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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.indexinglanguage.expressions;
import com.yahoo.document.DataType;
import com.yahoo.document.DocumentType;
import com.yahoo.vespa.indexinglanguage.ExpressionVisitor;
import com.yahoo.vespa.indexinglanguage.UpdateAdapter;
import com.yahoo.vespa.objects.ObjectOperation;
import com.yahoo.vespa.objects.ObjectPredicate;
/**
* @author Simon Thoresen Hult
*/
public final class GuardExpression extends CompositeExpression {
private final Expression exp;
private final boolean shouldExecute;
public GuardExpression(Expression exp) {
super(exp.requiredInputType());
this.exp = exp;
shouldExecute = shouldExecute(exp);
}
public Expression getInnerExpression() {
return exp;
}
@Override
public void setStatementOutputType(DataType type) {
exp.setStatementOutputType(type);
}
@Override
protected void doExecute(ExecutionContext context) {
if (!shouldExecute && context.getAdapter() instanceof UpdateAdapter) {
context.setValue(null);
} else {
exp.execute(context);
}
}
@Override
protected void doVerify(VerificationContext context) {
exp.verify(context);
}
@Override
public DataType createdOutputType() {
return exp.createdOutputType();
}
@Override
public String toString() {
return "guard " + toScriptBlock(exp);
}
@Override
public void selectMembers(ObjectPredicate predicate, ObjectOperation operation) {
select(exp, predicate, operation);
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof GuardExpression)) {
return false;
}
GuardExpression rhs = (GuardExpression)obj;
if (!exp.equals(rhs.exp)) {
return false;
}
return true;
}
@Override
public int hashCode() {
return getClass().hashCode() + exp.hashCode();
}
private static boolean shouldExecute(Expression exp) {
ExecutionGuard guard = new ExecutionGuard();
guard.visit(exp);
return guard.shouldExecute;
}
private static class ExecutionGuard extends ExpressionVisitor {
boolean shouldExecute = false;
@Override
protected void doVisit(Expression exp) {
if (exp instanceof InputExpression || exp instanceof SetLanguageExpression) {
shouldExecute = true;
}
}
}
}
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