Notification-based constraint set translation to imperative execution

• US 20090293046A1
• Filed: 05/21/2008
• Published: 11/26/2009
• Est. Priority Date: 05/21/2008
• Status: Active Grant

• Current Assignee: Optumsoft Inc.
• Original Assignee: Optumsoft Inc.
• Inventors: Cheriton, David R.
• Granted Patent: US 8,850,409 B2
• Time in Patent Office: Days
• US Class Current: 717/136
• CPC Class Codes: G06F 8/40 Transformation of program code
• CPC Class Codes: G06F 8/437 Type checking

Abstract

A method is provided for translating sets of constraint declarations to imperative code sequences based on defining an instantiatable object per set, inserting calls to a notification callback mechanism on state modification and defining calls in the constraint context as imperative code sequences that, in response to these callbacks, take actions to maintain these constraints.

Claims

1. A method for automatically translating input code including constraints to a computer executable imperative output program representation, the method comprising:

providing an input source program, wherein said input source program is expressed in a programming language that also provides for declarative specification of constraints, and wherein said input source program includes one or more constraints specified in accordance with said programming language;

wherein each of said one or more constraints specifies relations of constraint data members;

providing identification of which of said constraint data members are constraint inputs;

automatically providing constraint representations for said constraints;

wherein each of said constraint representations includes one or more corresponding constraint reactor objects for registration for input change notification upon instantiation, said constraint reactor objects having imperative procedures for enforcing said constraints, and wherein said corresponding constraint reactor objects are accessible in the scope of said corresponding constraint representation;

for each of some or all program data members of said input source program, automatically providing corresponding notification code to provide change notification and to accommodate registration for input change notification by constraint representations, and wherein said corresponding notification code is accessible in the scope of said corresponding program data member;

instantiating said constraint representations in said imperative output program representation, whereby changes to constraint inputs automatically lead to imperative constraint-driven updating; and

providing said imperative output program representation as an output.

2. The method of claim 1:

wherein said constraints in said input source code program are organized in constraint sets, each constraint set including one or more constraints;

wherein each of said constraint sets also includes explicit and/or implicit identification of which constraint data members of said included constraints are constraint inputs; and

wherein said corresponding constraint representations comprise constraint set object representations corresponding to each of said constraint sets.

3. The method of claim 1, wherein said providing corresponding notification code to provide change notification comprises automatically defining virtual updating procedures for each of said program data members, wherein said virtual updating procedures are invoked if the corresponding program data member changes.

4. The method of claim 3, wherein said providing a corresponding constraint representation comprises automatically defining real updating procedures for changes to inputs of each of said constraints.

5. The method of claim 4, wherein said automatically instantiating said notification code and said constraint representations comprises mapping invocations of said virtual updating procedures to corresponding invocations of said real updating procedures by type inheritance.

6. The method of claim 1, wherein said automatically instantiating said notification code and said constraint representations comprises:

for each program data member that is also an input to one or more constraint representation instances, constructing a notifiee list of constraint reactor object instances of said one or more constraint representation instances, wherein said each notifiee list is accessible in the same scope as said each program data member.

7. The method of claim 1, wherein at least one of said constraints is a multi-input constraint having two or more input constraint data members, and further comprising expressing said multi-input constraint as a set of single-input constraints, each single-input constraint having exactly one input constraint data member.

8. The method of claim 1, wherein for one or more of said program data members, said automatically providing corresponding notification code comprises providing two or more change notification procedures for said corresponding program data member, and providing for selection of which of said two or more change notification procedures to invoke depending on the nature and/or circumstances of the change to said corresponding program data member.

9. The method of claim 1, wherein one or more of said constraints is specified in the same scope as one or more of its corresponding inputs, and further comprising inserting in-scope imperative code in said imperative output program representation to enforce said one or more of said constraints.

10. The method of claim 1, wherein at least one of said constraint representations provides for selecting a thread of program control for execution of each of its corresponding constraint reactor objects.

11. The method of claim 1, wherein said automatically providing corresponding notification code comprises automatically encapsulating modification code of said program data members in corresponding mutator procedures that include notification code.

12. The method of claim 1, wherein at least one of said constraints is a representation-specific constraint relating to constraint data members having different representations.

13. The method of claim 1, wherein one or more of said constraints relate to complex event processing.

14. The method of claim 1, further comprising providing a run-time constraint engine to handle constraint sets that are not resolved during translation.

15. The method of claim 1, wherein said constraints specify a grammar for a target programming language in declarative terms.

16. The method of claim 1, wherein at least one of said constraints is located in a first program unit and at least one of its corresponding constraint inputs can change in a second program unit, and wherein said first and second program units are separately translated.

17. The method of claim 16, wherein said second program unit can be separately translated without knowledge of which of its program data members are constraint inputs.

18. The method of claim 1, wherein said programming language provides for specification of procedure triggers, and further comprising:

providing one or more procedure triggers specified in accordance with said programming language in said input source program;

for each of said procedure triggers, providing identification of which of said program data members are trigger inputs for said procedure trigger;

wherein each of said one or more procedure triggers includes one or more trigger procedures to be invoked when a corresponding trigger input changes;

for each of said procedure triggers, automatically providing a corresponding trigger representation;

wherein each of said trigger representations includes one or more corresponding trigger reactor objects for registration for input change notification upon instantiation, said trigger reactor objects including said one or more trigger procedures; and

wherein said corresponding trigger reactor objects are accessible in the scope of said corresponding trigger representation;

wherein said notification code also accommodates registration for input change notification by trigger representations;

instantiating said trigger representations in said imperative output program representation, whereby changes to trigger inputs automatically lead to execution of said trigger procedures.