Directly use string conversion methods on Bytes

This lets `read` reuse the string for `Str`-backed `Bytes`. Also makes `within` more generally applicable just like `at`.

crates/typst-library/src/diag.rs

@@ -617,9 +617,15 @@ pub trait LoadedWithin<T> {
     fn within(self, loaded: &Loaded) -> SourceResult<T>;
 }
 
-impl<T> LoadedWithin<T> for Result<T, LoadError> {
+impl<T, E> LoadedWithin<T> for Result<T, E>
+where
+    E: Into<LoadError>,
+{
     fn within(self, loaded: &Loaded) -> SourceResult<T> {
-        self.map_err(|err| load_err_in_text(loaded, err.pos, err.message))
+        self.map_err(|err| {
+            let LoadError { pos, message } = err.into();
+            load_err_in_text(loaded, pos, message)
+        })
     }
 }
 

crates/typst-library/src/loading/mod.rs

@@ -131,10 +131,6 @@ impl Loaded {
     pub fn new(source: Spanned<LoadSource>, bytes: Bytes) -> Self {
         Self { source, data: bytes }
     }
-
-    pub fn load_str(&self) -> SourceResult<&str> {
-        self.data.as_str().map_err(Into::into).within(self)
-    }
 }
 
 /// A loaded [`DataSource`].

crates/typst-library/src/loading/read.rs

@@ -1,7 +1,7 @@
 use ecow::EcoString;
 use typst_syntax::Spanned;
 
-use crate::diag::SourceResult;
+use crate::diag::{LoadedWithin, SourceResult};
 use crate::engine::Engine;
 use crate::foundations::{func, Cast};
 use crate::loading::{DataSource, Load, Readable};
@@ -38,7 +38,7 @@ pub fn read(
     let loaded = path.map(DataSource::Path).load(engine.world)?;
     Ok(match encoding {
         None => Readable::Bytes(loaded.data),
-        Some(Encoding::Utf8) => Readable::Str(loaded.load_str()?.into()),
+        Some(Encoding::Utf8) => Readable::Str(loaded.data.to_str().within(&loaded)?),
     })
 }
 

crates/typst-library/src/loading/toml.rs

@@ -33,7 +33,7 @@ pub fn toml(
     source: Spanned<DataSource>,
 ) -> SourceResult<Value> {
     let loaded = source.load(engine.world)?;
-    let raw = loaded.load_str()?;
+    let raw = loaded.data.as_str().within(&loaded)?;
     ::toml::from_str(raw).map_err(format_toml_error).within(&loaded)
 }
 

crates/typst-library/src/loading/xml.rs

@@ -61,7 +61,7 @@ pub fn xml(
     source: Spanned<DataSource>,
 ) -> SourceResult<Value> {
     let loaded = source.load(engine.world)?;
-    let text = loaded.load_str()?;
+    let text = loaded.data.as_str().within(&loaded)?;
     let document = roxmltree::Document::parse_with_options(
         text,
         ParsingOptions { allow_dtd: true, ..Default::default() },

crates/typst-library/src/model/bibliography.rs

@@ -356,7 +356,7 @@ impl Debug for Bibliography {
 
 /// Decode on library from one data source.
 fn decode_library(loaded: &Loaded) -> SourceResult<Library> {
-    let data = loaded.load_str()?;
+    let data = loaded.data.as_str().within(loaded)?;
 
     if let LoadSource::Path(file_id) = loaded.source.v {
         // If we got a path, use the extension to determine whether it is