Remove quick_xml::encoding::Decoder and Reader::decoder()

As quick-xml will pre-decode everything, it is unnecessary.

Author: dralley

Cargo.toml

@@ -84,7 +84,7 @@ async-tokio = ["tokio"]
 ## let mut buf = Vec::new();
 ## let mut unsupported = false;
 ## loop {
-##     if !reader.decoder().encoding().is_ascii_compatible() {
+##     if !reader.encoding().is_ascii_compatible() {
 ##         unsupported = true;
 ##         break;
 ##     }

Changelog.md

@@ -19,7 +19,11 @@
 
 ### Misc Changes
 
-[#441]: https://github.com/tafia/quick-xml/issues/441
+- [#441]: `Reader::decoder()` removed as it is no longer necessary (`Reader` already
+  decodes everything for you). `Reader::encoding()` is provided to make the current
+  encoding accessible as it was before.
+
+[#441]: https://github.com/tafia/quick-xml/pull/441
 
 ## 0.24.0 -- 2022-08-28
 

src/encoding.rs

@@ -75,74 +75,6 @@ impl<R: io::Read> io::BufRead for Utf8BytesReader<R> {
     }
 }
 
-/// Decoder of byte slices into strings.
-///
-/// If feature `encoding` is enabled, this encoding taken from the `"encoding"`
-/// XML declaration or assumes UTF-8, if XML has no <?xml ?> declaration, encoding
-/// key is not defined or contains unknown encoding.
-///
-/// The library supports any UTF-8 compatible encodings that crate `encoding_rs`
-/// is supported. [*UTF-16 and ISO-2022-JP are not supported at the present*][utf16].
-///
-/// If feature `encoding` is disabled, the decoder is always UTF-8 decoder:
-/// any XML declarations are ignored.
-///
-/// [utf16]: https://github.com/tafia/quick-xml/issues/158
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
-pub struct Decoder {
-    #[cfg(feature = "encoding")]
-    pub(crate) encoding: &'static Encoding,
-}
-
-impl Decoder {
-    pub(crate) fn utf8() -> Self {
-        Decoder {
-            #[cfg(feature = "encoding")]
-            encoding: UTF_8,
-        }
-    }
-
-    #[cfg(all(test, feature = "encoding", feature = "serialize"))]
-    pub(crate) fn utf16() -> Self {
-        Decoder { encoding: UTF_16LE }
-    }
-}
-
-impl Decoder {
-    /// Returns the `Reader`s encoding.
-    ///
-    /// This encoding will be used by [`decode`].
-    ///
-    /// [`decode`]: Self::decode
-    #[cfg(feature = "encoding")]
-    pub const fn encoding(&self) -> &'static Encoding {
-        self.encoding
-    }
-
-    /// ## Without `encoding` feature
-    ///
-    /// Decodes an UTF-8 slice regardless of XML declaration and ignoring BOM
-    /// if it is present in the `bytes`.
-    ///
-    /// ## With `encoding` feature
-    ///
-    /// Decodes specified bytes using encoding, declared in the XML, if it was
-    /// declared there, or UTF-8 otherwise, and ignoring BOM if it is present
-    /// in the `bytes`.
-    ///
-    /// ----
-    /// Returns an error in case of malformed sequences in the `bytes`.
-    pub fn decode<'b>(&self, bytes: &'b [u8]) -> Result<Cow<'b, str>> {
-        #[cfg(not(feature = "encoding"))]
-        let decoded = Ok(Cow::Borrowed(std::str::from_utf8(bytes)?));
-
-        #[cfg(feature = "encoding")]
-        let decoded = decode(bytes, self.encoding);
-
-        decoded
-    }
-}
-
 /// Decodes the provided bytes using the specified encoding.
 ///
 /// Returns an error in case of malformed or non-representable sequences in the `bytes`.

src/lib.rs

@@ -65,7 +65,6 @@ pub mod utils;
 pub mod writer;
 
 // reexports
-pub use crate::encoding::Decoder;
 #[cfg(feature = "serialize")]
 pub use crate::errors::serialize::DeError;
 pub use crate::errors::{Error, Result};

src/reader/buffered_reader.rs

@@ -437,9 +437,9 @@ mod test {
                 Reader::from_reader(b"\xFF\xFE<?xml encoding='windows-1251'?>".as_ref());
             let mut buf = Vec::new();
 
-            assert_eq!(reader.decoder().encoding(), UTF_8);
+            assert_eq!(reader.encoding(), UTF_8);
             reader.read_event_into(&mut buf).unwrap();
-            assert_eq!(reader.decoder().encoding(), WINDOWS_1251);
+            assert_eq!(reader.encoding(), WINDOWS_1251);
 
             assert_eq!(reader.read_event_into(&mut buf).unwrap(), Event::Eof);
         }
@@ -452,12 +452,12 @@ mod test {
             );
             let mut buf = Vec::new();
 
-            assert_eq!(reader.decoder().encoding(), UTF_8);
+            assert_eq!(reader.encoding(), UTF_8);
             reader.read_event_into(&mut buf).unwrap();
-            assert_eq!(reader.decoder().encoding(), UTF_16LE);
+            assert_eq!(reader.encoding(), UTF_16LE);
 
             reader.read_event_into(&mut buf).unwrap();
-            assert_eq!(reader.decoder().encoding(), UTF_16LE);
+            assert_eq!(reader.encoding(), UTF_16LE);
 
             assert_eq!(reader.read_event_into(&mut buf).unwrap(), Event::Eof);
         }

src/reader/mod.rs

@@ -6,7 +6,7 @@ use std::ops::Range;
 #[cfg(feature = "encoding")]
 use encoding_rs::{Encoding, UTF_8};
 
-use crate::encoding::{Decoder, Utf8BytesReader};
+use crate::encoding::Utf8BytesReader;
 use crate::errors::{Error, Result};
 use crate::events::Event;
 use crate::reader::parser::Parser;
@@ -283,8 +283,7 @@ macro_rules! read_to_end {
                     depth -= 1;
                 }
                 Ok(Event::Eof) => {
-                    let name = $self.decoder().decode($end.as_ref().as_bytes());
-                    return Err(Error::UnexpectedEof(format!("</{:?}>", name)));
+                    return Err(Error::UnexpectedEof(format!("</{:?}>", $end.as_ref())));
                 }
                 _ => (),
             }
@@ -529,16 +528,17 @@ impl<R> Reader<R> {
         }
     }
 
-    /// Get the decoder, used to decode bytes, read by this reader, to the strings.
+    /// Get the encoding this reader is currently using to decode strings.
     ///
     /// If `encoding` feature is enabled, the used encoding may change after
     /// parsing the XML declaration, otherwise encoding is fixed to UTF-8.
     ///
     /// If `encoding` feature is enabled and no encoding is specified in declaration,
     /// defaults to UTF-8.
+    #[cfg(feature = "encoding")]
     #[inline]
-    pub const fn decoder(&self) -> Decoder {
-        self.parser.decoder()
+    pub const fn encoding(&self) -> &'static Encoding {
+        self.parser.encoding.encoding()
     }
 }
 

src/reader/ns_reader.rs

@@ -780,7 +780,7 @@ impl<'i> NsReader<&'i [u8]> {
     ///
     /// ```ignore
     /// let span = reader.read_to_end(end)?;
-    /// let text = reader.decoder().decode(&reader.inner_slice[span]);
+    /// let text = std::str::from_utf8(&reader.inner_slice[span]);
     /// ```
     ///
     /// # Examples

src/reader/parser.rs

@@ -1,7 +1,6 @@
 #[cfg(feature = "encoding")]
 use encoding_rs::UTF_8;
 
-use crate::encoding::Decoder;
 use crate::errors::{Error, Result};
 use crate::events::{BytesCData, BytesDecl, BytesEnd, BytesStart, BytesText, Event};
 #[cfg(feature = "encoding")]
@@ -55,6 +54,16 @@ pub(super) struct Parser {
 
     #[cfg(feature = "encoding")]
     /// Reference to the encoding used to read an XML
+    ///
+    /// If feature `encoding` is enabled, this encoding is taken from the `"encoding"`
+    /// XML declaration or assumes UTF-8, if XML has no <?xml ?> declaration, encoding
+    /// key is not defined or contains unknown encoding.
+    ///
+    /// The library supports any UTF-8 compatible encodings that crate `encoding_rs`
+    /// is supported. [*UTF-16 and ISO-2022-JP are not supported at the present*][utf16].
+    ///
+    /// If feature `encoding` is disabled, the decoder is always UTF-8 decoder:
+    /// any XML declarations are ignored.
     pub encoding: EncodingRef,
 }
 
@@ -226,20 +235,6 @@ impl Parser {
             .split_off(self.opened_starts.pop().unwrap());
         Ok(Event::End(BytesEnd::new(name)))
     }
-
-    /// Get the decoder, used to decode bytes, read by this reader, to the strings.
-    ///
-    /// If `encoding` feature is enabled, the used encoding may change after
-    /// parsing the XML declaration, otherwise encoding is fixed to UTF-8.
-    ///
-    /// If `encoding` feature is enabled and no encoding is specified in declaration,
-    /// defaults to UTF-8.
-    pub const fn decoder(&self) -> Decoder {
-        Decoder {
-            #[cfg(feature = "encoding")]
-            encoding: self.encoding.encoding(),
-        }
-    }
 }
 
 impl Default for Parser {

src/reader/slice_reader.rs

@@ -158,7 +158,7 @@ impl<'a> Reader<&'a [u8]> {
     ///
     /// ```ignore
     /// let span = reader.read_to_end(end)?;
-    /// let text = reader.decoder().decode(&reader.inner_slice[span]);
+    /// let text = std::str::from_utf8(&reader.inner_slice[span]);
     /// ```
     ///
     /// # Examples
@@ -211,7 +211,7 @@ impl<'a> Reader<&'a [u8]> {
         let buffer = self.reader;
         let span = self.read_to_end(end)?;
 
-        self.decoder().decode(&buffer[0..span.len()])
+        Ok(Cow::Borrowed(std::str::from_utf8(&buffer[0..span.len()])?))
     }
 }
 
@@ -362,9 +362,9 @@ mod test {
         fn str_always_has_utf8() {
             let mut reader = Reader::from_str("<?xml encoding='UTF-16'?>");
 
-            assert_eq!(reader.decoder().encoding(), UTF_8);
+            assert_eq!(reader.encoding(), UTF_8);
             reader.read_event().unwrap();
-            assert_eq!(reader.decoder().encoding(), UTF_8);
+            assert_eq!(reader.encoding(), UTF_8);
 
             assert_eq!(reader.read_event().unwrap(), Event::Eof);
         }

tests/encodings.rs

@@ -59,15 +59,15 @@ mod detect {
                 let mut r = Reader::from_reader(
                     include_bytes!(concat!("documents/encoding/", $file, ".xml")).as_ref(),
                 );
-                assert_eq!(r.decoder().encoding(), UTF_8);
+                assert_eq!(r.encoding(), UTF_8);
 
                 let mut buf = Vec::new();
                 loop {
                     match dbg!(r.read_event_into(&mut buf).unwrap()) {
                         Event::Eof => break,
                         _ => {}
                     }
-                    assert_eq!(r.decoder().encoding(), $enc);
+                    assert_eq!(r.encoding(), $enc);
                     buf.clear();
                     $($break)?
                 }

tests/xmlrs_reader_tests.rs

@@ -394,7 +394,7 @@ fn test_bytes(input: &[u8], output: &[u8], trim: bool) {
     loop {
         let line = match reader.read_resolved_event_into(&mut Vec::new()) {
             Ok((_, Event::Decl(e))) => {
-                // Declaration could change decoder
+                // Declaration could change encoding
                 let version = e.version().unwrap();
                 let encoding = e.encoding().unwrap().unwrap();
                 format!("StartDocument({}, {})", version, encoding)