com.llamalad7.mixinextras.utils.GenericParamParser Maven / Gradle / Ivy

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package com.llamalad7.mixinextras.utils;

import org.apache.commons.lang3.StringUtils;
import org.objectweb.asm.Type;
import org.objectweb.asm.signature.SignatureReader;
import org.objectweb.asm.signature.SignatureVisitor;
import org.spongepowered.asm.util.asm.ASM;

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

public class GenericParamParser extends SignatureVisitor {
    private final List results = new ArrayList<>();

    private GenericParamParser() {
        super(ASM.API_VERSION);
    }

    public static List getParameterGenerics(String desc, String signature) {
        if (signature == null || signature.isEmpty()) {
            return Collections.nCopies(Type.getArgumentTypes(desc).length, null);
        }
        GenericParamParser parser = new GenericParamParser();
        new SignatureReader(signature).accept(parser);
        return parser.results;
    }

    @Override
    public SignatureVisitor visitParameterType() {
        int index = results.size();
        results.add(null);
        return new SignatureVisitor(api) {
            @Override
            public SignatureVisitor visitTypeArgument(char wildcard) {
                if (wildcard != SignatureVisitor.INSTANCEOF) {
                    return this;
                }
                return new SignatureVisitor(api) {
                    private int depth;
                    private int arrayDimensions;
                    private String internalName;

                    @Override
                    public SignatureVisitor visitArrayType() {
                        if (depth == 0) {
                            arrayDimensions++;
                        }
                        return this;
                    }

                    @Override
                    public void visitBaseType(char descriptor) {
                        if (depth == 0) {
                            results.set(index, Type.getType(StringUtils.repeat('[', arrayDimensions) + descriptor));
                        }
                    }

                    @Override
                    public void visitClassType(String name) {
                        if (++depth == 1) {
                            internalName = name;
                        }
                    }

                    @Override
                    public void visitInnerClassType(String name) {
                        if (depth == 1) {
                            internalName += '$' + name;
                        }
                    }

                    @Override
                    public void visitEnd() {
                        depth--;
                        String prefix = StringUtils.repeat('[', arrayDimensions);
                        results.set(index, Type.getType(prefix + (Type.getObjectType(internalName).getDescriptor())));
                    }
                };
            }
        };
    }
}