structor.go

package main

import (
	"fmt"
	"reflect"
	"strconv"
	"strings"
)

type s1 struct {
	S string
	I int
}

const t1 = "test 1\nbest 2\nfest 3\nvest 4"

type s2 struct {
	F float32
	S string
}

const t2 = "3.1415 trial\n2.7182 vile\n1.6180 vial\n6.0221 denial"

func main() {
	var output1 []s1
	TextToStruct(&output1, t1)
	fmt.Printf("%+v\n", output1)

	var output2 []s2
	TextToStruct(&output2, t2)
	fmt.Printf("%+v\n", output2)
}

func TextToStruct(s interface{}, text string) {
	p := reflect.ValueOf(s)
	if p.Kind() != reflect.Ptr {
		panic("not pointer")
	}
	a := p.Elem()
	if a.Kind() != reflect.Slice {
		panic("not pointer to slice")
	}
	t := a.Type().Elem()

	lines := strings.Split(text, "\n")
	a.Set(reflect.MakeSlice(reflect.SliceOf(t), len(lines), len(lines)))

	for j, line := range lines {
		words := strings.Split(line, " ")
		if len(words) != t.NumField() {
			panic("wrong word count")
		}
		for i := 0; i < t.NumField(); i++ {
			switch a.Index(j).Field(i).Kind() {
			case reflect.String:
				a.Index(j).Field(i).SetString(words[i])
			case reflect.Int:
				x, _ := strconv.Atoi(words[i])
				a.Index(j).Field(i).SetInt(int64(x))
			case reflect.Float32:
				x, _ := strconv.ParseFloat(words[i], 32)
				a.Index(j).Field(i).SetFloat(x)
			default:
				panic("unimplemented")
				// I'm not sure if there's generic conversion
			}
		}

	}
}