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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.exceptions.InvalidRequestException;
/**
* A CQL3 term, i.e. a column value with or without bind variables.
*
* A Term can be either terminal or non terminal. A term object is one that is typed and is obtained
* from a raw term (Term.Raw) by poviding the actual receiver to which the term is supposed to be a
* value of.
*/
public interface Term
{
/**
* Collects the column specification for the bind variables in this Term.
* This is obviously a no-op if the term is Terminal.
*
* @param boundNames the variables specification where to collect the
* bind variables of this term in.
*/
public void collectMarkerSpecification(VariableSpecifications boundNames);
/**
* Bind the values in this term to the values contained in {@code values}.
* This is obviously a no-op if the term is Terminal.
*
* @param options the values to bind markers to.
* @return the result of binding all the variables of this NonTerminal (or
* 'this' if the term is terminal).
*/
public Terminal bind(QueryOptions options) throws InvalidRequestException;
/**
* A shorter for bind(values).get().
* We expose it mainly because for constants it can avoids allocating a temporary
* object between the bind and the get (note that we still want to be able
* to separate bind and get for collections).
*/
public ByteBuffer bindAndGet(QueryOptions options) throws InvalidRequestException;
/**
* Whether or not that term contains at least one bind marker.
*
* Note that this is slightly different from being or not a NonTerminal,
* because calls to non pure functions will be NonTerminal (see #5616)
* even if they don't have bind markers.
*/
public abstract boolean containsBindMarker();
Iterable getFunctions();
/**
* A parsed, non prepared (thus untyped) term.
*
* This can be one of:
* - a constant
* - a collection literal
* - a function call
* - a marker
*/
public interface Raw extends AssignmentTestable
{
/**
* This method validates this RawTerm is valid for provided column
* specification and "prepare" this RawTerm, returning the resulting
* prepared Term.
*
* @param receiver the "column" this RawTerm is supposed to be a value of. Note
* that the ColumnSpecification may not correspond to a real column in the
* case this RawTerm describe a list index or a map key, etc...
* @return the prepared term.
*/
public Term prepare(String keyspace, ColumnSpecification receiver) throws InvalidRequestException;
}
public interface MultiColumnRaw extends Raw
{
public Term prepare(String keyspace, List receiver) throws InvalidRequestException;
}
/**
* A terminal term, one that can be reduced to a byte buffer directly.
*
* This includes most terms that don't have a bind marker (an exception
* being delayed call for non pure function that are NonTerminal even
* if they don't have bind markers).
*
* This can be only one of:
* - a constant value
* - a collection value
*
* Note that a terminal term will always have been type checked, and thus
* consumer can (and should) assume so.
*/
public abstract class Terminal implements Term
{
public void collectMarkerSpecification(VariableSpecifications boundNames) {}
public Terminal bind(QueryOptions options) { return this; }
public Set getFunctions()
{
return Collections.emptySet();
}
// While some NonTerminal may not have bind markers, no Term can be Terminal
// with a bind marker
public boolean containsBindMarker()
{
return false;
}
/**
* @return the serialized value of this terminal.
* @param protocolVersion
*/
public abstract ByteBuffer get(int protocolVersion) throws InvalidRequestException;
public ByteBuffer bindAndGet(QueryOptions options) throws InvalidRequestException
{
return get(options.getProtocolVersion());
}
}
public abstract class MultiItemTerminal extends Terminal
{
public abstract List getElements();
}
/**
* A non terminal term, i.e. a term that can only be reduce to a byte buffer
* at execution time.
*
* We have the following type of NonTerminal:
* - marker for a constant value
* - marker for a collection value (list, set, map)
* - a function having bind marker
* - a non pure function (even if it doesn't have bind marker - see #5616)
*/
public abstract class NonTerminal implements Term
{
public ByteBuffer bindAndGet(QueryOptions options) throws InvalidRequestException
{
Terminal t = bind(options);
return t == null ? null : t.get(options.getProtocolVersion());
}
}
}