Class CIndex

java.lang.Object
   |
   +----CIndex

public class CIndex

extends Object

• An index map containing the stems of all indexed words. Each stem is linked to its posting list via an unique id.
• An indexed array of posting lists.
• A hashed URL list. Each URL is linked to the appropriate document via an unique id.
• An indexed array of documents.

1. all tables are set up as either vectors or nested arrays to make extensions fast and easy.
2. all vectors and nested arrays are replaced by "normal" arrays to make retrieval fast and easy.

CIndex()

addPage(PPage)

adds a document to the index.

dump()

getMatchingWordIDs(String)

returns a all words within the idex that match a given wildcard expression (string*)

getPage(int)

returns a document from a given document ID.

getPage(String)

returns a document from a given URL.

getPostingList(int)

returns a given word's posting list

getPostingList(String)

returns a given word's posting list

getWordLink(String)

returns a given words ID as used in docReps.

optimize()

optimizes the index by replacing all vectors and nested arrays with "real" arrays.

statistics(PrintStream)

 public CIndex()

 public boolean addPage(PPage page)

adds a document to the index. The steps performed are:

1. add the document to the document table
2. add the document's URL to the URL table
3. create a local index for this document
4. rank all words based on the local index
5. create the document's docRep from the local index
6. merge the local index with the global index. Add all new words to the global word list.

Parameters:

page - page to be added to the index

Returns:

true, if the page was added, otherwise false.

 public void optimize()

optimizes the index by replacing all vectors and nested arrays with "real" arrays. The steps performed are:

• flatten the word list by using a 3-letter prefixed array
• flatten the posting array by un-nesting it
• optimize all posting lists by transforming them into arrays
• flatten the document list by un-nesting it
• replace the vectors holding each document's links by arrays

 public int getWordLink(String strWord)

returns a given words ID as used in docReps.

Returns:

an integer > 0 if the word was found, otherwise 0.

 public int[] getPostingList(String strWord)

returns a given word's posting list

Parameters:

strWord - word to be looked up

Returns:

posting list as an array of document IDs. If strWord is unknown, null will be returned.

 public int[] getPostingList(int idWord)

returns a given word's posting list

Parameters:

idWord - word ID to be looked up

Returns:

posting list as an array of document IDs

 public Vector getMatchingWordIDs(String mask)

returns a all words within the idex that match a given wildcard expression (string*)

Parameters:

mask - - wildcard expression

Returns:

Vector of all word's IDs that match the expression

 public CIndexedPage getPage(int idPage)

returns a document from a given document ID.

Parameters:

idPage - - document ID

Returns:

CIndexedPage object if the document was found, otherwise null.

 public CIndexedPage getPage(String strURL)

returns a document from a given URL.

Parameters:

strURL - - URL

Returns:

CIndexedPage object if the document was found, otherwise null.

 public void dump()

 public void statistics(PrintStream pout)