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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.searchlib.rankingexpression.rule;
import com.yahoo.searchlib.rankingexpression.ExpressionFunction;
import com.yahoo.searchlib.rankingexpression.RankingExpression;
import com.yahoo.searchlib.rankingexpression.evaluation.Context;
import com.yahoo.searchlib.rankingexpression.evaluation.Value;
import com.yahoo.tensor.TensorType;
import com.yahoo.tensor.evaluation.TypeContext;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.List;
/**
* A node referring either to a value in the context or to another named ranking expression.
*
* @author simon
* @author bratseth
*/
public final class ReferenceNode extends CompositeNode {
private final String name, output;
private final Arguments arguments;
public ReferenceNode(String name) {
this(name, null, null);
}
public ReferenceNode(String name, List<? extends ExpressionNode> arguments, String output) {
this.name = name;
this.arguments = arguments != null ? new Arguments(arguments) : new Arguments();
this.output = output;
}
public String getName() {
return name;
}
/** Returns the arguments, never null */
public Arguments getArguments() { return arguments; }
/** Returns a copy of this where the arguments are replaced by the given arguments */
public ReferenceNode setArguments(List<ExpressionNode> arguments) {
return new ReferenceNode(name, arguments, output);
}
/** Returns the specific output this references, or null if none specified */
public String getOutput() { return output; }
/** Returns a copy of this node with a modified output */
public ReferenceNode setOutput(String output) {
return new ReferenceNode(name, arguments.expressions(), output);
}
/** Returns an empty list as this has no children */
@Override
public List<ExpressionNode> children() { return arguments.expressions(); }
@Override
public String toString(SerializationContext context, Deque<String> path, CompositeNode parent) {
if (path == null)
path = new ArrayDeque<>();
String myName = this.name;
String myOutput = this.output;
List<ExpressionNode> myArguments = this.arguments.expressions();
String resolvedArgument = context.getBinding(myName);
if (resolvedArgument != null && this.arguments.expressions().size() == 0 && myOutput == null) {
// Replace this whole node with the value of the argument value that it maps to
myName = resolvedArgument;
myArguments = null;
myOutput = null;
} else if (context.getFunction(myName) != null) {
// Replace by the referenced expression
ExpressionFunction function = context.getFunction(myName);
if (function != null && myArguments != null && function.arguments().size() == myArguments.size() && myOutput == null) {
String myPath = name + this.arguments.expressions();
if (path.contains(myPath)) {
throw new IllegalStateException("Cycle in ranking expression function: " + path);
}
path.addLast(myPath);
ExpressionFunction.Instance instance = function.expand(context, myArguments, path);
path.removeLast();
context.addFunctionSerialization(RankingExpression.propertyName(instance.getName()), instance.getExpressionString());
myName = "rankingExpression(" + instance.getName() + ")";
myArguments = null;
myOutput = null;
}
}
// Always print the same way, the magic is already done.
StringBuilder ret = new StringBuilder(myName);
if (myArguments != null && myArguments.size() > 0) {
ret.append("(");
for (int i = 0; i < myArguments.size(); ++i) {
ret.append(myArguments.get(i).toString(context, path, this));
if (i < myArguments.size() - 1) {
ret.append(",");
}
}
ret.append(")");
}
ret.append(myOutput != null ? "." + myOutput : "");
return ret.toString();
}
@Override
public TensorType type(TypeContext context) {
// Don't support outputs of different type, for simplicity
return context.getType(toString());
}
@Override
public Value evaluate(Context context) {
if (arguments.expressions().isEmpty() && output == null)
return context.get(name);
return context.get(name, arguments, output);
}
@Override
public CompositeNode setChildren(List<ExpressionNode> newChildren) {
return new ReferenceNode(name, newChildren, output);
}
}
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