Refactor ast.Value to use Compare instead of Equal

ast/compile.go

@@ -854,7 +854,7 @@ func NewModuleTree(mods map[string]*Module) *ModuleTreeNode {
 			c, ok := node.Children[x.Value]
 			if !ok {
 				var hide bool
-				if i == 1 && x.Value.Equal(SystemDocumentKey) {
+				if i == 1 && x.Value.Compare(SystemDocumentKey) == 0 {
 					hide = true
 				}
 				c = &ModuleTreeNode{

ast/map.go

@@ -110,5 +110,5 @@ func valueHash(v util.T) int {
 func valueEq(a, b util.T) bool {
 	av := a.(Value)
 	bv := b.(Value)
-	return av.Equal(bv)
+	return av.Compare(bv) == 0
 }

ast/policy.go

@@ -819,7 +819,7 @@ func (expr *Expr) IsEquality() bool {
 	if len(terms) != 3 {
 		return false
 	}
-	return terms[0].Value.Equal(Equality.Name)
+	return terms[0].Value.Compare(Equality.Name) == 0
 }
 
 // IsBuiltin returns true if this expression refers to a built-in function.

ast/term.go

@@ -73,7 +73,7 @@ func (loc *Location) String() string {
 // - Variables, References
 // - Array Comprehensions
 type Value interface {
-	Equal(other Value) bool       // Equal returns true if this value equals the other value.
+	Compare(other Value) int      // Compare returns <0, 0, or >0 if this Value is less than, equal to, or greater than other, respectively.
 	Find(path Ref) (Value, error) // Find returns value referred to by path or an error if path is not found.
 	Hash() int                    // Returns hash code of the value.
 	IsGround() bool               // IsGround returns true if this value is not a variable or contains no variables.
@@ -269,7 +269,7 @@ func (term *Term) Equal(other *Term) bool {
 	if term == other {
 		return true
 	}
-	return term.Value.Equal(other.Value)
+	return term.Value.Compare(other.Value) == 0
 }
 
 // Hash returns the hash code of the Term's value.
@@ -377,6 +377,12 @@ func (null Null) Equal(other Value) bool {
 	}
 }
 
+// Compare compares null to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (null Null) Compare(other Value) int {
+	return Compare(null, other)
+}
+
 // Find returns the current value or a not found error.
 func (null Null) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -417,6 +423,12 @@ func (bol Boolean) Equal(other Value) bool {
 	}
 }
 
+// Compare compares bol to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (bol Boolean) Compare(other Value) int {
+	return Compare(bol, other)
+}
+
 // Find returns the current value or a not found error.
 func (bol Boolean) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -472,6 +484,12 @@ func (num Number) Equal(other Value) bool {
 	}
 }
 
+// Compare compares num to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (num Number) Compare(other Value) int {
+	return Compare(num, other)
+}
+
 // Find returns the current value or a not found error.
 func (num Number) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -531,6 +549,12 @@ func (str String) Equal(other Value) bool {
 	}
 }
 
+// Compare compares str to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (str String) Compare(other Value) int {
+	return Compare(str, other)
+}
+
 // Find returns the current value or a not found error.
 func (str String) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -573,6 +597,12 @@ func (v Var) Equal(other Value) bool {
 	}
 }
 
+// Compare compares v to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (v Var) Compare(other Value) int {
+	return Compare(v, other)
+}
+
 // Find returns the current value or a not found error.
 func (v Var) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -667,6 +697,12 @@ func (ref Ref) Equal(other Value) bool {
 	return Compare(ref, other) == 0
 }
 
+// Compare compares ref to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (ref Ref) Compare(other Value) int {
+	return Compare(ref, other)
+}
+
 // Find returns the current value or a not found error.
 func (ref Ref) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -786,6 +822,12 @@ func (arr Array) Equal(other Value) bool {
 	return Compare(arr, other) == 0
 }
 
+// Compare compares arr to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (arr Array) Compare(other Value) int {
+	return Compare(arr, other)
+}
+
 // Find returns the value at the index or an out-of-range error.
 func (arr Array) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -902,6 +944,12 @@ func (s *Set) Equal(v Value) bool {
 	return Compare(s, v) == 0
 }
 
+// Compare compares s to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (s *Set) Compare(other Value) int {
+	return Compare(s, other)
+}
+
 // Find returns the current value or a not found error.
 func (s *Set) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -1019,6 +1067,12 @@ func (obj Object) Equal(other Value) bool {
 	return Compare(obj, other) == 0
 }
 
+// Compare compares obj to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (obj Object) Compare(other Value) int {
+	return Compare(obj, other)
+}
+
 // Find returns the value at the key or undefined.
 func (obj Object) Find(path Ref) (Value, error) {
 	if len(path) == 0 {
@@ -1195,6 +1249,12 @@ func (ac *ArrayComprehension) Equal(other Value) bool {
 	return Compare(ac, other) == 0
 }
 
+// Compare compares ac to other, return <0, 0, or >0 if it is less than, equal to,
+// or greater than other.
+func (ac *ArrayComprehension) Compare(other Value) int {
+	return Compare(ac, other)
+}
+
 // Find returns the current value or a not found error.
 func (ac *ArrayComprehension) Find(path Ref) (Value, error) {
 	if len(path) == 0 {

ast/term_test.go

@@ -41,7 +41,7 @@ func TestInterfaceToValue(t *testing.T) {
 		return
 	}
 
-	if !v.Equal(expected) {
+	if v.Compare(expected) != 0 {
 		t.Errorf("Expected ast.Value to equal:\n%v\nBut got:\n%v", expected, v)
 	}
 }
@@ -146,7 +146,7 @@ func TestFind(t *testing.T) {
 			if err != nil {
 				t.Fatalf("Unexpected error occurred for %v: %v", tc.path, err)
 			}
-			if !result.Equal(expected.Value) {
+			if result.Compare(expected.Value) != 0 {
 				t.Fatalf("Expected value %v for %v but got: %v", expected, tc.path, result)
 			}
 		case error:

ast/unify_test.go

@@ -53,7 +53,7 @@ func TestUnify(t *testing.T) {
 		}
 
 		terms := expr.Terms.([]*Term)
-		if !terms[0].Value.Equal(Equality.Name) {
+		if terms[0].Value.Compare(Equality.Name) != 0 {
 			panic(terms)
 		}
 

server/authorizer/authorizer_test.go

@@ -178,7 +178,7 @@ func TestBasic(t *testing.T) {
 				code, err := response.Find(ast.RefTerm(ast.StringTerm("code")).Value.(ast.Ref))
 				if err != nil {
 					t.Fatalf("Missing code in response: %v", recorder)
-				} else if !code.Equal(ast.String(tc.expectedCode)) {
+				} else if code.Compare(ast.String(tc.expectedCode)) != 0 {
 					t.Fatalf("Expected code %v but got: %v", tc.expectedCode, recorder)
 				}
 

server/server_test.go

@@ -622,7 +622,7 @@ func TestPoliciesPutV1ParseError(t *testing.T) {
 		t.Fatalf("Expecfted to find name in errors but: %v", err)
 	}
 
-	if !name.Equal(ast.String("test")) {
+	if name.Compare(ast.String("test")) != 0 {
 		t.Fatalf("Expected name ot equal test but got: %v", name)
 	}
 }
@@ -658,7 +658,7 @@ q[x] { p[x] }`,
 		t.Fatalf("Expecfted to find name in errors but: %v", err)
 	}
 
-	if !name.Equal(ast.String("test")) {
+	if name.Compare(ast.String("test")) != 0 {
 		t.Fatalf("Expected name ot equal test but got: %v", name)
 	}
 }

topdown/aggregates.go

@@ -101,7 +101,7 @@ func builtinMin(a ast.Value) (ast.Value, error) {
 			// The null term is considered to be less than any other term,
 			// so in order for min of a set to make sense, we need to check
 			// for it.
-			if min.Value.Equal(ast.Null{}) {
+			if min.Value.Compare(ast.Null{}) == 0 {
 				return elem, nil
 			}
 

topdown/input.go

@@ -23,7 +23,7 @@ func MakeInput(pairs [][2]*ast.Term) (ast.Value, error) {
 	}
 
 	// Fast-path for the root case.
-	if len(pairs) == 1 && pairs[0][0].Value.Equal(ast.InputRootRef) {
+	if len(pairs) == 1 && pairs[0][0].Value.Compare(ast.InputRootRef) == 0 {
 		return pairs[0][1].Value, nil
 	}
 

topdown/input_test.go

@@ -75,7 +75,7 @@ func TestMakeInput(t *testing.T) {
 				continue
 			}
 			expected := ast.MustParseTerm(e)
-			if !expected.Value.Equal(input) {
+			if expected.Value.Compare(input) != 0 {
 				t.Errorf("%v (#%d): Expected input to equal %v but got: %v", tc.note, i+1, expected, input)
 			}
 		}

topdown/topdown.go

@@ -924,7 +924,7 @@ func evalExpr(t *Topdown, iter Iterator) error {
 				return err
 			}
 		}
-		if !v.Equal(ast.Boolean(false)) {
+		if v.Compare(ast.Boolean(false)) != 0 {
 			if v.IsGround() {
 				return iter(t)
 			}
@@ -1370,7 +1370,7 @@ func evalRefRuleCompleteDocSingle(t *Topdown, rule *ast.Rule, redo bool, last as
 
 		// If document is already defined, check for conflict.
 		if last != nil {
-			if !last.Equal(result) {
+			if last.Compare(result) != 0 {
 				return completeDocConflictErr(t.currentLocation(rule))
 			}
 		} else {
@@ -1560,7 +1560,7 @@ func evalRefRulePartialObjectDocFull(t *Topdown, ref ast.Ref, rules []*ast.Rule,
 				return fmt.Errorf("unbound variable: %v", value)
 			}
 
-			if exist := keys.Get(key); exist != nil && !exist.Equal(value) {
+			if exist := keys.Get(key); exist != nil && exist.Compare(value) != 0 {
 				return objectDocKeyConflictErr(t.currentLocation(rule))
 			}
 
@@ -1784,7 +1784,7 @@ func evalRefRuleResultRecObject(t *Topdown, obj ast.Object, ref, path ast.Ref, i
 					return err
 				}
 			}
-			if x.Equal(k) {
+			if x.Compare(k) == 0 {
 				match = idx
 				break
 			}
@@ -1949,7 +1949,7 @@ func evalTermsIndexed(t *Topdown, iter Iterator, index storage.Index, nonIndexed
 			// different binding for the same variable. This can arise if output
 			// variables in references on either side intersect (e.g., a[i] = g[i][j]).
 			skip := bindings.Iter(func(k, v ast.Value) bool {
-				if o := t.Binding(k); o != nil && !o.Equal(v) {
+				if o := t.Binding(k); o != nil && o.Compare(v) != 0 {
 					return true
 				}
 				prev = t.Bind(k, v, prev)

topdown/topdown_test.go

@@ -220,14 +220,14 @@ func TestPlugValue(t *testing.T) {
 
 	r1 := PlugValue(a, t1.Binding)
 
-	if !expected.Equal(r1) {
+	if expected.Compare(r1) != 0 {
 		t.Errorf("Expected %v but got %v", expected, r1)
 		return
 	}
 
 	r2 := PlugValue(a, t2.Binding)
 
-	if !expected.Equal(r2) {
+	if expected.Compare(r2) != 0 {
 		t.Errorf("Expected %v but got %v", expected, r2)
 	}
 
@@ -241,7 +241,7 @@ func TestPlugValue(t *testing.T) {
 
 	r3 := PlugValue(n, t3.Binding)
 
-	if !expected.Equal(r3) {
+	if expected.Compare(r3) != 0 {
 		t.Errorf("Expected %v but got: %v", expected, r3)
 	}
 }