Package org.jibx.runtime.impl
Class StringIntHashMap
- java.lang.Object
-
- org.jibx.runtime.impl.StringIntHashMap
-
public class StringIntHashMap extends java.lang.Object
Hash map usingString
values as keys mapped to primitiveint
values. This implementation is unsynchronized in order to provide the best possible performance for typical usage scenarios, so explicit synchronization must be implemented by a wrapper class or directly by the application in cases where instances are modified in a multithreaded environment. The map implementation is not very efficient when resizing, but works well when the size of the map is known in advance.- Version:
- 1.1
- Author:
- Dennis M. Sosnoski
-
-
Field Summary
Fields Modifier and Type Field Description protected static double
DEFAULT_FILL
Default fill fraction allowed before growing table.static int
DEFAULT_NOT_FOUND
Default value returned when key not found in table.protected int
m_arraySize
Size of array used for keys.protected int
m_entryCount
Number of entries present in table.protected int
m_entryLimit
Entries allowed before growing table.protected double
m_fillFraction
Fill fraction allowed for this hash table.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.protected int
m_notFoundValue
Value returned when key not found in table.protected int[]
m_valueTable
Array of value table slots.protected static int
MINIMUM_SIZE
Minimum size used for hash table.
-
Constructor Summary
Constructors Constructor Description StringIntHashMap()
Default constructor.StringIntHashMap(int count)
Constructor with only size supplied.StringIntHashMap(int count, double fill)
Constructor with size and fill fraction specified.StringIntHashMap(int count, double fill, int miss)
Constructor with full specification.StringIntHashMap(StringIntHashMap base)
Copy (clone) constructor.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
add(java.lang.String key, int value)
Add an entry to the table.private int
assignSlot(java.lang.String key, int value)
Assign slot for entry.java.lang.Object
clone()
Construct a copy of the table.boolean
containsKey(java.lang.String key)
Check if an entry is present in the table.private int
freeSlot(int slot)
Find free slot number for entry.int
get(java.lang.String key)
Find an entry in the table.protected void
internalRemove(int slot)
Internal remove pair from the table.private boolean
reinsert(int slot)
Reinsert an entry into the hash map.int
remove(java.lang.String key)
Remove an entry from the table.private void
restructure(java.lang.String[] keys, int[] values)
Restructure the table.private int
standardFind(java.lang.Object key)
Standard find key in table.private int
standardSlot(java.lang.Object key)
Standard base slot computation for a key.private int
stepSlot(int slot)
Step the slot number for an entry.
-
-
-
Field Detail
-
DEFAULT_NOT_FOUND
public static final int DEFAULT_NOT_FOUND
Default value returned when key not found in table.- See Also:
- Constant Field Values
-
DEFAULT_FILL
protected static final double DEFAULT_FILL
Default fill fraction allowed before growing table.- See Also:
- Constant Field Values
-
MINIMUM_SIZE
protected static final int MINIMUM_SIZE
Minimum size used for hash table.- See Also:
- Constant Field Values
-
m_fillFraction
protected final double m_fillFraction
Fill fraction allowed for this hash table.
-
m_entryCount
protected int m_entryCount
Number of entries present in table.
-
m_entryLimit
protected int m_entryLimit
Entries allowed before growing table.
-
m_arraySize
protected int m_arraySize
Size of array used for keys.
-
m_hitOffset
protected int m_hitOffset
Offset added (modulo table size) to slot number on collision.
-
m_keyTable
protected java.lang.String[] m_keyTable
Array of key table slots.
-
m_valueTable
protected int[] m_valueTable
Array of value table slots.
-
m_notFoundValue
protected int m_notFoundValue
Value returned when key not found in table.
-
-
Constructor Detail
-
StringIntHashMap
public StringIntHashMap(int count, double fill, int miss)
Constructor with full specification.- Parameters:
count
- number of values to assume in initial sizing of tablefill
- fraction full allowed for table before growingmiss
- value returned when key not found in table
-
StringIntHashMap
public StringIntHashMap(int count, double fill)
Constructor with size and fill fraction specified. Uses default hash technique and value returned when key not found in table.- Parameters:
count
- number of values to assume in initial sizing of tablefill
- fraction full allowed for table before growing
-
StringIntHashMap
public StringIntHashMap(int count)
Constructor with only size supplied. Uses default hash technique and values for fill fraction and value returned when key not found in table.- Parameters:
count
- number of values to assume in initial sizing of table
-
StringIntHashMap
public StringIntHashMap()
Default constructor.
-
StringIntHashMap
public StringIntHashMap(StringIntHashMap base)
Copy (clone) constructor.- Parameters:
base
- instance being copied
-
-
Method Detail
-
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
-
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
-
standardSlot
private final int standardSlot(java.lang.Object key)
Standard base slot computation for a key.- Parameters:
key
- key value to be computed- Returns:
- base slot for key
-
standardFind
private int standardFind(java.lang.Object key)
Standard find key in table. This method may be used directly for key lookup using either thehashCode()
method defined for the key objects or theSystem.identityHashCode()
method, and either theequals()
method defined for the key objects or the==
operator, 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
- 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)
-
reinsert
private boolean reinsert(int slot)
Reinsert an entry into the hash map. This is used when the table is being directly modified, and does not adjust the count present or check the table capacity.- Parameters:
slot
- position of entry to be reinserted into hash map- Returns:
true
if the slot number used by the entry has has changed,false
if not
-
internalRemove
protected void internalRemove(int slot)
Internal remove pair from the table. Removes the pair from the table by setting the key entry tonull
and adjusting the count present, then chains through the table to reinsert any other pairs which may have collided with the removed pair. If the associated value is an object reference, it should be set tonull
before this method is called.- Parameters:
slot
- index number of pair to be removed
-
restructure
private void restructure(java.lang.String[] keys, int[] values)
Restructure the table. This is used when the table is increasing or decreasing in size, and works directly with the old table representation arrays. It inserts pairs from the old arrays directly into the table without adjusting the count present or checking the table size.- Parameters:
keys
- array of keysvalues
- array of values
-
assignSlot
private int assignSlot(java.lang.String key, int value)
Assign slot for entry. Starts at the slot found by the hashed key value. If this slot is already occupied, it steps the slot number and checks the resulting slot, repeating until an unused slot is found. This method does not check for duplicate keys, so it should only be used for internal reordering of the tables.- Parameters:
key
- to be added to tablevalue
- associated value for key- Returns:
- slot at which entry was added
-
add
public int add(java.lang.String key, int value)
Add an entry to the table. If the key is already present in the table, this replaces the existing value associated with the key.- Parameters:
key
- key to be added to table (non-null
)value
- associated value for key- Returns:
- value previously associated with key, or reserved not found value if key not previously present in table
-
containsKey
public final boolean containsKey(java.lang.String key)
Check if an entry is present in the table. This method is supplied to support the use of values matching the reserved not found value.- Parameters:
key
- key for entry to be found- Returns:
true
if key found in table,false
if not
-
get
public final int get(java.lang.String key)
Find an entry in the table.- Parameters:
key
- key for entry to be returned- Returns:
- value for key, or reserved not found value if key not found
-
remove
public int remove(java.lang.String key)
Remove an entry from the table. If multiple entries are present with the same key value, only the first one found will be removed.- Parameters:
key
- key to be removed from table- Returns:
- value associated with removed key, or reserved not found value if key not found in table
-
clone
public java.lang.Object clone()
Construct a copy of the table.- Overrides:
clone
in classjava.lang.Object
- Returns:
- shallow copy of table
-
-