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Diffstat (limited to 'libjava/classpath/java/lang/Double.java')
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diff --git a/libjava/classpath/java/lang/Double.java b/libjava/classpath/java/lang/Double.java new file mode 100644 index 000000000..3ae1b0111 --- /dev/null +++ b/libjava/classpath/java/lang/Double.java @@ -0,0 +1,625 @@ +/* Double.java -- object wrapper for double + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 + Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package java.lang; + +import gnu.java.lang.CPStringBuilder; + +/** + * Instances of class <code>Double</code> represent primitive + * <code>double</code> values. + * + * Additionally, this class provides various helper functions and variables + * related to doubles. + * + * @author Paul Fisher + * @author Andrew Haley (aph@cygnus.com) + * @author Eric Blake (ebb9@email.byu.edu) + * @author Tom Tromey (tromey@redhat.com) + * @author Andrew John Hughes (gnu_andrew@member.fsf.org) + * @since 1.0 + * @status partly updated to 1.5 + */ +public final class Double extends Number implements Comparable<Double> +{ + /** + * Compatible with JDK 1.0+. + */ + private static final long serialVersionUID = -9172774392245257468L; + + /** + * The maximum positive value a <code>double</code> may represent + * is 1.7976931348623157e+308. + */ + public static final double MAX_VALUE = 1.7976931348623157e+308; + + /** + * The minimum positive value a <code>double</code> may represent + * is 5e-324. + */ + public static final double MIN_VALUE = 5e-324; + + /** + * The value of a double representation -1.0/0.0, negative + * infinity. + */ + public static final double NEGATIVE_INFINITY = -1.0 / 0.0; + + /** + * The value of a double representing 1.0/0.0, positive infinity. + */ + public static final double POSITIVE_INFINITY = 1.0 / 0.0; + + /** + * All IEEE 754 values of NaN have the same value in Java. + */ + public static final double NaN = 0.0 / 0.0; + + /** + * The number of bits needed to represent a <code>double</code>. + * @since 1.5 + */ + public static final int SIZE = 64; + + /** + * The primitive type <code>double</code> is represented by this + * <code>Class</code> object. + * @since 1.1 + */ + public static final Class<Double> TYPE = (Class<Double>) VMClassLoader.getPrimitiveClass('D'); + + /** + * Cache representation of 0 + */ + private static final Double ZERO = new Double(0.0d); + + /** + * Cache representation of 1 + */ + private static final Double ONE = new Double(1.0d); + + /** + * The immutable value of this Double. + * + * @serial the wrapped double + */ + private final double value; + + /** + * Create a <code>Double</code> from the primitive <code>double</code> + * specified. + * + * @param value the <code>double</code> argument + */ + public Double(double value) + { + this.value = value; + } + + /** + * Create a <code>Double</code> from the specified <code>String</code>. + * This method calls <code>Double.parseDouble()</code>. + * + * @param s the <code>String</code> to convert + * @throws NumberFormatException if <code>s</code> cannot be parsed as a + * <code>double</code> + * @throws NullPointerException if <code>s</code> is null + * @see #parseDouble(String) + */ + public Double(String s) + { + value = parseDouble(s); + } + + /** + * Convert the <code>double</code> to a <code>String</code>. + * Floating-point string representation is fairly complex: here is a + * rundown of the possible values. "<code>[-]</code>" indicates that a + * negative sign will be printed if the value (or exponent) is negative. + * "<code><number></code>" means a string of digits ('0' to '9'). + * "<code><digit></code>" means a single digit ('0' to '9').<br> + * + * <table border=1> + * <tr><th>Value of Double</th><th>String Representation</th></tr> + * <tr><td>[+-] 0</td> <td><code>[-]0.0</code></td></tr> + * <tr><td>Between [+-] 10<sup>-3</sup> and 10<sup>7</sup>, exclusive</td> + * <td><code>[-]number.number</code></td></tr> + * <tr><td>Other numeric value</td> + * <td><code>[-]<digit>.<number> + * E[-]<number></code></td></tr> + * <tr><td>[+-] infinity</td> <td><code>[-]Infinity</code></td></tr> + * <tr><td>NaN</td> <td><code>NaN</code></td></tr> + * </table> + * + * Yes, negative zero <em>is</em> a possible value. Note that there is + * <em>always</em> a <code>.</code> and at least one digit printed after + * it: even if the number is 3, it will be printed as <code>3.0</code>. + * After the ".", all digits will be printed except trailing zeros. The + * result is rounded to the shortest decimal number which will parse back + * to the same double. + * + * <p>To create other output formats, use {@link java.text.NumberFormat}. + * + * @XXX specify where we are not in accord with the spec. + * + * @param d the <code>double</code> to convert + * @return the <code>String</code> representing the <code>double</code> + */ + public static String toString(double d) + { + return VMDouble.toString(d, false); + } + + /** + * Convert a double value to a hexadecimal string. This converts as + * follows: + * <ul> + * <li> A NaN value is converted to the string "NaN". + * <li> Positive infinity is converted to the string "Infinity". + * <li> Negative infinity is converted to the string "-Infinity". + * <li> For all other values, the first character of the result is '-' + * if the value is negative. This is followed by '0x1.' if the + * value is normal, and '0x0.' if the value is denormal. This is + * then followed by a (lower-case) hexadecimal representation of the + * mantissa, with leading zeros as required for denormal values. + * The next character is a 'p', and this is followed by a decimal + * representation of the unbiased exponent. + * </ul> + * @param d the double value + * @return the hexadecimal string representation + * @since 1.5 + */ + public static String toHexString(double d) + { + if (isNaN(d)) + return "NaN"; + if (isInfinite(d)) + return d < 0 ? "-Infinity" : "Infinity"; + + long bits = doubleToLongBits(d); + CPStringBuilder result = new CPStringBuilder(); + + if (bits < 0) + result.append('-'); + result.append("0x"); + + final int mantissaBits = 52; + final int exponentBits = 11; + long mantMask = (1L << mantissaBits) - 1; + long mantissa = bits & mantMask; + long expMask = (1L << exponentBits) - 1; + long exponent = (bits >>> mantissaBits) & expMask; + + result.append(exponent == 0 ? '0' : '1'); + result.append('.'); + result.append(Long.toHexString(mantissa)); + if (exponent == 0 && mantissa != 0) + { + // Treat denormal specially by inserting '0's to make + // the length come out right. The constants here are + // to account for things like the '0x'. + int offset = 4 + ((bits < 0) ? 1 : 0); + // The silly +3 is here to keep the code the same between + // the Float and Double cases. In Float the value is + // not a multiple of 4. + int desiredLength = offset + (mantissaBits + 3) / 4; + while (result.length() < desiredLength) + result.insert(offset, '0'); + } + result.append('p'); + if (exponent == 0 && mantissa == 0) + { + // Zero, so do nothing special. + } + else + { + // Apply bias. + boolean denormal = exponent == 0; + exponent -= (1 << (exponentBits - 1)) - 1; + // Handle denormal. + if (denormal) + ++exponent; + } + + result.append(Long.toString(exponent)); + return result.toString(); + } + + /** + * Returns a <code>Double</code> object wrapping the value. + * In contrast to the <code>Double</code> constructor, this method + * may cache some values. It is used by boxing conversion. + * + * @param val the value to wrap + * @return the <code>Double</code> + * @since 1.5 + */ + public static Double valueOf(double val) + { + if ((val == 0.0) && (doubleToRawLongBits(val) == 0L)) + return ZERO; + else if (val == 1.0) + return ONE; + else + return new Double(val); + } + + /** + * Create a new <code>Double</code> object using the <code>String</code>. + * + * @param s the <code>String</code> to convert + * @return the new <code>Double</code> + * @throws NumberFormatException if <code>s</code> cannot be parsed as a + * <code>double</code> + * @throws NullPointerException if <code>s</code> is null. + * @see #parseDouble(String) + */ + public static Double valueOf(String s) + { + return valueOf(parseDouble(s)); + } + + /** + * Parse the specified <code>String</code> as a <code>double</code>. The + * extended BNF grammar is as follows:<br> + * <pre> + * <em>DecodableString</em>: + * ( [ <code>-</code> | <code>+</code> ] <code>NaN</code> ) + * | ( [ <code>-</code> | <code>+</code> ] <code>Infinity</code> ) + * | ( [ <code>-</code> | <code>+</code> ] <em>FloatingPoint</em> + * [ <code>f</code> | <code>F</code> | <code>d</code> + * | <code>D</code>] ) + * <em>FloatingPoint</em>: + * ( { <em>Digit</em> }+ [ <code>.</code> { <em>Digit</em> } ] + * [ <em>Exponent</em> ] ) + * | ( <code>.</code> { <em>Digit</em> }+ [ <em>Exponent</em> ] ) + * <em>Exponent</em>: + * ( ( <code>e</code> | <code>E</code> ) + * [ <code>-</code> | <code>+</code> ] { <em>Digit</em> }+ ) + * <em>Digit</em>: <em><code>'0'</code> through <code>'9'</code></em> + * </pre> + * + * <p>NaN and infinity are special cases, to allow parsing of the output + * of toString. Otherwise, the result is determined by calculating + * <em>n * 10<sup>exponent</sup></em> to infinite precision, then rounding + * to the nearest double. Remember that many numbers cannot be precisely + * represented in floating point. In case of overflow, infinity is used, + * and in case of underflow, signed zero is used. Unlike Integer.parseInt, + * this does not accept Unicode digits outside the ASCII range. + * + * <p>If an unexpected character is found in the <code>String</code>, a + * <code>NumberFormatException</code> will be thrown. Leading and trailing + * 'whitespace' is ignored via <code>String.trim()</code>, but spaces + * internal to the actual number are not allowed. + * + * <p>To parse numbers according to another format, consider using + * {@link java.text.NumberFormat}. + * + * @XXX specify where/how we are not in accord with the spec. + * + * @param str the <code>String</code> to convert + * @return the <code>double</code> value of <code>s</code> + * @throws NumberFormatException if <code>s</code> cannot be parsed as a + * <code>double</code> + * @throws NullPointerException if <code>s</code> is null + * @see #MIN_VALUE + * @see #MAX_VALUE + * @see #POSITIVE_INFINITY + * @see #NEGATIVE_INFINITY + * @since 1.2 + */ + public static double parseDouble(String str) + { + return VMDouble.parseDouble(str); + } + + /** + * Return <code>true</code> if the <code>double</code> has the same + * value as <code>NaN</code>, otherwise return <code>false</code>. + * + * @param v the <code>double</code> to compare + * @return whether the argument is <code>NaN</code>. + */ + public static boolean isNaN(double v) + { + // This works since NaN != NaN is the only reflexive inequality + // comparison which returns true. + return v != v; + } + + /** + * Return <code>true</code> if the <code>double</code> has a value + * equal to either <code>NEGATIVE_INFINITY</code> or + * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>. + * + * @param v the <code>double</code> to compare + * @return whether the argument is (-/+) infinity. + */ + public static boolean isInfinite(double v) + { + return v == POSITIVE_INFINITY || v == NEGATIVE_INFINITY; + } + + /** + * Return <code>true</code> if the value of this <code>Double</code> + * is the same as <code>NaN</code>, otherwise return <code>false</code>. + * + * @return whether this <code>Double</code> is <code>NaN</code> + */ + public boolean isNaN() + { + return isNaN(value); + } + + /** + * Return <code>true</code> if the value of this <code>Double</code> + * is the same as <code>NEGATIVE_INFINITY</code> or + * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>. + * + * @return whether this <code>Double</code> is (-/+) infinity + */ + public boolean isInfinite() + { + return isInfinite(value); + } + + /** + * Convert the <code>double</code> value of this <code>Double</code> + * to a <code>String</code>. This method calls + * <code>Double.toString(double)</code> to do its dirty work. + * + * @return the <code>String</code> representation + * @see #toString(double) + */ + public String toString() + { + return toString(value); + } + + /** + * Return the value of this <code>Double</code> as a <code>byte</code>. + * + * @return the byte value + * @since 1.1 + */ + public byte byteValue() + { + return (byte) value; + } + + /** + * Return the value of this <code>Double</code> as a <code>short</code>. + * + * @return the short value + * @since 1.1 + */ + public short shortValue() + { + return (short) value; + } + + /** + * Return the value of this <code>Double</code> as an <code>int</code>. + * + * @return the int value + */ + public int intValue() + { + return (int) value; + } + + /** + * Return the value of this <code>Double</code> as a <code>long</code>. + * + * @return the long value + */ + public long longValue() + { + return (long) value; + } + + /** + * Return the value of this <code>Double</code> as a <code>float</code>. + * + * @return the float value + */ + public float floatValue() + { + return (float) value; + } + + /** + * Return the value of this <code>Double</code>. + * + * @return the double value + */ + public double doubleValue() + { + return value; + } + + /** + * Return a hashcode representing this Object. <code>Double</code>'s hash + * code is calculated by:<br> + * <code>long v = Double.doubleToLongBits(doubleValue());<br> + * int hash = (int)(v^(v>>32))</code>. + * + * @return this Object's hash code + * @see #doubleToLongBits(double) + */ + public int hashCode() + { + long v = doubleToLongBits(value); + return (int) (v ^ (v >>> 32)); + } + + /** + * Returns <code>true</code> if <code>obj</code> is an instance of + * <code>Double</code> and represents the same double value. Unlike comparing + * two doubles with <code>==</code>, this treats two instances of + * <code>Double.NaN</code> as equal, but treats <code>0.0</code> and + * <code>-0.0</code> as unequal. + * + * <p>Note that <code>d1.equals(d2)</code> is identical to + * <code>doubleToLongBits(d1.doubleValue()) == + * doubleToLongBits(d2.doubleValue())</code>. + * + * @param obj the object to compare + * @return whether the objects are semantically equal + */ + public boolean equals(Object obj) + { + if (obj instanceof Double) + { + double d = ((Double) obj).value; + return (doubleToRawLongBits(value) == doubleToRawLongBits(d)) || + (isNaN(value) && isNaN(d)); + } + return false; + } + + /** + * Convert the double to the IEEE 754 floating-point "double format" bit + * layout. Bit 63 (the most significant) is the sign bit, bits 62-52 + * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0 + * (masked by 0x000fffffffffffffL) are the mantissa. This function + * collapses all versions of NaN to 0x7ff8000000000000L. The result of this + * function can be used as the argument to + * <code>Double.longBitsToDouble(long)</code> to obtain the original + * <code>double</code> value. + * + * @param value the <code>double</code> to convert + * @return the bits of the <code>double</code> + * @see #longBitsToDouble(long) + */ + public static long doubleToLongBits(double value) + { + if (isNaN(value)) + return 0x7ff8000000000000L; + else + return VMDouble.doubleToRawLongBits(value); + } + + /** + * Convert the double to the IEEE 754 floating-point "double format" bit + * layout. Bit 63 (the most significant) is the sign bit, bits 62-52 + * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0 + * (masked by 0x000fffffffffffffL) are the mantissa. This function + * leaves NaN alone, rather than collapsing to a canonical value. The + * result of this function can be used as the argument to + * <code>Double.longBitsToDouble(long)</code> to obtain the original + * <code>double</code> value. + * + * @param value the <code>double</code> to convert + * @return the bits of the <code>double</code> + * @see #longBitsToDouble(long) + */ + public static long doubleToRawLongBits(double value) + { + return VMDouble.doubleToRawLongBits(value); + } + + /** + * Convert the argument in IEEE 754 floating-point "double format" bit + * layout to the corresponding float. Bit 63 (the most significant) is the + * sign bit, bits 62-52 (masked by 0x7ff0000000000000L) represent the + * exponent, and bits 51-0 (masked by 0x000fffffffffffffL) are the mantissa. + * This function leaves NaN alone, so that you can recover the bit pattern + * with <code>Double.doubleToRawLongBits(double)</code>. + * + * @param bits the bits to convert + * @return the <code>double</code> represented by the bits + * @see #doubleToLongBits(double) + * @see #doubleToRawLongBits(double) + */ + public static double longBitsToDouble(long bits) + { + return VMDouble.longBitsToDouble(bits); + } + + /** + * Compare two Doubles numerically by comparing their <code>double</code> + * values. The result is positive if the first is greater, negative if the + * second is greater, and 0 if the two are equal. However, this special + * cases NaN and signed zero as follows: NaN is considered greater than + * all other doubles, including <code>POSITIVE_INFINITY</code>, and positive + * zero is considered greater than negative zero. + * + * @param d the Double to compare + * @return the comparison + * @since 1.2 + */ + public int compareTo(Double d) + { + return compare(value, d.value); + } + + /** + * Behaves like <code>new Double(x).compareTo(new Double(y))</code>; in + * other words this compares two doubles, special casing NaN and zero, + * without the overhead of objects. + * + * @param x the first double to compare + * @param y the second double to compare + * @return the comparison + * @since 1.4 + */ + public static int compare(double x, double y) + { + // handle the easy cases: + if (x < y) + return -1; + if (x > y) + return 1; + + // handle equality respecting that 0.0 != -0.0 (hence not using x == y): + long lx = doubleToRawLongBits(x); + long ly = doubleToRawLongBits(y); + if (lx == ly) + return 0; + + // handle NaNs: + if (x != x) + return (y != y) ? 0 : 1; + else if (y != y) + return -1; + + // handle +/- 0.0 + return (lx < ly) ? -1 : 1; + } +} |