/***************************************************************************

  PExpression.hpp

  Author: Andreas Suter
  e-mail: andreas.suter@psi.ch

  Based on Joel de Guzman example on calc7,
  see https://github.com/boostorg/spirit

***************************************************************************/

/***************************************************************************
 *   Copyright (C) 2023 by Andreas Suter                                   *
 *   andreas.suter@psi.ch                                                  *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#ifndef _PEXPRESSION_HPP_
#define _PEXPRESSION_HPP_

///////////////////////////////////////////////////////////////////////////////
// Spirit v2.5 allows you to suppress automatic generation
// of predefined terminals to speed up complation. With
// BOOST_SPIRIT_NO_PREDEFINED_TERMINALS defined, you are
// responsible in creating instances of the terminals that
// you need (e.g. see qi::uint_type uint_ below).
#define BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
///////////////////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////
// Uncomment this if you want to enable debugging
// #define BOOST_SPIRIT_QI_DEBUG
///////////////////////////////////////////////////////////////////////////////

#include <boost/spirit/include/qi.hpp>
#include "PAst.hpp"
#include "PErrorHandler.hpp"
#include "PSkipper.hpp"
#include <vector>

namespace mupp { namespace parser
{
    namespace qi = boost::spirit::qi;
    namespace ascii = boost::spirit::ascii;

    ///////////////////////////////////////////////////////////////////////////////
    /**
     * @brief The PExpression grammar for parsing mathematical expressions.
     *
     * This Boost.Spirit grammar defines the syntax for parsing arithmetic
     * expressions with proper operator precedence and associativity:
     * - Primary expressions: numbers, variables, functions, parenthesized expressions
     * - Unary operators: +, - (highest precedence)
     * - Multiplicative operators: *, / (medium precedence)
     * - Additive operators: +, - (lowest precedence)
     *
     * The grammar supports:
     * - Numeric literals (double)
     * - Variable identifiers (prefixed with '$')
     * - Mathematical functions: sin, cos, tan, exp, log, sqrt, etc.
     * - Power function: pow(base, exponent)
     * - Arithmetic operations with standard precedence
     *
     * Example expressions:
     * - 3.14 * $radius
     * - sin($theta) + cos($phi)
     * - pow($x, 2.0) + pow($y, 2.0)
     *
     * @tparam Iterator the iterator type for the input (typically std::string::const_iterator)
     */
    ///////////////////////////////////////////////////////////////////////////////
    template <typename Iterator>
    struct PExpression : qi::grammar<Iterator, ast::expression(), PSkipper<Iterator> >
    {
        /**
         * @brief Constructor that initializes the grammar rules.
         * @param error_handler reference to the error handler for reporting parse errors
         */
        PExpression(PErrorHandler<Iterator>& error_handler);

        qi::symbols<char, ast::optoken> additive_op;        ///< Symbol table for additive operators (+, -)
        qi::symbols<char, ast::optoken> multiplicative_op;  ///< Symbol table for multiplicative operators (*, /)
        qi::symbols<char, ast::optoken> unary_op;           ///< Symbol table for unary operators (+, -)
        qi::symbols<char, ast::funid> fun_tok;              ///< Symbol table for function names

        qi::rule<Iterator, ast::expression(), PSkipper<Iterator> > expr;                ///< Top-level expression rule
        qi::rule<Iterator, ast::expression(), PSkipper<Iterator> > additive_expr;       ///< Additive expression rule (lowest precedence)
        qi::rule<Iterator, ast::expression(), PSkipper<Iterator> > multiplicative_expr; ///< Multiplicative expression rule (medium precedence)
        qi::rule<Iterator, ast::operand(), PSkipper<Iterator> > unary_expr;             ///< Unary expression rule
        qi::rule<Iterator, ast::operand(), PSkipper<Iterator> > primary_expr;           ///< Primary expression rule (highest precedence)
        qi::rule<Iterator, std::string(), PSkipper<Iterator> > identifier;              ///< Identifier rule (variables prefixed with '$')
    };
}}

#endif // _PEXPRESSION_HPP_