add listing link preprocessor

Author: mianlang

book.toml

@@ -38,6 +38,7 @@ git-repository-url = "https://github.com/rust-lang/book"
 [preprocessor.trpl-note]
 
 [preprocessor.trpl-listing]
+[preprocessor.trpl-listing-link]
 output-mode = "default"
 
 [rust]

packages/mdbook-trpl/Cargo.toml

@@ -11,6 +11,10 @@ path = "src/bin/note.rs"
 name = "mdbook-trpl-listing"
 path = "src/bin/listing.rs"
 
+[[bin]]
+name = "mdbook-trpl-listing-link"
+path = "src/bin/listing_link.rs"
+
 [[bin]]
 name = "mdbook-trpl-heading"
 path = "src/bin/heading.rs"
@@ -29,6 +33,7 @@ pulldown-cmark-to-cmark = "19"
 serde_json = "1"
 thiserror = "1.0.60"
 toml = "0.8.12"
+regex = "1.5"
 
 [dev-dependencies]
 assert_cmd = "2"

packages/mdbook-trpl/src/bin/listing_link.rs

@@ -0,0 +1,39 @@
+use std::io;
+
+use clap::{self, Parser, Subcommand};
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor};
+
+use mdbook_trpl::listing_link::ListingLinkPreprocessor;
+
+fn main() -> Result<(), String> {
+    let cli = Cli::parse();
+    if let Some(Command::Supports { renderer }) = cli.command {
+        return if ListingLinkPreprocessor.supports_renderer(&renderer) {
+            Ok(())
+        } else {
+            Err(format!("Renderer '{renderer}' is unsupported"))
+        };
+    }
+
+    let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())
+        .map_err(|e| format!("{e}"))?;
+    let processed = ListingLinkPreprocessor
+        .run(&ctx, book)
+        .map_err(|e| format!("{e}"))?;
+    serde_json::to_writer(io::stdout(), &processed).map_err(|e| format!("{e}"))
+}
+
+/// A simple preprocessor for handling listing links in _The Rust Programming Language_.
+#[derive(Parser, Debug)]
+struct Cli {
+    #[command(subcommand)]
+    command: Option<Command>,
+}
+
+#[derive(Subcommand, Debug)]
+enum Command {
+    /// Is the renderer supported?
+    ///
+    /// All renderers are supported! This is the contract for mdBook.
+    Supports { renderer: String },
+}

packages/mdbook-trpl/src/lib.rs

@@ -2,6 +2,7 @@ mod config;
 mod figure;
 mod heading;
 mod listing;
+pub mod listing_link;
 mod note;
 
 pub use config::Mode;

packages/mdbook-trpl/src/listing_link/mod.rs

@@ -0,0 +1,31 @@
+use mdbook::{
+    book::Book,
+    errors::Result,
+    preprocess::{Preprocessor, PreprocessorContext},
+    BookItem,
+};
+use regex::Regex;
+
+pub struct ListingLinkPreprocessor;
+
+impl Preprocessor for ListingLinkPreprocessor {
+    fn name(&self) -> &str {
+        "trpl-listing-link"
+    }
+
+    fn run(&self, _ctx: &PreprocessorContext, mut book: Book) -> Result<Book> {
+        let re = Regex::new(r"Listing\s(\d+-\d+)").unwrap();
+
+        book.for_each_mut(|item| {
+            if let BookItem::Chapter(ref mut chapter) = item {
+                chapter.content = re.replace_all(&chapter.content, r##"<a href="#listing-$1" class="listing-link">Listing $1</a>"##).to_string();
+            }
+        });
+
+        Ok(book)
+    }
+
+    fn supports_renderer(&self, renderer: &str) -> bool {
+        renderer == "html" || renderer == "markdown" || renderer == "test"
+    }
+}