Rollup merge of #109187 - clubby789:askama-source, r=GuillaumeGomez

Render source page layout with Askama

~~I was looking at making `code_html` render into the buffer instead of in advance, but it turned out to need a pretty big refactor, so starting with rearranging the high-level layout.~~
Found another approach which required much less changes

cc #108868

src/librustdoc/html/highlight.rs

@@ -65,23 +65,6 @@ pub(crate) fn render_item_decl_with_highlighting(src: &str, out: &mut Buffer) {
     write!(out, "</pre>");
 }
 
-/// Highlights `src` as a source code page, returning the HTML output.
-pub(crate) fn render_source_with_highlighting(
-    src: &str,
-    out: &mut Buffer,
-    line_numbers: Buffer,
-    href_context: HrefContext<'_, '_>,
-    decoration_info: DecorationInfo,
-    extra: Option<&str>,
-) {
-    write_header(out, "", Some(line_numbers), Tooltip::None);
-    if let Some(extra) = extra {
-        out.push_str(extra);
-    }
-    write_code(out, src, Some(href_context), Some(decoration_info));
-    write_footer(out, None);
-}
-
 fn write_header(out: &mut Buffer, class: &str, extra_content: Option<Buffer>, tooltip: Tooltip) {
     write!(
         out,
@@ -143,8 +126,8 @@ fn can_merge(class1: Option<Class>, class2: Option<Class>, text: &str) -> bool {
 
 /// This type is used as a conveniency to prevent having to pass all its fields as arguments into
 /// the various functions (which became its methods).
-struct TokenHandler<'a, 'tcx> {
-    out: &'a mut Buffer,
+struct TokenHandler<'a, 'tcx, F: Write> {
+    out: &'a mut F,
     /// It contains the closing tag and the associated `Class`.
     closing_tags: Vec<(&'static str, Class)>,
     /// This is used because we don't automatically generate the closing tag on `ExitSpan` in
@@ -159,7 +142,7 @@ struct TokenHandler<'a, 'tcx> {
     href_context: Option<HrefContext<'a, 'tcx>>,
 }
 
-impl<'a, 'tcx> TokenHandler<'a, 'tcx> {
+impl<'a, 'tcx, F: Write> TokenHandler<'a, 'tcx, F> {
     fn handle_exit_span(&mut self) {
         // We can't get the last `closing_tags` element using `pop()` because `closing_tags` is
         // being used in `write_pending_elems`.
@@ -211,7 +194,7 @@ impl<'a, 'tcx> TokenHandler<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx> Drop for TokenHandler<'a, 'tcx> {
+impl<'a, 'tcx, F: Write> Drop for TokenHandler<'a, 'tcx, F> {
     /// When leaving, we need to flush all pending data to not have missing content.
     fn drop(&mut self) {
         if self.pending_exit_span.is_some() {
@@ -233,8 +216,8 @@ impl<'a, 'tcx> Drop for TokenHandler<'a, 'tcx> {
 /// item definition.
 ///
 /// More explanations about spans and how we use them here are provided in the
-fn write_code(
-    out: &mut Buffer,
+pub(super) fn write_code(
+    out: &mut impl Write,
     src: &str,
     href_context: Option<HrefContext<'_, '_>>,
     decoration_info: Option<DecorationInfo>,
@@ -883,7 +866,7 @@ impl<'src> Classifier<'src> {
 /// Called when we start processing a span of text that should be highlighted.
 /// The `Class` argument specifies how it should be highlighted.
 fn enter_span(
-    out: &mut Buffer,
+    out: &mut impl Write,
     klass: Class,
     href_context: &Option<HrefContext<'_, '_>>,
 ) -> &'static str {
@@ -894,8 +877,8 @@ fn enter_span(
 }
 
 /// Called at the end of a span of highlighted text.
-fn exit_span(out: &mut Buffer, closing_tag: &str) {
-    out.write_str(closing_tag);
+fn exit_span(out: &mut impl Write, closing_tag: &str) {
+    out.write_str(closing_tag).unwrap();
 }
 
 /// Called for a span of text. If the text should be highlighted differently
@@ -915,15 +898,15 @@ fn exit_span(out: &mut Buffer, closing_tag: &str) {
 /// will then try to find this `span` in the `span_correspondance_map`. If found, it'll then
 /// generate a link for this element (which corresponds to where its definition is located).
 fn string<T: Display>(
-    out: &mut Buffer,
+    out: &mut impl Write,
     text: T,
     klass: Option<Class>,
     href_context: &Option<HrefContext<'_, '_>>,
     open_tag: bool,
 ) {
     if let Some(closing_tag) = string_without_closing_tag(out, text, klass, href_context, open_tag)
     {
-        out.write_str(closing_tag);
+        out.write_str(closing_tag).unwrap();
     }
 }
 
@@ -937,24 +920,24 @@ fn string<T: Display>(
 ///   in `span_map.rs::collect_spans_and_sources`. If it cannot retrieve the information, then it's
 ///   the same as the second point (`klass` is `Some` but doesn't have a [`rustc_span::Span`]).
 fn string_without_closing_tag<T: Display>(
-    out: &mut Buffer,
+    out: &mut impl Write,
     text: T,
     klass: Option<Class>,
     href_context: &Option<HrefContext<'_, '_>>,
     open_tag: bool,
 ) -> Option<&'static str> {
     let Some(klass) = klass
     else {
-        write!(out, "{}", text);
+        write!(out, "{}", text).unwrap();
         return None;
     };
     let Some(def_span) = klass.get_span()
     else {
         if !open_tag {
-            write!(out, "{}", text);
+            write!(out, "{}", text).unwrap();
             return None;
         }
-        write!(out, "<span class=\"{}\">{}", klass.as_html(), text);
+        write!(out, "<span class=\"{}\">{}", klass.as_html(), text).unwrap();
         return Some("</span>");
     };
 
@@ -1009,28 +992,28 @@ fn string_without_closing_tag<T: Display>(
             if !open_tag {
                 // We're already inside an element which has the same klass, no need to give it
                 // again.
-                write!(out, "<a href=\"{}\">{}", href, text_s);
+                write!(out, "<a href=\"{}\">{}", href, text_s).unwrap();
             } else {
                 let klass_s = klass.as_html();
                 if klass_s.is_empty() {
-                    write!(out, "<a href=\"{}\">{}", href, text_s);
+                    write!(out, "<a href=\"{}\">{}", href, text_s).unwrap();
                 } else {
-                    write!(out, "<a class=\"{}\" href=\"{}\">{}", klass_s, href, text_s);
+                    write!(out, "<a class=\"{}\" href=\"{}\">{}", klass_s, href, text_s).unwrap();
                 }
             }
             return Some("</a>");
         }
     }
     if !open_tag {
-        write!(out, "{}", text_s);
+        write!(out, "{}", text_s).unwrap();
         return None;
     }
     let klass_s = klass.as_html();
     if klass_s.is_empty() {
-        write!(out, "{}", text_s);
+        out.write_str(&text_s).unwrap();
         Some("")
     } else {
-        write!(out, "<span class=\"{}\">{}", klass_s, text_s);
+        write!(out, "<span class=\"{}\">{}", klass_s, text_s).unwrap();
         Some("</span>")
     }
 }

src/librustdoc/html/sources.rs

@@ -1,12 +1,14 @@
 use crate::clean;
 use crate::docfs::PathError;
 use crate::error::Error;
+use crate::html::format;
 use crate::html::format::Buffer;
 use crate::html::highlight;
 use crate::html::layout;
 use crate::html::render::Context;
 use crate::visit::DocVisitor;
 
+use askama::Template;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_middle::ty::TyCtxt;
@@ -16,6 +18,7 @@ use rustc_span::source_map::FileName;
 use std::cell::RefCell;
 use std::ffi::OsStr;
 use std::fs;
+use std::ops::RangeInclusive;
 use std::path::{Component, Path, PathBuf};
 use std::rc::Rc;
 
@@ -299,39 +302,32 @@ pub(crate) fn print_src(
     decoration_info: highlight::DecorationInfo,
     source_context: SourceContext,
 ) {
+    #[derive(Template)]
+    #[template(path = "source.html")]
+    struct Source<Code: std::fmt::Display> {
+        embedded: bool,
+        needs_expansion: bool,
+        lines: RangeInclusive<usize>,
+        code_html: Code,
+    }
     let lines = s.lines().count();
-    let mut line_numbers = Buffer::empty_from(buf);
-    let extra;
-    line_numbers.write_str("<pre class=\"src-line-numbers\">");
+    let (embedded, needs_expansion, lines) = match source_context {
+        SourceContext::Standalone => (false, false, 1..=lines),
+        SourceContext::Embedded { offset, needs_expansion } => {
+            (true, needs_expansion, (1 + offset)..=(lines + offset))
+        }
+    };
     let current_href = context
         .href_from_span(clean::Span::new(file_span), false)
         .expect("only local crates should have sources emitted");
-    match source_context {
-        SourceContext::Standalone => {
-            extra = None;
-            for line in 1..=lines {
-                writeln!(line_numbers, "<a href=\"#{line}\" id=\"{line}\">{line}</a>")
-            }
-        }
-        SourceContext::Embedded { offset, needs_expansion } => {
-            extra = if needs_expansion {
-                Some(r#"<button class="expand">&varr;</button>"#)
-            } else {
-                None
-            };
-            for line_number in 1..=lines {
-                let line = line_number + offset;
-                writeln!(line_numbers, "<span>{line}</span>")
-            }
-        }
-    }
-    line_numbers.write_str("</pre>");
-    highlight::render_source_with_highlighting(
-        s,
-        buf,
-        line_numbers,
-        highlight::HrefContext { context, file_span, root_path, current_href },
-        decoration_info,
-        extra,
-    );
+    let code = format::display_fn(move |fmt| {
+        highlight::write_code(
+            fmt,
+            s,
+            Some(highlight::HrefContext { context, file_span, root_path, current_href }),
+            Some(decoration_info),
+        );
+        Ok(())
+    });
+    Source { embedded, needs_expansion, lines, code_html: code }.render_into(buf).unwrap();
 }

src/librustdoc/html/templates/source.html

@@ -0,0 +1,19 @@
+<div class="example-wrap"> {# #}
+    <pre class="src-line-numbers">
+        {% for line in lines.clone() %}
+            {% if embedded %}
+                <span>{{line|safe}}</span>
+            {%~ else %}
+                <a href="#{{line|safe}}" id="{{line|safe}}">{{line|safe}}</a>
+            {%~ endif %}
+        {% endfor %}
+    </pre> {# #}
+    <pre class="rust"> {# #}
+        <code>
+            {% if needs_expansion %}
+                <button class="expand">&varr;</button>
+            {% endif %}
+            {{code_html|safe}}
+        </code> {# #}
+    </pre> {# #}
+</div>