derive: Make Config `'static`

The configuration is made `'static`, because `toml` and `toml_edit` both
needs to implement serde's `DeserializeOwned` by now. We allocate the
strings once per template, so it is very unlikely that this change will
have any measurable impact, neither in compile time nor RAM usage.

4 files changed, 67 insertions, 71 deletions

diff --git a/askama_derive/src/config.rs b/askama_derive/src/config.rs
index 8c49217..4dcf1ea 100644
--- a/askama_derive/src/config.rs
+++ b/askama_derive/src/config.rs
@@ -1,4 +1,5 @@
 use std::collections::{BTreeMap, HashSet};
+use std::convert::TryFrom;
 use std::path::{Path, PathBuf};
 use std::{env, fs};
 
@@ -8,16 +9,16 @@ use serde::Deserialize;
 use crate::CompileError;
 
 #[derive(Debug)]
-pub(crate) struct Config<'a> {
+pub(crate) struct Config {
     pub(crate) dirs: Vec<PathBuf>,
-    pub(crate) syntaxes: BTreeMap<String, Syntax<'a>>,
-    pub(crate) default_syntax: &'a str,
+    pub(crate) syntaxes: BTreeMap<String, Syntax>,
+    pub(crate) default_syntax: String,
     pub(crate) escapers: Vec<(HashSet<String>, String)>,
     pub(crate) whitespace: WhitespaceHandling,
 }
 
-impl Config<'_> {
-    pub(crate) fn new(s: &str) -> std::result::Result<Config<'_>, CompileError> {
+impl Config {
+    pub(crate) fn new(s: &str) -> std::result::Result<Config, CompileError> {
         let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
         let default_dirs = vec![root.join("templates")];
 
@@ -39,19 +40,19 @@ impl Config<'_> {
                 dirs.map_or(default_dirs, |v| {
                     v.into_iter().map(|dir| root.join(dir)).collect()
                 }),
-                default_syntax.unwrap_or(DEFAULT_SYNTAX_NAME),
+                default_syntax.unwrap_or_else(|| DEFAULT_SYNTAX_NAME.to_owned()),
                 whitespace,
             ),
             None => (
                 default_dirs,
-                DEFAULT_SYNTAX_NAME,
+                DEFAULT_SYNTAX_NAME.to_owned(),
                 WhitespaceHandling::default(),
             ),
         };
 
         if let Some(raw_syntaxes) = raw.syntax {
             for raw_s in raw_syntaxes {
-                let name = raw_s.name;
+                let name = raw_s.name.clone();
 
                 if syntaxes
                     .insert(name.to_string(), Syntax::try_from(raw_s)?)
@@ -62,7 +63,7 @@ impl Config<'_> {
             }
         }
 
-        if !syntaxes.contains_key(default_syntax) {
+        if !syntaxes.contains_key(&default_syntax) {
             return Err(format!("default syntax \"{default_syntax}\" not found").into());
         }
 
@@ -120,32 +121,32 @@ impl Config<'_> {
 }
 
 #[derive(Debug)]
-pub(crate) struct Syntax<'a> {
-    pub(crate) block_start: &'a str,
-    pub(crate) block_end: &'a str,
-    pub(crate) expr_start: &'a str,
-    pub(crate) expr_end: &'a str,
-    pub(crate) comment_start: &'a str,
-    pub(crate) comment_end: &'a str,
+pub(crate) struct Syntax {
+    pub(crate) block_start: String,
+    pub(crate) block_end: String,
+    pub(crate) expr_start: String,
+    pub(crate) expr_end: String,
+    pub(crate) comment_start: String,
+    pub(crate) comment_end: String,
 }
 
-impl Default for Syntax<'_> {
+impl Default for Syntax {
     fn default() -> Self {
         Self {
-            block_start: "{%",
-            block_end: "%}",
-            expr_start: "{{",
-            expr_end: "}}",
-            comment_start: "{#",
-            comment_end: "#}",
+            block_start: "{%".to_owned(),
+            block_end: "%}".to_owned(),
+            expr_start: "{{".to_owned(),
+            expr_end: "}}".to_owned(),
+            comment_start: "{#".to_owned(),
+            comment_end: "#}".to_owned(),
         }
     }
 }
 
-impl<'a> TryFrom<RawSyntax<'a>> for Syntax<'a> {
+impl TryFrom<RawSyntax> for Syntax {
     type Error = CompileError;
 
-    fn try_from(raw: RawSyntax<'a>) -> std::result::Result<Self, Self::Error> {
+    fn try_from(raw: RawSyntax) -> std::result::Result<Self, Self::Error> {
         let default = Self::default();
         let syntax = Self {
             block_start: raw.block_start.unwrap_or(default.block_start),
@@ -182,21 +183,20 @@ impl<'a> TryFrom<RawSyntax<'a>> for Syntax<'a> {
 
 #[cfg_attr(feature = "serde", derive(Deserialize))]
 #[derive(Default)]
-struct RawConfig<'d> {
-    #[cfg_attr(feature = "serde", serde(borrow))]
-    general: Option<General<'d>>,
-    syntax: Option<Vec<RawSyntax<'d>>>,
-    escaper: Option<Vec<RawEscaper<'d>>>,
+struct RawConfig {
+    general: Option<General>,
+    syntax: Option<Vec<RawSyntax>>,
+    escaper: Option<Vec<RawEscaper>>,
 }
 
-impl RawConfig<'_> {
+impl RawConfig {
     #[cfg(feature = "config")]
-    fn from_toml_str(s: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
+    fn from_toml_str(s: &str) -> std::result::Result<RawConfig, CompileError> {
         toml::from_str(s).map_err(|e| format!("invalid TOML in {CONFIG_FILE_NAME}: {e}").into())
     }
 
     #[cfg(not(feature = "config"))]
-    fn from_toml_str(_: &str) -> std::result::Result<RawConfig<'_>, CompileError> {
+    fn from_toml_str(_: &str) -> std::result::Result<RawConfig, CompileError> {
         Err("TOML support not available".into())
     }
 }
@@ -222,29 +222,28 @@ impl Default for WhitespaceHandling {
 }
 
 #[cfg_attr(feature = "serde", derive(Deserialize))]
-struct General<'a> {
-    #[cfg_attr(feature = "serde", serde(borrow))]
-    dirs: Option<Vec<&'a str>>,
-    default_syntax: Option<&'a str>,
+struct General {
+    dirs: Option<Vec<String>>,
+    default_syntax: Option<String>,
     #[cfg_attr(feature = "serde", serde(default))]
     whitespace: WhitespaceHandling,
 }
 
 #[cfg_attr(feature = "serde", derive(Deserialize))]
-struct RawSyntax<'a> {
-    name: &'a str,
-    block_start: Option<&'a str>,
-    block_end: Option<&'a str>,
-    expr_start: Option<&'a str>,
-    expr_end: Option<&'a str>,
-    comment_start: Option<&'a str>,
-    comment_end: Option<&'a str>,
+struct RawSyntax {
+    name: String,
+    block_start: Option<String>,
+    block_end: Option<String>,
+    expr_start: Option<String>,
+    expr_end: Option<String>,
+    comment_start: Option<String>,
+    comment_end: Option<String>,
 }
 
 #[cfg_attr(feature = "serde", derive(Deserialize))]
-struct RawEscaper<'a> {
-    path: &'a str,
-    extensions: Vec<&'a str>,
+struct RawEscaper {
+    path: String,
+    extensions: Vec<String>,
 }
 
 pub(crate) fn read_config_file(
diff --git a/askama_derive/src/heritage.rs b/askama_derive/src/heritage.rs
index 9556145..010f723 100644
--- a/askama_derive/src/heritage.rs
+++ b/askama_derive/src/heritage.rs
@@ -44,7 +44,7 @@ pub(crate) struct Context<'a> {
 
 impl Context<'_> {
     pub(crate) fn new<'n>(
-        config: &Config<'_>,
+        config: &Config,
         path: &Path,
         nodes: &'n [Node<'n>],
     ) -> Result<Context<'n>, CompileError> {
diff --git a/askama_derive/src/input.rs b/askama_derive/src/input.rs
index 47d51bd..b8a0da4 100644
--- a/askama_derive/src/input.rs
+++ b/askama_derive/src/input.rs
@@ -9,8 +9,8 @@ use mime::Mime;
 
 pub(crate) struct TemplateInput<'a> {
     pub(crate) ast: &'a syn::DeriveInput,
-    pub(crate) config: &'a Config<'a>,
-    pub(crate) syntax: &'a Syntax<'a>,
+    pub(crate) config: &'a Config,
+    pub(crate) syntax: &'a Syntax,
     pub(crate) source: Source,
     pub(crate) print: Print,
     pub(crate) escaper: &'a str,
@@ -25,7 +25,7 @@ impl TemplateInput<'_> {
     /// `template()` attribute list fields.
     pub(crate) fn new<'n>(
         ast: &'n syn::DeriveInput,
-        config: &'n Config<'_>,
+        config: &'n Config,
         args: TemplateArgs,
     ) -> Result<TemplateInput<'n>, CompileError> {
         let TemplateArgs {
@@ -51,7 +51,7 @@ impl TemplateInput<'_> {
 
         // Validate syntax
         let syntax = syntax.map_or_else(
-            || Ok(config.syntaxes.get(config.default_syntax).unwrap()),
+            || Ok(config.syntaxes.get(&config.default_syntax).unwrap()),
             |s| {
                 config
                     .syntaxes
diff --git a/askama_derive/src/parser.rs b/askama_derive/src/parser.rs
index c59177a..bcf9c58 100644
--- a/askama_derive/src/parser.rs
+++ b/askama_derive/src/parser.rs
@@ -250,15 +250,15 @@ fn keyword<'a>(k: &'a str) -> impl FnMut(&'a str) -> IResult<&'a str, &'a str> {
 }
 
 struct State<'a> {
-    syntax: &'a Syntax<'a>,
+    syntax: &'a Syntax,
     loop_depth: Cell<usize>,
 }
 
 fn take_content<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
     let p_start = alt((
-        tag(s.syntax.block_start),
-        tag(s.syntax.comment_start),
-        tag(s.syntax.expr_start),
+        tag(s.syntax.block_start.as_str()),
+        tag(s.syntax.comment_start.as_str()),
+        tag(s.syntax.expr_start.as_str()),
     ));
 
     let (i, _) = not(eof)(i)?;
@@ -1162,8 +1162,8 @@ fn block_node<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
 fn block_comment_body<'a>(mut i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
     let mut level = 0;
     loop {
-        let (end, tail) = take_until(s.syntax.comment_end)(i)?;
-        match take_until::<_, _, Error<_>>(s.syntax.comment_start)(i) {
+        let (end, tail) = take_until(s.syntax.comment_end.as_str())(i)?;
+        match take_until::<_, _, Error<_>>(s.syntax.comment_start.as_str())(i) {
             Ok((start, _)) if start.as_ptr() < end.as_ptr() => {
                 level += 1;
                 i = &start[2..];
@@ -1209,28 +1209,25 @@ fn parse_template<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Vec<Node<'a
 }
 
 fn tag_block_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
-    tag(s.syntax.block_start)(i)
+    tag(s.syntax.block_start.as_str())(i)
 }
 fn tag_block_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
-    tag(s.syntax.block_end)(i)
+    tag(s.syntax.block_end.as_str())(i)
 }
 fn tag_comment_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
-    tag(s.syntax.comment_start)(i)
+    tag(s.syntax.comment_start.as_str())(i)
 }
 fn tag_comment_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
-    tag(s.syntax.comment_end)(i)
+    tag(s.syntax.comment_end.as_str())(i)
 }
 fn tag_expr_start<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
-    tag(s.syntax.expr_start)(i)
+    tag(s.syntax.expr_start.as_str())(i)
 }
 fn tag_expr_end<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, &'a str> {
-    tag(s.syntax.expr_end)(i)
+    tag(s.syntax.expr_end.as_str())(i)
 }
 
-pub(crate) fn parse<'a>(
-    src: &'a str,
-    syntax: &'a Syntax<'a>,
-) -> Result<Vec<Node<'a>>, CompileError> {
+pub(crate) fn parse<'a>(src: &'a str, syntax: &'a Syntax) -> Result<Vec<Node<'a>>, CompileError> {
     let state = State {
         syntax,
         loop_depth: Cell::new(0),
@@ -1498,8 +1495,8 @@ mod tests {
     #[test]
     fn change_delimiters_parse_filter() {
         let syntax = Syntax {
-            expr_start: "{=",
-            expr_end: "=}",
+            expr_start: "{=".to_owned(),
+            expr_end: "=}".to_owned(),
             ..Syntax::default()
         };