[Cyan]<CedarChest7.0>KeyNote>KeyNoteDatabase.mesa!2

KeyNoteDatabase.mesa

Jack Kent February 23, 1988 10:13:32 am PST

DIRECTORY

DB,

Rope;

KeyNoteDatabase: CEDAR DEFINITIONS = BEGIN

Important: KeyNote maintains the following invariant:

A KeyNote database will never have more than ONE version of a file. [Thus, before a version mumble!X is added to the database, we check to see if there is a mumble!X-1 and if so we delete it.]

Types

ROPE: TYPE = Rope.ROPE;

DatabaseHandle: TYPE = REF DatabaseHandleObject;

DatabaseHandleObject: TYPE;

SimpleProc: TYPE = PROCEDURE [] RETURNS [REF ANY];

GetTokenProc: TYPE = PROCEDURE [clientData: REF ANY] RETURNS [tokenProcReturnData: TokenProcReturnData];

TokenProcReturnData: TYPE = REF TokenProcReturnDataObject;

TokenProcReturnDataObject: TYPE = RECORD[newClientData: REF ANY, token: ROPE, frequency: INTEGER ];

ListOfFilesContainingToken: TYPE = LIST OF FilesContainingToken;

FilesContainingToken: TYPE = REF ANY;

FilesContainingToken: TYPE = REF FilesContainingTokenObject;

FilesContainingTokenObject: TYPE = RECORD [

fileName: ROPE,

frequency: INTEGER,

fileSize: INTEGER

];

ListOfTokensInFile: TYPE = LIST OF TokensInFile;

TokensInFile: TYPE = REF ANY;

TokensInFile: TYPE = REF TokensInFileObject;

TokensInFileObject: TYPE = RECORD [

token: ROPE,

frequency: INTEGER,

frequencyInUniverse: INTEGER

];

Procedures

these are the procedures that interact with a KeyNote database.

either databaseName must be empty or it should be the name of a KeyNote database

adminstrative procedures

OpenDatabase: PROC [databaseName: ROPE, readonly: BOOLEAN, oldDatabaseHandle: DatabaseHandle ← NIL] RETURNS [db: DatabaseHandle];

CloseDatabase: PROC [db: DatabaseHandle];

Abort: PROC [db: DatabaseHandle];

CommitChanges: PROC [db: DatabaseHandle];

procedures that either read or write to database:

All these operations are "carefully applied" in the Walnut sense.

AddTokensToDatabase: PROC [db: DatabaseHandle, fileName: ROPE, getTokenProc: GetTokenProc, clientData: REF ANY];

DoForEachTokenInFile: PROC [db: DatabaseHandle, forEachTokenInFileProc: SimpleProc ];

FindFrequencyWordInFile: PROC [db: DatabaseHandle, token: ROPE, fileName: ROPE] RETURNS [frequencyOfWordInFile: INTEGER];

finds the frequency of a given word in a given file

FindFrequencyWordInUniverse: PROC [db: DatabaseHandle, token: ROPE] RETURNS [numberOfFilesContainingToken: INTEGER];

finds the number of documents containing token

GetListOfFilesContainingToken: PROC [db: DatabaseHandle, token: ROPE] RETURNS [listOfFilesContainingToken: ListOfFilesContainingToken];

GetListOfTokensInFile: PROC [db: DatabaseHandle, fileName: ROPE] RETURNS [listOfTokensInFile: ListOfTokensInFile];

GetNumberOfTokensInUniverse: PROC [db: DatabaseHandle] RETURNS [INTEGER];

GetNumberOfFilesInUniverse: PROC [db: DatabaseHandle] RETURNS [INTEGER];

VerifyFileNonExistence: PROC [db: DatabaseHandle, fileName: ROPE] RETURNS [fileNotInDatabase: BOOLEAN];

Errors raised during the execution of an operation indicate uncommon or abnormal conditions. Clients should be prepared to catch these. Error is a signal because aborts might want to retry

Error: SIGNAL [ec: ErrorCode, explanation: ROPE ← NIL];

ErrorCode: TYPE = ATOM;

The possible ErrorCodes are:

$MultipleVersions -- encountered multiple versions of a file in databaseName

$bug -- such as "Bad value passed to FinishTransaction"

$db -- such as ""Can't access transaction"

END.