MapFilterFunction.java example

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presto-master
/*
 * Licensed 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 com.facebook.presto.operator.scalar;

import com.facebook.presto.bytecode.BytecodeBlock;
import com.facebook.presto.bytecode.BytecodeNode;
import com.facebook.presto.bytecode.ClassDefinition;
import com.facebook.presto.bytecode.MethodDefinition;
import com.facebook.presto.bytecode.Parameter;
import com.facebook.presto.bytecode.Scope;
import com.facebook.presto.bytecode.Variable;
import com.facebook.presto.bytecode.control.ForLoop;
import com.facebook.presto.bytecode.control.IfStatement;
import com.facebook.presto.metadata.BoundVariables;
import com.facebook.presto.metadata.FunctionKind;
import com.facebook.presto.metadata.FunctionRegistry;
import com.facebook.presto.metadata.Signature;
import com.facebook.presto.metadata.SqlScalarFunction;
import com.facebook.presto.spi.ConnectorSession;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.block.BlockBuilderStatus;
import com.facebook.presto.spi.block.InterleavedBlockBuilder;
import com.facebook.presto.spi.type.StandardTypes;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.spi.type.TypeManager;
import com.facebook.presto.spi.type.TypeSignatureParameter;
import com.facebook.presto.sql.gen.CallSiteBinder;
import com.facebook.presto.sql.gen.SqlTypeBytecodeExpression;
import com.google.common.collect.ImmutableList;
import com.google.common.primitives.Primitives;

import java.lang.invoke.MethodHandle;
import java.util.List;

import static com.facebook.presto.bytecode.Access.FINAL;
import static com.facebook.presto.bytecode.Access.PRIVATE;
import static com.facebook.presto.bytecode.Access.PUBLIC;
import static com.facebook.presto.bytecode.Access.STATIC;
import static com.facebook.presto.bytecode.Access.a;
import static com.facebook.presto.bytecode.CompilerUtils.defineClass;
import static com.facebook.presto.bytecode.CompilerUtils.makeClassName;
import static com.facebook.presto.bytecode.Parameter.arg;
import static com.facebook.presto.bytecode.ParameterizedType.type;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.add;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.and;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantInt;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantNull;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.lessThan;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.newInstance;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.notEqual;
import static com.facebook.presto.bytecode.instruction.VariableInstruction.incrementVariable;
import static com.facebook.presto.metadata.Signature.typeVariable;
import static com.facebook.presto.spi.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.sql.gen.SqlTypeBytecodeExpression.constantType;
import static com.facebook.presto.type.UnknownType.UNKNOWN;
import static com.facebook.presto.util.Reflection.methodHandle;

public final class MapFilterFunction
        extends SqlScalarFunction
{
    public static final MapFilterFunction MAP_FILTER_FUNCTION = new MapFilterFunction();

    private MapFilterFunction()
    {
        super(new Signature(
                "map_filter",
                FunctionKind.SCALAR,
                ImmutableList.of(typeVariable("K"), typeVariable("V")),
                ImmutableList.of(),
                parseTypeSignature("map(K,V)"),
                ImmutableList.of(parseTypeSignature("map(K,V)"), parseTypeSignature("function(K,V,boolean)")),
                false));
    }

    @Override
    public boolean isHidden()
    {
        return false;
    }

    @Override
    public boolean isDeterministic()
    {
        return false;
    }

    @Override
    public String getDescription()
    {
        return "return map containing entries that match the given predicate";
    }

    @Override
    public ScalarFunctionImplementation specialize(BoundVariables boundVariables, int arity, TypeManager typeManager, FunctionRegistry functionRegistry)
    {
        Type keyType = boundVariables.getTypeVariable("K");
        Type valueType = boundVariables.getTypeVariable("V");
        Type mapType = typeManager.getParameterizedType(StandardTypes.MAP, ImmutableList.of(
                TypeSignatureParameter.of(keyType.getTypeSignature()),
                TypeSignatureParameter.of(valueType.getTypeSignature())));
        return new ScalarFunctionImplementation(
                false,
                ImmutableList.of(false, false),
                generateFilter(keyType, valueType, mapType),
                isDeterministic());
    }

    private static MethodHandle generateFilter(Type keyType, Type valueType, Type mapType)
    {
        CallSiteBinder binder = new CallSiteBinder();
        Class<?> keyJavaType = Primitives.wrap(keyType.getJavaType());
        Class<?> valueJavaType = Primitives.wrap(valueType.getJavaType());

        ClassDefinition definition = new ClassDefinition(
                a(PUBLIC, FINAL),
                makeClassName("MapFilter"),
                type(Object.class));
        definition.declareDefaultConstructor(a(PRIVATE));

        Parameter session = arg("session", ConnectorSession.class);
        Parameter block = arg("block", Block.class);
        Parameter function = arg("function", MethodHandle.class);
        MethodDefinition method = definition.declareMethod(
                a(PUBLIC, STATIC),
                "filter",
                type(Block.class),
                ImmutableList.of(session, block, function));

        BytecodeBlock body = method.getBody();
        Scope scope = method.getScope();
        Variable positionCount = scope.declareVariable(int.class, "positionCount");
        Variable position = scope.declareVariable(int.class, "position");
        Variable blockBuilder = scope.declareVariable(BlockBuilder.class, "blockBuilder");
        Variable keyElement = scope.declareVariable(keyJavaType, "keyElement");
        Variable valueElement = scope.declareVariable(valueJavaType, "valueElement");
        Variable keep = scope.declareVariable(Boolean.class, "keep");

        // invoke block.getPositionCount()
        body.append(positionCount.set(block.invoke("getPositionCount", int.class)));

        // create the interleaved block builder
        body.append(blockBuilder.set(newInstance(
                InterleavedBlockBuilder.class,
                constantType(binder, mapType).invoke("getTypeParameters", List.class),
                newInstance(BlockBuilderStatus.class),
                positionCount)));

        SqlTypeBytecodeExpression keySqlType = constantType(binder, keyType);
        BytecodeNode loadKeyElement;
        if (!keyType.equals(UNKNOWN)) {
            // key element must be non-null
            loadKeyElement = new BytecodeBlock().append(keyElement.set(keySqlType.getValue(block, position).cast(keyJavaType)));
        }
        else {
            loadKeyElement = new BytecodeBlock().append(keyElement.set(constantNull(keyJavaType)));
        }

        SqlTypeBytecodeExpression valueSqlType = constantType(binder, valueType);
        BytecodeNode loadValueElement;
        if (!valueType.equals(UNKNOWN)) {
            loadValueElement = new IfStatement()
                    .condition(block.invoke("isNull", boolean.class, add(position, constantInt(1))))
                    .ifTrue(valueElement.set(constantNull(valueJavaType)))
                    .ifFalse(valueElement.set(valueSqlType.getValue(block, add(position, constantInt(1))).cast(valueJavaType)));
        }
        else {
            loadValueElement = new BytecodeBlock().append(valueElement.set(constantNull(valueJavaType)));
        }

        body.append(new ForLoop()
                .initialize(position.set(constantInt(0)))
                .condition(lessThan(position, positionCount))
                .update(incrementVariable(position, (byte) 2))
                .body(new BytecodeBlock()
                        .append(loadKeyElement)
                        .append(loadValueElement)
                        .append(keep.set(function.invoke("invokeExact", Boolean.class, session, keyElement, valueElement)))
                        .append(new IfStatement("if (keep != null && keep) ...")
                                .condition(and(notEqual(keep, constantNull(Boolean.class)), keep.cast(boolean.class)))
                                .ifTrue(new BytecodeBlock()
                                        .append(keySqlType.invoke("appendTo", void.class, block, position, blockBuilder))
                                        .append(valueSqlType.invoke("appendTo", void.class, block, add(position, constantInt(1)), blockBuilder))))));

        body.append(blockBuilder.invoke("build", Block.class).ret());

        Class<?> generatedClass = defineClass(definition, Object.class, binder.getBindings(), MapFilterFunction.class.getClassLoader());
        return methodHandle(generatedClass, "filter", ConnectorSession.class, Block.class, MethodHandle.class);
    }
}