None, Seq.tryExactlyOne emptySeq)
167+
168+
// non-singleton Seq
169+
letnonSingletonSeq=[0..1]
170+
Assert.AreEqual(None, Seq.tryExactlyOne nonSingletonSeq)
171+
147172
// null Seq
148173
letnullSeq:seq<'a>=null
149-
CheckThrowsArgumentNullException(fun()->Seq.exactlyOne nullSeq)
150-
()
151-
152-
174+
CheckThrowsArgumentNullException(fun()-> Seq.tryExactlyOne nullSeq|> ignore)
175+
()
176+
153177
[<Test>]
154178
memberthis.Init()=
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