src/java/org/apache/cassandra/cql3/functions/FunctionResolver.java - cassandra - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package org.apache.cassandra.cql3.functions;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;

 import org.apache.cassandra.cql3.AbstractMarker;
 import org.apache.cassandra.cql3.AssignmentTestable;
 import org.apache.cassandra.cql3.ColumnIdentifier;
 import org.apache.cassandra.cql3.ColumnSpecification;
 import org.apache.cassandra.schema.Schema;
 import org.apache.cassandra.db.marshal.AbstractType;
 import org.apache.cassandra.exceptions.InvalidRequestException;

 import static java.util.stream.Collectors.joining;
 import static org.apache.cassandra.cql3.statements.RequestValidations.invalidRequest;

 public final class FunctionResolver
 {
     private FunctionResolver()
     {
     }

     // We special case the token function because that's the only function whose argument types actually
     // depend on the table on which the function is called. Because it's the sole exception, it's easier
     // to handle it as a special case.
     private static final FunctionName TOKEN_FUNCTION_NAME = FunctionName.nativeFunction("token");

     public static ColumnSpecification makeArgSpec(String receiverKs, String receiverCf, Function fun, int i)
     {
         return new ColumnSpecification(receiverKs,
                                        receiverCf,
                                        new ColumnIdentifier("arg" + i + '(' + fun.name().toString().toLowerCase() + ')', true),
                                        fun.argTypes().get(i));
     }

     /**
      * @param keyspace the current keyspace
      * @param name the name of the function
      * @param providedArgs the arguments provided for the function call
      * @param receiverKs the receiver's keyspace
      * @param receiverCf the receiver's table
      * @param receiverType if the receiver type is known (during inserts, for example), this should be the type of
      *                     the receiver
      * @throws InvalidRequestException
      */
     public static Function get(String keyspace,
                                FunctionName name,
                                List<? extends AssignmentTestable> providedArgs,
                                String receiverKs,
                                String receiverCf,
                                AbstractType<?> receiverType)
     throws InvalidRequestException
     {
         Collection<Function> candidates = collectCandidates(keyspace, name, receiverKs, receiverCf, receiverType);

         if (candidates.isEmpty())
             return null;

         // Fast path if there is only one choice
         if (candidates.size() == 1)
         {
             Function fun = candidates.iterator().next();
             validateTypes(keyspace, fun, providedArgs, receiverKs, receiverCf);
             return fun;
         }

         return pickBestMatch(keyspace, name, providedArgs, receiverKs, receiverCf, receiverType, candidates);
     }

     private static Collection<Function> collectCandidates(String keyspace,
                                                           FunctionName name,
                                                           String receiverKs,
                                                           String receiverCf,
                                                           AbstractType<?> receiverType)
     {
         Collection<Function> candidates = new ArrayList<>();

         if (name.equalsNativeFunction(TOKEN_FUNCTION_NAME))
             candidates.add(new TokenFct(Schema.instance.getTableMetadata(receiverKs, receiverCf)));

         // The toJson() function can accept any type of argument, so instances of it are not pre-declared.  Instead,
         // we create new instances as needed while handling selectors (which is the only place that toJson() is supported,
         // due to needing to know the argument types in advance).
         if (name.equalsNativeFunction(ToJsonFct.NAME))
             throw new InvalidRequestException("toJson() may only be used within the selection clause of SELECT statements");

         // Similarly, we can only use fromJson when we know the receiver type (such as inserts)
         if (name.equalsNativeFunction(FromJsonFct.NAME))
         {
             if (receiverType == null)
                 throw new InvalidRequestException("fromJson() cannot be used in the selection clause of a SELECT statement");
             candidates.add(FromJsonFct.getInstance(receiverType));
         }

         if (!name.hasKeyspace())
         {
             // function name not fully qualified
             // add 'SYSTEM' (native) candidates
             candidates.addAll(Schema.instance.getFunctions(name.asNativeFunction()));
             // add 'current keyspace' candidates
             candidates.addAll(Schema.instance.getFunctions(new FunctionName(keyspace, name.name)));
         }
         else
         {
             // function name is fully qualified (keyspace + name)
             candidates.addAll(Schema.instance.getFunctions(name));
         }

         return candidates;
     }

     private static Function pickBestMatch(String keyspace,
                                           FunctionName name,
                                           List<? extends AssignmentTestable> providedArgs,
                                           String receiverKs,
                                           String receiverCf,
                                           AbstractType<?> receiverType,
                                           Collection<Function> candidates)
     {
         List<Function> compatibles = null;
         for (Function toTest : candidates)
         {
             if (matchReturnType(toTest, receiverType))
             {
                 AssignmentTestable.TestResult r = matchAguments(keyspace, toTest, providedArgs, receiverKs, receiverCf);
                 switch (r)
                 {
                     case EXACT_MATCH:
                         // We always favor exact matches
                         return toTest;
                     case WEAKLY_ASSIGNABLE:
                         if (compatibles == null)
                             compatibles = new ArrayList<>();
                         compatibles.add(toTest);
                         break;
                 }
             }
         }

         if (compatibles == null)
         {
             if (OperationFcts.isOperation(name))
                 throw invalidRequest("the '%s' operation is not supported between %s and %s",
                                      OperationFcts.getOperator(name), providedArgs.get(0), providedArgs.get(1));

             throw invalidRequest("Invalid call to function %s, none of its type signatures match (known type signatures: %s)",
                                  name, format(candidates));
         }

         if (compatibles.size() > 1)
         {
             if (OperationFcts.isOperation(name))
             {
                 if (receiverType != null && !containsMarkers(providedArgs))
                 {
                     for (Function toTest : compatibles)
                     {
                         List<AbstractType<?>> argTypes = toTest.argTypes();
                         if (receiverType.equals(argTypes.get(0)) && receiverType.equals(argTypes.get(1)))
                             return toTest;
                     }
                 }
                 throw invalidRequest("Ambiguous '%s' operation with args %s and %s: use type hint to disambiguate, example '(int) ?'",
                                      OperationFcts.getOperator(name), providedArgs.get(0), providedArgs.get(1));
             }

             if (OperationFcts.isNegation(name))
                 throw invalidRequest("Ambiguous negation: use type casts to disambiguate");

             throw invalidRequest("Ambiguous call to function %s (can be matched by following signatures: %s): use type casts to disambiguate",
                                  name, format(compatibles));
         }

         return compatibles.get(0);
     }

     /**
      * Checks if at least one of the specified arguments is a marker.
      *
      * @param args the arguments to check
      * @return {@code true} if if at least one of the specified arguments is a marker, {@code false} otherwise
      */
     private static boolean containsMarkers(List<? extends AssignmentTestable> args)
     {
         return args.stream().anyMatch(AbstractMarker.Raw.class::isInstance);
     }

     /**
      * Checks that the return type of the specified function can be assigned to the specified receiver.
      *
      * @param fun the function to check
      * @param receiverType the receiver type
      * @return {@code true} if the return type of the specified function can be assigned to the specified receiver,
      * {@code false} otherwise.
      */
     private static boolean matchReturnType(Function fun, AbstractType<?> receiverType)
     {
         return receiverType == null || fun.returnType().testAssignment(receiverType.udfType()).isAssignable();
     }

     // This method and matchArguments are somewhat duplicate, but this method allows us to provide more precise errors in the common
     // case where there is no override for a given function. This is thus probably worth the minor code duplication.
     private static void validateTypes(String keyspace,
                                       Function fun,
                                       List<? extends AssignmentTestable> providedArgs,
                                       String receiverKs,
                                       String receiverCf)
     {
         if (providedArgs.size() != fun.argTypes().size())
             throw invalidRequest("Invalid number of arguments in call to function %s: %d required but %d provided",
                                  fun.name(), fun.argTypes().size(), providedArgs.size());

         for (int i = 0; i < providedArgs.size(); i++)
         {
             AssignmentTestable provided = providedArgs.get(i);

             // If the concrete argument is a bind variables, it can have any type.
             // We'll validate the actually provided value at execution time.
             if (provided == null)
                 continue;

             ColumnSpecification expected = makeArgSpec(receiverKs, receiverCf, fun, i);
             if (!provided.testAssignment(keyspace, expected).isAssignable())
                 throw invalidRequest("Type error: %s cannot be passed as argument %d of function %s of type %s",
                                      provided, i, fun.name(), expected.type.asCQL3Type());
         }
     }

     private static AssignmentTestable.TestResult matchAguments(String keyspace,
                                                                Function fun,
                                                                List<? extends AssignmentTestable> providedArgs,
                                                                String receiverKs,
                                                                String receiverCf)
     {
         if (providedArgs.size() != fun.argTypes().size())
             return AssignmentTestable.TestResult.NOT_ASSIGNABLE;

         // It's an exact match if all are exact match, but is not assignable as soon as any is non assignable.
         AssignmentTestable.TestResult res = AssignmentTestable.TestResult.EXACT_MATCH;
         for (int i = 0; i < providedArgs.size(); i++)
         {
             AssignmentTestable provided = providedArgs.get(i);
             if (provided == null)
             {
                 res = AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE;
                 continue;
             }

             ColumnSpecification expected = makeArgSpec(receiverKs, receiverCf, fun, i);
             AssignmentTestable.TestResult argRes = provided.testAssignment(keyspace, expected);
             if (argRes == AssignmentTestable.TestResult.NOT_ASSIGNABLE)
                 return AssignmentTestable.TestResult.NOT_ASSIGNABLE;
             if (argRes == AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE)
                 res = AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE;
         }
         return res;
     }

     private static String format(Collection<Function> funs)
     {
         return funs.stream().map(Function::toString).collect(joining(", "));
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package org.apache.cassandra.cql3.functions;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.List;

	import org.apache.cassandra.cql3.AbstractMarker;
	import org.apache.cassandra.cql3.AssignmentTestable;
	import org.apache.cassandra.cql3.ColumnIdentifier;
	import org.apache.cassandra.cql3.ColumnSpecification;
	import org.apache.cassandra.schema.Schema;
	import org.apache.cassandra.db.marshal.AbstractType;
	import org.apache.cassandra.exceptions.InvalidRequestException;

	import static java.util.stream.Collectors.joining;
	import static org.apache.cassandra.cql3.statements.RequestValidations.invalidRequest;

	public final class FunctionResolver
	{
	private FunctionResolver()
	{
	}

	// We special case the token function because that's the only function whose argument types actually
	// depend on the table on which the function is called. Because it's the sole exception, it's easier
	// to handle it as a special case.
	private static final FunctionName TOKEN_FUNCTION_NAME = FunctionName.nativeFunction("token");

	public static ColumnSpecification makeArgSpec(String receiverKs, String receiverCf, Function fun, int i)
	{
	return new ColumnSpecification(receiverKs,
	receiverCf,
	new ColumnIdentifier("arg" + i + '(' + fun.name().toString().toLowerCase() + ')', true),
	fun.argTypes().get(i));
	}

	/**
	* @param keyspace the current keyspace
	* @param name the name of the function
	* @param providedArgs the arguments provided for the function call
	* @param receiverKs the receiver's keyspace
	* @param receiverCf the receiver's table
	* @param receiverType if the receiver type is known (during inserts, for example), this should be the type of
	* the receiver
	* @throws InvalidRequestException
	*/
	public static Function get(String keyspace,
	FunctionName name,
	List<? extends AssignmentTestable> providedArgs,
	String receiverKs,
	String receiverCf,
	AbstractType<?> receiverType)
	throws InvalidRequestException
	{
	Collection<Function> candidates = collectCandidates(keyspace, name, receiverKs, receiverCf, receiverType);

	if (candidates.isEmpty())
	return null;

	// Fast path if there is only one choice
	if (candidates.size() == 1)
	{
	Function fun = candidates.iterator().next();
	validateTypes(keyspace, fun, providedArgs, receiverKs, receiverCf);
	return fun;
	}

	return pickBestMatch(keyspace, name, providedArgs, receiverKs, receiverCf, receiverType, candidates);
	}

	private static Collection<Function> collectCandidates(String keyspace,
	FunctionName name,
	String receiverKs,
	String receiverCf,
	AbstractType<?> receiverType)
	{
	Collection<Function> candidates = new ArrayList<>();

	if (name.equalsNativeFunction(TOKEN_FUNCTION_NAME))
	candidates.add(new TokenFct(Schema.instance.getTableMetadata(receiverKs, receiverCf)));

	// The toJson() function can accept any type of argument, so instances of it are not pre-declared. Instead,
	// we create new instances as needed while handling selectors (which is the only place that toJson() is supported,
	// due to needing to know the argument types in advance).
	if (name.equalsNativeFunction(ToJsonFct.NAME))
	throw new InvalidRequestException("toJson() may only be used within the selection clause of SELECT statements");

	// Similarly, we can only use fromJson when we know the receiver type (such as inserts)
	if (name.equalsNativeFunction(FromJsonFct.NAME))
	{
	if (receiverType == null)
	throw new InvalidRequestException("fromJson() cannot be used in the selection clause of a SELECT statement");
	candidates.add(FromJsonFct.getInstance(receiverType));
	}

	if (!name.hasKeyspace())
	{
	// function name not fully qualified
	// add 'SYSTEM' (native) candidates
	candidates.addAll(Schema.instance.getFunctions(name.asNativeFunction()));
	// add 'current keyspace' candidates
	candidates.addAll(Schema.instance.getFunctions(new FunctionName(keyspace, name.name)));
	}
	else
	{
	// function name is fully qualified (keyspace + name)
	candidates.addAll(Schema.instance.getFunctions(name));
	}

	return candidates;
	}

	private static Function pickBestMatch(String keyspace,
	FunctionName name,
	List<? extends AssignmentTestable> providedArgs,
	String receiverKs,
	String receiverCf,
	AbstractType<?> receiverType,
	Collection<Function> candidates)
	{
	List<Function> compatibles = null;
	for (Function toTest : candidates)
	{
	if (matchReturnType(toTest, receiverType))
	{
	AssignmentTestable.TestResult r = matchAguments(keyspace, toTest, providedArgs, receiverKs, receiverCf);
	switch (r)
	{
	case EXACT_MATCH:
	// We always favor exact matches
	return toTest;
	case WEAKLY_ASSIGNABLE:
	if (compatibles == null)
	compatibles = new ArrayList<>();
	compatibles.add(toTest);
	break;
	}
	}
	}

	if (compatibles == null)
	{
	if (OperationFcts.isOperation(name))
	throw invalidRequest("the '%s' operation is not supported between %s and %s",
	OperationFcts.getOperator(name), providedArgs.get(0), providedArgs.get(1));

	throw invalidRequest("Invalid call to function %s, none of its type signatures match (known type signatures: %s)",
	name, format(candidates));
	}

	if (compatibles.size() > 1)
	{
	if (OperationFcts.isOperation(name))
	{
	if (receiverType != null && !containsMarkers(providedArgs))
	{
	for (Function toTest : compatibles)
	{
	List<AbstractType<?>> argTypes = toTest.argTypes();
	if (receiverType.equals(argTypes.get(0)) && receiverType.equals(argTypes.get(1)))
	return toTest;
	}
	}
	throw invalidRequest("Ambiguous '%s' operation with args %s and %s: use type hint to disambiguate, example '(int) ?'",
	OperationFcts.getOperator(name), providedArgs.get(0), providedArgs.get(1));
	}

	if (OperationFcts.isNegation(name))
	throw invalidRequest("Ambiguous negation: use type casts to disambiguate");

	throw invalidRequest("Ambiguous call to function %s (can be matched by following signatures: %s): use type casts to disambiguate",
	name, format(compatibles));
	}

	return compatibles.get(0);
	}

	/**
	* Checks if at least one of the specified arguments is a marker.
	*
	* @param args the arguments to check
	* @return {@code true} if if at least one of the specified arguments is a marker, {@code false} otherwise
	*/
	private static boolean containsMarkers(List<? extends AssignmentTestable> args)
	{
	return args.stream().anyMatch(AbstractMarker.Raw.class::isInstance);
	}

	/**
	* Checks that the return type of the specified function can be assigned to the specified receiver.
	*
	* @param fun the function to check
	* @param receiverType the receiver type
	* @return {@code true} if the return type of the specified function can be assigned to the specified receiver,
	* {@code false} otherwise.
	*/
	private static boolean matchReturnType(Function fun, AbstractType<?> receiverType)
	{
	return receiverType == null \|\| fun.returnType().testAssignment(receiverType.udfType()).isAssignable();
	}

	// This method and matchArguments are somewhat duplicate, but this method allows us to provide more precise errors in the common
	// case where there is no override for a given function. This is thus probably worth the minor code duplication.
	private static void validateTypes(String keyspace,
	Function fun,
	List<? extends AssignmentTestable> providedArgs,
	String receiverKs,
	String receiverCf)
	{
	if (providedArgs.size() != fun.argTypes().size())
	throw invalidRequest("Invalid number of arguments in call to function %s: %d required but %d provided",
	fun.name(), fun.argTypes().size(), providedArgs.size());

	for (int i = 0; i < providedArgs.size(); i++)
	{
	AssignmentTestable provided = providedArgs.get(i);

	// If the concrete argument is a bind variables, it can have any type.
	// We'll validate the actually provided value at execution time.
	if (provided == null)
	continue;

	ColumnSpecification expected = makeArgSpec(receiverKs, receiverCf, fun, i);
	if (!provided.testAssignment(keyspace, expected).isAssignable())
	throw invalidRequest("Type error: %s cannot be passed as argument %d of function %s of type %s",
	provided, i, fun.name(), expected.type.asCQL3Type());
	}
	}

	private static AssignmentTestable.TestResult matchAguments(String keyspace,
	Function fun,
	List<? extends AssignmentTestable> providedArgs,
	String receiverKs,
	String receiverCf)
	{
	if (providedArgs.size() != fun.argTypes().size())
	return AssignmentTestable.TestResult.NOT_ASSIGNABLE;

	// It's an exact match if all are exact match, but is not assignable as soon as any is non assignable.
	AssignmentTestable.TestResult res = AssignmentTestable.TestResult.EXACT_MATCH;
	for (int i = 0; i < providedArgs.size(); i++)
	{
	AssignmentTestable provided = providedArgs.get(i);
	if (provided == null)
	{
	res = AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE;
	continue;
	}

	ColumnSpecification expected = makeArgSpec(receiverKs, receiverCf, fun, i);
	AssignmentTestable.TestResult argRes = provided.testAssignment(keyspace, expected);
	if (argRes == AssignmentTestable.TestResult.NOT_ASSIGNABLE)
	return AssignmentTestable.TestResult.NOT_ASSIGNABLE;
	if (argRes == AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE)
	res = AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE;
	}
	return res;
	}

	private static String format(Collection<Function> funs)
	{
	return funs.stream().map(Function::toString).collect(joining(", "));
	}
	}