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

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

@@ -0,0 +1,77 @@
+// Copyright 2020 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 cel
+
+import (
+	"github.com/google/cel-go/checker"
+	"github.com/google/cel-go/interpreter/functions"
+	"github.com/google/cel-go/parser"
+)
+
+// Library provides a collection of EnvOption and ProgramOption values used to confiugre a CEL
+// environment for a particular use case or with a related set of functionality.
+//
+// Note, the ProgramOption values provided by a library are expected to be static and not vary
+// between calls to Env.Program(). If there is a need for such dynamic configuration, prefer to
+// configure these options outside the Library and within the Env.Program() call directly.
+type Library interface {
+	// CompileOptions returns a collection of funcitional options for configuring the Parse / Check
+	// environment.
+	CompileOptions() []EnvOption
+
+	// ProgramOptions returns a collection of functional options which should be included in every
+	// Program generated from the Env.Program() call.
+	ProgramOptions() []ProgramOption
+}
+
+// Lib creates an EnvOption out of a Library, allowing libraries to be provided as functional args,
+// and to be linked to each other.
+func Lib(l Library) EnvOption {
+	return func(e *Env) (*Env, error) {
+		var err error
+		for _, opt := range l.CompileOptions() {
+			e, err = opt(e)
+			if err != nil {
+				return nil, err
+			}
+		}
+		e.progOpts = append(e.progOpts, l.ProgramOptions()...)
+		return e, nil
+	}
+}
+
+// StdLib returns an EnvOption for the standard library of CEL functions and macros.
+func StdLib() EnvOption {
+	return Lib(stdLibrary{})
+}
+
+// stdLibrary implements the Library interface and provides functional options for the core CEL
+// features documented in the specification.
+type stdLibrary struct{}
+
+// EnvOptions returns options for the standard CEL function declarations and macros.
+func (stdLibrary) CompileOptions() []EnvOption {
+	return []EnvOption{
+		Declarations(checker.StandardDeclarations()...),
+		Macros(parser.AllMacros...),
+	}
+}
+
+// ProgramOptions returns function implementations for the standard CEL functions.
+func (stdLibrary) ProgramOptions() []ProgramOption {
+	return []ProgramOption{
+		Functions(functions.StandardOverloads()...),
+	}
+}