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package objx
import (
"regexp"
"strconv"
"strings"
)
// arrayAccesRegexString is the regex used to extract the array number
// from the access path
const arrayAccesRegexString = `^(.+)\[([0-9]+)\]$`
// arrayAccesRegex is the compiled arrayAccesRegexString
var arrayAccesRegex = regexp.MustCompile(arrayAccesRegexString)
// 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
}
// access accesses the object using the selector and performs the
// appropriate action.
func access(current, selector, value interface{}, isSet bool) interface{} {
switch selector.(type) {
case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
if array, ok := current.([]interface{}); ok {
index := intFromInterface(selector)
if index >= len(array) {
return nil
}
return array[index]
}
return nil
case string:
selStr := selector.(string)
selSegs := strings.SplitN(selStr, PathSeparator, 2)
thisSel := selSegs[0]
index := -1
var err error
if strings.Contains(thisSel, "[") {
arrayMatches := arrayAccesRegex.FindStringSubmatch(thisSel)
if len(arrayMatches) > 0 {
// Get the key into the map
thisSel = arrayMatches[1]
// Get the index into the array at the key
index, err = strconv.Atoi(arrayMatches[2])
if err != nil {
// This should never happen. If it does, something has gone
// seriously wrong. Panic.
panic("objx: Array index is not an integer. Must use array[int].")
}
}
}
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 len(selSegs) <= 1 && isSet {
curMSI[thisSel] = value
return nil
}
current = curMSI[thisSel]
default:
current = nil
}
// do we need to access the item of an array?
if index > -1 {
if array, ok := current.([]interface{}); ok {
if index < len(array) {
current = array[index]
} else {
current = nil
}
}
}
if len(selSegs) > 1 {
current = access(current, selSegs[1], value, isSet)
}
}
return current
}
// intFromInterface converts an interface object to the largest
// representation of an unsigned integer using a type switch and
// assertions
func intFromInterface(selector interface{}) int {
var value int
switch selector.(type) {
case int:
value = selector.(int)
case int8:
value = int(selector.(int8))
case int16:
value = int(selector.(int16))
case int32:
value = int(selector.(int32))
case int64:
value = int(selector.(int64))
case uint:
value = int(selector.(uint))
case uint8:
value = int(selector.(uint8))
case uint16:
value = int(selector.(uint16))
case uint32:
value = int(selector.(uint32))
case uint64:
value = int(selector.(uint64))
default:
return 0
}
return value
}
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