Initial QSfera import

Server/vendor/github.com/open-policy-agent/opa/v1/rego/plugins.go

@@ -0,0 +1,49 @@
+// Copyright 2023 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 rego
+
+import (
+	"context"
+	"sync"
+
+	"github.com/open-policy-agent/opa/v1/ast"
+	"github.com/open-policy-agent/opa/v1/ir"
+)
+
+var targetPlugins = map[string]TargetPlugin{}
+var pluginMtx sync.Mutex
+
+type TargetPlugin interface {
+	IsTarget(string) bool
+	PrepareForEval(context.Context, *ir.Policy, ...PrepareOption) (TargetPluginEval, error)
+}
+
+type TargetPluginEval interface {
+	Eval(context.Context, *EvalContext, ast.Value) (ast.Value, error)
+}
+
+func (*Rego) targetPlugin(tgt string) TargetPlugin {
+	for _, p := range targetPlugins {
+		if p.IsTarget(tgt) {
+			return p
+		}
+	}
+	return nil
+}
+
+func RegisterPlugin(name string, p TargetPlugin) {
+	pluginMtx.Lock()
+	defer pluginMtx.Unlock()
+	if _, ok := targetPlugins[name]; ok {
+		panic("plugin already registered " + name)
+	}
+	targetPlugins[name] = p
+}
+
+func ResetTargetPlugins() {
+	pluginMtx.Lock()
+	defer pluginMtx.Unlock()
+	targetPlugins = map[string]TargetPlugin{}
+}