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package objx
import (
"reflect"
"regexp"
"strconv"
"strings"
)
const (
// PathSeparator is the character used to separate the elements
// of the keypath.
//
// For example, `location.address.city`
PathSeparator string = "."
// arrayAccessRegexString is the regex used to extract the array number
// from the access path
arrayAccessRegexString = `^(.+)\[([0-9]+)\]$`
// mapAccessRegexString is the regex used to extract the map key
// from the access path
mapAccessRegexString = `^([^\[]*)\[([^\]]+)\](.*)$`
)
// arrayAccessRegex is the compiled arrayAccessRegexString
var arrayAccessRegex = regexp.MustCompile(arrayAccessRegexString)
// mapAccessRegex is the compiled mapAccessRegexString
var mapAccessRegex = regexp.MustCompile(mapAccessRegexString)
// Get gets the value using the specified selector and
// returns it inside a new Obj object.
//
// If it cannot find the value, Get will return a nil
// value inside an instance of Obj.
//
// Get can only operate directly on map[string]interface{} and []interface.
//
// # Example
//
// To access the title of the third chapter of the second book, do:
//
// o.Get("books[1].chapters[2].title")
func (m Map) Get(selector string) *Value {
rawObj := access(m, selector, nil, false)
return &Value{data: rawObj}
}
// Set sets the value using the specified selector and
// returns the object on which Set was called.
//
// Set can only operate directly on map[string]interface{} and []interface
//
// # Example
//
// To set the title of the third chapter of the second book, do:
//
// o.Set("books[1].chapters[2].title","Time to Go")
func (m Map) Set(selector string, value interface{}) Map {
access(m, selector, value, true)
return m
}
// getIndex returns the index, which is hold in s by two branches.
// It also returns s without the index part, e.g. name[1] will return (1, name).
// If no index is found, -1 is returned
func getIndex(s string) (int, string) {
arrayMatches := arrayAccessRegex.FindStringSubmatch(s)
if len(arrayMatches) > 0 {
// Get the key into the map
selector := arrayMatches[1]
// Get the index into the array at the key
// We know this can't fail because arrayMatches[2] is an int for sure
index, _ := strconv.Atoi(arrayMatches[2])
return index, selector
}
return -1, s
}
// getKey returns the key which is held in s by two brackets.
// It also returns the next selector.
func getKey(s string) (string, string) {
selSegs := strings.SplitN(s, PathSeparator, 2)
thisSel := selSegs[0]
nextSel := ""
if len(selSegs) > 1 {
nextSel = selSegs[1]
}
mapMatches := mapAccessRegex.FindStringSubmatch(s)
if len(mapMatches) > 0 {
if _, err := strconv.Atoi(mapMatches[2]); err != nil {
thisSel = mapMatches[1]
nextSel = "[" + mapMatches[2] + "]" + mapMatches[3]
if thisSel == "" {
thisSel = mapMatches[2]
nextSel = mapMatches[3]
}
if nextSel == "" {
selSegs = []string{"", ""}
} else if nextSel[0] == '.' {
nextSel = nextSel[1:]
}
}
}
return thisSel, nextSel
}
// access accesses the object using the selector and performs the
// appropriate action.
func access(current interface{}, selector string, value interface{}, isSet bool) interface{} {
thisSel, nextSel := getKey(selector)
indexes := []int{}
for strings.Contains(thisSel, "[") {
prevSel := thisSel
index := -1
index, thisSel = getIndex(thisSel)
indexes = append(indexes, index)
if prevSel == thisSel {
break
}
}
if curMap, ok := current.(Map); ok {
current = map[string]interface{}(curMap)
}
// get the object in question
switch current.(type) {
case map[string]interface{}:
curMSI := current.(map[string]interface{})
if nextSel == "" && isSet {
curMSI[thisSel] = value
return nil
}
_, ok := curMSI[thisSel].(map[string]interface{})
if !ok {
_, ok = curMSI[thisSel].(Map)
}
if (curMSI[thisSel] == nil || !ok) && len(indexes) == 0 && isSet {
curMSI[thisSel] = map[string]interface{}{}
}
current = curMSI[thisSel]
default:
current = nil
}
// do we need to access the item of an array?
if len(indexes) > 0 {
num := len(indexes)
for num > 0 {
num--
index := indexes[num]
indexes = indexes[:num]
if array, ok := interSlice(current); ok {
if index < len(array) {
current = array[index]
} else {
current = nil
break
}
}
}
}
if nextSel != "" {
current = access(current, nextSel, value, isSet)
}
return current
}
func interSlice(slice interface{}) ([]interface{}, bool) {
if array, ok := slice.([]interface{}); ok {
return array, ok
}
s := reflect.ValueOf(slice)
if s.Kind() != reflect.Slice {
return nil, false
}
ret := make([]interface{}, s.Len())
for i := 0; i < s.Len(); i++ {
ret[i] = s.Index(i).Interface()
}
return ret, true
}
|
