juno-machine/src/JunoSolve.i3

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 Last modified on Mon Sep 12 17:05:54 PDT 1994 by heydon                   


INTERFACE JunoSolve;

 Defines a procedure for solving a conjunctive normal form constraint. This
   procedure performs both unification closure to solve for list structure,
   and Newton-Raphson iteration to solve for numeric values. 


IMPORT RTVal;

TYPE
  Private <: ROOT;
  Public = Private OBJECT
    known: BOOLEAN;
    val: RTVal.T;
  END;
  Var <: Public;
  Vars = REF ARRAY OF Var;

 If x is a Var, the x.known implies x.val is a legal Juno value. If
   x.known = FALSE but x.val # NIL, then x.val is a hint for the initial
   value of x. 


TYPE
  Constraint <: REFANY;
  Constraints = REF ARRAY OF Constraint;

PROCEDURE New(known := FALSE; val: RTVal.T := NIL): Var;

 Return a new, valid Var with the given field values. It will remain
   valid until the next call to Dispose. 

PROCEDURE NewEqual(x, y: Var): Constraint;

 Return the constraint x = y. 

PROCEDURE NewCons(x, y, z: Var): Constraint;

 Return the constraint x = (y,z). 

PROCEDURE NewPlus(x, y, z: Var): Constraint;

 Return the constraint x = y + z. 

PROCEDURE NewTimes(x, y, z: Var): Constraint;

 Return the constraint x = y * z. 

PROCEDURE NewAtan(x, y, z: Var): Constraint;

 Return the constraint x = ATAN(y, z). 

PROCEDURE NewSin(x, y: Var): Constraint;

 Return the constraint x = SIN(y). 

PROCEDURE NewCos(x, y: Var): Constraint;

 Return the constraint x = COS(y). 

PROCEDURE NewExp(x, y: Var): Constraint;

 Return constraint x = EXP(y). 

PROCEDURE NewReal(x: Var): Constraint;

 Return the constraint REAL(x). 

PROCEDURE NewText(x: Var): Constraint;

 Return constraint TEXT(x). 

PROCEDURE Dispose();

 Invalidate and reclaim all existing Var's and Constraint's. 

PROCEDURE P(READONLY c: ARRAY OF Constraint): BOOLEAN;

 Solve c for its unknowns and return TRUE, setting their val fields so
   as to solve the constraints. Return FALSE if there is no solution. If P
   returns FALSE, it can have arbitrary effects on the known and val
   fields of variables referenced in c.


   Requires that Init has been called on every variable referenced in c
   since each was last passed in a call to P. 

END JunoSolve.