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// Copyright 2015 xeipuuv ( https://github.com/xeipuuv )
//
// 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 xeipuuv
// author-github https://github.com/xeipuuv
// author-mail xeipuuv@gmail.com
//
// repository-name gojsonpointer
// repository-desc An implementation of JSON Pointer - Go language
//
// description Main and unique file.
//
// created 25-02-2013
package gojsonpointer
import (
"errors"
"fmt"
"reflect"
"strconv"
"strings"
)
const (
const_empty_pointer = ``
const_pointer_separator = `/`
const_invalid_start = `JSON pointer must be empty or start with a "` + const_pointer_separator + `"`
)
type implStruct struct {
mode string // "SET" or "GET"
inDocument interface{}
setInValue interface{}
getOutNode interface{}
getOutKind reflect.Kind
outError error
}
type JsonPointer struct {
referenceTokens []string
}
// NewJsonPointer parses the given string JSON pointer and returns an object
func NewJsonPointer(jsonPointerString string) (p JsonPointer, err error) {
// Pointer to the root of the document
if len(jsonPointerString) == 0 {
// Keep referenceTokens nil
return
}
if jsonPointerString[0] != '/' {
return p, errors.New(const_invalid_start)
}
p.referenceTokens = strings.Split(jsonPointerString[1:], const_pointer_separator)
return
}
// Uses the pointer to retrieve a value from a JSON document
func (p *JsonPointer) Get(document interface{}) (interface{}, reflect.Kind, error) {
is := &implStruct{mode: "GET", inDocument: document}
p.implementation(is)
return is.getOutNode, is.getOutKind, is.outError
}
// Uses the pointer to update a value from a JSON document
func (p *JsonPointer) Set(document interface{}, value interface{}) (interface{}, error) {
is := &implStruct{mode: "SET", inDocument: document, setInValue: value}
p.implementation(is)
return document, is.outError
}
// Uses the pointer to delete a value from a JSON document
func (p *JsonPointer) Delete(document interface{}) (interface{}, error) {
is := &implStruct{mode: "DEL", inDocument: document}
p.implementation(is)
return document, is.outError
}
// Both Get and Set functions use the same implementation to avoid code duplication
func (p *JsonPointer) implementation(i *implStruct) {
kind := reflect.Invalid
// Full document when empty
if len(p.referenceTokens) == 0 {
i.getOutNode = i.inDocument
i.outError = nil
i.getOutKind = kind
i.outError = nil
return
}
node := i.inDocument
previousNodes := make([]interface{}, len(p.referenceTokens))
previousTokens := make([]string, len(p.referenceTokens))
for ti, token := range p.referenceTokens {
isLastToken := ti == len(p.referenceTokens)-1
previousNodes[ti] = node
previousTokens[ti] = token
switch v := node.(type) {
case map[string]interface{}:
decodedToken := decodeReferenceToken(token)
if _, ok := v[decodedToken]; ok {
node = v[decodedToken]
if isLastToken && i.mode == "SET" {
v[decodedToken] = i.setInValue
} else if isLastToken && i.mode == "DEL" {
delete(v, decodedToken)
}
} else if isLastToken && i.mode == "SET" {
v[decodedToken] = i.setInValue
} else {
i.outError = fmt.Errorf("Object has no key '%s'", decodedToken)
i.getOutKind = reflect.Map
i.getOutNode = nil
return
}
case []interface{}:
tokenIndex, err := strconv.Atoi(token)
if err != nil {
i.outError = fmt.Errorf("Invalid array index '%s'", token)
i.getOutKind = reflect.Slice
i.getOutNode = nil
return
}
if tokenIndex < 0 || tokenIndex >= len(v) {
i.outError = fmt.Errorf("Out of bound array[0,%d] index '%d'", len(v), tokenIndex)
i.getOutKind = reflect.Slice
i.getOutNode = nil
return
}
node = v[tokenIndex]
if isLastToken && i.mode == "SET" {
v[tokenIndex] = i.setInValue
} else if isLastToken && i.mode == "DEL" {
v[tokenIndex] = v[len(v)-1]
v[len(v)-1] = nil
v = v[:len(v)-1]
previousNodes[ti-1].(map[string]interface{})[previousTokens[ti-1]] = v
}
default:
i.outError = fmt.Errorf("Invalid token reference '%s'", token)
i.getOutKind = reflect.ValueOf(node).Kind()
i.getOutNode = nil
return
}
}
i.getOutNode = node
i.getOutKind = reflect.ValueOf(node).Kind()
i.outError = nil
}
// Pointer to string representation function
func (p *JsonPointer) String() string {
if len(p.referenceTokens) == 0 {
return const_empty_pointer
}
pointerString := const_pointer_separator + strings.Join(p.referenceTokens, const_pointer_separator)
return pointerString
}
// Specific JSON pointer encoding here
// ~0 => ~
// ~1 => /
// ... and vice versa
func decodeReferenceToken(token string) string {
step1 := strings.Replace(token, `~1`, `/`, -1)
step2 := strings.Replace(step1, `~0`, `~`, -1)
return step2
}
func encodeReferenceToken(token string) string {
step1 := strings.Replace(token, `~`, `~0`, -1)
step2 := strings.Replace(step1, `/`, `~1`, -1)
return step2
}
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