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Unique Keyword Detection Routine

IP.com Disclosure Number: IPCOM000084611D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 4 page(s) / 113K

Publishing Venue

IBM

Related People

Kaufmann, SM: AUTHOR

Abstract

An operating system programming routine is described which provides a highly efficient and easily maintainable means of determining the existence of specified keywords and whether or not those keywords have been found before. This routine is an improvement over the syntax scan algorithms used in OS/VS1 Commands and OS/VS1 Scheduler Interpreter. It eliminates any need for padding table entries. It eliminates any restrictions on number of table entries which previously existed, due to the restriction on "unique" bits imposed with other algorithms. It requires minimal storage and the processing of keywords or subkeywords is transparent to the routine.

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Unique Keyword Detection Routine

An operating system programming routine is described which provides a highly efficient and easily maintainable means of determining the existence of specified keywords and whether or not those keywords have been found before. This routine is an improvement over the syntax scan algorithms used in OS/VS1 Commands and OS/VS1 Scheduler Interpreter. It eliminates any need for padding table entries. It eliminates any restrictions on number of table entries which previously existed, due to the restriction on "unique" bits imposed with other algorithms. It requires minimal storage and the processing of keywords or subkeywords is transparent to the routine.

The Unique Keyword Detection Routine (UKDR) described herein provides a means of determining if one of several valid keywords exists and has not already been found in a given character string. When this is the case, the routine exits to the corresponding routine to perform the necessary processing for that keyword. "Keyword" in this context is any string of characters that has special meaning to the function using this routine and can be such character strings as "RDR=", "FIND", "(", "(,", etc. The routine is table driven, so various levels of keywords can be grouped into separate tables. This permits a keyword processing routine, already invoked by the UKDR, to call UKDR again with a pointer to its own table of keywords. So any number of sublevels of a given keyword can be detected using the UKDR.

The UKDR requires two types of tables. The first is an Address Table where each entry in the table contains the address of a keyword processor routine. An example of such an Address Table is shown in Fig. 1. The second is a Keyword Table consisting of keyword entries and a header entry. An example of one much Keyword Table is shown in Fig. 2. The header entry in the Keyword Table contains an indication of the total number of keyword entries in that particular table and the length of the unique keyword bit field contained in the table entries. This eliminates the need for all the Keyword Tables to have the same size bit field, the required size of which is dependent on the number of keywords in the particular table.

Each keyword entry consists of the following: (1) an offset into the Address Table (thereby enabling several keywords to specify the same routine for its processing); (2) the length of the keyword (thus eliminating any fixed length or maximum length keyword requirements); (3) a field containing a keyword bit which is unique to the entry in that particular Keyword Table; and (4) the actual keyword. Several Keyword Tables can be created and used, but they must all refer to a single Address Table.

The flow chart of Fig. 3 describes the UKDR mechanism. The UKDR requires the following as input: (1) a pointer to a Keyword Table, (2) a pointer to a keyword bit string field w...