plugin.hpp

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/*
 
Copyright 2025 | Leong Fan FUNG | funglf | stanleyfunglf@gmail.com
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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*/
 
#pragma once
#include <concepts>
#include <utility>
#include <iomanip>
#include <stdexcept>
#include <sstream>
#include <string>
#include <vector>
 
namespace comppare::plugin
{
    template <class InTup, class OutTup>
    class Plugin
    {
    public:
        virtual ~Plugin() = default;
        virtual void initialize(int & /*argc*/, char ** /*argv*/) {}
        virtual void run() {}
    };
 
    template <template <class, class> class P, class InTup, class OutTup, class Func>
    concept ValidPlugin =
        requires { { P<InTup, OutTup>::instance() } -> std::same_as<std::shared_ptr<P<InTup, OutTup>>>; } &&
        requires(const std::string &name, Func &&user_fn, const InTup &inputs, OutTup &outputs) { std::declval<P<InTup, OutTup> &>().register_impl(name, user_fn, inputs, outputs); } &&
        std::derived_from<P<InTup, OutTup>, plugin::Plugin<InTup, OutTup>>;
 
    class PluginArgParser
    {
    public:
        explicit PluginArgParser(std::string header, bool strict_missing_value = false)
            : header_(std::move(header)), strict_(strict_missing_value) {}
 
        PluginArgParser(const PluginArgParser &) = delete;
        PluginArgParser &operator=(const PluginArgParser &) = delete;
        PluginArgParser(PluginArgParser &&) = default;
        PluginArgParser &operator=(PluginArgParser &&) = default;
        ~PluginArgParser() = default;
 
        [[nodiscard]] std::pair<int, char **> parse(int argc, char **argv)
        {
            args_.clear();
            cargv_.clear();
 
            if (argc <= 0 || argv == nullptr || argv[0] == nullptr)
            {
                args_.push_back(header_.empty() ? "program" : header_);
            }
            else
            {
                args_.emplace_back(argv[0]);
            }
 
            const std::string eq_prefix = header_ + "=";
            std::vector<std::string> tokens;
 
            for (int i = 1; i < argc; ++i)
            {
                if (!argv || argv[i] == nullptr)
                    break;
                const std::string cur(argv[i]);
 
                if (starts_with(cur, eq_prefix))
                {
                    const std::string value = cur.substr(eq_prefix.size());
                    append_tokens(tokens, value);
                }
                else if (cur == header_)
                {
                    if (i + 1 < argc && argv[i + 1] != nullptr)
                    {
                        const std::string value(argv[++i]); // consume value
                        append_tokens(tokens, value);
                    }
                    else if (strict_)
                    {
                        throw std::invalid_argument(header_ + " requires a value");
                    }
                }
            }
 
            for (const auto &t : tokens)
                args_.push_back(t);
 
            cargv_.reserve(args_.size() + 1);
            for (const auto &s : args_)
                cargv_.push_back(const_cast<char *>(s.c_str()));
            cargv_.push_back(nullptr);
 
            return {static_cast<int>(args_.size()), cargv_.data()};
        }
 
        [[nodiscard]] int argc() const { return static_cast<int>(args_.size()); }
        [[nodiscard]] char **argv() { return cargv_.data(); } // valid after parse()
        [[nodiscard]] const std::vector<std::string> &args() const { return args_; }
 
    private:
        std::string header_;
        bool strict_;
        std::vector<std::string> args_;
        std::vector<char *> cargv_;
 
        static bool starts_with(const std::string &s, const std::string &prefix)
        {
            return s.size() >= prefix.size() && s.compare(0, prefix.size(), prefix) == 0;
        }
 
        // shell-like split that respects quotes: R"(--x "a b" c)" -> {"--x","a b","c"}
        static std::vector<std::string> split_shell_like(const std::string &s)
        {
            std::vector<std::string> out;
            std::istringstream iss(s);
            std::string tok;
            while (iss >> std::quoted(tok))
                out.push_back(tok);
            return out;
        }
 
        static void append_tokens(std::vector<std::string> &dst, const std::string &value)
        {
            auto toks = split_shell_like(value);
            dst.insert(dst.end(), toks.begin(), toks.end());
        }
    };
 
} // namespace comppare::plugin