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// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchdefinition;
import com.yahoo.searchlib.rankingexpression.ExpressionFunction;
import com.yahoo.searchlib.rankingexpression.rule.Arguments;
import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
import com.yahoo.searchlib.rankingexpression.rule.FunctionReferenceContext;
import com.yahoo.searchlib.rankingexpression.rule.ReferenceNode;
import com.yahoo.tensor.TensorType;
import com.yahoo.tensor.evaluation.TypeContext;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
/**
* A context which only contains type information.
* This returns empty tensor types (double) for unknown features which are not
* query, attribute or constant features, as we do not have information about which such
* features exist (but we know those that exist are doubles).
*
* @author bratseth
*/
public class MapEvaluationTypeContext extends FunctionReferenceContext implements TypeContext {
private final Map<ReferenceNode.Reference, TensorType> featureTypes = new HashMap<>();
public MapEvaluationTypeContext(Collection<ExpressionFunction> functions) {
super(functions);
}
public MapEvaluationTypeContext(Map<String, ExpressionFunction> functions,
Map<String, String> bindings,
Map<ReferenceNode.Reference, TensorType> featureTypes) {
super(functions, bindings);
this.featureTypes.putAll(featureTypes);
}
public void setType(Name name, TensorType type) {
// TODO: Use a type parameter if we do this both here and in getType ...
if ( ! (name instanceof ReferenceNode.Reference))
throw new IllegalArgumentException("Not expecting unstructured names here");
featureTypes.put((ReferenceNode.Reference)name, type);
}
@Override
public TensorType getType(Name name) {
if ( ! (name instanceof ReferenceNode.Reference))
throw new IllegalArgumentException("Not expecting unstructured names here");
ReferenceNode.Reference reference = (ReferenceNode.Reference)name;
if (isSimpleFeature(reference)) {
// The argument may be a local identifier bound to the actual value
String argument = simpleArgument(reference.arguments()).get();
reference = ReferenceNode.Reference.simple(reference.name(), bindings.getOrDefault(argument, argument));
return featureTypes.get(reference);
}
Optional<ExpressionFunction> function = functionInvocation(reference);
if (function.isPresent())
return function.get().getBody().type(this.withBindings(bind(function.get().arguments(), reference.arguments())));
// We do not know what this is - since we do not have complete knowledge abut the match features
// in Java we must assume this is a match feature and return the double type - which is the type of all
// all match features
return TensorType.empty;
}
/**
* Return whether the reference (discarding the output) is a simple feature
* ("attribute(name)", "constant(name)" or "query(name)").
* We disregard the output because all outputs under a simple feature have the same type.
*/
private boolean isSimpleFeature(ReferenceNode.Reference reference) {
Optional<String> argument = simpleArgument(reference.arguments());
if ( ! argument.isPresent()) return false;
return reference.name().equals("attribute") ||
reference.name().equals("constant") ||
reference.name().equals("query");
}
/**
* If the reference (discarding the output) is a simple feature
* ("attribute(name)", "constant(name)" or "query(name)"),
* it is returned. Otherwise empty is returned.
* We disregard the output because all outputs under a simple feature have the same type.
*/
private Optional<String> simpleFeature(ReferenceNode.Reference reference) {
Optional<String> argument = simpleArgument(reference.arguments());
if ( ! argument.isPresent()) return Optional.empty();
// The argument may be a "local value" bound to another value, or else it is the "global" argument of the feature
String actualArgument = bindings.getOrDefault(argument.get(), argument.get());
String feature = asFeatureString(reference.name(), actualArgument);
if (FeatureNames.isSimpleFeature(feature))
return Optional.of(feature);
else
return Optional.empty();
}
private String asFeatureString(String name, String argument) {
return name + "(" + argument + ")";
}
/**
* If these arguments contains one simple argument string, it is returned.
* Otherwise null is returned.
*/
private Optional<String> simpleArgument(Arguments arguments) {
if (arguments.expressions().size() != 1) return Optional.empty();
ExpressionNode argument = arguments.expressions().get(0);
if ( ! (argument instanceof ReferenceNode)) return Optional.empty();
ReferenceNode refArgument = (ReferenceNode)argument;
if ( ! refArgument.isBindableName()) return Optional.empty();
return Optional.of(refArgument.getName());
}
private Optional<ExpressionFunction> functionInvocation(ReferenceNode.Reference reference) {
if (reference.output() != null) return Optional.empty();
return Optional.ofNullable(functions().get(reference.name()));
}
/** Binds the given list of formal arguments to their actual values */
private Map<String, String> bind(List<String> formalArguments,
Arguments invocationArguments) {
// TODO: What is our position on argument overloading/argument count differences?
Map<String, String> bindings = new HashMap<>(formalArguments.size());
for (int i = 0; i < formalArguments.size(); i++) {
String identifier = invocationArguments.expressions().get(i).toString(); // TODO: ...
identifier = super.bindings.getOrDefault(identifier, identifier);
bindings.put(formalArguments.get(i), identifier);
}
return bindings;
}
public Map<ReferenceNode.Reference, TensorType> featureTypes() {
return Collections.unmodifiableMap(featureTypes);
}
@Override
public MapEvaluationTypeContext withBindings(Map<String, String> bindings) {
if (bindings.isEmpty() && this.bindings.isEmpty()) return this;
return new MapEvaluationTypeContext(functions(), bindings, featureTypes);
}
}
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