All Downloads are FREE. Search and download functionalities are using the official Maven repository.

persistence.antlr.collections.impl.BitSet Maven / Gradle / Ivy

There is a newer version: 2.1-60f
Show newest version
package persistence.antlr.collections.impl;

/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/license.html
 *
 */

import persistence.antlr.CharFormatter;

/**A BitSet to replace java.util.BitSet.
 * Primary differences are that most set operators return new sets
 * as opposed to oring and anding "in place".  Further, a number of
 * operations were added.  I cannot contain a BitSet because there
 * is no way to access the internal bits (which I need for speed)
 * and, because it is final, I cannot subclass to add functionality.
 * Consider defining set degree.  Without access to the bits, I must
 * call a method n times to test the ith bit...ack!
 *
 * Also seems like or() from util is wrong when size of incoming set is bigger
 * than this.bits.length.
 *
 * @author Terence Parr
 * @author 
Pete Wells */ public class BitSet implements Cloneable { protected final static int BITS = 64; // number of bits / long protected final static int NIBBLE = 4; protected final static int LOG_BITS = 6; // 2^6 == 64 /* We will often need to do a mod operator (i mod nbits). Its * turns out that, for powers of two, this mod operation is * same as (i & (nbits-1)). Since mod is slow, we use a * precomputed mod mask to do the mod instead. */ protected final static int MOD_MASK = BITS - 1; /** The actual data bits */ protected long bits[]; /** Construct a bitset of size one word (64 bits) */ public BitSet() { this(BITS); } /** Construction from a static array of longs */ public BitSet(long[] bits_) { bits = bits_; } /** Construct a bitset given the size * @param nbits The size of the bitset in bits */ public BitSet(int nbits) { bits = new long[((nbits - 1) >> LOG_BITS) + 1]; } /** or this element into this set (grow as necessary to accommodate) */ public void add(int el) { //System.out.println("add("+el+")"); int n = wordNumber(el); //System.out.println("word number is "+n); //System.out.println("bits.length "+bits.length); if (n >= bits.length) { growToInclude(el); } bits[n] |= bitMask(el); } public BitSet and(BitSet a) { BitSet s = (BitSet)this.clone(); s.andInPlace(a); return s; } public void andInPlace(BitSet a) { int min = Math.min(bits.length, a.bits.length); for (int i = min - 1; i >= 0; i--) { bits[i] &= a.bits[i]; } // clear all bits in this not present in a (if this bigger than a). for (int i = min; i < bits.length; i++) { bits[i] = 0; } } private final static long bitMask(int bitNumber) { int bitPosition = bitNumber & MOD_MASK; // bitNumber mod BITS return 1L << bitPosition; } public void clear() { for (int i = bits.length - 1; i >= 0; i--) { bits[i] = 0; } } public void clear(int el) { int n = wordNumber(el); if (n >= bits.length) { // grow as necessary to accommodate growToInclude(el); } bits[n] &= ~bitMask(el); } public Object clone() { BitSet s; try { s = (BitSet)super.clone(); s.bits = new long[bits.length]; System.arraycopy(bits, 0, s.bits, 0, bits.length); } catch (CloneNotSupportedException e) { throw new InternalError(); } return s; } public int degree() { int deg = 0; for (int i = bits.length - 1; i >= 0; i--) { long word = bits[i]; if (word != 0L) { for (int bit = BITS - 1; bit >= 0; bit--) { if ((word & (1L << bit)) != 0) { deg++; } } } } return deg; } /** code "inherited" from java.util.BitSet */ public boolean equals(Object obj) { if ((obj != null) && (obj instanceof BitSet)) { BitSet set = (BitSet)obj; int n = Math.min(bits.length, set.bits.length); for (int i = n; i-- > 0;) { if (bits[i] != set.bits[i]) { return false; } } if (bits.length > n) { for (int i = bits.length; i-- > n;) { if (bits[i] != 0) { return false; } } } else if (set.bits.length > n) { for (int i = set.bits.length; i-- > n;) { if (set.bits[i] != 0) { return false; } } } return true; } return false; } /** Find ranges in a set element array. @param elems The array of * elements representing the set, usually from Bit Set.toArray(). * @return Vector of ranges. */ public static Vector getRanges(int[] elems) { if (elems.length == 0) { return null; } int begin = elems[0]; int end = elems[elems.length - 1]; if (elems.length <= 2) { // Not enough elements for a range expression return null; } Vector ranges = new Vector(5); // look for ranges for (int i = 0; i < elems.length - 2; i++) { int lastInRange; lastInRange = elems.length - 1; for (int j = i + 1; j < elems.length; j++) { if (elems[j] != elems[j - 1] + 1) { lastInRange = j - 1; break; } } // found a range if (lastInRange - i > 2) { ranges.appendElement(new IntRange(elems[i], elems[lastInRange])); } } return ranges; } /** * Grows the set to a larger number of bits. * @param bit element that must fit in set */ public void growToInclude(int bit) { int newSize = Math.max(bits.length << 1, numWordsToHold(bit)); long newbits[] = new long[newSize]; System.arraycopy(bits, 0, newbits, 0, bits.length); bits = newbits; } public boolean member(int el) { int n = wordNumber(el); if (n >= bits.length) return false; return (bits[n] & bitMask(el)) != 0; } public boolean nil() { for (int i = bits.length - 1; i >= 0; i--) { if (bits[i] != 0) return false; } return true; } public BitSet not() { BitSet s = (BitSet)this.clone(); s.notInPlace(); return s; } public void notInPlace() { for (int i = bits.length - 1; i >= 0; i--) { bits[i] = ~bits[i]; } } /** complement bits in the range 0..maxBit. */ public void notInPlace(int maxBit) { notInPlace(0, maxBit); } /** complement bits in the range minBit..maxBit.*/ public void notInPlace(int minBit, int maxBit) { // make sure that we have room for maxBit growToInclude(maxBit); for (int i = minBit; i <= maxBit; i++) { int n = wordNumber(i); bits[n] ^= bitMask(i); } } private final int numWordsToHold(int el) { return (el >> LOG_BITS) + 1; } public static BitSet of(int el) { BitSet s = new BitSet(el + 1); s.add(el); return s; } /** return this | a in a new set */ public BitSet or(BitSet a) { BitSet s = (BitSet)this.clone(); s.orInPlace(a); return s; } public void orInPlace(BitSet a) { // If this is smaller than a, grow this first if (a.bits.length > bits.length) { setSize(a.bits.length); } int min = Math.min(bits.length, a.bits.length); for (int i = min - 1; i >= 0; i--) { bits[i] |= a.bits[i]; } } // remove this element from this set public void remove(int el) { int n = wordNumber(el); if (n >= bits.length) { growToInclude(el); } bits[n] &= ~bitMask(el); } /** * Sets the size of a set. * @param nwords how many words the new set should be */ private void setSize(int nwords) { long newbits[] = new long[nwords]; int n = Math.min(nwords, bits.length); System.arraycopy(bits, 0, newbits, 0, n); bits = newbits; } public int size() { return bits.length << LOG_BITS; // num words * bits per word } /** return how much space is being used by the bits array not * how many actually have member bits on. */ public int lengthInLongWords() { return bits.length; } /**Is this contained within a? */ public boolean subset(BitSet a) { if (a == null || !(a instanceof BitSet)) return false; return this.and(a).equals(this); } /**Subtract the elements of 'a' from 'this' in-place. * Basically, just turn off all bits of 'this' that are in 'a'. */ public void subtractInPlace(BitSet a) { if (a == null) return; // for all words of 'a', turn off corresponding bits of 'this' for (int i = 0; i < bits.length && i < a.bits.length; i++) { bits[i] &= ~a.bits[i]; } } public int[] toArray() { int[] elems = new int[degree()]; int en = 0; for (int i = 0; i < (bits.length << LOG_BITS); i++) { if (member(i)) { elems[en++] = i; } } return elems; } public long[] toPackedArray() { return bits; } public String toString() { return toString(","); } /** Transform a bit set into a string by formatting each element as an integer * @separator The string to put in between elements * @return A commma-separated list of values */ public String toString(String separator) { String str = ""; for (int i = 0; i < (bits.length << LOG_BITS); i++) { if (member(i)) { if (str.length() > 0) { str += separator; } str = str + i; } } return str; } /** Transform a bit set into a string of characters. * @separator The string to put in between elements * @param formatter An object implementing the CharFormatter interface. * @return A commma-separated list of character constants. */ public String toString(String separator, CharFormatter formatter) { String str = ""; for (int i = 0; i < (bits.length << LOG_BITS); i++) { if (member(i)) { if (str.length() > 0) { str += separator; } str = str + formatter.literalChar(i); } } return str; } /**Create a string representation where instead of integer elements, the * ith element of vocabulary is displayed instead. Vocabulary is a Vector * of Strings. * @separator The string to put in between elements * @return A commma-separated list of character constants. */ public String toString(String separator, Vector vocabulary) { if (vocabulary == null) { return toString(separator); } String str = ""; for (int i = 0; i < (bits.length << LOG_BITS); i++) { if (member(i)) { if (str.length() > 0) { str += separator; } if (i >= vocabulary.size()) { str += ""; } else if (vocabulary.elementAt(i) == null) { str += "<" + i + ">"; } else { str += (String)vocabulary.elementAt(i); } } } return str; } /** * Dump a comma-separated list of the words making up the bit set. * Split each 64 bit number into two more manageable 32 bit numbers. * This generates a comma-separated list of C++-like unsigned long constants. */ public String toStringOfHalfWords() { String s = new String(); for (int i = 0; i < bits.length; i++) { if (i != 0) s += ", "; long tmp = bits[i]; tmp &= 0xFFFFFFFFL; s += (tmp + "UL"); s += ", "; tmp = bits[i] >>> 32; tmp &= 0xFFFFFFFFL; s += (tmp + "UL"); } return s; } /** * Dump a comma-separated list of the words making up the bit set. * This generates a comma-separated list of Java-like long int constants. */ public String toStringOfWords() { String s = new String(); for (int i = 0; i < bits.length; i++) { if (i != 0) s += ", "; s += (bits[i] + "L"); } return s; } /** Print out the bit set but collapse char ranges. */ public String toStringWithRanges(String separator, CharFormatter formatter) { String str = ""; int[] elems = this.toArray(); if (elems.length == 0) { return ""; } // look for ranges int i = 0; while (i < elems.length) { int lastInRange; lastInRange = 0; for (int j = i + 1; j < elems.length; j++) { if (elems[j] != elems[j - 1] + 1) { break; } lastInRange = j; } // found a range if (str.length() > 0) { str += separator; } if (lastInRange - i >= 2) { str += formatter.literalChar(elems[i]); str += ".."; str += formatter.literalChar(elems[lastInRange]); i = lastInRange; // skip past end of range for next range } else { // no range, just print current char and move on str += formatter.literalChar(elems[i]); } i++; } return str; } private final static int wordNumber(int bit) { return bit >> LOG_BITS; // bit / BITS } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy