Change unescape_ functions from Fn to FnMut.

Changelog.md

@@ -17,7 +17,11 @@
 ### Misc Changes
 
 - [#584]: Export `EscapeError` from the crate
+- [#581]: Relax requirements for `unsescape_*` set of functions -- their now use
+  `FnMut` instead of `Fn` for `resolve_entity` parameters, like `Iterator::map`
+  from `std`.
 
+[#581]: https://github.com/tafia/quick-xml/pull/581
 [#584]: https://github.com/tafia/quick-xml/pull/584
 
 

src/escapei.rs

@@ -159,11 +159,11 @@ pub fn unescape(raw: &str) -> Result<Cow<str>, EscapeError> {
 /// [HTML5 escapes]: https://dev.w3.org/html5/html-author/charref
 pub fn unescape_with<'input, 'entity, F>(
     raw: &'input str,
-    resolve_entity: F,
+    mut resolve_entity: F,
 ) -> Result<Cow<'input, str>, EscapeError>
 where
     // the lifetime of the output comes from a capture or is `'static`
-    F: Fn(&str) -> Option<&'entity str>,
+    F: FnMut(&str) -> Option<&'entity str>,
 {
     let bytes = raw.as_bytes();
     let mut unescaped = None;

src/events/attributes.rs

@@ -60,7 +60,7 @@ impl<'a> Attribute<'a> {
     #[cfg(any(doc, not(feature = "encoding")))]
     pub fn unescape_value_with<'entity>(
         &self,
-        resolve_entity: impl Fn(&str) -> Option<&'entity str>,
+        resolve_entity: impl FnMut(&str) -> Option<&'entity str>,
     ) -> XmlResult<Cow<'a, str>> {
         // from_utf8 should never fail because content is always UTF-8 encoded
         let decoded = match &self.value {
@@ -91,7 +91,7 @@ impl<'a> Attribute<'a> {
     pub fn decode_and_unescape_value_with<'entity, B>(
         &self,
         reader: &Reader<B>,
-        resolve_entity: impl Fn(&str) -> Option<&'entity str>,
+        resolve_entity: impl FnMut(&str) -> Option<&'entity str>,
     ) -> XmlResult<Cow<'a, str>> {
         let decoded = match &self.value {
             Cow::Borrowed(bytes) => reader.decoder().decode(bytes)?,

src/events/mod.rs

@@ -740,7 +740,7 @@ impl<'a> BytesText<'a> {
     /// non-UTF-8 encoding.
     pub fn unescape_with<'entity>(
         &self,
-        resolve_entity: impl Fn(&str) -> Option<&'entity str>,
+        resolve_entity: impl FnMut(&str) -> Option<&'entity str>,
     ) -> Result<Cow<'a, str>> {
         let decoded = match &self.content {
             Cow::Borrowed(bytes) => self.decoder.decode(bytes)?,