1 // ***********************************************************************
2 // Copyright (c) 2008 Charlie Poole
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22 // ***********************************************************************
25 #define NUNIT_FRAMEWORK
29 namespace NUnit.Framework.Constraints
32 /// The ConstraintOperator class is used internally by a
33 /// ConstraintBuilder to represent an operator that
34 /// modifies or combines constraints.
36 /// Constraint operators use left and right precedence
37 /// _values to determine whether the top operator on the
38 /// stack should be reduced before pushing a new operator.
40 public abstract class ConstraintOperator
42 private object leftContext;
43 private object rightContext;
46 /// The precedence value used when the operator
47 /// is about to be pushed to the stack.
49 protected int left_precedence;
52 /// The precedence value used when the operator
53 /// is on the top of the stack.
55 protected int right_precedence;
58 /// The syntax element preceding this operator
60 public object LeftContext
62 get { return leftContext; }
63 set { leftContext = value; }
67 /// The syntax element following this operator
69 public object RightContext
71 get { return rightContext; }
72 set { rightContext = value; }
76 /// The precedence value used when the operator
77 /// is about to be pushed to the stack.
79 public virtual int LeftPrecedence
81 get { return left_precedence; }
85 /// The precedence value used when the operator
86 /// is on the top of the stack.
88 public virtual int RightPrecedence
90 get { return right_precedence; }
94 /// Reduce produces a constraint from the operator and
95 /// any arguments. It takes the arguments from the constraint
96 /// stack and pushes the resulting constraint on it.
98 /// <param name="stack"></param>
99 public abstract void Reduce(ConstraintBuilder.ConstraintStack stack);