From 03f17f5cdf9c3d2dceed1ad20ee87b125ee0feb3 Mon Sep 17 00:00:00 2001
From: David Sharnoff <muir@idiom.org>
Date: Sun, 7 Nov 2021 22:03:33 -0800
Subject: [PATCH] can now split tag values

---
 parsetag.go      | 42 ++++++++++++++++++++++++++++++------------
 parsetag_test.go | 26 ++++++++++++++++++++++++++
 unpack.go        | 24 +++++++++++++++++++++---
 3 files changed, 77 insertions(+), 15 deletions(-)

diff --git a/parsetag.go b/parsetag.go
index f4006fc..22a6171 100644
--- a/parsetag.go
+++ b/parsetag.go
@@ -127,29 +127,47 @@ func (tag Tag) Fill(model interface{}, opts ...FillOptArg) error {
 	var walkErr error
 	WalkStructElements(v.Type(), func(f reflect.StructField) bool {
 		tag := f.Tag.Get(opt.tag)
-		name := f.Name
 		if tag == "-" {
 			return false
 		}
 		count++
-		i, err := strconv.Atoi(tag)
+		parts := strings.Split(tag, ",")
 		var value string
-		if err == nil {
-			// positional!
-			if i >= len(elements) {
-				return true
+		if len(parts) > 0 && parts[0] != "" {
+			i, err := strconv.Atoi(parts[0])
+			if err == nil {
+				// positional!
+				if i >= len(elements) {
+					return true
+				}
+				value = elements[i]
+			} else {
+				value = kv[parts[0]]
 			}
-			value = elements[i]
 		} else {
-			if tag != "" {
-				name = tag
-			}
-			value = kv[name]
+			value = kv[f.Name]
 		}
 		if value == "" {
 			return true
 		}
-		set, err := MakeStringSetter(f.Type)
+		var sso []StringSetterArg
+		if len(parts) > 1 {
+			for _, part := range parts[1:] {
+				if strings.HasPrefix(part, "split=") {
+					splitOn := part[len("split="):]
+					switch splitOn {
+					case "comma":
+						splitOn = ","
+					case "quote":
+						splitOn = `"`
+					case "space":
+						splitOn = " "
+					}
+					sso = append(sso, WithSplitOn(splitOn))
+				}
+			}
+		}
+		set, err := MakeStringSetter(f.Type, sso...)
 		if err != nil {
 			walkErr = errors.Wrapf(err, "Cannot set %s", f.Type)
 			return true
diff --git a/parsetag_test.go b/parsetag_test.go
index b5d5bd4..38776b7 100644
--- a/parsetag_test.go
+++ b/parsetag_test.go
@@ -1,6 +1,7 @@
 package reflectutils_test
 
 import (
+	"encoding/json"
 	"reflect"
 	"testing"
 
@@ -29,3 +30,28 @@ func ts(t *testing.T, tag reflect.StructTag, want ...string) {
 	}
 	assert.Equal(t, want, s, tag)
 }
+
+func TestFill(t *testing.T) {
+	type tagData struct {
+		P0 []string `tf:"0,split=space" json:",omitempty"`
+	}
+	type testStruct struct {
+		T1 string `xyz:"a b" want:"{\"P0\":[\"a\",\"b\"]}"`
+	}
+	var x testStruct
+	reflectutils.WalkStructElements(reflect.TypeOf(x), func(f reflect.StructField) bool {
+		var got tagData
+		t.Logf("%s: %s", f.Name, f.Tag)
+		err := reflectutils.SplitTag(f.Tag).Set().Get("xyz").Fill(&got, reflectutils.WithTag("tf"))
+		if !assert.NoErrorf(t, err, "extract tag %s", f.Name) {
+			return true
+		}
+		var want tagData
+		err = json.Unmarshal([]byte(f.Tag.Get("want")), &want)
+		if !assert.NoErrorf(t, err, "extract want %s", f.Name) {
+			return true
+		}
+		assert.Equal(t, want, got, f.Name)
+		return true
+	})
+}
diff --git a/unpack.go b/unpack.go
index 91d984a..6253383 100644
--- a/unpack.go
+++ b/unpack.go
@@ -11,6 +11,18 @@ import (
 
 var textUnmarshallerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
 
+type stringSetterOpts struct {
+	split string
+}
+
+type StringSetterArg func(*stringSetterOpts)
+
+func WithSplitOn(s string) StringSetterArg {
+	return func(o *stringSetterOpts) {
+		o.split = s
+	}
+}
+
 // MakeStringSetter handles setting a reflect.Value from a string.
 // Based on type, it returns a function to do the work.  It is assumed that the
 // reflect.Type matches the reflect.Value.  If not, panic is likely.
@@ -22,7 +34,13 @@ var textUnmarshallerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem
 //
 // Maps, structs, channels, interfaces, channels, and funcs are not supported unless
 // they happen to implent encoding.TextUnmarshaler.
-func MakeStringSetter(t reflect.Type) (func(target reflect.Value, value string) error, error) {
+func MakeStringSetter(t reflect.Type, optArgs ...StringSetterArg) (func(target reflect.Value, value string) error, error) {
+	opts := stringSetterOpts{
+		split: ",",
+	}
+	for _, f := range optArgs {
+		f(&opts)
+	}
 	if t.AssignableTo(textUnmarshallerType) {
 		return func(target reflect.Value, value string) error {
 			p := reflect.New(t.Elem())
@@ -111,7 +129,7 @@ func MakeStringSetter(t reflect.Type) (func(target reflect.Value, value string)
 			return nil, err
 		}
 		return func(target reflect.Value, value string) error {
-			for i, v := range strings.SplitN(value, ",", target.Cap()) {
+			for i, v := range strings.SplitN(value, opts.split, target.Cap()) {
 				err := setElem(target.Index(i), v)
 				if err != nil {
 					return err
@@ -125,7 +143,7 @@ func MakeStringSetter(t reflect.Type) (func(target reflect.Value, value string)
 			return nil, err
 		}
 		return func(target reflect.Value, value string) error {
-			values := strings.Split(value, ",")
+			values := strings.Split(value, opts.split)
 			a := reflect.MakeSlice(target.Type(), len(values), len(values))
 			for i, v := range values {
 				err := setElem(a.Index(i), v)