41 lines
1.2 KiB
Java
41 lines
1.2 KiB
Java
package function.builtin.special;
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import function.ArgumentValidator;
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import function.FunctionNames;
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import function.LispSpecialFunction;
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import recursion.TailCall;
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import sexpression.Cons;
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import sexpression.SExpression;
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import static function.builtin.EVAL.eval;
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import static recursion.TailCalls.done;
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import static recursion.TailCalls.tailCall;
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import static sexpression.Nil.NIL;
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@FunctionNames({ "PROGN", "BEGIN" })
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public class PROGN extends LispSpecialFunction {
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private ArgumentValidator argumentValidator;
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public PROGN(String name) {
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this.argumentValidator = new ArgumentValidator(name);
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}
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@Override
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public SExpression call(Cons argumentList) {
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argumentValidator.validate(argumentList);
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return callTailRecursive(argumentList, NIL).invoke();
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}
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private TailCall<SExpression> callTailRecursive(Cons argumentList, SExpression lastValue) {
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if (argumentList.isNull())
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return done(lastValue);
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SExpression currentValue = eval(argumentList.getFirst());
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Cons remainingValues = (Cons) argumentList.getRest();
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return tailCall(() -> callTailRecursive(remainingValues, currentValue));
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}
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}
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