io.datakernel.codegen.ExpressionComparator.java Source code

Introduction

Here is the source code for io.datakernel.codegen.ExpressionComparator.java

Source

/*
 * Copyright (C) 2015 SoftIndex LLC.
 *
 * 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 io.datakernel.codegen;

import io.datakernel.codegen.utils.Preconditions;
import org.objectweb.asm.Label;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.GeneratorAdapter;
import org.objectweb.asm.commons.Method;

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

import static io.datakernel.codegen.Utils.isPrimitiveType;
import static io.datakernel.codegen.Utils.wrap;
import static org.objectweb.asm.Type.INT_TYPE;
import static org.objectweb.asm.commons.GeneratorAdapter.NE;

/**
 * Defines methods to compare some fields
 */
public final class ExpressionComparator implements Expression {
    private final List<Expression> left = new ArrayList<>();
    private final List<Expression> right = new ArrayList<>();

    ExpressionComparator() {
    }

    ExpressionComparator(List<Expression> left, List<Expression> right) {
        Preconditions.check(left.size() == right.size());
        this.left.addAll(left);
        this.right.addAll(right);
    }

    public ExpressionComparator add(Expression left, Expression right) {
        this.left.add(left);
        this.right.add(right);
        return this;
    }

    @Override
    public Type type(Context ctx) {
        return INT_TYPE;
    }

    @Override
    public Type load(Context ctx) {
        GeneratorAdapter g = ctx.getGeneratorAdapter();

        Label labelNe = new Label();

        for (int i = 0; i < left.size(); i++) {
            Type leftFieldType = left.get(i).load(ctx);
            Type rightFieldType = right.get(i).load(ctx);

            Preconditions.check(leftFieldType.equals(rightFieldType));
            if (isPrimitiveType(leftFieldType)) {
                g.invokeStatic(wrap(leftFieldType),
                        new Method("compare", INT_TYPE, new Type[] { leftFieldType, leftFieldType }));
                g.dup();
                g.ifZCmp(NE, labelNe);
                g.pop();
            } else {
                g.invokeVirtual(leftFieldType,
                        new Method("compareTo", INT_TYPE, new Type[] { Type.getType(Object.class) }));
                g.dup();
                g.ifZCmp(NE, labelNe);
                g.pop();
            }
        }

        g.push(0);

        g.mark(labelNe);

        return INT_TYPE;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        ExpressionComparator that = (ExpressionComparator) o;

        if (left != null ? !left.equals(that.left) : that.left != null)
            return false;
        if (right != null ? !right.equals(that.right) : that.right != null)
            return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = left != null ? left.hashCode() : 0;
        result = 31 * result + (right != null ? right.hashCode() : 0);
        return result;
    }
}