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<?php |
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namespace DataValues; |
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use InvalidArgumentException; |
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/** |
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* Class representing a quantity with associated unit and uncertainty interval. |
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* The amount is stored as a @see DecimalValue object. |
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* |
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* For simple numeric amounts use @see NumberValue. |
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* |
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* @since 0.1 |
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* |
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* @license GPL-2.0+ |
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* @author Daniel Kinzler |
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*/ |
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class QuantityValue extends DataValueObject { |
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/** |
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* The quantity's amount |
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* |
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* @var DecimalValue |
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*/ |
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private $amount; |
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/** |
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* The quantity's unit identifier (use "1" for unitless quantities). |
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* |
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* @var string |
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*/ |
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private $unit; |
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/** |
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* The quantity's upper bound |
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* |
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* @var DecimalValue |
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*/ |
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private $upperBound; |
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/** |
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* The quantity's lower bound |
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* |
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* @var DecimalValue |
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*/ |
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private $lowerBound; |
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/** |
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* Constructs a new QuantityValue object, representing the given value. |
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* |
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* @since 0.1 |
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* |
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* @param DecimalValue $amount |
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* @param string $unit A unit identifier. Must not be empty, use "1" for unit-less quantities. |
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* @param DecimalValue $upperBound The upper bound of the quantity, inclusive. |
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* @param DecimalValue $lowerBound The lower bound of the quantity, inclusive. |
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* |
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* @throws IllegalValueException |
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*/ |
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public function __construct( DecimalValue $amount, $unit, DecimalValue $upperBound, DecimalValue $lowerBound ) { |
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if ( $lowerBound->compare( $amount ) > 0 ) { |
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throw new IllegalValueException( '$lowerBound ' . $lowerBound->getValue() . ' must be <= $amount ' . $amount->getValue() ); |
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} |
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if ( $upperBound->compare( $amount ) < 0 ) { |
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throw new IllegalValueException( '$upperBound ' . $upperBound->getValue() . ' must be >= $amount ' . $amount->getValue() ); |
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} |
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if ( !is_string( $unit ) || $unit === '' ) { |
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throw new IllegalValueException( '$unit must be a non-empty string. Use "1" for unit-less quantities.' ); |
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} |
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$this->amount = $amount; |
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$this->unit = $unit; |
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$this->upperBound = $upperBound; |
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$this->lowerBound = $lowerBound; |
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} |
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/** |
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* Returns a QuantityValue representing the given amount. |
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* If no upper or lower bound is given, the amount is assumed to be absolutely exact, |
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* that is, the amount itself will be used as the upper and lower bound. |
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* |
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* This is a convenience wrapper around the constructor that accepts native values |
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* instead of DecimalValue objects. |
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* |
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* @note: if the amount or a bound is given as a string, the string must conform |
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* to the rules defined by @see DecimalValue. |
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* |
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* @since 0.1 |
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* |
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* @param string|int|float|DecimalValue $amount |
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* @param string $unit A unit identifier. Must not be empty, use "1" for unit-less quantities. |
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* @param string|int|float|DecimalValue|null $upperBound |
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* @param string|int|float|DecimalValue|null $lowerBound |
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* |
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* @return self |
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* @throws IllegalValueException |
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*/ |
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public static function newFromNumber( $amount, $unit = '1', $upperBound = null, $lowerBound = null ) { |
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$amount = self::asDecimalValue( 'amount', $amount ); |
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$upperBound = self::asDecimalValue( 'upperBound', $upperBound, $amount ); |
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$lowerBound = self::asDecimalValue( 'lowerBound', $lowerBound, $amount ); |
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return new self( $amount, $unit, $upperBound, $lowerBound ); |
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} |
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/** |
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* Converts $number to a DecimalValue if possible and necessary. |
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* |
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* @note: if the $number is given as a string, it must conform to the rules |
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* defined by @see DecimalValue. |
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* |
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* @param string $name The variable name to use in exception messages |
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* @param string|int|float|DecimalValue|null $number |
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* @param DecimalValue|null $default |
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* |
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* @throws IllegalValueException |
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* @throws InvalidArgumentException |
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* @return DecimalValue |
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*/ |
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private static function asDecimalValue( $name, $number, DecimalValue $default = null ) { |
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if ( !is_string( $name ) ) { |
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throw new InvalidArgumentException( '$name must be a string' ); |
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} |
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if ( $number === null ) { |
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if ( $default === null ) { |
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throw new InvalidArgumentException( '$' . $name . ' must not be null' ); |
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} |
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$number = $default; |
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} |
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if ( $number instanceof DecimalValue ) { |
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// nothing to do |
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} elseif ( is_int( $number ) || is_float( $number ) || is_string( $number ) ) { |
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$number = new DecimalValue( $number ); |
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} else { |
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throw new IllegalValueException( '$' . $name . ' must be a string, int, or float' ); |
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} |
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return $number; |
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} |
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/** |
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* @see Serializable::serialize |
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* |
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* @since 0.1 |
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* |
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* @return string |
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*/ |
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public function serialize() { |
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return serialize( array( |
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$this->amount, |
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$this->unit, |
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$this->upperBound, |
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$this->lowerBound, |
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) ); |
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} |
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/** |
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* @see Serializable::unserialize |
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* |
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* @since 0.1 |
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* |
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* @param string $data |
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*/ |
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public function unserialize( $data ) { |
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list( $amount, $unit, $upperBound, $lowerBound ) = unserialize( $data ); |
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$this->__construct( $amount, $unit, $upperBound, $lowerBound ); |
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} |
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/** |
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* @see DataValue::getType |
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* |
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* @since 0.1 |
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* |
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* @return string |
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*/ |
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public static function getType() { |
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return 'quantity'; |
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} |
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/** |
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* @see DataValue::getSortKey |
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* |
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* @since 0.1 |
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* |
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* @return float |
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*/ |
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public function getSortKey() { |
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return $this->amount->getValueFloat(); |
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} |
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/** |
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* Returns the quantity object. |
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* @see DataValue::getValue |
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* |
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* @since 0.1 |
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* |
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* @return self |
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*/ |
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public function getValue() { |
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return $this; |
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} |
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/** |
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* Returns the amount represented by this quantity. |
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* |
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* @since 0.1 |
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* |
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* @return DecimalValue |
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*/ |
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public function getAmount() { |
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return $this->amount; |
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} |
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/** |
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* Returns this quantity's upper bound. |
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* |
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* @since 0.1 |
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* |
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* @return DecimalValue |
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*/ |
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public function getUpperBound() { |
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return $this->upperBound; |
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} |
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/** |
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* Returns this quantity's lower bound. |
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* |
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* @since 0.1 |
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* |
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* @return DecimalValue |
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*/ |
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public function getLowerBound() { |
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return $this->lowerBound; |
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} |
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/** |
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* Returns the size of the uncertainty interval. |
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* This can roughly be interpreted as "amount +/- uncertainty/2". |
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* |
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* The exact interpretation of the uncertainty interval is left to the concrete application or |
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* data point. For example, the uncertainty interval may be defined to be that part of a |
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* normal distribution that is required to cover the 95th percentile. |
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* |
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* @since 0.1 |
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* |
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* @return float |
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*/ |
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public function getUncertainty() { |
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return $this->upperBound->getValueFloat() - $this->lowerBound->getValueFloat(); |
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} |
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/** |
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* Returns a DecimalValue representing the symmetrical offset to be applied |
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* to the raw amount for a rough representation of the uncertainty interval, |
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* as in "amount +/- offset". |
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* |
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* The offset is calculated as max( amount - lowerBound, upperBound - amount ). |
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* |
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* @since 0.1 |
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* |
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* @return DecimalValue |
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*/ |
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public function getUncertaintyMargin() { |
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$math = new DecimalMath(); |
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$lowerMargin = $math->sum( $this->amount, $this->lowerBound->computeComplement() ); |
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$upperMargin = $math->sum( $this->upperBound, $this->amount->computeComplement() ); |
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$margin = $math->max( $lowerMargin, $upperMargin ); |
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return $margin; |
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} |
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/** |
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* Returns the order of magnitude of the uncertainty as the exponent of |
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* last significant digit in the amount-string. The value returned by this |
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* is suitable for use with @see DecimalMath::roundToExponent(). |
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* |
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* @example: if two digits after the decimal point are significant, this |
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* returns -2. |
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* |
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* @example: if the last two digits before the decimal point are insignificant, |
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* this returns 2. |
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* |
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* Note that this calculation assumes a symmetric uncertainty interval, |
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* and can be misleading. |
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* |
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* @since 0.1 |
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* |
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* @return int |
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*/ |
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public function getOrderOfUncertainty() { |
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// the desired precision is given by the distance between the amount and |
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// whatever is closer, the upper or lower bound. |
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//TODO: use DecimalMath to avoid floating point errors! |
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$amount = $this->amount->getValueFloat(); |
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$upperBound = $this->upperBound->getValueFloat(); |
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$lowerBound = $this->lowerBound->getValueFloat(); |
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$precision = min( $amount - $lowerBound, $upperBound - $amount ); |
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if ( $precision === 0.0 ) { |
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// If there is no uncertainty, the order of uncertainty is a bit more than what we have digits for. |
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return -strlen( $this->amount->getFractionalPart() ); |
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} |
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// e.g. +/- 200 -> 2; +/- 0.02 -> -2 |
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// note: we really want floor( log10( $precision ) ), but have to account for |
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// small errors made in the floating point operations above. |
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// @todo: use bcmath (via DecimalMath) to avoid this if possible |
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$orderOfUncertainty = floor( log10( $precision + 0.0000000005 ) ); |
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return (int)$orderOfUncertainty; |
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} |
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/** |
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* Returns the unit held by this quantity. |
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* Unit-less quantities should use "1" as their unit. |
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* |
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* @since 0.1 |
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* |
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* @return string |
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*/ |
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public function getUnit() { |
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return $this->unit; |
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} |
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/** |
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* Returns a transformed value derived from this QuantityValue by applying |
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* the given transformation to the amount and the upper and lower bounds. |
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* The resulting amount and bounds are rounded to the significant number of |
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* digits. Note that for exact quantities (with at least one bound equal to |
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* the amount), no rounding is applied (since they are considered to have |
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* infinite precision). |
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* |
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* The transformation is provided as a callback, which must implement a |
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* monotonously increasing, fully differentiable function mapping a DecimalValue |
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* to a DecimalValue. Typically, it will be a linear transformation applying a |
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* factor and an offset. |
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* |
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* @param string $newUnit The unit of the transformed quantity. |
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* |
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* @param callable $transformation A callback that implements the desired transformation. |
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* The transformation will be called three times, once for the amount, once |
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* for the lower bound, and once for the upper bound. It must return a DecimalValue. |
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* The first parameter passed to $transformation is the DecimalValue to transform |
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* In addition, any extra parameters passed to transform() will be passed through |
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* to the transformation callback. |
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* |
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* @param mixed ... Any extra parameters will be passed to the $transformation function. |
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* |
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* @throws InvalidArgumentException |
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* @return self |
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*/ |
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public function transform( $newUnit, $transformation ) { |
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if ( !is_callable( $transformation ) ) { |
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throw new InvalidArgumentException( '$transformation must be callable.' ); |
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} |
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if ( !is_string( $newUnit ) || $newUnit === '' ) { |
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throw new InvalidArgumentException( '$newUnit must be a non-empty string. Use "1" for unit-less quantities.' ); |
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} |
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// Apply transformation by calling the $transform callback. |
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// The first argument for the callback is the DataValue to transform. In addition, |
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// any extra arguments given for transform() are passed through. |
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$args = func_get_args(); |
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array_shift( $args ); |
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$args[0] = $this->amount; |
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$amount = call_user_func_array( $transformation, $args ); |
375
|
|
|
|
376
|
|
|
$args[0] = $this->upperBound; |
377
|
|
|
$upperBound = call_user_func_array( $transformation, $args ); |
378
|
|
|
|
379
|
|
|
$args[0] = $this->lowerBound; |
380
|
|
|
$lowerBound = call_user_func_array( $transformation, $args ); |
381
|
|
|
|
382
|
|
|
// use a preliminary QuantityValue to determine the significant number of digits |
383
|
|
|
$transformed = new self( $amount, $newUnit, $upperBound, $lowerBound ); |
384
|
|
|
$roundingExponent = $transformed->getOrderOfUncertainty(); |
385
|
|
|
|
386
|
|
|
// apply rounding to the significant digits |
387
|
|
|
$math = new DecimalMath(); |
388
|
|
|
|
389
|
|
|
$amount = $math->roundToExponent( $amount, $roundingExponent ); |
390
|
|
|
$upperBound = $math->roundToExponent( $upperBound, $roundingExponent ); |
391
|
|
|
$lowerBound = $math->roundToExponent( $lowerBound, $roundingExponent ); |
392
|
|
|
|
393
|
|
|
return new self( $amount, $newUnit, $upperBound, $lowerBound ); |
394
|
|
|
} |
395
|
|
|
|
396
|
|
|
public function __toString() { |
397
|
|
|
return $this->amount->getValue() |
398
|
|
|
. '[' . $this->lowerBound->getValue() |
399
|
|
|
. '..' . $this->upperBound->getValue() |
400
|
|
|
. ']' |
401
|
|
|
. ( $this->unit === '1' ? '' : $this->unit ); |
402
|
|
|
} |
403
|
|
|
|
404
|
|
|
/** |
405
|
|
|
* @see DataValue::getArrayValue |
406
|
|
|
* |
407
|
|
|
* @since 0.1 |
408
|
|
|
* |
409
|
|
|
* @return array |
410
|
|
|
*/ |
411
|
|
|
public function getArrayValue() { |
412
|
|
|
return array( |
413
|
|
|
'amount' => $this->amount->getArrayValue(), |
414
|
|
|
'unit' => $this->unit, |
415
|
|
|
'upperBound' => $this->upperBound->getArrayValue(), |
416
|
|
|
'lowerBound' => $this->lowerBound->getArrayValue(), |
417
|
|
|
); |
418
|
|
|
} |
419
|
|
|
|
420
|
|
|
/** |
421
|
|
|
* Constructs a new instance of the DataValue from the provided data. |
422
|
|
|
* This can round-trip with @see getArrayValue |
423
|
|
|
* |
424
|
|
|
* @since 0.1 |
425
|
|
|
* |
426
|
|
|
* @param mixed $data |
427
|
|
|
* |
428
|
|
|
* @return self |
429
|
|
|
* @throws IllegalValueException |
430
|
|
|
*/ |
431
|
|
|
public static function newFromArray( $data ) { |
432
|
|
|
self::requireArrayFields( $data, array( 'amount', 'unit', 'upperBound', 'lowerBound' ) ); |
433
|
|
|
|
434
|
|
|
return new static( |
435
|
|
|
DecimalValue::newFromArray( $data['amount'] ), |
436
|
|
|
$data['unit'], |
437
|
|
|
DecimalValue::newFromArray( $data['upperBound'] ), |
438
|
|
|
DecimalValue::newFromArray( $data['lowerBound'] ) |
439
|
|
|
); |
440
|
|
|
} |
441
|
|
|
|
442
|
|
|
/** |
443
|
|
|
* @see Comparable::equals |
444
|
|
|
* |
445
|
|
|
* @since 0.1 |
446
|
|
|
* |
447
|
|
|
* @param mixed $target |
448
|
|
|
* |
449
|
|
|
* @return bool |
450
|
|
|
*/ |
451
|
|
|
public function equals( $target ) { |
452
|
|
|
if ( $this === $target ) { |
453
|
|
|
return true; |
454
|
|
|
} |
455
|
|
|
|
456
|
|
|
return $target instanceof self |
457
|
|
|
&& $this->toArray() === $target->toArray(); |
458
|
|
|
} |
459
|
|
|
|
460
|
|
|
} |
461
|
|
|
|
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: