Pin new dependency: github.com/google/cel-go v0.9.0

vendor/github.com/google/cel-go/interpreter/interpreter.go

@@ -0,0 +1,137 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package interpreter provides functions to evaluate parsed expressions with
+// the option to augment the evaluation with inputs and functions supplied at
+// evaluation time.
+package interpreter
+
+import (
+	"github.com/google/cel-go/common/containers"
+	"github.com/google/cel-go/common/types/ref"
+	"github.com/google/cel-go/interpreter/functions"
+
+	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
+)
+
+// Interpreter generates a new Interpretable from a checked or unchecked expression.
+type Interpreter interface {
+	// NewInterpretable creates an Interpretable from a checked expression and an
+	// optional list of InterpretableDecorator values.
+	NewInterpretable(checked *exprpb.CheckedExpr,
+		decorators ...InterpretableDecorator) (Interpretable, error)
+
+	// NewUncheckedInterpretable returns an Interpretable from a parsed expression
+	// and an optional list of InterpretableDecorator values.
+	NewUncheckedInterpretable(expr *exprpb.Expr,
+		decorators ...InterpretableDecorator) (Interpretable, error)
+}
+
+// TrackState decorates each expression node with an observer which records the value
+// associated with the given expression id. EvalState must be provided to the decorator.
+// This decorator is not thread-safe, and the EvalState must be reset between Eval()
+// calls.
+func TrackState(state EvalState) InterpretableDecorator {
+	observer := func(id int64, val ref.Val) {
+		state.SetValue(id, val)
+	}
+	return decObserveEval(observer)
+}
+
+// ExhaustiveEval replaces operations that short-circuit with versions that evaluate
+// expressions and couples this behavior with the TrackState() decorator to provide
+// insight into the evaluation state of the entire expression. EvalState must be
+// provided to the decorator. This decorator is not thread-safe, and the EvalState
+// must be reset between Eval() calls.
+func ExhaustiveEval(state EvalState) InterpretableDecorator {
+	ex := decDisableShortcircuits()
+	obs := TrackState(state)
+	return func(i Interpretable) (Interpretable, error) {
+		var err error
+		i, err = ex(i)
+		if err != nil {
+			return nil, err
+		}
+		return obs(i)
+	}
+}
+
+// Optimize will pre-compute operations such as list and map construction and optimize
+// call arguments to set membership tests. The set of optimizations will increase over time.
+func Optimize() InterpretableDecorator {
+	return decOptimize()
+}
+
+type exprInterpreter struct {
+	dispatcher  Dispatcher
+	container   *containers.Container
+	provider    ref.TypeProvider
+	adapter     ref.TypeAdapter
+	attrFactory AttributeFactory
+}
+
+// NewInterpreter builds an Interpreter from a Dispatcher and TypeProvider which will be used
+// throughout the Eval of all Interpretable instances gerenated from it.
+func NewInterpreter(dispatcher Dispatcher,
+	container *containers.Container,
+	provider ref.TypeProvider,
+	adapter ref.TypeAdapter,
+	attrFactory AttributeFactory) Interpreter {
+	return &exprInterpreter{
+		dispatcher:  dispatcher,
+		container:   container,
+		provider:    provider,
+		adapter:     adapter,
+		attrFactory: attrFactory}
+}
+
+// NewStandardInterpreter builds a Dispatcher and TypeProvider with support for all of the CEL
+// builtins defined in the language definition.
+func NewStandardInterpreter(container *containers.Container,
+	provider ref.TypeProvider,
+	adapter ref.TypeAdapter,
+	resolver AttributeFactory) Interpreter {
+	dispatcher := NewDispatcher()
+	dispatcher.Add(functions.StandardOverloads()...)
+	return NewInterpreter(dispatcher, container, provider, adapter, resolver)
+}
+
+// NewIntepretable implements the Interpreter interface method.
+func (i *exprInterpreter) NewInterpretable(
+	checked *exprpb.CheckedExpr,
+	decorators ...InterpretableDecorator) (Interpretable, error) {
+	p := newPlanner(
+		i.dispatcher,
+		i.provider,
+		i.adapter,
+		i.attrFactory,
+		i.container,
+		checked,
+		decorators...)
+	return p.Plan(checked.GetExpr())
+}
+
+// NewUncheckedIntepretable implements the Interpreter interface method.
+func (i *exprInterpreter) NewUncheckedInterpretable(
+	expr *exprpb.Expr,
+	decorators ...InterpretableDecorator) (Interpretable, error) {
+	p := newUncheckedPlanner(
+		i.dispatcher,
+		i.provider,
+		i.adapter,
+		i.attrFactory,
+		i.container,
+		decorators...)
+	return p.Plan(expr)
+}