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// Copyright 2016 CNI authors
//
// 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 convert
import (
"fmt"
"github.com/containernetworking/cni/pkg/types"
)
// ConvertFn should convert from the given arbitrary Result type into a
// Result implementing CNI specification version passed in toVersion.
// The function is guaranteed to be passed a Result type matching the
// fromVersion it was registered with, and is guaranteed to be
// passed a toVersion matching one of the toVersions it was registered with.
type ConvertFn func(from types.Result, toVersion string) (types.Result, error)
type converter struct {
// fromVersion is the CNI Result spec version that convertFn accepts
fromVersion string
// toVersions is a list of versions that convertFn can convert to
toVersions []string
convertFn ConvertFn
}
var converters []*converter
func findConverter(fromVersion, toVersion string) *converter {
for _, c := range converters {
if c.fromVersion == fromVersion {
for _, v := range c.toVersions {
if v == toVersion {
return c
}
}
}
}
return nil
}
// Convert converts a CNI Result to the requested CNI specification version,
// or returns an error if the conversion could not be performed or failed
func Convert(from types.Result, toVersion string) (types.Result, error) {
if toVersion == "" {
toVersion = "0.1.0"
}
fromVersion := from.Version()
// Shortcut for same version
if fromVersion == toVersion {
return from, nil
}
// Otherwise find the right converter
c := findConverter(fromVersion, toVersion)
if c == nil {
return nil, fmt.Errorf("no converter for CNI result version %s to %s",
fromVersion, toVersion)
}
return c.convertFn(from, toVersion)
}
// RegisterConverter registers a CNI Result converter. SHOULD NOT BE CALLED
// EXCEPT FROM CNI ITSELF.
func RegisterConverter(fromVersion string, toVersions []string, convertFn ConvertFn) {
// Make sure there is no converter already registered for these
// from and to versions
for _, v := range toVersions {
if findConverter(fromVersion, v) != nil {
panic(fmt.Sprintf("converter already registered for %s to %s",
fromVersion, v))
}
}
converters = append(converters, &converter{
fromVersion: fromVersion,
toVersions: toVersions,
convertFn: convertFn,
})
}
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