SLExpressionNode.java

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package com.oracle.truffle.sl.nodes;

import com.oracle.truffle.api.dsl.TypeSystemReference;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.instrumentation.Instrumentable;
import com.oracle.truffle.api.nodes.NodeInfo;
import com.oracle.truffle.api.nodes.UnexpectedResultException;

/**
 * Base class for all SL nodes that produce a value and therefore benefit from type specialization.
 * The annotation {@link TypeSystemReference} specifies the SL types. Specifying it here defines the
 * type system for all subclasses.
 */
@TypeSystemReference(SLTypes.class)
@NodeInfo(description = "The abstract base node for all expressions")
@Instrumentable(factory = SLExpressionNodeWrapper.class)
public abstract class SLExpressionNode extends SLStatementNode {

    /**
     * The execute method when no specialization is possible. This is the most general case,
     * therefore it must be provided by all subclasses.
     */
    public abstract Object executeGeneric(VirtualFrame frame);

    /**
     * When we use an expression at places where a {@link SLStatementNode statement} is already
     * sufficient, the return value is just discarded.
     */
    @Override
    public void executeVoid(VirtualFrame frame) {
        executeGeneric(frame);
    }

    /*
     * Execute methods for specialized types. They all follow the same pattern: they call the
     * generic execution method and then expect a result of their return type. Type-specialized
     * subclasses overwrite the appropriate methods.
     */

    public long executeLong(VirtualFrame frame) throws UnexpectedResultException {
        return SLTypesGen.expectLong(executeGeneric(frame));
    }

    public boolean executeBoolean(VirtualFrame frame) throws UnexpectedResultException {
        return SLTypesGen.expectBoolean(executeGeneric(frame));
    }
}