120 lines
3.1 KiB
Go
120 lines
3.1 KiB
Go
package objx
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import (
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"regexp"
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"strconv"
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"strings"
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)
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const (
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// PathSeparator is the character used to separate the elements
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// of the keypath.
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//
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// For example, `location.address.city`
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PathSeparator string = "."
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// arrayAccesRegexString is the regex used to extract the array number
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// from the access path
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arrayAccesRegexString = `^(.+)\[([0-9]+)\]$`
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)
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// arrayAccesRegex is the compiled arrayAccesRegexString
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var arrayAccesRegex = regexp.MustCompile(arrayAccesRegexString)
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// Get gets the value using the specified selector and
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// returns it inside a new Obj object.
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//
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// If it cannot find the value, Get will return a nil
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// value inside an instance of Obj.
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//
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// Get can only operate directly on map[string]interface{} and []interface.
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//
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// Example
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//
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// To access the title of the third chapter of the second book, do:
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//
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// o.Get("books[1].chapters[2].title")
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func (m Map) Get(selector string) *Value {
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rawObj := access(m, selector, nil, false)
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return &Value{data: rawObj}
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}
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// Set sets the value using the specified selector and
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// returns the object on which Set was called.
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//
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// Set can only operate directly on map[string]interface{} and []interface
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//
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// Example
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//
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// To set the title of the third chapter of the second book, do:
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//
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// o.Set("books[1].chapters[2].title","Time to Go")
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func (m Map) Set(selector string, value interface{}) Map {
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access(m, selector, value, true)
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return m
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}
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// getIndex returns the index, which is hold in s by two braches.
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// It also returns s withour the index part, e.g. name[1] will return (1, name).
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// If no index is found, -1 is returned
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func getIndex(s string) (int, string) {
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arrayMatches := arrayAccesRegex.FindStringSubmatch(s)
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if len(arrayMatches) > 0 {
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// Get the key into the map
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selector := arrayMatches[1]
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// Get the index into the array at the key
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// We know this cannt fail because arrayMatches[2] is an int for sure
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index, _ := strconv.Atoi(arrayMatches[2])
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return index, selector
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}
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return -1, s
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}
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// access accesses the object using the selector and performs the
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// appropriate action.
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func access(current interface{}, selector string, value interface{}, isSet bool) interface{} {
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selSegs := strings.SplitN(selector, PathSeparator, 2)
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thisSel := selSegs[0]
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index := -1
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if strings.Contains(thisSel, "[") {
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index, thisSel = getIndex(thisSel)
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}
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if curMap, ok := current.(Map); ok {
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current = map[string]interface{}(curMap)
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}
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// get the object in question
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switch current.(type) {
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case map[string]interface{}:
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curMSI := current.(map[string]interface{})
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if len(selSegs) <= 1 && isSet {
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curMSI[thisSel] = value
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return nil
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}
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_, ok := curMSI[thisSel].(map[string]interface{})
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if (curMSI[thisSel] == nil || !ok) && index == -1 && isSet {
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curMSI[thisSel] = map[string]interface{}{}
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}
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current = curMSI[thisSel]
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default:
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current = nil
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}
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// do we need to access the item of an array?
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if index > -1 {
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if array, ok := current.([]interface{}); ok {
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if index < len(array) {
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current = array[index]
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} else {
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current = nil
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}
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}
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}
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if len(selSegs) > 1 {
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current = access(current, selSegs[1], value, isSet)
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}
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return current
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}
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