92 lines
2.5 KiB
Java
92 lines
2.5 KiB
Java
package function.builtin.special;
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import static function.builtin.EVAL.evaluateFunctionArgumentList;
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import error.LispException;
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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 sexpression.Cons;
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import sexpression.SExpression;
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import table.ExecutionContext;
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@FunctionNames({ "RECUR" })
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public class RECUR extends LispSpecialFunction {
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private ArgumentValidator argumentValidator;
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private ExecutionContext executionContext;
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public RECUR(String name) {
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this.argumentValidator = new ArgumentValidator(name);
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this.executionContext = ExecutionContext.getInstance();
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}
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@Override
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public SExpression call(Cons argumentList) {
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verifyValidRecurCall();
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argumentValidator.validate(argumentList);
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Cons recurArguments = getRecurArguments(argumentList);
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executionContext.setRecur();
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return recurArguments;
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}
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private void verifyValidRecurCall() {
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if (!executionContext.isInFunctionCall())
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throw new RecurOutsideOfFunctionException();
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if (executionContext.isRecurInitializing())
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throw new NestedRecurException();
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}
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private Cons getRecurArguments(Cons argumentList) {
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Cons recurArguments = argumentList;
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try {
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executionContext.setRecurInitializing();
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if (isRecurArgumentListEvaluated())
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recurArguments = evaluateFunctionArgumentList(argumentList);
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} finally {
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executionContext.clearRecurInitializing();
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}
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return recurArguments;
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}
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private boolean isRecurArgumentListEvaluated() {
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return executionContext.getCurrentFunction().isArgumentListEvaluated();
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}
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public static class RecurOutsideOfFunctionException extends LispException {
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private static final long serialVersionUID = 1L;
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@Override
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public String getMessage() {
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return "recur called outide of function";
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}
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}
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public static class NestedRecurException extends LispException {
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private static final long serialVersionUID = 1L;
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@Override
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public String getMessage() {
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return "nested call to recur";
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}
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}
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public static class RecurNotInTailPositionException extends LispException {
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private static final long serialVersionUID = 1L;
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@Override
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public String getMessage() {
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return "recur not in tail position";
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}
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}
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}
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