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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 ai.vespa.models.evaluation;
import com.google.common.annotations.Beta;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.yahoo.searchlib.rankingexpression.ExpressionFunction;
import com.yahoo.searchlib.rankingexpression.evaluation.ContextIndex;
import com.yahoo.searchlib.rankingexpression.evaluation.ExpressionOptimizer;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
/**
* A named collection of functions
*
* @author bratseth
*/
@Beta
public class Model {
private final String name;
/** Free functions */
private final ImmutableList<ExpressionFunction> functions;
/** Instances of each usage of the above function, where variables (if any) are replaced by their bindings */
private final ImmutableMap<FunctionReference, ExpressionFunction> referencedFunctions;
/** Context prototypes, indexed by function name (as all invocations of the same function share the same context prototype) */
private final ImmutableMap<String, LazyArrayContext> contextPrototypes;
private final ExpressionOptimizer expressionOptimizer = new ExpressionOptimizer();
/** Programmatically create a model containing functions without constant of function references only */
public Model(String name, Collection<ExpressionFunction> functions) {
this(name, functions, Collections.emptyMap(), Collections.emptyList());
}
Model(String name,
Collection<ExpressionFunction> functions,
Map<FunctionReference, ExpressionFunction> referencedFunctions,
List<Constant> constants) {
this.name = name;
this.functions = ImmutableList.copyOf(functions);
ImmutableMap.Builder<String, LazyArrayContext> contextBuilder = new ImmutableMap.Builder<>();
for (ExpressionFunction function : functions) {
try {
contextBuilder.put(function.getName(),
new LazyArrayContext(function.getBody(), referencedFunctions, constants, this));
}
catch (RuntimeException e) {
throw new IllegalArgumentException("Could not prepare an evaluation context for " + function, e);
}
}
this.contextPrototypes = contextBuilder.build();
ImmutableMap.Builder<FunctionReference, ExpressionFunction> functionsBuilder = new ImmutableMap.Builder<>();
for (Map.Entry<FunctionReference, ExpressionFunction> function : referencedFunctions.entrySet()) {
ExpressionFunction optimizedFunction = optimize(function.getValue(),
contextPrototypes.get(function.getKey().functionName()));
functionsBuilder.put(function.getKey(), optimizedFunction);
}
this.referencedFunctions = functionsBuilder.build();
}
/** Returns an optimized version of the given function */
private ExpressionFunction optimize(ExpressionFunction function, ContextIndex context) {
// Note: Optimization is in-place but we do not depend on that outside this method
expressionOptimizer.optimize(function.getBody(), context);
return function;
}
public String name() { return name; }
/**
* Returns an immutable list of the free functions of this.
* The functions returned always specifies types of all arguments and the return value
*/
public List<ExpressionFunction> functions() { return functions; }
/** Returns the given function, or throws a IllegalArgumentException if it does not exist */
ExpressionFunction requireFunction(String name) {
ExpressionFunction function = function(name);
if (function == null)
throw new IllegalArgumentException("No function named '" + name + "' in " + this + ". Available functions: " +
functions.stream().map(f -> f.getName()).collect(Collectors.joining(", ")));
return function;
}
/** Returns the given function, or throws a IllegalArgumentException if it does not exist */
private LazyArrayContext requireContextProprotype(String name) {
LazyArrayContext context = contextPrototypes.get(name);
if (context == null) // Implies function is not present
throw new IllegalArgumentException("No function named '" + name + "' in " + this + ". Available functions: " +
functions.stream().map(f -> f.getName()).collect(Collectors.joining(", ")));
return context;
}
/** Returns the function withe the given name, or null if none */ // TODO: Parameter overloading?
ExpressionFunction function(String name) {
for (ExpressionFunction function : functions)
if (function.getName().equals(name))
return function;
return null;
}
/** Returns an immutable map of the referenced function instances of this */
Map<FunctionReference, ExpressionFunction> referencedFunctions() { return referencedFunctions; }
/** Returns the given referred function, or throws a IllegalArgumentException if it does not exist */
ExpressionFunction requireReferencedFunction(FunctionReference reference) {
ExpressionFunction function = referencedFunctions.get(reference);
if (function == null)
throw new IllegalArgumentException("No " + reference + " in " + this + ". References: " +
referencedFunctions.keySet().stream()
.map(FunctionReference::serialForm)
.collect(Collectors.joining(", ")));
return function;
}
/**
* Returns an evaluator which can be used to evaluate the given function in a single thread once.
*
* Usage:
* <code>Tensor result = model.evaluatorOf("myFunction").bind("foo", value).bind("bar", value).evaluate()</code>
*
* @param names the names identifying the function - this can be from 0 to 2, specifying function or "signature"
* name, and "output", respectively. Names which are unnecessary to determine the desired function
* uniquely (e.g if there is just one function or output) can be omitted.
* A two-component name can alternatively be specified as a single argument with components separated
* by dot.
* @throws IllegalArgumentException if the function is not present, or not uniquely identified by the names given
*/
public FunctionEvaluator evaluatorOf(String ... names) { // TODO: Parameter overloading?
if (names.length == 0) {
if (functions.size() > 1)
throwUndeterminedFunction("More than one function is available in " + this + ", but no name is given");
return evaluatorOf(functions.get(0));
}
else if (names.length == 1) {
String name = names[0];
ExpressionFunction function = function(name);
if (function != null) return evaluatorOf(function);
List<ExpressionFunction> functionsStartingByName =
functions.stream().filter(f -> f.getName().startsWith(name + ".")).collect(Collectors.toList());
if (functionsStartingByName.size() == 0)
throwUndeterminedFunction("No function '" + name + "' in " + this);
else if (functionsStartingByName.size() == 1)
return evaluatorOf(functionsStartingByName.get(0));
else
throwUndeterminedFunction("Multiple functions start by '" + name + "' in " + this);
}
else if (names.length == 2) {
String name = names[0] + "." + names[1];
ExpressionFunction function = function(name);
if (function == null) throwUndeterminedFunction("No function '" + name + "' in " + this);
return evaluatorOf(function);
}
throw new IllegalArgumentException("No more than 2 names can be given when choosing a function, got " +
Arrays.toString(names));
}
/** Returns a single-use evaluator of a function */
private FunctionEvaluator evaluatorOf(ExpressionFunction function) {
return new FunctionEvaluator(function, requireContextProprotype(function.getName()).copy());
}
private void throwUndeterminedFunction(String message) {
throw new IllegalArgumentException(message + ". Available functions: " +
functions.stream().map(f -> f.getName()).collect(Collectors.joining(", ")));
}
@Override
public String toString() { return "model '" + name + "'"; }
}
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