// 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
//
//     https://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.

// Code generated by protoc-gen-go_gapic. DO NOT EDIT.

// Package expr is an auto-generated package for the
// Common Expression Language.
//
// Defines common types for the Common Expression Language.
//
//   NOTE: This package is in alpha. It is not stable, and is likely to change.
//
// Use of Context
//
// The ctx passed to NewClient is used for authentication requests and
// for creating the underlying connection, but is not used for subsequent calls.
// Individual methods on the client use the ctx given to them.
//
// To close the open connection, use the Close() method.
//
// For information about setting deadlines, reusing contexts, and more
// please visit godoc.org/cloud.google.com/go.
package expr // import "cloud.google.com/go/expr/apiv1alpha1"

import (
	"context"
	"runtime"
	"strings"
	"unicode"

	"google.golang.org/grpc/metadata"
)

const versionClient = "20200324"

func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
	out, _ := metadata.FromOutgoingContext(ctx)
	out = out.Copy()
	for _, md := range mds {
		for k, v := range md {
			out[k] = append(out[k], v...)
		}
	}
	return metadata.NewOutgoingContext(ctx, out)
}

// DefaultAuthScopes reports the default set of authentication scopes to use with this package.
func DefaultAuthScopes() []string {
	return []string{}
}

// versionGo returns the Go runtime version. The returned string
// has no whitespace, suitable for reporting in header.
func versionGo() string {
	const develPrefix = "devel +"

	s := runtime.Version()
	if strings.HasPrefix(s, develPrefix) {
		s = s[len(develPrefix):]
		if p := strings.IndexFunc(s, unicode.IsSpace); p >= 0 {
			s = s[:p]
		}
		return s
	}

	notSemverRune := func(r rune) bool {
		return !strings.ContainsRune("0123456789.", r)
	}

	if strings.HasPrefix(s, "go1") {
		s = s[2:]
		var prerelease string
		if p := strings.IndexFunc(s, notSemverRune); p >= 0 {
			s, prerelease = s[:p], s[p:]
		}
		if strings.HasSuffix(s, ".") {
			s += "0"
		} else if strings.Count(s, ".") < 2 {
			s += ".0"
		}
		if prerelease != "" {
			s += "-" + prerelease
		}
		return s
	}
	return "UNKNOWN"
}