55 lines
1.7 KiB
Java
55 lines
1.7 KiB
Java
package function.builtin.predicate;
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import function.ArgumentValidator;
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import function.FunctionNames;
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import function.LispFunction;
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import recursion.TailCall;
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import sexpression.Cons;
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import sexpression.LispNumber;
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import sexpression.SExpression;
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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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import static sexpression.Symbol.T;
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@FunctionNames({ "<" })
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public class NUMERIC_LESS extends LispFunction {
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private ArgumentValidator argumentValidator;
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public NUMERIC_LESS(String name) {
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this.argumentValidator = new ArgumentValidator(name);
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this.argumentValidator.setMinimumNumberOfArguments(1);
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this.argumentValidator.setEveryArgumentExpectedType(LispNumber.class);
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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).invoke();
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}
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private TailCall<SExpression> callTailRecursive(Cons argumentList) {
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Cons remainingArguments = (Cons) argumentList.getRest();
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if (remainingArguments.isNull())
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return done(T);
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SExpression firstArgument = argumentList.getFirst();
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SExpression secondArgument = remainingArguments.getFirst();
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LispNumber number1 = (LispNumber) firstArgument;
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LispNumber number2 = (LispNumber) secondArgument;
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if (!isFirstLesser(number1, number2))
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return done(NIL);
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return tailCall(() -> callTailRecursive(remainingArguments));
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}
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private boolean isFirstLesser(LispNumber number1, LispNumber number2) {
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return number1.getValue().compareTo(number2.getValue()) < 0;
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}
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}
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