use crate::nop_lib::Nop; use clap::{App, Arg, ArgMatches, SubCommand}; use mdbook::book::Book; use mdbook::errors::Error; use mdbook::preprocess::{CmdPreprocessor, Preprocessor, PreprocessorContext}; use semver::{Version, VersionReq}; use std::io; use std::process; pub fn make_app() -> App<'static, 'static> { App::new("nop-preprocessor") .about("A mdbook preprocessor which does precisely nothing") .subcommand( SubCommand::with_name("supports") .arg(Arg::with_name("renderer").required(true)) .about("Check whether a renderer is supported by this preprocessor"), ) } fn main() { let matches = make_app().get_matches(); // Users will want to construct their own preprocessor here let preprocessor = Nop::new(); if let Some(sub_args) = matches.subcommand_matches("supports") { handle_supports(&preprocessor, sub_args); } else if let Err(e) = handle_preprocessing(&preprocessor) { eprintln!("{}", e); process::exit(1); } } fn handle_preprocessing(pre: &dyn Preprocessor) -> Result<(), Error> { let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())?; let book_version = Version::parse(&ctx.mdbook_version)?; let version_req = VersionReq::parse(mdbook::MDBOOK_VERSION)?; if version_req.matches(&book_version) != true { eprintln!( "Warning: The {} plugin was built against version {} of mdbook, \ but we're being called from version {}", pre.name(), mdbook::MDBOOK_VERSION, ctx.mdbook_version ); } let processed_book = pre.run(&ctx, book)?; serde_json::to_writer(io::stdout(), &processed_book)?; Ok(()) } fn handle_supports(pre: &dyn Preprocessor, sub_args: &ArgMatches) -> ! { let renderer = sub_args.value_of("renderer").expect("Required argument"); let supported = pre.supports_renderer(&renderer); // Signal whether the renderer is supported by exiting with 1 or 0. if supported { process::exit(0); } else { process::exit(1); } } /// The actual implementation of the `Nop` preprocessor. This would usually go /// in your main `lib.rs` file. mod nop_lib { use super::*; /// A no-op preprocessor. pub struct Nop; impl Nop { pub fn new() -> Nop { Nop } } impl Preprocessor for Nop { fn name(&self) -> &str { "nop-preprocessor" } fn run(&self, ctx: &PreprocessorContext, book: Book) -> Result { // In testing we want to tell the preprocessor to blow up by setting a // particular config value if let Some(nop_cfg) = ctx.config.get_preprocessor(self.name()) { if nop_cfg.contains_key("blow-up") { anyhow::bail!("Boom!!1!"); } } // we *are* a no-op preprocessor after all Ok(book) } fn supports_renderer(&self, renderer: &str) -> bool { renderer != "not-supported" } } }