Package org.jibx.util
Class StringSizedSet
- java.lang.Object
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- org.jibx.util.StringSizedSet
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public class StringSizedSet extends java.lang.Object
Fixed size hash set ofString
values.- Author:
- Dennis M. Sosnoski
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Field Summary
Fields Modifier and Type Field Description static double
DEFAULT_FILL_FRACTION
Default fill fraction for sizing of tables.protected int
m_arraySize
Size of array used for keys.protected int
m_hitOffset
Offset added (modulo table size) to slot number on collision.protected java.lang.String[]
m_keyTable
Array of key table slots.
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Constructor Summary
Constructors Constructor Description StringSizedSet(int count)
Constructor with only value count specified.StringSizedSet(int count, double fill)
Constructor with full specification.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
add(java.lang.String key)
Add a key to the set.void
clear()
Set the table to the empty state.boolean
contains(java.lang.String key)
Check if an entry is present in the table.private int
freeSlot(int slot)
Find free slot number for entry.private int
standardFind(java.lang.String key)
Standard find key in table.private int
standardSlot(java.lang.String key)
Standard base slot computation for a key.private int
stepSlot(int slot)
Step the slot number for an entry.
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Field Detail
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DEFAULT_FILL_FRACTION
public static final double DEFAULT_FILL_FRACTION
Default fill fraction for sizing of tables.- See Also:
- Constant Field Values
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m_arraySize
protected final int m_arraySize
Size of array used for keys.
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m_keyTable
protected final java.lang.String[] m_keyTable
Array of key table slots.
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m_hitOffset
protected final int m_hitOffset
Offset added (modulo table size) to slot number on collision.
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Constructor Detail
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StringSizedSet
public StringSizedSet(int count, double fill)
Constructor with full specification.- Parameters:
count
- number of values to assume in sizing of tablefill
- fraction fill for table (maximum of0.7
, to prevent excessive collisions)
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StringSizedSet
public StringSizedSet(int count)
Constructor with only value count specified. Uses default fill fraction and miss value.- Parameters:
count
- number of values to assume in initial sizing of table
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Method Detail
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stepSlot
private final int stepSlot(int slot)
Step the slot number for an entry. Adds the collision offset (modulo the table size) to the slot number.- Parameters:
slot
- slot number to be stepped- Returns:
- stepped slot number
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freeSlot
private final int freeSlot(int slot)
Find free slot number for entry. Starts at the slot based directly on the hashed key value. If this slot is already occupied, it adds the collision offset (modulo the table size) to the slot number and checks that slot, repeating until an unused slot is found.- Parameters:
slot
- initial slot computed from key- Returns:
- slot at which entry was added
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standardSlot
private final int standardSlot(java.lang.String key)
Standard base slot computation for a key. This method may be used directly for key lookup using either thehashCode()
method defined for the key objects or theSystem.identityHashCode()
method, as selected by the hash technique constructor parameter. To implement a hash class based on some other methods of hashing and/or equality testing, define a separate method in the subclass with a different name and use that method instead. This avoids the overhead caused by overrides of a very heavily used method.- Parameters:
key
- key value to be computed- Returns:
- base slot for key
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standardFind
private int standardFind(java.lang.String key)
Standard find key in table. This usesequals
comparisons for the key values.- Parameters:
key
- to be found in table- Returns:
- index of matching key, or
-index-1
of slot to be used for inserting key in table if not already present (always negative)
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add
public boolean add(java.lang.String key)
Add a key to the set. If the key is already present in the set, this does nothing.- Parameters:
key
- key to be added to table (non-null
)- Returns:
true
if added,false
if already present value if key not previously present in table
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contains
public final boolean contains(java.lang.String key)
Check if an entry is present in the table.- Parameters:
key
- key to be found- Returns:
true
if key found in table,false
if not
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clear
public void clear()
Set the table to the empty state.
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