From 58bb4d921f81393208056f63bf58b25404562f20 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Kijewski?= <rene.kijewski@fu-berlin.de>
Date: Wed, 6 Aug 2025 17:22:22 +0200
Subject: [PATCH] derive: remove trait `BufferFmt`

---
 askama_derive/src/generator/expr.rs   |  2 +-
 askama_derive/src/generator/filter.rs |  8 +++---
 askama_derive/src/generator/node.rs   | 13 +++++-----
 askama_derive/src/integration.rs      | 35 ++++++++++++---------------
 4 files changed, 25 insertions(+), 33 deletions(-)

diff --git a/askama_derive/src/generator/expr.rs b/askama_derive/src/generator/expr.rs
index e4fdf5fd..44abb235 100644
--- a/askama_derive/src/generator/expr.rs
+++ b/askama_derive/src/generator/expr.rs
@@ -363,7 +363,7 @@ impl<'a> Generator<'a, '_> {
             if i > 0 {
                 buf.write_token(Token![,], span);
             }
-            buf.write(self.visit_arg(ctx, arg, span)?, ctx.template_span);
+            buf.write_tokens(self.visit_arg(ctx, arg, span)?);
         }
         Ok(())
     }
diff --git a/askama_derive/src/generator/filter.rs b/askama_derive/src/generator/filter.rs
index b0abdd52..c2d84477 100644
--- a/askama_derive/src/generator/filter.rs
+++ b/askama_derive/src/generator/filter.rs
@@ -292,11 +292,9 @@ impl<'a> Generator<'a, '_> {
             let arg = self.visit_arg(ctx, filter, ctx.span_for_node(filter.span()))?;
 
             let tmp = tmp.into_token_stream();
-            quote_into!(buf, span, { askama::filters::reject(
-               #tmp,
-               // coerce [T, &T, &&T...] to &T
-               (&&&(#arg))
-               as &_)?
+            quote_into!(buf, span, {
+                // coerce [T, &T, &&T...] to &T
+                askama::filters::reject(#tmp, (&&&(#arg)) as &_)?
             });
         }
 
diff --git a/askama_derive/src/generator/node.rs b/askama_derive/src/generator/node.rs
index 60eafd8f..d0f57d33 100644
--- a/askama_derive/src/generator/node.rs
+++ b/askama_derive/src/generator/node.rs
@@ -580,9 +580,11 @@ impl<'a> Generator<'a, '_> {
                     Ok(size_hint)
                 })?;
                 let cond_buf = cond_buf.into_token_stream();
-                loop_buf.write_tokens(quote_spanned!(span=> if !#var_did_loop {
-                    #cond_buf
-                }));
+                quote_into!(&mut loop_buf, span, {
+                    if !#var_did_loop {
+                        #cond_buf
+                    }
+                });
             } else {
                 this.handle_ws(loop_block.ws3);
                 size_hint2 = this.write_buf_writable(ctx, &mut loop_buf)?;
@@ -1159,10 +1161,7 @@ impl<'a> Generator<'a, '_> {
                                     // multiple times, e.g. in the case of macro
                                     // parameters being used multiple times.
                                     _ => {
-                                        value.write(
-                                            this.visit_expr_root(&call_ctx, expr)?,
-                                            span_span,
-                                        );
+                                        value.write_tokens(this.visit_expr_root(&call_ctx, expr)?);
                                         // We need to normalize the arg to write it, thus we need to add it to
                                         // locals in the normalized manner
                                         let id = field_new(arg, span_span);
diff --git a/askama_derive/src/integration.rs b/askama_derive/src/integration.rs
index 7e3b52e5..fdb2e9a4 100644
--- a/askama_derive/src/integration.rs
+++ b/askama_derive/src/integration.rs
@@ -119,6 +119,16 @@ impl ToTokens for Buffer {
     }
 }
 
+impl IntoIterator for Buffer {
+    type Item = <TokenStream as IntoIterator>::Item;
+    type IntoIter = <TokenStream as IntoIterator>::IntoIter;
+
+    #[inline]
+    fn into_iter(self) -> Self::IntoIter {
+        self.buf.into_iter()
+    }
+}
+
 impl Buffer {
     pub(crate) fn new() -> Self {
         Self {
@@ -154,29 +164,24 @@ impl Buffer {
         self.string_literals.push((literal, span));
     }
 
+    #[inline]
     pub(crate) fn into_token_stream(mut self) -> TokenStream {
         self.handle_str_lit();
         self.buf
     }
 
+    #[inline]
     pub(crate) fn is_discard(&self) -> bool {
         self.discard
     }
 
+    #[inline]
     pub(crate) fn set_discard(&mut self, discard: bool) {
         self.discard = discard;
     }
 
-    pub(crate) fn write(&mut self, src: impl BufferFmt, span: proc_macro2::Span) {
-        if self.discard {
-            return;
-        }
-
-        self.handle_str_lit();
-        src.append_to(&mut self.buf, span);
-    }
-
-    pub(crate) fn write_tokens(&mut self, src: TokenStream) {
+    #[inline]
+    pub(crate) fn write_tokens(&mut self, src: impl IntoIterator<Item = TokenTree>) {
         if self.discard {
             return;
         }
@@ -269,16 +274,6 @@ impl Buffer {
     }
 }
 
-pub(crate) trait BufferFmt {
-    fn append_to(self, buf: &mut TokenStream, span: proc_macro2::Span);
-}
-
-impl BufferFmt for TokenStream {
-    fn append_to(self, buf: &mut TokenStream, _span: proc_macro2::Span) {
-        buf.extend(self);
-    }
-}
-
 /// Similar to `write!(dest, "{src:?}")`, but only escapes the strictly needed characters,
 /// and without the surrounding `"…"` quotation marks.
 pub(crate) fn string_escape(dest: &mut String, src: &str) {