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##
## Datastructures: GAP package providing common datastructures.
##
## Copyright (C) 2015-2017 The datastructures team.
## For list of the team members, please refer to the COPYRIGHT file.
##
## This package is licensed under the GPL 2 or later, please refer
## to the COPYRIGHT.md and LICENSE files for details.
##
##
## Memoisation with hash table
##
InstallGlobalFunction(MemoizeFunction,
function ( func, extra... )
local cache, original, options, r;
options := rec( flush := true,
contract := ReturnTrue,
errorHandler := function(args...) return fail; end
);
if Length( extra ) > 0 then
for r in RecNames( extra[1] ) do
if IsBound( options.(r) ) then
options.(r) := extra[1].(r);
else
ErrorNoReturn( "Invalid option: ", r );
fi;
od;
fi;
cache := HashMap();
if options.flush then
InstallMethod( FlushCaches, [ ], function ( )
cache := HashMap();
TryNextMethod();
end );
fi;
return function ( args... )
local v;
if not CallFuncList(options.contract, args) then
v := CallFuncListWrap(options.errorHandler, args);
if v <> [] then
return v[1];
fi;
return;
fi;
if args in cache then
v := cache[args];
else
v := CallFuncList(func, args);
cache[args] := v;
fi;
return v;
end;
end);
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