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

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

@@ -0,0 +1,58 @@
+// 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 functions defines the standard builtin functions supported by the
+// interpreter and as declared within the checker#StandardDeclarations.
+package functions
+
+import "github.com/google/cel-go/common/types/ref"
+
+// Overload defines a named overload of a function, indicating an operand trait
+// which must be present on the first argument to the overload as well as one
+// of either a unary, binary, or function implementation.
+//
+// The majority of  operators within the expression language are unary or binary
+// and the specializations simplify the call contract for implementers of
+// types with operator overloads. Any added complexity is assumed to be handled
+// by the generic FunctionOp.
+type Overload struct {
+	// Operator name as written in an expression or defined within
+	// operators.go.
+	Operator string
+
+	// Operand trait used to dispatch the call. The zero-value indicates a
+	// global function overload or that one of the Unary / Binary / Function
+	// definitions should be used to execute the call.
+	OperandTrait int
+
+	// Unary defines the overload with a UnaryOp implementation. May be nil.
+	Unary UnaryOp
+
+	// Binary defines the overload with a BinaryOp implementation. May be nil.
+	Binary BinaryOp
+
+	// Function defines the overload with a FunctionOp implementation. May be
+	// nil.
+	Function FunctionOp
+}
+
+// UnaryOp is a function that takes a single value and produces an output.
+type UnaryOp func(value ref.Val) ref.Val
+
+// BinaryOp is a function that takes two values and produces an output.
+type BinaryOp func(lhs ref.Val, rhs ref.Val) ref.Val
+
+// FunctionOp is a function with accepts zero or more arguments and produces
+// an value (as interface{}) or error as a result.
+type FunctionOp func(values ...ref.Val) ref.Val