io.github.theangrydev.op.generation.jvm.attribute.instruction.Instructions.java Source code

Introduction

Here is the source code for io.github.theangrydev.op.generation.jvm.attribute.instruction.Instructions.java

Source

/*
 * Copyright 2015-2016 Liam Williams <liam.williams@zoho.com>.
 *
 * This file is part of op.
 *
 * op is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * op is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with op.  If not, see <http://www.gnu.org/licenses/>.
 */
package io.github.theangrydev.op.generation.jvm.attribute.instruction;

import com.google.common.base.Preconditions;
import io.github.theangrydev.op.generation.jvm.ClassFileWriter;
import io.github.theangrydev.op.generation.jvm.IntValue;
import io.github.theangrydev.op.generation.jvm.WithSizeInBytes;

import java.io.DataOutput;
import java.io.IOException;
import java.util.List;

import static com.google.common.collect.Lists.newArrayList;
import static io.github.theangrydev.op.generation.jvm.IntValue.intValue;

public class Instructions implements ClassFileWriter, WithSizeInBytes {
    private static final int MAX_INSTRUCTION_BYTES = 65535;

    private final List<Instruction> instructions;
    private final IntValue sizeOfInstructionsInBytes;

    private Instructions(List<Instruction> instructions, IntValue sizeOfInstructionsInBytes) {
        this.instructions = instructions;
        this.sizeOfInstructionsInBytes = sizeOfInstructionsInBytes;
    }

    public static Instructions instructions(Instruction... instructions) {
        return instructions(newArrayList(instructions));
    }

    public static Instructions instructions(List<Instruction> instructions) {
        Preconditions.checkState(!instructions.isEmpty(), "Code must have at least one operation!");

        int sizeOfInstructionsInBytes = instructions.stream().mapToInt(Instruction::sizeInBytes).sum();
        Preconditions.checkState(sizeOfInstructionsInBytes <= MAX_INSTRUCTION_BYTES,
                "Total size of instructions must be less than %s bytes but was %s", MAX_INSTRUCTION_BYTES,
                sizeOfInstructionsInBytes);

        return new Instructions(instructions, intValue(sizeOfInstructionsInBytes));
    }

    @Override
    public int sizeInBytes() {
        return sizeOfInstructionsInBytes.sizeInBytes() + sizeOfInstructionsInBytes.value();
    }

    @Override
    public void writeTo(DataOutput dataOutput) throws IOException {
        sizeOfInstructionsInBytes.writeTo(dataOutput);
        for (Instruction instruction : instructions) {
            instruction.writeTo(dataOutput);
        }
    }
}