Initial QSfera import

Server/vendor/github.com/open-policy-agent/opa/v1/topdown/sets.go

@@ -0,0 +1,106 @@
+// Copyright 2016 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+package topdown
+
+import (
+	"github.com/open-policy-agent/opa/v1/ast"
+	"github.com/open-policy-agent/opa/v1/topdown/builtins"
+)
+
+// Deprecated: deprecated in v0.4.2 in favour of minus/infix "-" operation.
+func builtinSetDiff(_ BuiltinContext, operands []*ast.Term, iter func(*ast.Term) error) error {
+
+	s1, err := builtins.SetOperand(operands[0].Value, 1)
+	if err != nil {
+		return err
+	}
+
+	s2, err := builtins.SetOperand(operands[1].Value, 2)
+	if err != nil {
+		return err
+	}
+
+	return iter(ast.NewTerm(s1.Diff(s2)))
+}
+
+// builtinSetIntersection returns the intersection of the given input sets
+func builtinSetIntersection(_ BuiltinContext, operands []*ast.Term, iter func(*ast.Term) error) error {
+
+	inputSet, err := builtins.SetOperand(operands[0].Value, 1)
+	if err != nil {
+		return err
+	}
+
+	// empty input set
+	if inputSet.Len() == 0 {
+		return iter(ast.InternedEmptySet)
+	}
+
+	var result ast.Set
+
+	err = inputSet.Iter(func(x *ast.Term) error {
+		n, err := builtins.SetOperand(x.Value, 1)
+		if err != nil {
+			return err
+		}
+
+		if result == nil {
+			result = n
+		} else {
+			result = result.Intersect(n)
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	return iter(ast.NewTerm(result))
+}
+
+// builtinSetUnion returns the union of the given input sets
+func builtinSetUnion(_ BuiltinContext, operands []*ast.Term, iter func(*ast.Term) error) error {
+	// The set union logic here is manually inlined on purpose. By lifting
+	// this logic up a level and not doing pairwise set unions, we avoid
+	// many heap allocations. We also pre-allocate the result set by first
+	// counting total elements across all input sets.
+	inputSet, err := builtins.SetOperand(operands[0].Value, 1)
+	if err != nil {
+		return err
+	}
+
+	// First pass: count total elements for pre-allocation
+	totalSize := 0
+	err = inputSet.Iter(func(x *ast.Term) error {
+		item, err := builtins.SetOperand(x.Value, 1)
+		if err != nil {
+			return err
+		}
+		totalSize += item.Len()
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	// Pre-allocate result set with estimated capacity
+	result := ast.NewSetWithCapacity(totalSize)
+
+	err = inputSet.Iter(func(x *ast.Term) error {
+		item, _ := builtins.SetOperand(x.Value, 1) // error checked above
+		item.Foreach(result.Add)
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	return iter(ast.NewTerm(result))
+}
+
+func init() {
+	RegisterBuiltinFunc(ast.SetDiff.Name, builtinSetDiff)
+	RegisterBuiltinFunc(ast.Intersection.Name, builtinSetIntersection)
+	RegisterBuiltinFunc(ast.Union.Name, builtinSetUnion)
+}