Equation.h

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/*--------------------------------------------------------------------------------------------
Copyright (c) 2019, NDEVR LLC
tyler.parke@ndevr.org
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 |  \  |  | |  __ \  |  ___|\ \   / / |   __  \
 |   \ |  | | |  \ \ | |___  \ \ / /  |  |__)  |
 |  . \|  | | |__/ / | |___   \ V /   |   _   /
 |  |\    |_|_____/__|_____|___\_/____|  | \  \
 |__| \__________________________________|  \__\
 
Subject to the terms of the Enterprise+ Agreement, NDEVR hereby grants 
Licensee a limited, non-exclusive, non-transferable, royalty-free license 
(without the right to sublicense) to use the API solely for the purpose of 
Licensee's internal development efforts to develop applications for which 
the API was provided.
 
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.
 
Library: Base
File: Equation
Included in API: True
Author(s): Tyler Parke
 *-----------------------------------------------------------------------------------------**/
#pragma once
#include <NDEVR/String.h>
#include <NDEVR/Dictionary.h>
#include <cmath>
namespace NDEVR
{
    /**--------------------------------------------------------------------------------------------------
    \brief Stores in a compressed way, a formula that can be solved.
    A formula is made of up variables, numbers, and operations. Formulas can be simplified, or potentially
        solved to a numeric value.
    **/
    template<class t_type>
    class Equation
    {
    public:
        Equation()
        {}
        struct EquationPart
        {
            char operation;
            t_type value;
        };
        void setVariable(const String& var, t_type value)
        {
            m_variables[var] = value;
            if (m_variable_locations.hasKey(var))
            {
                Buffer<uint04>& locations = m_variable_locations[var];
                for (uint04 i = 0; i < locations.size(); i++)
                    m_equation_stack[locations[i]].value = value;
            }
        }
        void refreshVariables()
        {
            for (const auto& variable : m_variables)
            {
                Buffer<uint04>& locations = m_variable_locations[variable.first];
                for (uint04 i = 0; i < locations.size(); i++)
                    m_equation_stack[locations[i]].value = variable.second;
            }
        }
        static t_type solve(t_type left, const char op, t_type right)
        {
            switch (op)
            {
            case '+': return left + right;
            case '-': return left - right;
            case '/': return left / right;
            case '*': return left * right;
            case '^': return std::pow(left, right);
            case '%': return std::fmod(left, right);
            case 's': return std::sin(right);
            case 'c': return std::cos(right);
            case 't': return std::tan(right);
            case 'q': return std::sqrt(right);
            case '\0': return right;
            default: return Constant<t_type>::Invalid;
            }
        }
        t_type solve() const
        {
            uint04 index = 0;
            t_type value = solve(cast<t_type>(0), index);
 
            if (index != m_equation_stack.size())
                return Constant<t_type>::Invalid;
            return value;
        }
        void add(char operation, t_type value)
        {
            EquationPart part{};
            part.value = value;
            part.operation = operation;
            m_equation_stack.add(part);
        }
        static uint04 getOrderPriority(const char op)
        {
            switch (op)
            {
            case '+': return 10;
            case '-': return 10;
            case '/': return 20;
            case '*': return 20;
            case '^': return 30;
            case '%': return 30;
            case 's': return 40;
            case 'c': return 40;
            case 't': return 40;
            case 'q': return 40;
            default: return Constant<t_type>::Invalid;
            }
        }
        void addOrderOfOps(char operation, t_type value)
        {
            EquationPart part;
            part.value = value;
            part.operation = operation;
            uint04 insertion_index = m_equation_stack.size();
            m_equation_stack.add(insertion_index, part);
        }
        void add(char operation, const String& value)
        {
            m_variable_locations[value].add(m_equation_stack.size());
 
            EquationPart part{};
            part.value = Constant<t_type>::Invalid;
            part.operation = operation;
 
            m_equation_stack.add(part);
        }
        t_type solve(t_type start, uint04& current_index) const
        {
            for (; current_index < m_equation_stack.size(); current_index++)
            {
                if (IsInvalid(m_equation_stack[current_index].value))
                    return Constant<t_type>::Invalid;
                const char current = m_equation_stack[current_index].operation;
                switch (current)
                {
                case '\0': start += m_equation_stack[current_index].value; break;
                case '+': start += m_equation_stack[current_index].value; break;
                case '-': start -= m_equation_stack[current_index].value; break;
                case '/': start /= m_equation_stack[current_index].value; break;
                case '*': start *= m_equation_stack[current_index].value; break;
                case '^': start = std::pow(start, m_equation_stack[current_index].value); break;
                case '%': start = std::fmod(start, m_equation_stack[current_index].value); break;
                case 's':
                case 'c':
                case 't':
                case 'q':
                case '(':
                {
                    const char lead_operation = cast<char>(m_equation_stack[current_index].value);
                    t_type inner_solve = solve(cast<t_type>(0), ++current_index);
                    if (current_index >= m_equation_stack.size())
                        return Constant<t_type>::Invalid;//no closing ')'
                    switch (current)
                    {
                    case 's': inner_solve = sin(inner_solve); break;
                    case 'c': inner_solve = cos(inner_solve); break;
                    case 't': inner_solve = tan(inner_solve); break;
                    case 'q': inner_solve = sqrt(inner_solve); break;
                    default: break;
                    }
                    start = solve(start, lead_operation, inner_solve);
                } break;
                case ')': return start;
                default: lib_assert(false, "unknown operator");
                }
            }
            return start;
        }
        Dictionary<String, Buffer<uint04>> m_variable_locations;
        Dictionary<String, t_type> m_variables;
        Buffer<EquationPart> m_equation_stack;
    };
    
}