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Annotation of loncom/homework/math_parser/CalcEnv.pm, revision 1.3

1.1       damieng     1: # The LearningOnline Network with CAPA - LON-CAPA
                      2: # CalcEnv
                      3: #
1.3     ! raeburn     4: # $Id: CalcEnv.pm,v 1.3 2023/03/13 18:30:00 raeburn Exp $
        !             5: #
1.1       damieng     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 {
1.2       damieng    41:     my ($class, $unit_mode) = @_;
                     42:     if (!defined $unit_mode) {
                     43:         $unit_mode = 0;
                     44:     }
1.1       damieng    45:     my $self = {
1.2       damieng    46:         _unit_mode => $unit_mode,
1.1       damieng    47:     };
                     48:     if ($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__