66 lines
1.9 KiB
Java
66 lines
1.9 KiB
Java
/**
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* Serene (simple) - A PoC lisp to collect data on Serenes concepts
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* Copyright (C) 2019-2020 Sameer Rahmani <lxsameer@gnu.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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package serene.simple.builtin;
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import java.util.List;
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import java.util.function.Function;
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import serene.simple.IDoc;
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import serene.simple.IScope;
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import serene.simple.ListNode;
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import serene.simple.SereneException;
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public class ReduceFn extends AFn implements IDoc {
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public String fnName() {
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return "reduce";
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};
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public String getDoc() {
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return "(reduce f coll initial-value): Reduce the COLL by applying F.";
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}
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public Object eval(IScope scope) throws SereneException{
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List<Object> args = this.arguments();
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if (args.size() != 3) {
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throw new SereneException(
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String.format("reduce expects 3 parameters. Got %s", args.size()));
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}
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Function<Object,Object> fn = (Function<Object, Object>) args.get(0);
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ListNode<Object> coll = (ListNode<Object>) args.get(1);
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Object initialValue = args.get(2);
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while(true) {
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Object x = coll.first();
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if (x == null)
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break;
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Object[] fnArgs = { initialValue, x };
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coll = coll.rest();
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initialValue = fn.apply(fnArgs);
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}
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return initialValue;
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}
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}
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