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    1: # The LearningOnline Network with CAPA - LON-CAPA
    2: # CalcEnv
    3: #
    4: # $Id: CalcEnv.pm,v 1.3 2023/03/13 22:31:22 raeburn Exp $
    5: #
    6: # Copyright (C) 2014 Michigan State University Board of Trustees
    7: #
    8: # This program is free software: you can redistribute it and/or modify
    9: # it under the terms of the GNU General Public License as published by
   10: # the Free Software Foundation, either version 3 of the License, or
   11: # (at your option) any later version.
   12: #
   13: # This program is distributed in the hope that it will be useful,
   14: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   15: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   16: # GNU General Public License for more details.
   17: #
   18: # You should have received a copy of the GNU General Public License
   19: # along with this program. If not, see <http://www.gnu.org/licenses/>.
   20: #
   21: 
   22: ##
   23: # Calculation environment, using either units or variables.
   24: ##
   25: package Apache::math_parser::CalcEnv;
   26: 
   27: use strict;
   28: use warnings;
   29: use utf8;
   30: 
   31: use File::Slurp;
   32: 
   33: use aliased 'Apache::math_parser::Quantity';
   34: use aliased 'Apache::math_parser::Units';
   35: 
   36: ##
   37: # Constructor
   38: # @param {boolean} unit_mode
   39: ##
   40: sub new {
   41:     my ($class, $unit_mode) = @_;
   42:     if (!defined $unit_mode) {
   43:         $unit_mode = 0;
   44:     }
   45:     my $self = {
   46:         _unit_mode => $unit_mode,
   47:     };
   48:     if ($self->{_unit_mode}) {
   49:         $self->{_units} = Units->new();
   50:     } else {
   51:         $self->{_variables} = { }; # hash variable name -> quantity
   52:     }
   53:     my $constants_txt = read_file("$Apache::lonnet::perlvar{'lonTabDir'}/constants.json");
   54:     $self->{_constants} = JSON::DWIW->new->from_json($constants_txt);
   55:     $self->{_tolerance} = 0;
   56:     bless $self, $class;
   57:     return $self;
   58: }
   59: 
   60: # Attribute helpers
   61: 
   62: ##
   63: # Unit mode ?
   64: # @returns {boolean}
   65: ##
   66: sub unit_mode {
   67:     my $self = shift;
   68:     return $self->{_unit_mode};
   69: }
   70: 
   71: ##
   72: # Units
   73: # @returns {Units}
   74: ##
   75: sub units {
   76:     my $self = shift;
   77:     return $self->{_units};
   78: }
   79: 
   80: ##
   81: # Variables
   82: # @returns {Object.<string, Quantity>} hash variable name -> quantity
   83: ##
   84: sub variables {
   85:     my $self = shift;
   86:     return $self->{_variables};
   87: }
   88: 
   89: ##
   90: # The constants, read from constants.json.
   91: # @returns {hash} A hash name -> hash with the keys value and units
   92: ##
   93: sub constants {
   94:     my $self = shift;
   95:     return $self->{_constants};
   96: }
   97: 
   98: ##
   99: # Tolerance
  100: # @returns {string|float} tolerance
  101: ##
  102: sub tolerance {
  103:     my $self = shift;
  104:     return $self->{_tolerance};
  105: }
  106: 
  107: 
  108: ##
  109: # Changes an existing unit or defines a new one.
  110: # @param {string} symbol - name used in math expressions
  111: # @param {string} convert - SI equivalent or using other units to help converting to SI
  112: ##
  113: sub setUnit {
  114:     my( $self, $symbol, $convert ) = @_;
  115:     $self->units->{_derived}->{$symbol} = $convert;
  116: }
  117: 
  118: ##
  119: # Changes an existing variable value or defines a new one.
  120: # @param {string} symbol - name used in math expressions
  121: # @param {float|Quantity} value - number value or Quantity
  122: ##
  123: sub setVariable {
  124:     my( $self, $symbol, $value ) = @_;
  125:     if ($value->isa(Quantity)) {
  126:         $self->variables->{$symbol} = $value;
  127:     } else {
  128:         $self->variables->{$symbol} = Quantity->new($value);
  129:     }
  130: }
  131: 
  132: ##
  133: # Defines the tolerance to use for = operations.
  134: # @param {string|float} tolerance
  135: ##
  136: sub setTolerance {
  137:     my( $self, $tolerance ) = @_;
  138:     $self->{_tolerance} = $tolerance;
  139: }
  140: 
  141: ##
  142: # Returns a variable quantity or undef.
  143: # @param {string} symbol - name used in math expressions
  144: # @returns {Quantity}
  145: ##
  146: sub getVariable {
  147:     my( $self, $symbol ) = @_;
  148:     return $self->variables->{$symbol};
  149: }
  150: 
  151: ##
  152: # Returns a constant quantity or undef.
  153: # @param {string} symbol - name used in math expressions
  154: # @returns {Quantity}
  155: ##
  156: sub getConstant {
  157:     my( $self, $symbol ) = @_;
  158:     my $cst = $self->constants->{$symbol};
  159:     if (!defined $cst) {
  160:         return undef;
  161:     }
  162:     return Quantity->new($cst->{"value"}, $cst->{"units"});
  163: }
  164: 
  165: ##
  166: # Converts a unit name into a Quantity. Throws an exception if the unit is not known.
  167: # @param {string} name - the unit name
  168: # @returns {Quantity}
  169: ##
  170: sub convertToSI {
  171:     my ( $self, $name ) = @_;
  172:     return $self->units->convertToSI($self, $name);
  173: }
  174: 
  175: 
  176: 1;
  177: __END__