Golang structure field parsing helper

ParseStructs.go

/**
 * Recursive struct parser for parsing string fields in go structure
 *  Copyright 2017 Ryan Kurte
 *  Released under the MIT License (https://choosealicense.com/licenses/mit/)
 */

package parser

import (
	"log"
	"os"
	"reflect"
)

// Parse is a string parsing function to be called when strings are found
type Parse func(in string) string

// ParseStructStrings reflects over a structure and calls Parse when strings are located
func ParseStructStrings(parse Parse, obj interface{}) {
	parseStringsRecursive(parse, reflect.ValueOf(obj))
}

func parseStringsRecursive(parse Parse, val reflect.Value) {
	switch val.Kind() {
	case reflect.Ptr:
		o := val.Elem()
		if !o.IsValid() {
			log.Panicf("Reflecting parser error: invalid pointer %+v", val)
		}
		parseStringsRecursive(parse, o)
	case reflect.Struct:
		for i := 0; i < val.NumField(); i++ {
			parseStringsRecursive(parse, val.Field(i))
		}
	case reflect.Slice:
		for i := 0; i < val.Len(); i++ {
			parseStringsRecursive(parse, val.Index(i))
		}
	case reflect.Map:
		for _, k := range val.MapKeys() {
			mapVal := val.MapIndex(k)
			if mapVal.Kind() == reflect.String {
				val.SetMapIndex(k, reflect.ValueOf(parse(mapVal.String())))
			} else {
				// TODO: this is going to fail so hard with objects in maps
				log.Panicf("Reflecting parser error: structs-in-maps not supported")
			}
		}
	case reflect.String:
		value := parse(val.String())
		val.SetString(value)
	}
}