change: allow unescape_with to override standard replacements

This involves swapping the order in which the main loop of that function
checks for `named_entities` and `entity_resolver` closures, namely we
check the user-provided `entity_resolver` first. This shouldn't be a
breaking change unless some existing client code already had overridden
`named_entity` replacements, but those replacements would have been
noops under the previous implementation so the fix should be trivial.

Changelog.md

@@ -34,6 +34,8 @@ to get an offset of the error position. For `SyntaxError`s the range
   it can handle every attribute that does not match existing cases within an enum variant.
 - [#722]: Allow to pass owned strings to `Writer::create_element`. This is breaking change!
 - [#275]: Added `ElementWriter::new_line()` which enables pretty printing elements with multiple attributes.
+- [#734]: Allow to override resolution of predefined entities (`lt`, `gt`, `apos`, `quot`, `amp`)
+  in `unescape_with` family of methods.
 
 ### Bug Fixes
 
@@ -81,6 +83,7 @@ to get an offset of the error position. For `SyntaxError`s the range
 [#704]: https://github.com/tafia/quick-xml/pull/704
 [#705]: https://github.com/tafia/quick-xml/pull/705
 [#722]: https://github.com/tafia/quick-xml/pull/722
+[#734]: https://github.com/tafia/quick-xml/pull/734
 [#738]: https://github.com/tafia/quick-xml/pull/738
 
 

src/escape.rs

@@ -192,8 +192,39 @@ pub fn unescape(raw: &str) -> Result<Cow<str>, EscapeError> {
 ///
 /// If feature [`escape-html`] is enabled, then recognizes all [HTML5 escapes].
 ///
+/// Predefined entities will be resolved _after_ trying to resolve with `resolve_entity`,
+/// which allows you to override default behavior which required in some XML dialects.
+///
+/// Character references (`&#hh;`) cannot be overridden, they are resolved before
+/// calling `resolve_entity`.
+///
+/// Note, that entities will not be resolved recursively. In order to satisfy the
+/// XML [requirements] you should unescape nested entities by yourself.
+///
+/// # Example
+///
+/// ```
+/// # use quick_xml::escape::unescape_with;
+/// # use pretty_assertions::assert_eq;
+/// let override_named_entities = |entity: &str| match entity {
+///     // Override standard entities
+///     "lt" => Some("FOO"),
+///     "gt" => Some("BAR"),
+///     // Resolve custom entities
+///     "baz" => Some("&lt;"),
+///     // All other entities produces EscapeError::UnrecognizedSymbol error
+///     _ => None,
+/// };
+///
+/// assert_eq!(
+///     unescape_with("&amp;&lt;test&gt;&baz;", override_named_entities).unwrap(),
+///     "&FOOtestBAR&lt;"
+/// );
+/// ```
+///
 /// [`escape-html`]: ../index.html#escape-html
 /// [HTML5 escapes]: https://dev.w3.org/html5/html-author/charref
+/// [requirements]: https://www.w3.org/TR/xml11/#intern-replacement
 pub fn unescape_with<'input, 'entity, F>(
     raw: &'input str,
     mut resolve_entity: F,
@@ -221,10 +252,10 @@ where
                 if let Some(entity) = pat.strip_prefix('#') {
                     let codepoint = parse_number(entity, start..end)?;
                     unescaped.push_str(codepoint.encode_utf8(&mut [0u8; 4]));
-                } else if let Some(value) = named_entity(pat) {
-                    unescaped.push_str(value);
                 } else if let Some(value) = resolve_entity(pat) {
                     unescaped.push_str(value);
+                } else if let Some(value) = named_entity(pat) {
+                    unescaped.push_str(value);
                 } else {
                     return Err(EscapeError::UnrecognizedSymbol(
                         start + 1..end,