Initial QSfera import

Server/vendor/github.com/open-policy-agent/opa/v1/ast/conflicts.go

@@ -0,0 +1,79 @@
+// Copyright 2019 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 ast
+
+import (
+	"slices"
+	"strings"
+)
+
+// CheckPathConflicts returns a set of errors indicating paths that
+// are in conflict with the result of the provided callable.
+func CheckPathConflicts(c *Compiler, exists func([]string) (bool, error)) Errors {
+	var errs Errors
+
+	root := c.RuleTree.Child(DefaultRootDocument.Value)
+	if root == nil {
+		return nil
+	}
+
+	if len(c.pathConflictCheckRoots) == 0 || slices.Contains(c.pathConflictCheckRoots, "") {
+		for _, child := range root.Children {
+			errs = append(errs, checkDocumentConflicts(child, exists, nil)...)
+		}
+		return errs
+	}
+
+	for _, rootPath := range c.pathConflictCheckRoots {
+		// traverse AST from `path` to go to the new root
+		paths := strings.Split(rootPath, "/")
+		node := root
+		for _, key := range paths {
+			node = node.Child(String(key))
+			if node == nil {
+				break
+			}
+		}
+
+		if node == nil {
+			// could not find the node from the AST (e.g. `path` is from a data file)
+			// then no conflict is possible
+			continue
+		}
+
+		for _, child := range node.Children {
+			errs = append(errs, checkDocumentConflicts(child, exists, paths)...)
+		}
+	}
+
+	return errs
+}
+
+func checkDocumentConflicts(node *TreeNode, exists func([]string) (bool, error), path []string) Errors {
+
+	switch key := node.Key.(type) {
+	case String:
+		path = append(path, string(key))
+	default: // other key types cannot conflict with data
+		return nil
+	}
+
+	if len(node.Values) > 0 {
+		s := strings.Join(path, "/")
+		if ok, err := exists(path); err != nil {
+			return Errors{NewError(CompileErr, node.Values[0].Loc(), "conflict check for data path %v: %v", s, err.Error())}
+		} else if ok {
+			return Errors{NewError(CompileErr, node.Values[0].Loc(), "conflicting rule for data path %v found", s)}
+		}
+	}
+
+	var errs Errors
+
+	for _, child := range node.Children {
+		errs = append(errs, checkDocumentConflicts(child, exists, path)...)
+	}
+
+	return errs
+}