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/*
 * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package io.github.dmlloyd.classfile.impl;

import io.github.dmlloyd.classfile.CodeBuilder;
import io.github.dmlloyd.classfile.CustomAttribute;
import io.github.dmlloyd.classfile.FieldBuilder;
import io.github.dmlloyd.classfile.MethodBuilder;
import io.github.dmlloyd.classfile.PseudoInstruction;
import io.github.dmlloyd.classfile.constantpool.PoolEntry;
import java.lang.constant.ClassDesc;
import java.lang.constant.MethodTypeDesc;
import java.util.AbstractList;
import java.util.Collection;
import java.util.List;
import java.util.function.Function;

import io.github.dmlloyd.classfile.Attribute;
import io.github.dmlloyd.classfile.AttributeMapper;
import io.github.dmlloyd.classfile.Attributes;
import io.github.dmlloyd.classfile.BufWriter;
import io.github.dmlloyd.classfile.ClassFile;
import io.github.dmlloyd.classfile.extras.constant.ExtraClassDesc;
import io.github.dmlloyd.classfile.Opcode;
import io.github.dmlloyd.classfile.constantpool.ClassEntry;
import io.github.dmlloyd.classfile.constantpool.ModuleEntry;
import io.github.dmlloyd.classfile.constantpool.NameAndTypeEntry;
import io.github.dmlloyd.classfile.extras.constant.ModuleDesc;

import io.github.dmlloyd.classfile.extras.reflect.AccessFlag;

import static io.github.dmlloyd.classfile.ClassFile.ACC_STATIC;
import io.github.dmlloyd.classfile.attribute.CodeAttribute;
import io.github.dmlloyd.classfile.components.ClassPrinter;
import java.util.function.Consumer;

import static java.lang.constant.ConstantDescs.CD_double;
import static java.lang.constant.ConstantDescs.CD_long;
import static java.lang.constant.ConstantDescs.CD_void;

/**
 * Helper to create and manipulate type descriptors, where type descriptors are
 * represented as JVM type descriptor strings and symbols are represented as
 * name strings
 */
public class Util {

    private Util() {
    }

    public static  Consumer> writingAll(Iterable container) {
        record ForEachConsumer(Iterable container) implements Consumer> {
            @Override
            public void accept(Consumer consumer) {
                container.forEach(consumer);
            }
        }
        return new ForEachConsumer<>(container);
    }

    public static Consumer buildingCode(Consumer codeHandler) {
        record WithCodeMethodHandler(Consumer codeHandler) implements Consumer {
            @Override
            public void accept(MethodBuilder builder) {
                builder.withCode(codeHandler);
            }
        }
        return new WithCodeMethodHandler(codeHandler);
    }

    public static Consumer buildingFlags(int flags) {
        record WithFlagFieldHandler(int flags) implements Consumer {
            @Override
            public void accept(FieldBuilder builder) {
                builder.withFlags(flags);
            }
        }
        return new WithFlagFieldHandler(flags);
    }

    private static final int ATTRIBUTE_STABILITY_COUNT = AttributeMapper.AttributeStability.values().length;

    public static boolean isAttributeAllowed(final Attribute attr,
                                             final ClassFileImpl context) {
        return attr instanceof BoundAttribute
                ? ATTRIBUTE_STABILITY_COUNT - attr.attributeMapper().stability().ordinal() > context.attributesProcessingOption().ordinal()
                : true;
    }

    public static int parameterSlots(MethodTypeDesc mDesc) {
        int count = mDesc.parameterCount();
        for (int i = count - 1; i >= 0; i--) {
            if (isDoubleSlot(mDesc.parameterType(i))) {
                count++;
            }
        }
        return count;
    }

    public static int[] parseParameterSlots(int flags, MethodTypeDesc mDesc) {
        int[] result = new int[mDesc.parameterCount()];
        int count = ((flags & ACC_STATIC) != 0) ? 0 : 1;
        for (int i = 0; i < result.length; i++) {
            result[i] = count;
            count += paramSlotSize(mDesc.parameterType(i));
        }
        return result;
    }

    public static int maxLocals(int flags, MethodTypeDesc mDesc) {
        return parameterSlots(mDesc) + ((flags & ACC_STATIC) == 0 ? 1 : 0) ;
    }

    /**
     * Converts a descriptor of classes or interfaces into
     * a binary name. Rejects primitive types or arrays.
     * This is an inverse of {@link ClassDesc#of(String)}.
     */
    public static String toBinaryName(ClassDesc cd) {
        return toInternalName(cd).replace('/', '.');
    }

    public static String toInternalName(ClassDesc cd) {
        var desc = cd.descriptorString();
        if (desc.charAt(0) == 'L')
            return desc.substring(1, desc.length() - 1);
        throw new IllegalArgumentException(desc);
    }

    public static ClassDesc toClassDesc(String classInternalNameOrArrayDesc) {
        return classInternalNameOrArrayDesc.charAt(0) == '['
                ? ClassDesc.ofDescriptor(classInternalNameOrArrayDesc)
                : ExtraClassDesc.ofInternalName(classInternalNameOrArrayDesc);
    }

    public static List mappedList(List list, Function mapper) {
        return new AbstractList<>() {
            @Override
            public U get(int index) {
                return mapper.apply(list.get(index));
            }

            @Override
            public int size() {
                return list.size();
            }
        };
    }

    public static List entryList(List list) {
        var result = new ClassEntry[list.size()]; // null check
        for (int i = 0; i < result.length; i++) {
            result[i] = TemporaryConstantPool.INSTANCE.classEntry(list.get(i));
        }
        return List.of(result);
    }

    public static List moduleEntryList(List list) {
        var result = new ModuleEntry[list.size()]; // null check
        for (int i = 0; i < result.length; i++) {
            result[i] = TemporaryConstantPool.INSTANCE.moduleEntry(TemporaryConstantPool.INSTANCE.utf8Entry(list.get(i).name()));
        }
        return List.of(result);
    }

    public static void checkKind(Opcode op, Opcode.Kind k) {
        if (op.kind() != k)
            throw badOpcodeKindException(op, k);
    }

    public static IllegalArgumentException badOpcodeKindException(Opcode op, Opcode.Kind k) {
        return new IllegalArgumentException(
                String.format("Wrong opcode kind specified; found %s(%s), expected %s", op, op.kind(), k));
    }

    public static int flagsToBits(AccessFlag.Location location, Collection flags) {
        int i = 0;
        for (AccessFlag f : flags) {
            if (!f.locations().contains(location)) {
                throw new IllegalArgumentException("unexpected flag: " + f + " use in target location: " + location);
            }
            i |= f.mask();
        }
        return i;
    }

    public static int flagsToBits(AccessFlag.Location location, AccessFlag... flags) {
        int i = 0;
        for (AccessFlag f : flags) {
            if (!f.locations().contains(location)) {
                throw new IllegalArgumentException("unexpected flag: " + f + " use in target location: " + location);
            }
            i |= f.mask();
        }
        return i;
    }

    public static boolean has(AccessFlag.Location location, int flagsMask, AccessFlag flag) {
        return (flag.mask() & flagsMask) == flag.mask() && flag.locations().contains(location);
    }

    public static ClassDesc fieldTypeSymbol(NameAndTypeEntry nat) {
        return ((AbstractPoolEntry.NameAndTypeEntryImpl)nat).fieldTypeSymbol();
    }

    public static MethodTypeDesc methodTypeSymbol(NameAndTypeEntry nat) {
        return ((AbstractPoolEntry.NameAndTypeEntryImpl)nat).methodTypeSymbol();
    }

    @SuppressWarnings("unchecked")
    private static > void writeAttribute(BufWriterImpl writer, Attribute attr) {
        if (attr instanceof CustomAttribute ca) {
            var mapper = (AttributeMapper) ca.attributeMapper();
            mapper.writeAttribute(writer, (T) ca);
        } else {
            assert attr instanceof BoundAttribute || attr instanceof UnboundAttribute;
            ((Writable) attr).writeTo(writer);
        }
    }

    public static void writeAttributes(BufWriterImpl buf, List> list) {
        buf.writeU2(list.size());
        for (var e : list) {
            writeAttribute(buf, e);
        }
    }

    static void writeList(BufWriterImpl buf, List list) {
        buf.writeU2(list.size());
        for (var e : list) {
            e.writeTo(buf);
        }
    }

    public static int slotSize(ClassDesc desc) {
        return desc == CD_void ? 0 : isDoubleSlot(desc) ? 2 : 1;
    }

    public static int paramSlotSize(ClassDesc desc) {
        return isDoubleSlot(desc) ? 2 : 1;
    }

    public static boolean isDoubleSlot(ClassDesc desc) {
        return desc == CD_double || desc == CD_long;
    }

    public static void dumpMethod(SplitConstantPool cp,
                                  ClassDesc cls,
                                  String methodName,
                                  MethodTypeDesc methodDesc,
                                  int acc,
                                  RawBytecodeHelper.CodeRange bytecode,
                                  Consumer dump) {

        // try to dump debug info about corrupted bytecode
        try {
            var cc = ClassFile.of();
            var clm = cc.parse(cc.build(cp.classEntry(cls), cp, clb ->
                clb.withMethod(methodName, methodDesc, acc, mb ->
                    ((DirectMethodBuilder) mb).writeAttribute(new UnboundAttribute.AdHocAttribute(Attributes.code()) {
                        @Override
                        public void writeBody(BufWriterImpl b) {
                            b.writeU2(- 1);//max stack
                            b.writeU2(- 1);//max locals
                            b.writeInt(bytecode.length());
                            b.writeBytes(bytecode.array(), 0, bytecode.length());
                            b.writeU2(0);//exception handlers
                            b.writeU2(0);//attributes
                        }
                    }))));
            ClassPrinter.toYaml(clm.methods().get(0).code().get(), ClassPrinter.Verbosity.TRACE_ALL, dump);
        } catch (Error | Exception __) {
            // fallback to bytecode hex dump
            dumpBytesHex(dump, bytecode.array(), bytecode.length());
        }
    }

    public static void dumpBytesHex(Consumer dump, byte[] bytes, int length) {
        for (int i = 0; i < length; i++) {
            if (i % 16 == 0) {
                dump.accept("%n%04x:".formatted(i));
            }
            dump.accept(" %02x".formatted(bytes[i]));
        }
    }

    public static void writeListIndices(BufWriter writer, List list) {
        writer.writeU2(list.size());
        for (PoolEntry info : list) {
            writer.writeIndex(info);
        }
    }

    public static boolean writeLocalVariable(BufWriterImpl buf, PseudoInstruction lvOrLvt) {
        return ((WritableLocalVariable) lvOrLvt).writeLocalTo(buf);
    }

    /**
     * A generic interface for objects to write to a
     * buf writer. Do not implement unless necessary,
     * as this writeTo is public, which can be troublesome.
     */
    interface Writable {
        void writeTo(BufWriterImpl writer);
    }

    interface WritableLocalVariable {
        boolean writeLocalTo(BufWriterImpl buf);
    }
}




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