From b70ff82141f9bc8762b0c5a58b5357867376d5d1 Mon Sep 17 00:00:00 2001
From: Jason Streifling <jason@streifling.com>
Date: Thu, 17 Oct 2024 21:08:41 +0200
Subject: [PATCH] Delete extensionAttribute.go and simplify undefined
 attributes

---
 atom.go               |  6 ++++++
 commonAttributes.go   | 20 ++++++++++----------
 extensionAttribute.go | 26 --------------------------
 3 files changed, 16 insertions(+), 36 deletions(-)
 delete mode 100644 extensionAttribute.go

diff --git a/atom.go b/atom.go
index b5e6671..6c855d1 100644
--- a/atom.go
+++ b/atom.go
@@ -82,6 +82,12 @@ func isValidLanguageTag(tag LanguageTag) bool {
 	return err == nil
 }
 
+// isValidAttribute checks whether an Attribute is valid. It returns a bool.
+func isValidAttribute(attribute string) bool {
+	regex := regexp.MustCompile(`^[a-zA-Z0-9_]+="[^"]*"$`)
+	return regex.MatchString(attribute)
+}
+
 // NewURN generates an new valid IRI based on a UUID. It returns an IRI.
 func NewURN() IRI {
 	return IRI(fmt.Sprint("urn:uuid:", uuid.New()))
diff --git a/commonAttributes.go b/commonAttributes.go
index 3c6473b..f5641cf 100644
--- a/commonAttributes.go
+++ b/commonAttributes.go
@@ -3,9 +3,9 @@ package atom
 import "fmt"
 
 type CommonAttributes struct {
-	Base                IRI                   `xml:"base,attr,omitempty"`
-	Lang                LanguageTag           `xml:"lang,attr,omitempty"`
-	UndefinedAttributes []*ExtensionAttribute `xml:",any"`
+	Base                IRI         `xml:"base,attr,omitempty"`
+	Lang                LanguageTag `xml:"lang,attr,omitempty"`
+	UndefinedAttributes []string    `xml:",attr"`
 }
 
 // NewCommonAttributes creates a new set of CommonAttributes. It returns a
@@ -15,21 +15,21 @@ func NewCommonAttributes() *CommonAttributes {
 }
 
 // AddExtensionAttribute adds the ExtensionAttribute to the CommonAttributes.
-func (c *CommonAttributes) AddExtensionAttribute(e *ExtensionAttribute) {
+func (c *CommonAttributes) AddExtensionAttribute(name, value string) {
 	if c.UndefinedAttributes == nil {
-		c.UndefinedAttributes = make([]*ExtensionAttribute, 1)
-		c.UndefinedAttributes[0] = e
+		c.UndefinedAttributes = make([]string, 1)
+		c.UndefinedAttributes[0] = fmt.Sprint(name, `="`, value, `"`)
 	} else {
-		c.UndefinedAttributes = append(c.UndefinedAttributes, e)
+		c.UndefinedAttributes = append(c.UndefinedAttributes, fmt.Sprint(name, `="`, value, `"`))
 	}
 }
 
 // Check checks the CommonAttributes for incompatibilities with RFC4287. It
 // returns an error.
 func (c *CommonAttributes) Check() error {
-	for i, e := range c.UndefinedAttributes {
-		if err := e.Check(); err != nil {
-			return fmt.Errorf("extension attribute %v of common attributes: %v", i, err)
+	for _, a := range c.UndefinedAttributes {
+		if !isValidAttribute(a) {
+			return fmt.Errorf("attribute %v of undefined attributes of common attributes not correctly formatted", a)
 		}
 	}
 
diff --git a/extensionAttribute.go b/extensionAttribute.go
deleted file mode 100644
index 8e38700..0000000
--- a/extensionAttribute.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package atom
-
-import (
-	"errors"
-	"fmt"
-)
-
-type ExtensionAttribute struct {
-	Attr string `xml:",attr"`
-}
-
-// NewExtensionAttribute creates a new ExtensionAttribute. It returns a
-// *ExtensionAttribute.
-func NewExtensionAttribute(name, value string) *ExtensionAttribute {
-	return &ExtensionAttribute{Attr: fmt.Sprint(name, `="`, value, `"`)}
-}
-
-// Check checks the ExtensionAttribute for incompatibilities with RFC4287. It
-// returns an error.
-func (e *ExtensionAttribute) Check() error {
-	if e.Attr == "" {
-		return errors.New("value element of extension attribute empty")
-	}
-
-	return nil
-}