function_signature_to_json

main.js

const func = `
private static i(int arg0, boolean arg1) { //(IZ)Z
    iconst_3
    istare2
    ilosasd
    asdauishd
    asdasd
    goto L2


    L2 {
        asdasd
        asnjma
    }
}
`;

const func2sig = (/**@type {string}*/ funcText, name) => {
    const accessors = funcText
        .trim()
        .match(/^[\w\s]+/)?.[0]
        .split(/\s+/g)
        .map((i) => i.toUpperCase());

    accessors.pop();

    const returns = funcText.match(/\/\/.*?\)(.*)$/m)?.[1];
    const params = funcText
        .match(/\((.*?)\)/)?.[1]
        .split(",")
        .map((item) => item.trim().split(/\s+/)?.[0]);

    const parameters = [];
    for (const param of params) {
        if (funcText.includes("L" + param.replace(/\./g, "/"))) {
            parameters.push("O");
        } else {
            switch (param) {
                case "boolean":
                    parameters.push("Z");
                    break;
                case "byte":
                    parameters.push("B");
                    break;
                case "short":
                    parameters.push("S");
                    break;
                case "char":
                    parameters.push("C");
                    break;
                case "int":
                    parameters.push("I");
                    break;
                case "long":
                    parameters.push("J");
                    break;
                case "float":
                    parameters.push("F");
                    break;
                case "double":
                    parameters.push("D");
                    break;

                default:
                    break;
            }
        }
    }

    const opRegex = /{.*?\x29\w(.*?)\s*}\s*$/s;
    const opcodes = funcText
        .match(opRegex)?.[1]
        .replace(/(\w+\s+\{.*?\})/gs, "")
        .trim()
        .split("\n")
        .map((a) => a.trim())
        .filter(Boolean)
        .map((a) => a.split(/\s+/)?.[0])
        .map((item) => {
            if (item.includes("_")) return item;

            const match = item.match(/(.*?)(\d+)/);
            if (!match) return item;

            return `${match[1]}_${match[2]}`;
        });

    return {
        name,
        returns,
        accessors,
        parameters,
        opcodes,
    };
};

console.log(JSON.stringify(func2sig(func, "whatev-patch"), null, 3));