Merge pull request #118 from DataValues/release0100

Release 0.10.0 with refined float to string conversion
wmde · Apr 11, 2018 · 8272ed7 · 8272ed7
2 parents b86eb12 + 0fcde54
commit 8272ed7
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Showing 4 changed files with 84 additions and 49 deletions.
diff --git a/Number.php b/Number.php
@@ -15,4 +15,4 @@
 	return 1;
 }
 
-define( 'DATAVALUES_NUMBER_VERSION', '0.9.1' );
+define( 'DATAVALUES_NUMBER_VERSION', '0.10.0' );
diff --git a/README.md b/README.md
@@ -50,9 +50,16 @@ the [Wikidata project](https://www.wikidata.org/).
 
 ## Release notes
 
+### 0.10.0 (2018-04-10)
+
+* Changed the float to string conversion algorithm for `DecimalValue`, `QuantityValue`, and
+  `UnboundedQuantityValue`. Instead of a hundred mostly irrelevant decimal places it now uses PHP's
+  "serialize_precision" default of 17 significant digits.
+* Drop compatibility with data-values/interfaces 0.1 and data-values/common 0.2
+
 ### 0.9.1 (2017-08-09)
 
-* Allow use with ~0.4.0 of DataValues/Common
+* Allow use with data-values/common 0.4
 
 ### 0.9.0 (2017-08-09)
 
@@ -103,7 +110,7 @@ the [Wikidata project](https://www.wikidata.org/).
 #### Other changes
 * Fixed `DecimalValue` and `QuantityValue` allowing values with a newline at the end.
 * `DecimalValue` strings are trimmed now, allowing any number of leading and trailing whitespace.
-* Added explicit compatibility with DataValues Common 0.2 and 0.3.
+* Added explicit compatibility with data-values/common 0.2 and 0.3.
 
 ### 0.6.0 (2015-09-09)
 

diff --git a/src/DataValues/DecimalValue.php b/src/DataValues/DecimalValue.php
@@ -91,29 +91,31 @@ private function convertToDecimal( $number ) {
 			throw new InvalidArgumentException( '$number must not be NAN or INF.' );
 		}
 
-		$decimal = strval( abs( $number ) );
-		$decimal = preg_replace_callback(
-			'/(\d*)\.(\d*)E([-+]\d+)/i',
-			function ( $matches ) {
-				list( , $before, $after, $exponent ) = $matches;
-
-				// Fill with as many zeros as necessary, and move the decimal point
-				if ( $exponent < 0 ) {
-					$before = str_repeat( '0', -$exponent - strlen( $before ) + 1 ) . $before;
-					$before = substr_replace( $before, '.', $exponent, 0 );
-				} else {
-					$after .= str_repeat( '0', $exponent - strlen( $after ) );
-					$after = substr_replace( $after, '.', $exponent, 0 );
-				}
-
-				// Remove not needed ".0" or just "." from the end
-				return $before . rtrim( rtrim( $after, '0' ), '.' );
-			},
-			$decimal,
-			1
-		);
-
-		return ( $number < 0 ? '-' : '+' ) . $decimal;
+		/**
+		 * The 16 digits after the decimal point are derived from PHP's "serialize_precision"
+		 * default of 17 significant digits (including 1 digit before the decimal point). This
+		 * ensures a full float-string-float roundtrip.
+		 * @see http://php.net/manual/en/ini.core.php#ini.serialize-precision
+		 */
+		$decimal = sprintf( '%.16e', abs( $number ) );
+		list( $base, $exponent ) = explode( 'e', $decimal );
+		list( $before, $after ) = explode( '.', $base );
+
+		// Fill with as many zeros as necessary, and move the decimal point
+		if ( $exponent < 0 ) {
+			$before = str_repeat( '0', -$exponent - strlen( $before ) + 1 ) . $before;
+			$before = substr_replace( $before, '.', $exponent, 0 );
+		} else {
+			$pad = $exponent - strlen( $after );
+			if ( $pad > 0 ) {
+				$after .= str_repeat( '0', $pad );
+			}
+			// Always add the decimal point back, even if the exponent is 0
+			$after = substr_replace( $after, '.', $exponent, 0 );
+		}
+
+		// Remove not needed ".0" or just "." from the end
+		return ( $number < 0 ? '-' : '+' ) . $before . rtrim( rtrim( $after, '0' ), '.' );
 	}
 
 	/**

diff --git a/tests/DataValues/DecimalValueTest.php b/tests/DataValues/DecimalValueTest.php
@@ -98,7 +98,10 @@ public function testTrailingNewlineRobustness() {
 	 * @dataProvider provideFloats
 	 */
 	public function testFloatInputs( $float, $expectedPrefix ) {
+		$originalLocale = setlocale( LC_NUMERIC, '0' );
+		setlocale( LC_NUMERIC, 'de_DE.utf8' );
 		$value = DecimalValue::newFromArray( $float );
+		setlocale( LC_NUMERIC, $originalLocale );
 
 		$this->assertStringStartsWith( $expectedPrefix, $value->getValue(), 'getValue' );
 	}
@@ -179,38 +182,61 @@ public function getSignProvider() {
 	/**
 	 * @dataProvider getValueProvider
 	 */
-	public function testGetValue( DecimalValue $value, $expected ) {
-		$actual = $value->getValue();
+	public function testGetValue( $value, $expected ) {
+		$precision = ini_set( 'serialize_precision', '2' );
+		$actual = ( new DecimalValue( $value ) )->getValue();
+		ini_set( 'serialize_precision', $precision );
+
 		$this->assertSame( $expected, $actual );
 	}
 
 	public function getValueProvider() {
 		$argLists = [];
 
-		$argLists[] = [ new DecimalValue( 42 ), '+42' ];
-		$argLists[] = [ new DecimalValue( -42 ), '-42' ];
-		$argLists[] = [ new DecimalValue( -42.0 ), '-42' ];
-		$argLists[] = [ new DecimalValue( '-42' ), '-42' ];
-		$argLists[] = [ new DecimalValue( 4.5 ), '+4.5' ];
-		$argLists[] = [ new DecimalValue( -4.5 ), '-4.5' ];
-		$argLists[] = [ new DecimalValue( '+4.2' ), '+4.2' ];
-		$argLists[] = [ new DecimalValue( 0 ), '+0' ];
-		$argLists[] = [ new DecimalValue( 0.0 ), '+0' ];
-		$argLists[] = [ new DecimalValue( 1.0 ), '+1' ];
-		$argLists[] = [ new DecimalValue( 0.5 ), '+0.5' ];
-		$argLists[] = [ new DecimalValue( '-0.42' ), '-0.42' ];
-		$argLists[] = [ new DecimalValue( '-0.0' ), '+0.0' ];
-		$argLists[] = [ new DecimalValue( '-0' ), '+0' ];
-		$argLists[] = [ new DecimalValue( '+0.0' ), '+0.0' ];
-		$argLists[] = [ new DecimalValue( '+0' ), '+0' ];
-		$argLists[] = [ new DecimalValue( 2147483649 ), '+2147483649' ];
-		$argLists[] = [ new DecimalValue( 1000000000000000 ), '+1000000000000000' ];
+		$argLists[] = [ 42, '+42' ];
+		$argLists[] = [ -42, '-42' ];
+		$argLists[] = [ -42.0, '-42' ];
+		$argLists[] = [ '-42', '-42' ];
+		$argLists[] = [ 4.5, '+4.5' ];
+		$argLists[] = [ -4.5, '-4.5' ];
+		$argLists[] = [ '+4.2', '+4.2' ];
+		$argLists[] = [ 0, '+0' ];
+		$argLists[] = [ 0.0, '+0' ];
+		$argLists[] = [ 1.0, '+1' ];
+		$argLists[] = [ 0.5, '+0.5' ];
+		$argLists[] = [ '-0.42', '-0.42' ];
+		$argLists[] = [ '-0.0', '+0.0' ];
+		$argLists[] = [ '-0', '+0' ];
+		$argLists[] = [ '+0.0', '+0.0' ];
+		$argLists[] = [ '+0', '+0' ];
+		$argLists[] = [ 2147483649, '+2147483649' ];
+		$argLists[] = [ 1000000000000000, '+1000000000000000' ];
+		$argLists[] = [
+			1 + 1e-12 / 3,
+			'+1.0000000000003333'
+		];
+		$argLists[] = [
+			1 + 1e-13 / 3,
+			'+1.0000000000000333'
+		];
+		$argLists[] = [
+			1 + 1e-14 / 3,
+			'+1.0000000000000033'
+		];
+		$argLists[] = [
+			1 + 1e-15 / 3,
+			'+1.0000000000000004'
+		];
+		$argLists[] = [
+			1 + 1e-16 / 3,
+			'+1'
+		];
 		$argLists[] = [
-			new DecimalValue( 1 + 1e-12 / 3 ),
-			'+1.0000000000003'
+			1 - 1e-16,
+			'+0.99999999999999989'
 		];
 		$argLists[] = [
-			new DecimalValue( 1 + 1e-14 / 3 ),
+			1 - 1e-17,
 			'+1'
 		];