Adapt to TypeScript 4.1

Author: KSXGitHub

lib/utils.ts

@@ -1,46 +1,31 @@
-export type IsFinite<Tuple extends any[], Finite, Infinite> = {
-  empty: Finite
-  nonEmpty: ((..._: Tuple) => any) extends ((_: infer First, ..._1: infer Rest) => any)
+export type IsFinite<Tuple extends any[], Finite, Infinite> =
+  Tuple extends [] ? Finite :
+  Tuple extends Array<infer Element> ?
+  Element[] extends Tuple ?
+    Infinite
+  : Tuple extends [any, ...infer Rest]
     ? IsFinite<Rest, Finite, Infinite>
     : never
-  infinite: Infinite
-}[
-  Tuple extends [] ? 'empty' :
-  Tuple extends (infer Element)[] ?
-  Element[] extends Tuple ?
-    'infinite'
-  : 'nonEmpty'
   : never
-]
 
-export type _SplitInfiniteTuple<Tuple extends any[], Holder extends any[] = []> = {
-  matched: [Holder, Tuple]
-  unmatched: ((..._: Tuple) => any) extends ((_: infer First, ..._1: infer Rest) => any)
-    ? _SplitInfiniteTuple<Rest, Prepend<Holder, First>>
-    : never
-  finite: [Tuple, []]
-}[
-  Tuple extends (infer Element)[] ?
-    Element[] extends Tuple ? 'matched' : 'unmatched'
+export type _SplitInfiniteTuple<Tuple extends any[], Holder extends any[] = []> =
+  Tuple extends Array<infer Element> ?
+  Element[] extends Tuple ? [Tuple, Holder] :
+  Tuple extends [infer First, ...infer Rest] ?
+    _SplitInfiniteTuple<Rest, Prepend<Holder, First>>
+  : never
   : never
-]
 
 export type First<Tuple extends any[], Default = never> =
   Tuple extends [any, ...any[]] ? Tuple[0] : Default
 
-export type Last<Tuple extends any[], Default = never> = {
-  empty: Default
-  single: Tuple extends [infer SoleElement] ? SoleElement : never
-  multi: ((..._: Tuple) => any) extends ((_: any, ..._1: infer Next) => any) ? Last<Next> : Default
-  infinite: Tuple extends (infer Element)[] ? Element : never
-}[
-  Tuple extends [] ? 'empty' :
-  Tuple extends [any] ? 'single' :
-    Tuple extends (infer Element)[]
-      ? Element[] extends Tuple ? 'infinite'
-      : 'multi'
+export type Last<Tuple extends any[], Default = never> =
+  Tuple extends [] ? Default :
+  Tuple extends [infer SoleElement] ? SoleElement :
+  Tuple extends Array<infer Element> ?
+    Element[] extends Tuple ? Element :
+    Tuple extends [any, ...infer Next] ? Last<Next> : Default
   : never
-]
 
 export type Tail<Tuple extends any[]> =
   ((...args: Tuple) => any) extends ((_: any, ..._1: infer Rest) => any)
@@ -51,7 +36,7 @@ export type Prepend<Tuple extends any[], Addend> = [Addend, ...Tuple]
 
 export type Reverse<Tuple extends any[], Prefix extends any[] = []> = {
   empty: Prefix,
-  nonEmpty: ((..._: Tuple) => any) extends ((_: infer First, ..._1: infer Next) => any)
+  nonEmpty: Tuple extends [infer First, ...infer Next]
     ? Reverse<Next, Prepend<Prefix, First>>
     : never
   infinite: {
@@ -68,23 +53,18 @@ export type Concat<Left extends any[], Right extends any[]> = [...Left, ...Right
 
 export type Repeat<Type, Count extends number, Holder extends any[] = []> =
   Count extends never ? never :
-  number extends Count
-    ? Type[]
-    : {
-      fit: Holder
-      unfit: Repeat<Type, Count, Prepend<Holder, Type>>
-      union: Count extends Holder['length'] | infer Rest ?
-          Rest extends number ?
-            Repeat<Type, Holder['length']> | Repeat<Type, Rest>
-          : never
-          : never
-    }[
-        Holder['length'] extends Count ? // It is possible for Count to be a union
-        Count extends Holder['length'] ? // Make sure that Count is not a union
-          'fit'
-        : 'union'
-        : 'unfit'
-      ]
+  number extends Count ? Type[] :
+  Holder['length'] extends Count ? // It is possible for Count to be a union
+  Count extends Holder['length'] ? // Make sure that Count is not a union
+    Holder
+  // Count is a union
+  : Count extends Holder['length'] | infer Rest ?
+    Rest extends number ?
+      Repeat<Type, Holder['length']> | Repeat<Type, Rest>
+    : never
+    : never
+  // Count is not Holder['length']
+  : Repeat<Type, Count, Prepend<Holder, Type>>
 
 export type ConcatMultiple<TupleSet extends any[][]> = {
   empty: []
@@ -103,100 +83,67 @@ export type ConcatMultiple<TupleSet extends any[][]> = {
   TupleSet extends [] ? 'empty' : IsFinite<TupleSet, 'nonEmpty', 'infinite'>
 ]
 
-export type Drop<
-  Tuple extends any[],
-  Quantity extends number,
-  Count extends any[] = []
-> = {
-  matched: Tuple
-  unmatched: ((...args: Tuple) => any) extends ((_: any, ..._1: infer Rest) => any)
+export type Drop<Tuple extends any[], Quantity extends number, Count extends any[] = []> =
+  Tuple extends [] ? Tuple :
+  Quantity extends Count['length'] ? Tuple :
+  ((...args: Tuple) => any) extends ((_: any, ..._1: infer Rest) => any)
     ? Drop<Rest, Quantity, Prepend<Count, Count['length']>>
-    : never
-}[
-  Tuple extends [] ? 'matched' :
-  Quantity extends Count['length'] ? 'matched' :
-  'unmatched'
-]
+  : never
 
 export type SliceStartQuantity<
   Tuple extends any[],
   Start extends number,
   Quantity extends number,
   Holder extends any[] = [],
   Count extends any[] = []
-> = {
-  before: SliceStartQuantity<
+> =
+  Tuple extends [] ? Reverse<Holder> :
+  Quantity extends Holder['length'] ? Reverse<Holder> :
+  Start extends Count['length'] ?
+    Tuple extends [infer First, ...infer Rest]
+    ? SliceStartQuantity<Rest, Start, Quantity, Prepend<Holder, First>, Count>
+    : never
+  : SliceStartQuantity<
     Tail<Tuple>,
     Start,
     Quantity,
     Holder,
     Prepend<Count, Count['length']>
   >
-  start: ((...args: Tuple) => any) extends ((_: infer First, ..._1: infer Rest) => any)
-    ? SliceStartQuantity<
-      Rest,
-      Start,
-      Quantity,
-      Prepend<Holder, First>,
-      Count
-    >
-    : never
-  end: Reverse<Holder>
-}[
-  Tuple extends [] ? 'end' :
-  Quantity extends Holder['length'] ? 'end' :
-  Start extends Count['length'] ? 'start' :
-  'before'
-]
 
 export type FillTuple<Tuple extends any[], Replacement, Holder extends any[] = []> = {
   empty: Holder
-  nonEmpty: ((...a: Tuple) => any) extends ((a: infer First, ...b: infer Rest) => any)
+  nonEmpty: Tuple extends [any, ...infer Rest]
     ? FillTuple<Rest, Replacement, Prepend<Holder, Replacement>>
     : never
   infinite: Replacement[]
 }[
   Tuple extends [] ? 'empty' : IsFinite<Tuple, 'nonEmpty', 'infinite'>
 ]
 
-export type CompareLength<Left extends any[], Right extends any[]> = {
-  fitBoth: 'equal'
-  fitLeft: 'shorterLeft'
-  fitRight: 'shorterRight'
-  unfit: ((..._: Left) => any) extends ((_: any, ..._1: infer LeftRest) => any) ?
-    ((..._: Right) => any) extends ((_: any, ..._1: infer RightRest) => any) ?
-      CompareLength<LeftRest, RightRest>
-    : never
-    : never
-}[
-  Left['length'] extends Right['length'] ? 'fitBoth' :
-  Left extends [] ? 'fitLeft' :
-  Right extends [] ? 'fitRight' :
-  'unfit'
-]
+export type CompareLength<Left extends any[], Right extends any[]> =
+  Left['length'] extends Right['length'] ? 'equal' :
+  Left extends [] ? 'shorterLeft' :
+  Right extends [] ? 'shorterRight' :
+  CompareLength<Tail<Left>, Tail<Right>>
 
 export type SortTwoTuple<Left extends any[], Right extends any[], WhenEqual = [Left, Right]> = {
   equal: WhenEqual
   shorterLeft: [Left, Right]
   shorterRight: [Right, Left]
 }[CompareLength<Left, Right>]
 
-export type ShortestTuple<TupleSet extends any[][], Shortest = any[]> = {
-  empty: Shortest
-  nonEmpty: ((..._: TupleSet) => any) extends ((_: infer Head, ..._1: infer Tail) => any) ?
+export type ShortestTuple<TupleSet extends any[][], Shortest extends any[] = any[]> =
+  TupleSet extends [] ? Shortest :
+  ((..._: TupleSet) => any) extends ((_: infer Head, ..._1: infer Tail) => any) ?
     Tail extends any[] ?
-    Shortest extends any[] ?
     Head extends any[] ?
       Tail extends Head[]
         ? SortTwoTuple<Shortest, Head>[0]
         : ShortestTuple<Tail, SortTwoTuple<Shortest, Head>[0]>
     : never
     : never
-    : never
-    : never
-}[
-  TupleSet extends [] ? 'empty' : 'nonEmpty'
-]
+  : never
 
 export type LongestTuple<TupleSet extends any[][], Longest = []> = {
   empty: Longest