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##
#W print.gi GAP4 package `Utils' Chris Wensley
##
#Y Copyright (C) 2015-2025, The GAP Group
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## these operations have not been transferred from any other package
##
#M PrintSelection( <args> )
#M PrintSelectionFromList( <list>, <first>, <step>, <last> )
#M PrintSelectionFromIterator( <iterator>, <first>, <step>, <last> )
##
BindGlobal( "PrintSelection",
function( arg )
local nargs, obj, first, step, last, L, ok;
nargs := Length( arg );
obj := arg[1];
if ( ( nargs = 1 ) or ( nargs > 4 ) ) then
Error( "expecting 2, 3 or 4 arguments" );
elif ( nargs = 2 ) then
L := arg[2];
if IsList( L ) then
ok := ForAll( L, IsPosInt );
if not ok then
Error( "L must only contain positive integers" );
fi;
if IsList( obj ) then
PrintSelectionFromListByList( obj, L );
elif IsIterator( obj ) then
PrintSelectionFromIteratorByList( obj, L );
else
PrintSelectionFromIteratorByList( Iterator( obj ), L );
fi;
else
Error( "second argument not a list" );
fi;
else
first := arg[2];
step := arg[3];
if ( nargs = 3 ) then
if IsList( obj ) then
last := Length( obj );
else
last := infinity;
fi;
else
last := arg[4];
fi;
if IsList( obj ) then
PrintSelectionFromList( obj, first, step, last );
elif IsIterator( obj ) then
PrintSelectionFromIterator( obj, first, step, last );
else
PrintSelectionFromIterator( Iterator( obj ), first, step, last );
fi;
fi;
end );
InstallMethod( PrintSelectionFromList, "generic method for lists",
true, [ IsList, IsPosInt, IsPosInt, IsPosInt ], 0,
function( L, first, step, last )
local len, i;
len := Minimum( Length( L ), last );
if ( first <= len ) then
Print( first, " : ", L[first], "\n" );
len := len-first;
i := first;
while ( len >= step ) do
i := i+step;
Print( i, " : ", L[i], "\n" );
len := len-step;
od;
fi;
end );
InstallOtherMethod( PrintSelectionFromIterator, "generic method for iterators",
true, [ IsIterator, IsPosInt, IsPosInt, IsAdditiveElement ], 0,
function( iter0, first, step, last )
local iter, pos, i, x;
if ( last < first ) then
Error( "expecting first <= last" );
fi;
iter := ShallowCopy( iter0 );
i := 0;
while( ( i < first ) and not IsDoneIterator( iter ) ) do
i := i+1;
x := NextIterator( iter );
od;
if ( i = first ) then
pos := first;
Print( pos, " : ", x, "\n" );
fi;
while ( not IsDoneIterator( iter ) and ( pos < last ) ) do
while ( not IsDoneIterator( iter ) and ( pos < last ) ) do
i := 0;
while( ( i<step ) and ( pos+i < last )
and not IsDoneIterator( iter ) ) do
i := i+1;
x := NextIterator( iter );
od;
pos := pos + i;
if ( i = step ) then
Print( pos, " : ", x, "\n" );
fi;
od;
od;
end );
InstallMethod( PrintSelectionFromListByList, "generic method for lists",
true, [ IsList, IsList ], 0,
function( L, posL )
local len, i;
if not ForAll( posL, IsPosInt ) then
Error( "posL should be a list of positive integers" );
fi;
len := Length( L );
for i in [1..len] do
if ( i in posL ) then
Print( i, " : ", L[i], "\n" );
fi;
od;
end );
InstallMethod( PrintSelectionFromIteratorByList, "generic method for iterators",
true, [ IsIterator, IsList ], 0,
function( iter0, posL )
local iter, max, i, x;
if not ForAll( posL, IsPosInt ) then
Error( "posL should be a list of positive integers" );
fi;
iter := ShallowCopy( iter0 );
max := Maximum( posL );
i := 0;
while ( ( i < max ) and not IsDoneIterator( iter ) ) do
x := NextIterator( iter );
i := i+1;
if ( i in posL ) then
Print( i, " : ", x, "\n" );
fi;
od;
end );
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##
#E print.gi . . . . . . . . . . . . . . . . . . . . . . . . . . . ends here
