54 lines
1.7 KiB
Java
54 lines
1.7 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;
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public class CondSpecialForm extends SpecialForm {
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private ListNode<Node> conditions;
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public CondSpecialForm(ListNode<Node> listNode) {
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super(listNode);
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if (!(listNode.rest().first() instanceof ListNode)) {
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throw new SereneException("Let bindings should be a list of pairs.");
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}
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this.conditions = (ListNode<Node>) listNode.rest();
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}
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@Override
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public Object eval(IScope scope) {
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for (Object x : this.conditions) {
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if (!(x instanceof ListNode))
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throw new SereneException(
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String.format("Expect a pair instead of '%s' for 'cond'.",
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x.toString()));
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Object pred = ((ListNode<Node>) x).first().eval(scope);
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if (pred != null && pred != Boolean.FALSE) {
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return ((ListNode<Node>) x).rest().first().eval(scope);
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}
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}
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return null;
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}
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}
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