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Removed/commented out/tagged some unused local variables.

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Added a JUnit test for the new Trie that fails at present since the Trie is
case-insensitive.  Running JUnit tests is not something our build system
knows about at present, but Eclipse 2.0 makes it very easy.

Fixed a few compiler errors due to imports I'd forgotten.
This commit is contained in:
dchandler 2002-11-02 16:01:40 +00:00
parent b8391e923d
commit a6cc4a7ff3
31 changed files with 292 additions and 179 deletions
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252
source/org/thdl/util/Trie.java
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@ -88,115 +88,161 @@ package org.thdl.util;
public class Trie
{
/** Size of the m_nextChar array. */
public static final int ALPHA_SIZE = 128;
/** Size of the m_nextChar array. */
public static final int ALPHA_SIZE = 128;
/** The root node of the tree. */
Node m_Root;
/**
* Constructs a trie.
*/
public Trie()
{
m_Root = new Node();
}
/**
* Puts an object into the trie for lookup.
*
* @param key must be a 7-bit ASCII string
* @param value any java object.
*
* @return The old object that matched key, or null.
*/
public Object put(String key, Object value)
{
final int len = key.length();
Node node = m_Root;
for (int i = 0; i < len; i++)
{
Node nextNode = node.m_nextChar[Character.toUpperCase(key.charAt(i))];
if (nextNode != null)
{
node = nextNode;
}
else
{
for (; i < len; i++)
{
Node newNode = new Node();
node.m_nextChar[Character.toUpperCase(key.charAt(i))] = newNode;
node = newNode;
}
break;
}
}
Object ret = node.m_Value;
node.m_Value = value;
return ret;
}
/**
* Gets an object that matches the key.
*
* @param key must be a 7-bit ASCII string
*
* @return The object that matches the key, or null.
*/
public Object get(String key)
{
final int len = key.length();
Node node = m_Root;
for (int i = 0; i < len; i++)
{
try
{
node = node.m_nextChar[Character.toUpperCase(key.charAt(i))];
}
catch (ArrayIndexOutOfBoundsException e)
{
// the key is not 7-bit ASCII so we won't find it here
node = null;
}
if (node == null)
return null;
}
return node.m_Value;
}
/**
* The node representation for the trie.
*/
class Node
{
/** The root node of the tree. */
Node m_Root;
/**
* Constructor, creates a Node[ALPHA_SIZE].
* Constructs a trie.
*/
Node()
public Trie()
{
m_nextChar = new Node[ALPHA_SIZE];
m_Value = null;
m_Root = new Node();
}
/** The next nodes. */
Node m_nextChar[];
/**
* Puts an object into the trie for lookup.
*
* @param key must be a 7-bit ASCII string
* @param value any java object, but not null.
*
* @return The old object that matched key, or null.
* @throws NullPointerException if value is null or if key is null
*/
public Object put(String key, Object value)
{
if (null == value) throw new NullPointerException();
/** The value. */
Object m_Value;
}
final int len = key.length();
Node node = m_Root;
for (int i = 0; i < len; i++)
{
Node nextNode = node.m_nextChar[Character.toUpperCase(key.charAt(i))];
if (nextNode != null)
{
node = nextNode;
}
else
{
for (; i < len; i++)
{
Node newNode = new Node();
node.m_nextChar[Character.toUpperCase(key.charAt(i))] = newNode;
node.m_isLeaf = false;
node = newNode;
}
break;
}
}
Object ret = node.m_Value;
node.m_Value = value;
return ret;
}
/**
* Gets an object that matches the key.
*
* @param key must be a 7-bit ASCII string
*
* @return The object that matches the key, or null.
*/
public Object get(String key)
{
final int len = key.length();
Node node = m_Root;
for (int i = 0; i < len; i++)
{
try
{
node = node.m_nextChar[Character.toUpperCase(key.charAt(i))];
}
catch (ArrayIndexOutOfBoundsException e)
{
// the key is not 7-bit ASCII so we won't find it here
node = null;
}
if (node == null)
return null;
}
return node.m_Value;
}
/**
* Returns true if and only if key is a prefix of another, distinct
* member of the trie. Note that key may be in the trie as well as
* a prefix of something in the trie, but not all keys in the trie
* are prefixes of other keys. (In the trie you might naturally
* construct for the extended Wylie keyboard, "t" is a prefix, as is
* "ts", but "tsh", though a member of the trie, is not a prefix
* because there is no string x such that x begins with "tsh" but is
* not equal to "tsh" that is in the trie.)
*
* @param key must be a 7-bit ASCII string
*
* @return The object that matches the key, or null. */
public boolean hasPrefix(String key)
{
final int len = key.length();
Node node = m_Root;
for (int i = 0; i < len; i++)
{
try
{
node = node.m_nextChar[Character.toUpperCase(key.charAt(i))];
}
catch (ArrayIndexOutOfBoundsException e)
{
// the key is not 7-bit ASCII so we won't find it here
node = null;
}
if (node == null)
return false;
}
return !node.m_isLeaf;
}
/**
* The node representation for the trie.
*/
class Node
{
/**
* Constructor, creates a Node[ALPHA_SIZE].
*/
Node()
{
m_nextChar = new Node[ALPHA_SIZE];
m_Value = null;
m_isLeaf = true;
}
/** The next nodes. */
Node m_nextChar[];
/** The value. */
Object m_Value;
/** True if and only if this node has no children. */
boolean m_isLeaf;
}
}