Replace custom Cow with actual Cow

3 files changed, 42 insertions, 47 deletions

diff --git a/askama_shared/src/generator.rs b/askama_shared/src/generator.rs
index daf22ae..924d747 100644
--- a/askama_shared/src/generator.rs
+++ b/askama_shared/src/generator.rs
@@ -665,27 +665,25 @@ impl<'a, S: std::hash::BuildHasher> Generator<'a, S> {
             return self.write_block(buf, None, ws);
         }
 
-        let (def, own_ctx) = if let Some(s) = scope {
-            let path = ctx.imports.get(s).ok_or_else(|| {
-                CompileError::String(format!("no import found for scope '{}'", s))
-            })?;
-            let mctx = self.contexts.get(path.as_path()).ok_or_else(|| {
-                CompileError::String(format!("context for '{:?}' not found", path))
-            })?;
-            (
-                mctx.macros.get(name).ok_or_else(|| {
-                    CompileError::String(format!("macro '{}' not found in scope '{}'", name, s))
-                })?,
-                mctx,
-            )
-        } else {
-            (
-                ctx.macros
+        let (def, own_ctx) =
+            if let Some(s) = scope {
+                let path = ctx.imports.get(s).ok_or_else(|| {
+                    CompileError::from(format!("no import found for scope {:?}", s))
+                })?;
+                let mctx = self.contexts.get(path.as_path()).ok_or_else(|| {
+                    CompileError::from(format!("context for {:?} not found", path))
+                })?;
+                let def = mctx.macros.get(name).ok_or_else(|| {
+                    CompileError::from(format!("macro {:?} not found in scope {:?}", name, s))
+                })?;
+                (def, mctx)
+            } else {
+                let def = ctx
+                    .macros
                     .get(name)
-                    .ok_or_else(|| CompileError::String(format!("macro '{}' not found", name)))?,
-                ctx,
-            )
-        };
+                    .ok_or_else(|| CompileError::from(format!("macro {:?} not found", name)))?;
+                (def, ctx)
+            };
 
         self.flush_ws(ws); // Cannot handle_ws() here: whitespace from macro definition comes first
         self.locals.push();
@@ -698,7 +696,7 @@ impl<'a, S: std::hash::BuildHasher> Generator<'a, S> {
         let mut is_first_variable = true;
         for (i, arg) in def.args.iter().enumerate() {
             let expr = args.get(i).ok_or_else(|| {
-                CompileError::String(format!("macro '{}' takes more than {} arguments", name, i))
+                CompileError::from(format!("macro {:?} takes more than {} arguments", name, i))
             })?;
 
             match expr {
@@ -900,7 +898,7 @@ impl<'a, S: std::hash::BuildHasher> Generator<'a, S> {
         let heritage = self
             .heritage
             .as_ref()
-            .ok_or(CompileError::Static("no block ancestors available"))?;
+            .ok_or_else(|| CompileError::from("no block ancestors available"))?;
         let (ctx, def) = heritage.blocks[cur.0].get(cur.1).ok_or_else(|| {
             CompileError::from(match name {
                 None => format!("no super() block found for block '{}'", cur.0),
@@ -1170,7 +1168,7 @@ impl<'a, S: std::hash::BuildHasher> Generator<'a, S> {
                 .escapers
                 .iter()
                 .find_map(|(escapers, escaper)| escapers.contains(name).then(|| escaper))
-                .ok_or(CompileError::Static("invalid escaper for escape filter"))?,
+                .ok_or_else(|| CompileError::from("invalid escaper for escape filter"))?,
             None => self.input.escaper,
         };
         buf.write("::askama::filters::escape(");
diff --git a/askama_shared/src/input.rs b/askama_shared/src/input.rs
index b9341a2..ef27630 100644
--- a/askama_shared/src/input.rs
+++ b/askama_shared/src/input.rs
@@ -34,7 +34,7 @@ impl TemplateInput<'_> {
         for attr in &ast.attrs {
             if attr.path.is_ident("template") {
                 if template_args.is_some() {
-                    return Err(CompileError::Static("duplicated 'template' attribute"));
+                    return Err("duplicated 'template' attribute".into());
                 }
 
                 match attr.parse_meta() {
@@ -47,7 +47,7 @@ impl TemplateInput<'_> {
             }
         }
         let template_args =
-            template_args.ok_or(CompileError::Static("no attribute 'template' found"))?;
+            template_args.ok_or_else(|| CompileError::from("no attribute 'template' found"))?;
 
         // Loop over the meta attributes and find everything that we
         // understand. Return a CompileError if something is not right.
@@ -157,9 +157,10 @@ impl TemplateInput<'_> {
         let syntax = syntax.map_or_else(
             || Ok(config.syntaxes.get(config.default_syntax).unwrap()),
             |s| {
-                config.syntaxes.get(&s).ok_or_else(|| {
-                    CompileError::String(format!("attribute syntax {} not exist", s))
-                })
+                config
+                    .syntaxes
+                    .get(&s)
+                    .ok_or_else(|| CompileError::from(format!("attribute syntax {} not exist", s)))
             },
         )?;
 
@@ -181,7 +182,7 @@ impl TemplateInput<'_> {
         }
 
         let escaper = escaper.ok_or_else(|| {
-            CompileError::String(format!("no escaper defined for extension '{}'", escaping,))
+            CompileError::from(format!("no escaper defined for extension '{}'", escaping))
         })?;
 
         let mime_type =
diff --git a/askama_shared/src/lib.rs b/askama_shared/src/lib.rs
index 911367a..b2bebd0 100644
--- a/askama_shared/src/lib.rs
+++ b/askama_shared/src/lib.rs
@@ -3,6 +3,7 @@
 #![deny(elided_lifetimes_in_paths)]
 #![deny(unreachable_pub)]
 
+use std::borrow::Cow;
 use std::collections::{BTreeMap, HashSet};
 use std::convert::TryFrom;
 use std::path::{Path, PathBuf};
@@ -204,9 +205,7 @@ struct RawConfig<'d> {
 impl RawConfig<'_> {
     #[cfg(feature = "config")]
     fn from_toml_str(s: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
-        toml::from_str(s).map_err(|e| {
-            CompileError::String(format!("invalid TOML in {}: {}", CONFIG_FILE_NAME, e))
-        })
+        toml::from_str(s).map_err(|e| format!("invalid TOML in {}: {}", CONFIG_FILE_NAME, e).into())
     }
 
     #[cfg(not(feature = "config"))]
@@ -243,9 +242,8 @@ pub fn read_config_file() -> std::result::Result<String, CompileError> {
     let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
     let filename = root.join(CONFIG_FILE_NAME);
     if filename.exists() {
-        fs::read_to_string(&filename).map_err(|_| {
-            CompileError::String(format!("unable to read {}", filename.to_str().unwrap()))
-        })
+        fs::read_to_string(&filename)
+            .map_err(|_| format!("unable to read {:?}", filename.to_str().unwrap()).into())
     } else {
         Ok("".to_string())
     }
@@ -261,10 +259,11 @@ where
 #[allow(clippy::match_wild_err_arm)]
 pub fn get_template_source(tpl_path: &Path) -> std::result::Result<String, CompileError> {
     match fs::read_to_string(tpl_path) {
-        Err(_) => Err(CompileError::String(format!(
+        Err(_) => Err(format!(
             "unable to open template file '{}'",
             tpl_path.to_str().unwrap()
-        ))),
+        )
+        .into()),
         Ok(mut source) => {
             if source.ends_with('\n') {
                 let _ = source.pop();
@@ -294,29 +293,26 @@ static DEFAULT_ESCAPERS: &[(&[&str], &str)] = &[
 ];
 
 #[derive(Debug)]
-pub enum CompileError {
-    Static(&'static str),
-    String(String),
-}
+pub struct CompileError(Cow<'static, str>);
 
 impl fmt::Display for CompileError {
+    #[inline]
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            CompileError::Static(s) => write!(fmt, "{}", s),
-            CompileError::String(s) => write!(fmt, "{}", s),
-        }
+        fmt.write_str(&self.0)
     }
 }
 
 impl From<&'static str> for CompileError {
+    #[inline]
     fn from(s: &'static str) -> Self {
-        CompileError::Static(s)
+        Self(s.into())
     }
 }
 
 impl From<String> for CompileError {
+    #[inline]
     fn from(s: String) -> Self {
-        CompileError::String(s)
+        Self(s.into())
     }
 }