libcruft-util/cpp.hpp

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2018 Danny Robson <danny@nerdcruft.net>
 */

#ifndef CRUFT_UTIL_CPP_HPP
#define CRUFT_UTIL_CPP_HPP

#include "string.hpp"
#include "view.hpp"

#include <filesystem>
#include <string>
#include <map>
#include <stdexcept>
#include <stack>

namespace cruft::cpp {
    ///////////////////////////////////////////////////////////////////////////
    struct context {
        std::stack<std::filesystem::path> source;
        std::map<std::string,std::string> defines;
    };


    ///////////////////////////////////////////////////////////////////////////
    /// an abstract base that performs processing for a directive
    class directive {
    public:
        virtual ~directive () = default;

        /// handles a preprocessor directive by:
        /// * perform some processing on any number of input lines,
        /// * optionally writes to the supplied stream,
        /// * and returns the line that should be consumed next
        ///
        /// \param lines is a tokenised view over all the lines of the input
        /// \return the next line that processing should continue from
        virtual cruft::tokeniser<const char*>::iterator
        process (std::ostream&,
                 context&,
                 cruft::view<cruft::tokeniser<const char*>::iterator> lines) const = 0;
    };


    ///////////////////////////////////////////////////////////////////////////
    class processor {
    public:
        processor ();
        void add (std::string token, std::unique_ptr<directive>);

        void process (std::ostream&, const std::filesystem::path&) const;

        std::filesystem::path
        resolve (const std::filesystem::path&) const;

        cruft::tokeniser<const char*>::iterator
        process (std::ostream&,
                 context&,
                 cruft::view<cruft::tokeniser<const char*>::iterator>) const;

    private:
        std::map<std::string, std::unique_ptr<directive>> m_directives;
    };


    ///////////////////////////////////////////////////////////////////////////
    /// thrown when a processor encounters a directive it has not been
    /// configured to handle
    class unknown_directive : public std::runtime_error {
        using runtime_error::runtime_error;
    };


    ///////////////////////////////////////////////////////////////////////////
    /// silently ignores configured directive by advancing the input cursor
    /// past the provided line without writing to the output stream.
    class ignore : public directive {
        cruft::tokeniser<const char*>::iterator
        process (std::ostream&,
                 context&,
                 cruft::view<cruft::tokeniser<const char*>::iterator> lines) const override
        { return lines.begin ()++; }
    };


    ///------------------------------------------------------------------------
    /// copies the supplied directive to the output stream without any
    /// modification
    class passthrough : public directive {
    public:
        passthrough (const std::string &name);

        virtual cruft::tokeniser<const char*>::iterator
        process (std::ostream&,
                 context&,
                 cruft::view<cruft::tokeniser<const char*>::iterator>) const override;

    private:
        const std::string m_name;
    };


    ///------------------------------------------------------------------------
    /// handles include directives by copying the contents of the referenced
    /// path into the input stream
    class include : public directive {
    public:
        include (processor &_parent);

        void add (const std::filesystem::path&);

        virtual cruft::tokeniser<const char*>::iterator
        process (std::ostream&,
                 context&,
                 cruft::view<cruft::tokeniser<const char*>::iterator>) const override;

    private:
        processor &m_parent;
        std::vector<std::filesystem::path> m_paths;
    };
};

#endif