infra: create mdbook-trpl-figure preprocessor

nostarch/book.toml

@@ -14,5 +14,8 @@ build-dir = "../tmp"
 [preprocessor.trpl-listing]
 output-mode = "simple"
 
+[preprocessor.trpl-figure]
+output-mode = "simple"
+
 [rust]
 edition = "2021"

packages/mdbook_trpl/Cargo.toml

@@ -11,6 +11,10 @@ path = "src/bin/note/main.rs"
 name = "mdbook-trpl-listing"
 path = "src/bin/listing/main.rs"
 
+[[bin]]
+name = "mdbook-trpl-figure"
+path = "src/bin/figure/main.rs"
+
 [dependencies]
 clap = { version = "4", features = ["derive"] }
 html_parser = "0.7.0"

packages/mdbook_trpl/src/bin/figure/main.rs

@@ -0,0 +1,42 @@
+use std::io;
+
+use clap::{self, Parser, Subcommand};
+
+use mdbook::preprocess::{CmdPreprocessor, Preprocessor};
+use mdbook_trpl::Figure;
+
+fn main() -> Result<(), String> {
+    match Cli::parse().command {
+        Some(Command::Supports { renderer }) => {
+            if Figure.supports_renderer(&renderer) {
+                Ok(())
+            } else {
+                Err(format!("Renderer '{renderer}' is unsupported"))
+            }
+        }
+        None => {
+            let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())
+                .map_err(|e| format!("{e}"))?;
+            let processed =
+                Figure.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 figures with images in _The Rust
+/// Programming Language_ book.
+#[derive(Parser, Debug)]
+struct Cli {
+    #[command(subcommand)]
+    command: Option<Command>,
+}
+
+#[derive(Subcommand, Debug)]
+enum Command {
+    /// Is the renderer supported?
+    ///
+    /// Supported renderers are `'html'`, `'markdown'`, and `'test'`.
+    Supports { renderer: String },
+}

packages/mdbook_trpl/src/figure/mod.rs

@@ -0,0 +1,54 @@
+use mdbook::{book::Book, errors::Result, preprocess::Preprocessor};
+
+use pulldown_cmark::Event::{self, *};
+
+use crate::config::Mode;
+
+/// A simple preprocessor to rewrite `<figure>`s with `<img>`s.
+///
+/// This is a no-op by default; it only operates on the book chapters when the
+/// `[preprocessor.trpl-figure]` has `output-mode = "simple"`.
+///
+/// Takes in Markdown containing like this:
+///
+/// ```markdown
+/// <figure>
+///
+/// <img src="http://www.example.com/some-cool-image.jpg">
+///
+/// <figcaption>Figure 1-2: A description of the image</figcaption>
+///
+/// </figure>
+/// ```
+///
+/// Spits out Markdown like this:
+///
+/// ```markdown
+/// <img src="http://www.example.com/some-cool-image.jpg">
+///
+/// Figure 1-2: A description of the image
+/// ```
+pub struct TrplFigure;
+impl TrplFigure {
+    pub fn supports_renderer(&self, renderer: &str) -> bool {
+        renderer == "html" || renderer == "markdown" || renderer == "test"
+    }
+}
+
+impl Preprocessor for TrplFigure {
+    fn name(&self) -> &str {
+        "trpl-figure"
+    }
+
+    fn run(
+        &self,
+        ctx: &mdbook::preprocess::PreprocessorContext,
+        book: Book,
+    ) -> Result<Book> {
+        if let Mode::Simple = Mode::from_context(ctx, self.name())? {}
+        todo!();
+        Ok(book)
+    }
+}
+
+mod tests;

packages/mdbook_trpl/src/lib.rs

@@ -1,6 +1,11 @@
-pub mod config;
+mod config;
+mod error;
+mod figure;
 mod listing;
 mod note;
 
+pub use config::Mode;
+pub use error::Report;
+pub use figure::TrplFigure as Figure;
 pub use listing::TrplListing as Listing;
 pub use note::TrplNote as Note;