Methods and interface for building command expressions in a computer system

• US 5,798,757 A
• Filed: 11/13/1995
• Issued: 08/25/1998
• Est. Priority Date: 12/15/1993
• Status: Expired due to Fees

• Current Assignee: Borland Software Corporation (Open Text Corporation)
• Original Assignee: Borland International, Inc. (Open Text Corporation)
• Inventors: Smith, Kenneth Wayne
• Primary Examiner(s): Voeltz, Emanuel Todd
• Assistant Examiner(s): Chaki, Kakali
• Application Number:
  US08/557,661
• Time in Patent Office: 1,016 Days
• Field of Search: 395/701, 395/708, 395/613, 395/764, 395/792, 395/338, 345/338
• US Class Current: 715/709
• CPC Class Codes: G06F 8/33 Intelligent editors

Abstract

The system of the present invention comprises a development system having an Expression Builder for assisting a user with creating an expression. With full syntax checking enabled, the user builds an expression in "token" mode. As the user enters each token element, the system attempts to validate the expression and, if the expression is valid, displays the result. If the expression is incomplete or invalid, however, the system displays a message explaining what is needed. The Expression Builder of the present invention employs placeholders or "proxies" for representing elements in an expression which should be replaced before the expression is valid. The expression is dynamically adjusted during user editing as required to maintain expression validity. In this manner, the user is provided with in situ assistance in constructing syntactically-correct expressions.

Claims

1. In a computer system for evaluating expressions entered by a user, the expressions comprising a plurality of tokens which evaluate to a result, said plurality of tokens comprising at least one operator token specifying what type of operation is to occur upon evaluation of the expression and at least one operand token specifying a data member which said at least one operator token is to operate on, a method for assisting the user with correctly creating an expression, the method comprising:

(a) storing a set of rules specifying valid relationships between adjacent tokens, said set of rules including rules specifying valid relationships between adjacent operator and operand tokens;

(b) receiving user input for placing at least one token in said expression being created;

(c) determining validity of said expression being created by applying said rules to adjacent ones of said at least one token; and

(d) if said expression being created is determined not to be valid in step (c), automatically modifying said expression so that validity of said expression being created is maintained.

2. The method of claim 1, wherein said tokens comprise nonreducible textual elements in said expression being created.

3. The method of claim 1, further comprising:

constraining user input so that new tokens are placed in said expression only at locations between existing tokens.

4. The method of claim 1, further comprising:

(e) receiving user input for removing at least one token from said expression being created; and

(f) repeating steps (c) and (d) for all said at least tokens deleted.

5. The method of claim 4, wherein step (f) includes:

deleting at least one token for a token whose presence in the expression would render the expression invalid.

6. The method of claim 1, wherein said tokens include a pair of grouping tokens for grouping related ones of said tokens.

7. The method of claim 6, wherein said pair of grouping tokens comprise "(" and ")" tokens.

8. The method of claim 1, wherein said tokens include a function token comprising a function name followed by a left paren, said function token corresponding with a matching right paren token.

9. The method of claim 8, wherein said tokens include comma-delimited function parameter tokens corresponding with a function token.

10. In a system for processing commands entered by a user, the commands including expressions which resolve to a result, said commands comprising at least one operand token specifying a data member and at least one operator token specifying a particular type of operation to occur to particular data members upon evaluation of expressions, a method for assisting the user with construction of a valid expression, the method comprising:

(a) receiving input from the user specifying a desired expression;

(b) dividing said input into a plurality of tokens, said plurality of tokens including adjacent operator and operand tokens;

(c) determining validity of said desired expression by comparing said tokens against a set of rules specifying valid relationships between tokens; and

(d) if said desired expression being created is determined not to be valid in step (c), automatically modifying said desired expression so that validity of said desired expression is maintained.

11. A development system for creating syntactically-correct expressions from data entered by a user, the expressions comprising a plurality of tokens which evaluate to a result, said plurality of tokens comprising at least one operand token specifying a data member and at least one operator token specifying a particular type of operation to occur to particular data members upon evaluation of expressions, the system comprising:

a computer having a processor and a memory;

means for storing in said memory information specifying valid relationships between tokens, said information including rules specifying valid relationships between adjacent operator and operand tokens;

input means for receiving user input for placing at least one token in a particular expression being created;

means for determining validity of said particular expression being created by applying said rules to adjacent ones of said at least one token; and

means for automatically modifying said particular expression so that validity of said particular expression being created is maintained.

12. A computer system for creating an expression comprising:

a processor and a memory;

means for storing syntactic information for a desired target language in said memory, said information specifying valid combinations of operand and operator elements for an expression;

an interface means for specifying an edit operation at a desired location in the expression, said edit operation for adding or deleting an element to an expression comprising operand and operator elements;

comparison means for comparing said edit operation with said syntactic information; and

means for automatically modifying said edit operation so that the expression maintains valid combinations of elements.

13. The system of claim 12, wherein said modifying means includes means for adding additional elements to the expression if required to maintain a valid combination of elements.

14. The system of claim 12 wherein said modifying means includes means for deleting elements present in the expression if required to maintain a valid combination of elements.

15. The system of claim 12, wherein said interface means includes means for positioning an edit caret to a desired location in the expression, said edit caret being constrained such that it may only be positioned from one element of the expression to another.