traefik/vendor/github.com/go-openapi/jsonpointer/pointer.go
2017-03-09 13:13:02 +01:00

238 lines
6 KiB
Go

// Copyright 2013 sigu-399 ( https://github.com/sigu-399 )
//
// 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.
// author sigu-399
// author-github https://github.com/sigu-399
// author-mail sigu.399@gmail.com
//
// repository-name jsonpointer
// repository-desc An implementation of JSON Pointer - Go language
//
// description Main and unique file.
//
// created 25-02-2013
package jsonpointer
import (
"errors"
"fmt"
"reflect"
"strconv"
"strings"
"github.com/go-openapi/swag"
)
const (
emptyPointer = ``
pointerSeparator = `/`
invalidStart = `JSON pointer must be empty or start with a "` + pointerSeparator
)
var jsonPointableType = reflect.TypeOf(new(JSONPointable)).Elem()
// JSONPointable is an interface for structs to implement when they need to customize the
// json pointer process
type JSONPointable interface {
JSONLookup(string) (interface{}, error)
}
type implStruct struct {
mode string // "SET" or "GET"
inDocument interface{}
setInValue interface{}
getOutNode interface{}
getOutKind reflect.Kind
outError error
}
// New creates a new json pointer for the given string
func New(jsonPointerString string) (Pointer, error) {
var p Pointer
err := p.parse(jsonPointerString)
return p, err
}
// Pointer the json pointer reprsentation
type Pointer struct {
referenceTokens []string
}
// "Constructor", parses the given string JSON pointer
func (p *Pointer) parse(jsonPointerString string) error {
var err error
if jsonPointerString != emptyPointer {
if !strings.HasPrefix(jsonPointerString, pointerSeparator) {
err = errors.New(invalidStart)
} else {
referenceTokens := strings.Split(jsonPointerString, pointerSeparator)
for _, referenceToken := range referenceTokens[1:] {
p.referenceTokens = append(p.referenceTokens, referenceToken)
}
}
}
return err
}
// Get uses the pointer to retrieve a value from a JSON document
func (p *Pointer) Get(document interface{}) (interface{}, reflect.Kind, error) {
return p.get(document, swag.DefaultJSONNameProvider)
}
// GetForToken gets a value for a json pointer token 1 level deep
func GetForToken(document interface{}, decodedToken string) (interface{}, reflect.Kind, error) {
return getSingleImpl(document, decodedToken, swag.DefaultJSONNameProvider)
}
func getSingleImpl(node interface{}, decodedToken string, nameProvider *swag.NameProvider) (interface{}, reflect.Kind, error) {
kind := reflect.Invalid
rValue := reflect.Indirect(reflect.ValueOf(node))
kind = rValue.Kind()
switch kind {
case reflect.Struct:
if rValue.Type().Implements(jsonPointableType) {
r, err := node.(JSONPointable).JSONLookup(decodedToken)
if err != nil {
return nil, kind, err
}
return r, kind, nil
}
nm, ok := nameProvider.GetGoNameForType(rValue.Type(), decodedToken)
if !ok {
return nil, kind, fmt.Errorf("object has no field %q", decodedToken)
}
fld := rValue.FieldByName(nm)
return fld.Interface(), kind, nil
case reflect.Map:
kv := reflect.ValueOf(decodedToken)
mv := rValue.MapIndex(kv)
if mv.IsValid() && !swag.IsZero(mv) {
return mv.Interface(), kind, nil
}
return nil, kind, fmt.Errorf("object has no key %q", decodedToken)
case reflect.Slice:
tokenIndex, err := strconv.Atoi(decodedToken)
if err != nil {
return nil, kind, err
}
sLength := rValue.Len()
if tokenIndex < 0 || tokenIndex >= sLength {
return nil, kind, fmt.Errorf("index out of bounds array[0,%d] index '%d'", sLength, tokenIndex)
}
elem := rValue.Index(tokenIndex)
return elem.Interface(), kind, nil
default:
return nil, kind, fmt.Errorf("invalid token reference %q", decodedToken)
}
}
func (p *Pointer) get(node interface{}, nameProvider *swag.NameProvider) (interface{}, reflect.Kind, error) {
if nameProvider == nil {
nameProvider = swag.DefaultJSONNameProvider
}
kind := reflect.Invalid
// Full document when empty
if len(p.referenceTokens) == 0 {
return node, kind, nil
}
for _, token := range p.referenceTokens {
decodedToken := Unescape(token)
r, knd, err := getSingleImpl(node, decodedToken, nameProvider)
if err != nil {
return nil, knd, err
}
node, kind = r, knd
}
rValue := reflect.ValueOf(node)
kind = rValue.Kind()
return node, kind, nil
}
// DecodedTokens returns the decoded tokens
func (p *Pointer) DecodedTokens() []string {
result := make([]string, 0, len(p.referenceTokens))
for _, t := range p.referenceTokens {
result = append(result, Unescape(t))
}
return result
}
// IsEmpty returns true if this is an empty json pointer
// this indicates that it points to the root document
func (p *Pointer) IsEmpty() bool {
return len(p.referenceTokens) == 0
}
// Pointer to string representation function
func (p *Pointer) String() string {
if len(p.referenceTokens) == 0 {
return emptyPointer
}
pointerString := pointerSeparator + strings.Join(p.referenceTokens, pointerSeparator)
return pointerString
}
// Specific JSON pointer encoding here
// ~0 => ~
// ~1 => /
// ... and vice versa
const (
encRefTok0 = `~0`
encRefTok1 = `~1`
decRefTok0 = `~`
decRefTok1 = `/`
)
// Unescape unescapes a json pointer reference token string to the original representation
func Unescape(token string) string {
step1 := strings.Replace(token, encRefTok1, decRefTok1, -1)
step2 := strings.Replace(step1, encRefTok0, decRefTok0, -1)
return step2
}
// Escape escapes a pointer reference token string
func Escape(token string) string {
step1 := strings.Replace(token, decRefTok0, encRefTok0, -1)
step2 := strings.Replace(step1, decRefTok1, encRefTok1, -1)
return step2
}