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Diffstat (limited to 'src/main/java/com/lowagie/text/pdf/IntHashtable.java')
| -rw-r--r-- | src/main/java/com/lowagie/text/pdf/IntHashtable.java | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/src/main/java/com/lowagie/text/pdf/IntHashtable.java b/src/main/java/com/lowagie/text/pdf/IntHashtable.java new file mode 100644 index 0000000..633439a --- /dev/null +++ b/src/main/java/com/lowagie/text/pdf/IntHashtable.java @@ -0,0 +1,338 @@ +// IntHashtable - a Hashtable that uses ints as the keys
+//
+// This is 90% based on JavaSoft's java.util.Hashtable.
+//
+// Visit the ACME Labs Java page for up-to-date versions of this and other
+// fine Java utilities: http://www.acme.com/java/
+
+package com.lowagie.text.pdf;
+
+import java.util.Arrays;
+import java.util.NoSuchElementException;
+import java.util.Iterator;
+
+/// A Hashtable that uses ints as the keys.
+// <P>
+// Use just like java.util.Hashtable, except that the keys must be ints.
+// This is much faster than creating a new Integer for each access.
+// <P>
+// <A HREF="/resources/classes/Acme/IntHashtable.java">Fetch the software.</A><BR>
+// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
+// <P>
+// @see java.util.Hashtable
+
+public class IntHashtable implements Cloneable {
+ /// The hash table data.
+ private IntHashtableEntry table[];
+
+ /// The total number of entries in the hash table.
+ private int count;
+
+ /// Rehashes the table when count exceeds this threshold.
+ private int threshold;
+
+ /// The load factor for the hashtable.
+ private float loadFactor;
+
+ /// Constructs a new, empty hashtable with the specified initial
+ // capacity and the specified load factor.
+ // @param initialCapacity the initial number of buckets
+ // @param loadFactor a number between 0.0 and 1.0, it defines
+ // the threshold for rehashing the hashtable into
+ // a bigger one.
+ // @exception IllegalArgumentException If the initial capacity
+ // is less than or equal to zero.
+ // @exception IllegalArgumentException If the load factor is
+ // less than or equal to zero.
+ public IntHashtable( int initialCapacity, float loadFactor ) {
+ if ( initialCapacity <= 0 || loadFactor <= 0.0 )
+ throw new IllegalArgumentException();
+ this.loadFactor = loadFactor;
+ table = new IntHashtableEntry[initialCapacity];
+ threshold = (int) ( initialCapacity * loadFactor );
+ }
+
+ /// Constructs a new, empty hashtable with the specified initial
+ // capacity.
+ // @param initialCapacity the initial number of buckets
+ public IntHashtable( int initialCapacity ) {
+ this( initialCapacity, 0.75f );
+ }
+
+ /// Constructs a new, empty hashtable. A default capacity and load factor
+ // is used. Note that the hashtable will automatically grow when it gets
+ // full.
+ public IntHashtable() {
+ this( 101, 0.75f );
+ }
+
+ /// Returns the number of elements contained in the hashtable.
+ public int size() {
+ return count;
+ }
+
+ /// Returns true if the hashtable contains no elements.
+ public boolean isEmpty() {
+ return count == 0;
+ }
+
+ /// Returns true if the specified object is an element of the hashtable.
+ // This operation is more expensive than the containsKey() method.
+ // @param value the value that we are looking for
+ // @exception NullPointerException If the value being searched
+ // for is equal to null.
+ // @see IntHashtable#containsKey
+ public boolean contains( int value ) {
+ IntHashtableEntry tab[] = table;
+ for ( int i = tab.length ; i-- > 0 ; ) {
+ for ( IntHashtableEntry e = tab[i] ; e != null ; e = e.next ) {
+ if ( e.value == value )
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /// Returns true if the collection contains an element for the key.
+ // @param key the key that we are looking for
+ // @see IntHashtable#contains
+ public boolean containsKey( int key ) {
+ IntHashtableEntry tab[] = table;
+ int hash = key;
+ int index = ( hash & 0x7FFFFFFF ) % tab.length;
+ for ( IntHashtableEntry e = tab[index] ; e != null ; e = e.next ) {
+ if ( e.hash == hash && e.key == key )
+ return true;
+ }
+ return false;
+ }
+
+ /// Gets the object associated with the specified key in the
+ // hashtable.
+ // @param key the specified key
+ // @returns the element for the key or null if the key
+ // is not defined in the hash table.
+ // @see IntHashtable#put
+ public int get( int key ) {
+ IntHashtableEntry tab[] = table;
+ int hash = key;
+ int index = ( hash & 0x7FFFFFFF ) % tab.length;
+ for ( IntHashtableEntry e = tab[index] ; e != null ; e = e.next ) {
+ if ( e.hash == hash && e.key == key )
+ return e.value;
+ }
+ return 0;
+ }
+
+ /// Rehashes the content of the table into a bigger table.
+ // This method is called automatically when the hashtable's
+ // size exceeds the threshold.
+ protected void rehash() {
+ int oldCapacity = table.length;
+ IntHashtableEntry oldTable[] = table;
+
+ int newCapacity = oldCapacity * 2 + 1;
+ IntHashtableEntry newTable[] = new IntHashtableEntry[newCapacity];
+
+ threshold = (int) ( newCapacity * loadFactor );
+ table = newTable;
+
+ for ( int i = oldCapacity ; i-- > 0 ; ) {
+ for ( IntHashtableEntry old = oldTable[i] ; old != null ; ) {
+ IntHashtableEntry e = old;
+ old = old.next;
+
+ int index = ( e.hash & 0x7FFFFFFF ) % newCapacity;
+ e.next = newTable[index];
+ newTable[index] = e;
+ }
+ }
+ }
+
+ /// Puts the specified element into the hashtable, using the specified
+ // key. The element may be retrieved by doing a get() with the same key.
+ // The key and the element cannot be null.
+ // @param key the specified key in the hashtable
+ // @param value the specified element
+ // @exception NullPointerException If the value of the element
+ // is equal to null.
+ // @see IntHashtable#get
+ // @return the old value of the key, or null if it did not have one.
+ public int put( int key, int value ) {
+ // Makes sure the key is not already in the hashtable.
+ IntHashtableEntry tab[] = table;
+ int hash = key;
+ int index = ( hash & 0x7FFFFFFF ) % tab.length;
+ for ( IntHashtableEntry e = tab[index] ; e != null ; e = e.next ) {
+ if ( e.hash == hash && e.key == key ) {
+ int old = e.value;
+ e.value = value;
+ return old;
+ }
+ }
+
+ if ( count >= threshold ) {
+ // Rehash the table if the threshold is exceeded.
+ rehash();
+ return put( key, value );
+ }
+
+ // Creates the new entry.
+ IntHashtableEntry e = new IntHashtableEntry();
+ e.hash = hash;
+ e.key = key;
+ e.value = value;
+ e.next = tab[index];
+ tab[index] = e;
+ ++count;
+ return 0;
+ }
+
+ /// Removes the element corresponding to the key. Does nothing if the
+ // key is not present.
+ // @param key the key that needs to be removed
+ // @return the value of key, or null if the key was not found.
+ public int remove( int key ) {
+ IntHashtableEntry tab[] = table;
+ int hash = key;
+ int index = ( hash & 0x7FFFFFFF ) % tab.length;
+ for ( IntHashtableEntry e = tab[index], prev = null ; e != null ; prev = e, e = e.next ) {
+ if ( e.hash == hash && e.key == key ) {
+ if ( prev != null )
+ prev.next = e.next;
+ else
+ tab[index] = e.next;
+ --count;
+ return e.value;
+ }
+ }
+ return 0;
+ }
+
+ /// Clears the hash table so that it has no more elements in it.
+ public void clear() {
+ IntHashtableEntry tab[] = table;
+ for ( int index = tab.length; --index >= 0; )
+ tab[index] = null;
+ count = 0;
+ }
+
+ public Object clone() {
+ try {
+ IntHashtable t = (IntHashtable)super.clone();
+ t.table = new IntHashtableEntry[table.length];
+ for (int i = table.length ; i-- > 0 ; ) {
+ t.table[i] = (table[i] != null)
+ ? (IntHashtableEntry)table[i].clone() : null;
+ }
+ return t;
+ } catch (CloneNotSupportedException e) {
+ // this shouldn't happen, since we are Cloneable
+ throw new InternalError();
+ }
+ }
+
+ public int[] toOrderedKeys() {
+ int res[] = getKeys();
+ Arrays.sort(res);
+ return res;
+ }
+
+ public int[] getKeys() {
+ int res[] = new int[count];
+ int ptr = 0;
+ int index = table.length;
+ IntHashtableEntry entry = null;
+ while (true) {
+ if (entry == null)
+ while ((index-- > 0) && ((entry = table[index]) == null));
+ if (entry == null)
+ break;
+ IntHashtableEntry e = entry;
+ entry = e.next;
+ res[ptr++] = e.key;
+ }
+ return res;
+ }
+
+ public int getOneKey() {
+ if (count == 0)
+ return 0;
+ int index = table.length;
+ IntHashtableEntry entry = null;
+ while ((index-- > 0) && ((entry = table[index]) == null));
+ if (entry == null)
+ return 0;
+ return entry.key;
+ }
+
+ static class IntHashtableEntry {
+ int hash;
+ int key;
+ int value;
+ IntHashtableEntry next;
+
+ public int getKey() {
+ return key;
+ }
+
+ public int getValue() {
+ return value;
+ }
+
+ protected Object clone() {
+ IntHashtableEntry entry = new IntHashtableEntry();
+ entry.hash = hash;
+ entry.key = key;
+ entry.value = value;
+ entry.next = (next != null) ? (IntHashtableEntry)next.clone() : null;
+ return entry;
+ }
+ }
+
+ public Iterator getEntryIterator() {
+ return new IntHashtableIterator(table);
+ }
+
+ static class IntHashtableIterator implements Iterator {
+ // boolean keys;
+ int index;
+ IntHashtableEntry table[];
+ IntHashtableEntry entry;
+
+ IntHashtableIterator(IntHashtableEntry table[] /* , boolean keys */) {
+ this.table = table;
+ // this.keys = keys;
+ this.index = table.length;
+ }
+
+ public boolean hasNext() {
+ if (entry != null) {
+ return true;
+ }
+ while (index-- > 0) {
+ if ((entry = table[index]) != null) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ public Object next() {
+ if (entry == null) {
+ while ((index-- > 0) && ((entry = table[index]) == null));
+ }
+ if (entry != null) {
+ IntHashtableEntry e = entry;
+ entry = e.next;
+ return e;
+ }
+ throw new NoSuchElementException("IntHashtableIterator");
+ }
+
+ public void remove() {
+ throw new UnsupportedOperationException("remove() not supported.");
+ }
+
+ }
+}
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