public class GnappoProduct {

/**

• @param args
• @throws SchemeException

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*/

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public static void main(String[] args) throws SchemeException {

// TODO Auto-generated method stub SchemeFactoryManager fm = SchemeFactoryManager.instance();

fm.put("pow",

new SchemeFactory() {

public SchemeExpression create(Object... args) {

return new SchemeExpressionPower((SchemeExpression) args[0],

(SchemeExpression) args[1]);

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}

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});

SchemeExpression power = fm.create("pow",

fm.create("SchemeExpressionInt", 2), fm.create("SchemeExpressionInt", 4));

power.prettyPrint(System.out); System.out.println(); System.out.print(power.evaluate(null));

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}

private static class SchemeExpressionPower extends SchemeExpressionAbstract {

private SchemeExpression exp1; private SchemeExpression exp2;

public SchemeExpressionPower(SchemeExpression expr1,

SchemeExpression expr2) { exp1 = expr1; exp2 = expr2;

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}

public SchemeValue evaluate(SchemeEnvironment env)

throws SchemeException { return SchemeFactoryManager.instance()

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.create("SchemeExpressionInt",

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((int) (Math.pow(exp1.evaluate(env).asInt(),

exp2.evaluate(env).asInt())))).evaluate(env);

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}

public void prettyPrint(PrintStream out) {

out.print("(pow "); exp1.prettyPrint(out); out.print(" "); exp2.prettyPrint(out); out.print(")");

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}

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}

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}