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- General List Sorting Utilities MLG - 22 December 1981
- ------------------------------
- The module Gsort (use LOAD GSORT) contains a number of general sorting
- functions and associated key comparison functions. The Key comparison
- functions are given 2 objects to compare, return NIL if they are not
- in correct order:
- BeforeFn(a:any,b:any):Extra-Boolean; % return NIL if not in order
- The package defines:
- NumberSortFn(N1:number,N2:Number)
- StringSortFn(S1:String,N2:string) [Sc1 and Sc2 are faster versions]
- IdSortFn(D1:id,D2:id) [IdC1 and IDc2 are faster]
- AtomSortFn(X1:atom,X2:Atom)
- The general sorting functions expect a SortFn (which MUST be an ID)
- GsortP(Lst:x-list,BeforeFn:id):Boolean % T if x-list is sorted
- Gsort(Lst:x-list,BeforeFn:id):x-list % Tree-sort of x-list
- GMergeSort(Lst:x-list,BeforeFn:id):x-list % Merge-sort of x-list
-
- Currently, Gsort is often fastest, but GMergeSort is more stable.
- Example: To sort a list of Ids call Gsort(Dlist,'Idsortfn)
- or Gsort(Dlist,'IDc2) for faster sort.
-
- To sort list of records (e.g. pairs), user must define comparison:
- E.g. to sort LP, a List of dotted pairs (Number . Info), define
-
- procedure NPSortFn(P1,P2); NumberSortFn(Car p1, Car P2);
- then execute Gsort(LP,'NPSortfn);
- See PU:Gsort.Red for the code.
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