Lexesis/include/Lexesis/re.h

/*
Lexesis - A language agnostic lexical analyser generator
Copyright © 2016-2017 Thomas Avé, Robin Jadoul

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, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#pragma once
#ifndef RE_H
#define RE_H

#include "Lexesis/automata.h"

#include <memory>
#include <stdexcept>

namespace lxs {
    /**
     * An abstract regular expression
     */
    class RE
    {
        public:
            virtual ~RE() {}
            /**
             * Convert this regex to an ENFA
             * This extends the given enfa, and attaches itself to the given `attach` state
             */
            virtual State toENFA(ENFA& enfa, State attach) = 0;

            /**
             * Convert this regex to a text regex (useful to check if parsing was correct)
             */
            virtual std::string toRe() = 0;
    };

    /**
     * A regex for the empty language
     */
    class EmptyRE : public RE
    {
        public:
            EmptyRE() {}
            ~EmptyRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();
    };

    /**
     * A regex for the language containing only the empty string
     */
    class EpsilonRE : public RE
    {
        public:
            EpsilonRE() {}
            ~EpsilonRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();
    };

    /**
     * A regex for the language containing a single character
     */
    class SingleRE : public RE
    {
        public:
            /**
             * @param c The character of the language
             */
            SingleRE(char c) : c(c) {}
            ~SingleRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();

            char c;
    };

    /**
     * A regex for the language containing multiple single-symbol strings
     */
    class MultiRE : public RE
    {
        public:
            /**
             * @param chars The list of symbols contained in the language
             */
            MultiRE(std::vector<char> chars) : chars(std::move(chars)) {}
            ~MultiRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();

            std::vector<char> chars;
    };

    /**
     * A regex for the concatenation of two languages
     */
    class ConcatRE : public RE
    {
        public:
            /**
             * @param e The first language
             * @param f The second language
             */
            ConcatRE(std::shared_ptr<RE> e, std::shared_ptr<RE> f) : e(e), f(f) {}
            ~ConcatRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();

            std::shared_ptr<RE> e, f;
    };

    /**
     * The regex for the kleene star of a language
     */
    class StarRE : public RE
    {
        public:
            /**
             * @param e The language to apply the star to
             */
            StarRE(std::shared_ptr<RE> e) : e(e) {}
            ~StarRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();

            std::shared_ptr<RE> e;
    };

    /**
     * A regex for the sum/disjunction of two languages
     */
    class PlusRE : public RE
    {
        public:
            /**
             * @param e The first language
             * @param f The second language
             */
            PlusRE(std::shared_ptr<RE> e, std::shared_ptr<RE> f) : e(e), f(f) {}
            ~PlusRE() {}
            virtual State toENFA(ENFA& enfa, State attach);
            virtual std::string toRe();

            std::shared_ptr<RE> e, f;
    };


} //namespace lxs

#endif //RE_H