283 lines
10 KiB
PHP
283 lines
10 KiB
PHP
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<?php
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// +----------------------------------------------------------------------+
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// | PHP version 4.0 |
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// +----------------------------------------------------------------------+
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// | Copyright (c) 1997, 1998, 1999, 2000, 2001 The PHP Group |
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// +----------------------------------------------------------------------+
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// | This source file is subject to version 2.0 of the PHP license, |
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// | that is bundled with this package in the file LICENSE, and is |
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// | available at through the world-wide-web at |
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// | http://www.php.net/license/2_02.txt. |
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// | If you did not receive a copy of the PHP license and are unable to |
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// | obtain it through the world-wide-web, please send a note to |
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// | license@php.net so we can mail you a copy immediately. |
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// +----------------------------------------------------------------------+
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// | Authors: Stanislav Okhvat <stanis@ngs.ru> |
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// | Co-authored by : CVH, Chris Hansel <chris@cpi-service.com> |
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// +----------------------------------------------------------------------+
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//
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// $Id: UnitConvertor.php,v 1.00 2002/02/20 11:40:00 stasokhvat Exp $
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/**
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* UnitConvertor is able to convert between different units and currencies.
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*
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* @author Stanislav Okhvat <stanis@sibfair.nsk.su, stanis@ngs.ru>
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* @version $Id: UnitConvertor.php,v 1.00 2002/03/01 17:00:00 stasokhvat Exp $
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* @package UnitConvertor
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* @access public
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* @history 01.03.2002 Implemented the code for regular and offset-based
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* conversions
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*
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* 13.12.2004
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* By Chris Hansel (CVH): changed getConvSpecs in order to have it look up
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* intermediary conversions (also see comments in check_key).
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*
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* Intermediary conversions are useful when no conversion ratio is specified
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* between two units when we calculate between the two. For example, we want
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* to convert between Fahrenheit and Kelvin, and we have only
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* specified how to convert Centigrade<->Fahrenheit and
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* Centigrade<->Kelvin. While a direct (Fahrenheit->Kelvin) or
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* reverse (Kelvin->Fahrenheit) lookups fail, looking for an intermediary
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* unit linking the two (Centigrade) helps us do the conversion.
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*
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* 13.12.2004
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* Chris Hansel (CVH): $to_array argument of addConversion method can now
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* contain units as 'unit1/unit2/unit3', when all units stand for the same
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* thing. See examples in unitconv.php
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*/
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class UnitConvertor
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{
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/**
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* Stores conversion ratios.
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*
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* @var array
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* @access private
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*/
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var $conversion_table = array();
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/**
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* Decimal point character (default is "." - American - set in constructor).
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*
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* @var string
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* @access private
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*/
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var $decimal_point;
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/**
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* Thousands separator (default is "," - American - set in constructor).
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*
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* @var string
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* @access private
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*/
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var $thousand_separator;
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/**
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* For future use
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*
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* @var array
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* @access private
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*/
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var $bases = array();
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/**
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* Constructor. Initializes the UnitConvertor object with the most important
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* properties.
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*
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* @param string decimal point character
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* @param string thousand separator character
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* @return void
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* @access public
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*/
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function UnitConvertor($dec_point = '.', $thousand_sep = ',')
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{
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$this->decimal_point = $dec_point;
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$this->thousand_separator = $thousand_sep;
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} // end func UnitConvertor
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/**
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* Adds a conversion ratio to the conversion table.
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*
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* @param string the name of unit from which to convert
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* @param array array(
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* "pound"=>array("ratio"=>'', "offset"=>'')
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* )
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* "pound" - name of unit to set conversion ration to
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* "ratio" - 'double' conversion ratio which, when
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* multiplied by the number of $from_unit units produces
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* the result
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* "offset" - an offset from 0 which will be added to
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* the result when converting (needed for temperature
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* conversions and defaults to 0).
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* @return boolean true if successful, false otherwise
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* @access public
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*/
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function addConversion($from_unit, $to_array)
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{
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if (!isset($this->conversion_table[$from_unit])) {
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while(list($key, $val) = each($to_array))
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{
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if (strstr($key, '/'))
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{
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$to_units = explode('/', $key);
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foreach ($to_units as $to_unit)
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{
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$this->bases[$from_unit][] = $to_unit;
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if (!is_array($val))
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{
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$this->conversion_table[$from_unit."_".$to_unit] = array("ratio"=>$val, "offset"=>0);
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}
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else
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{
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$this->conversion_table[$from_unit."_".$to_unit] =
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array(
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"ratio"=>$val['ratio'],
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"offset"=>(isset($val['offset']) ? $val['offset'] : 0)
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);
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}
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}
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}
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else
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{
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$this->bases[$from_unit][] = $key;
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if (!is_array($val))
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{
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$this->conversion_table[$from_unit."_".$key] = array("ratio"=>$val, "offset"=>0);
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}
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else
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{
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$this->conversion_table[$from_unit."_".$key] =
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array(
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"ratio"=>$val['ratio'],
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"offset"=>(isset($val['offset']) ? $val['offset'] : 0)
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);
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}
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}
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}
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return true;
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}
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return false;
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} // end func addConversion
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/**
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* Converts from one unit to another using specified precision.
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*
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* @param double value to convert
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* @param string name of the source unit from which to convert
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* @param string name of the target unit to which we are converting
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* @param integer double precision of the end result
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* @return void
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* @access public
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*/
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function convert($value, $from_unit, $to_unit, $precision)
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{
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if ($this->getConvSpecs($from_unit, $to_unit, $value, $converted ))
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{
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return number_format($converted , (int)$precision, $this->decimal_point, $this->thousand_separator);
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} else {
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return false;
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}
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} // end func
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/**
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* CVH : changed this Function getConvSpecs in order to have it look up
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* intermediary Conversions from the
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* "base" unit being that one that has the highest hierarchical order in one
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* "logical" Conversion_Array
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* when taking $conv->addConversion('km',
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* array('meter'=>1000, 'dmeter'=>10000, 'centimeter'=>100000,
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* 'millimeter'=>1000000, 'mile'=>0.62137, 'naut.mile'=>0.53996,
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* 'inch(es)/zoll'=>39370, 'ft/foot/feet'=>3280.8, 'yd/yard'=>1093.6));
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* "km" would be the logical base unit for all units of dinstance, thus,
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* if the function fails to find a direct or reverse conversion in the table
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* it is only logical to suspect that if there is a chance
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* converting the value it only is via the "base" unit, and so
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* there is not even a need for a recursive search keeping the perfomance
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* acceptable and the ressource small...
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*
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* CVH check_key checks for a key in the Conversiontable and returns a value
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*/
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function check_key( $key) {
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if ( array_key_exists ($key,$this->conversion_table)) {
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if (! empty($this->conversion_table[$key])) {
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return $this->conversion_table[$key];
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}
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}
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return false;
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}
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/**
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* Key function. Finds the conversion ratio and offset from one unit to another.
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*
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* @param string name of the source unit from which to convert
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* @param string name of the target unit to which we are converting
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* @param double conversion ratio found. Returned by reference.
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* @param double offset which needs to be added (or subtracted, if negative)
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* to the result to convert correctly.
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* For temperature or some scientific conversions,
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* i.e. Fahrenheit -> Celcius
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* @return boolean true if ratio and offset are found for the supplied
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* units, false otherwise
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* @access private
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*/
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function getConvSpecs($from_unit, $to_unit, $value, &$converted)
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{
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$key = $from_unit."_".$to_unit;
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$revkey = $to_unit."_".$from_unit;
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$found = false;
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if ($ct_arr = $this->check_key($key)) {
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// Conversion Specs found directly
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$ratio = (double)$ct_arr['ratio'];
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$offset = $ct_arr['offset'];
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$converted = (double)(($value * $ratio)+ $offset);
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return true;
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} // not found in direct order, try reverse order
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elseif ($ct_arr = $this->check_key($revkey)) {
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$ratio = (double)(1/$ct_arr['ratio']);
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$offset = -$ct_arr['offset'];
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$converted = (double)(($value + $offset) * $ratio);
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return true;
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} // not found test for intermediary conversion
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else {
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// return ratio = 1 if keyparts match
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if ($key == $revkey) {
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$ratio = 1;
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$offset = 0;
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$converted = $value;
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return true;
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}
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// otherwise search intermediary
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reset($this->conversion_table);
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while (list($convk, $i1_value) = each($this->conversion_table)) {
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// split the key into parts
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$keyparts = preg_split("/_/",$convk);
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// return ratio = 1 if keyparts match
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// Now test if either part matches the from or to unit
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if ($keyparts[1] == $to_unit && ($i2_value = $this->check_key($keyparts[0]."_".$from_unit))) {
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// an intermediary $keyparts[0] was found
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// now let us put things together intermediary 1 and 2
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$converted = (double)(((($value - $i2_value['offset']) / $i2_value['ratio']) * $i1_value['ratio'])+ $i1_value['offset']);
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$found = true;
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} elseif ($keyparts[1] == $from_unit && ($i2_value = $this->check_key($keyparts[0]."_".$to_unit))) {
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// an intermediary $keyparts[0] was found
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// now let us put things together intermediary 2 and 1
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$converted = (double)(((($value - $i1_value['offset']) / $i1_value['ratio']) + $i2_value['offset']) * $i2_value['ratio']);
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$found = true;
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}
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}
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return $found;
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}
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} // end func getConvSpecs
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} // end class UnitConvertor
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?>
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