Expand command line interface

src/main.rs

@@ -5,34 +5,95 @@ use std::process;
 
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use codespan_reporting::term::{self, termcolor, Config, Styles};
+use pico_args::Arguments;
 use same_file::is_same_file;
 use termcolor::{ColorChoice, StandardStream, WriteColor};
 
-use typst::diag::Error;
+use typst::diag::{Error, StrResult};
 use typst::export;
+use typst::font::{FaceInfo, FontStore};
+use typst::library::text::THEME;
 use typst::loading::FsLoader;
+use typst::parse::TokenMode;
 use typst::source::SourceStore;
+use typst::syntax;
 use typst::Context;
 
+/// What to do.
+enum Command {
+    Typeset(TypesetCommand),
+    Highlight(HighlightCommand),
+    Fonts(FontsCommand),
+}
+
+/// Typeset a .typ file into a PDF file.
+struct TypesetCommand {
+    input: PathBuf,
+    output: PathBuf,
+    root: Option<PathBuf>,
+}
+
 const HELP: &'static str = "\
 typst creates PDF files from .typ files
 
 USAGE:
   typst [OPTIONS] <input.typ> [output.pdf]
+  typst [SUBCOMMAND] ...
+
+ARGS:
+  <input.typ>    Path to input Typst file
+  [output.pdf]   Path to output PDF file
 
 OPTIONS:
   -h, --help     Print this help
   --root <dir>   Configure the root for absolute paths
 
-ARGS:
-  <input.typ>    Path to input Typst file
-  [output.pdf]   Path to output PDF
+SUBCOMMANDS:
+  --highlight    Highlight .typ files to HTML
+  --fonts        List all discovered system fonts
 ";
 
+/// Highlight a .typ file into a HTML file.
+struct HighlightCommand {
+    input: PathBuf,
+    output: PathBuf,
+}
+
+const HELP_HIGHLIGHT: &'static str = "\
+typst --highlight creates highlighted HTML from .typ files
+
+USAGE:
+  typst --highlight [OPTIONS] <input.typ> [output.html]
+
+ARGS:
+  <input.typ>    Path to input Typst file
+  [output.html]  Path to output HTML file
+
+OPTIONS:
+  -h, --help     Print this help
+";
+
+/// List discovered fonts.
+struct FontsCommand {
+    variants: bool,
+}
+
+const HELP_FONTS: &'static str = "\
+typst --fonts lists all discovered system fonts
+
+USAGE:
+  typst --fonts [OPTIONS]
+
+OPTIONS:
+  -h, --help     Print this help
+  --variants     Also list style variants of each font family
+";
+
+/// Entry point.
 fn main() {
-    let args = parse_args();
-    let ok = args.is_ok();
-    if let Err(msg) = args.and_then(try_main) {
+    let command = parse_args();
+    let ok = command.is_ok();
+    if let Err(msg) = command.and_then(dispatch) {
         print_error(&msg).unwrap();
         if !ok {
             println!("\nfor more information, try --help");
@@ -41,95 +102,71 @@ fn main() {
     }
 }
 
-/// The main compiler logic.
-fn try_main(args: Args) -> Result<(), String> {
-    // Create a loader for fonts and files.
-    let mut loader = FsLoader::new();
-    let mut builder = Context::builder();
-    if let Some(root) = &args.root {
-        builder.root(root);
-    }
-
-    // Search for fonts in the project directory.
-    if let Some(dir) = args.input.parent() {
-        if args.root.is_none() {
-            builder.root(dir);
-        }
-
-        if dir.as_os_str().is_empty() {
-            // Just a filename, so directory is current directory.
-            loader.search_path(".");
-        } else {
-            loader.search_path(dir);
-        }
-    }
-
-    // Search system fonts only now to give local fonts priority.
-    loader.search_system();
-
-    // Create the context which holds loaded source files, fonts, images and
-    // cached artifacts.
-    let mut ctx = builder.build(loader.wrap());
-
-    // Ensure that the source file is not overwritten.
-    if is_same_file(&args.input, &args.output).unwrap_or(false) {
-        Err("source and destination files are the same")?;
-    }
-
-    // Load the source file.
-    let id = ctx
-        .sources
-        .load(&args.input)
-        .map_err(|_| "failed to load source file")?;
-
-    // Typeset.
-    match ctx.typeset(id) {
-        // Export the PDF.
-        Ok(frames) => {
-            let buffer = export::pdf(&ctx, &frames);
-            fs::write(&args.output, buffer).map_err(|_| "failed to write PDF file")?;
-        }
-
-        // Print diagnostics.
-        Err(errors) => {
-            print_diagnostics(&ctx.sources, *errors)
-                .map_err(|_| "failed to print diagnostics")?;
-        }
-    }
-
-    Ok(())
-}
-
-struct Args {
-    input: PathBuf,
-    output: PathBuf,
-    root: Option<PathBuf>,
-}
-
 /// Parse command line arguments.
-fn parse_args() -> Result<Args, String> {
-    let mut args = pico_args::Arguments::from_env();
-    if args.contains(["-h", "--help"]) {
-        print!("{}", HELP);
-        std::process::exit(0);
+fn parse_args() -> StrResult<Command> {
+    let mut args = Arguments::from_env();
+    let help = args.contains(["-h", "--help"]);
+
+    let command = if args.contains("--highlight") {
+        if help {
+            print_help(HELP_HIGHLIGHT);
+        }
+
+        let (input, output) = parse_input_output(&mut args, "html")?;
+        Command::Highlight(HighlightCommand { input, output })
+    } else if args.contains("--fonts") {
+        if help {
+            print_help(HELP_FONTS);
+        }
+
+        Command::Fonts(FontsCommand { variants: args.contains("--variants") })
+    } else {
+        if help {
+            print_help(HELP);
+        }
+
+        let root = args.opt_value_from_str("--root").map_err(|_| "missing root path")?;
+        let (input, output) = parse_input_output(&mut args, "pdf")?;
+        Command::Typeset(TypesetCommand { input, output, root })
+    };
+
+    // Don't allow excess arguments.
+    let rest = args.finish();
+    if !rest.is_empty() {
+        Err(format!(
+            "unexpected argument{}",
+            if rest.len() > 1 { "s" } else { "" }
+        ))?;
     }
 
-    let root = args.opt_value_from_str("--root").map_err(|_| "malformed root")?;
+    Ok(command)
+}
+
+/// Parse two freestanding path arguments, with the output path being optional.
+/// If it is omitted, it is determined from the input path's filename with the
+/// given extension.
+fn parse_input_output(args: &mut Arguments, ext: &str) -> StrResult<(PathBuf, PathBuf)> {
     let input: PathBuf = args.free_from_str().map_err(|_| "missing input file")?;
     let output = match args.opt_free_from_str().ok().flatten() {
         Some(output) => output,
         None => {
             let name = input.file_name().ok_or("source path does not point to a file")?;
-            Path::new(name).with_extension("pdf")
+            Path::new(name).with_extension(ext)
         }
     };
 
-    // Don't allow excess arguments.
-    if !args.finish().is_empty() {
-        Err("too many arguments")?;
+    // Ensure that the source file is not overwritten.
+    if is_same_file(&input, &output).unwrap_or(false) {
+        Err("source and destination files are the same")?;
     }
 
-    Ok(Args { input, output, root })
+    Ok((input, output))
+}
+
+/// Print a help string and quit.
+fn print_help(help: &'static str) {
+    print!("{help}");
+    std::process::exit(0);
 }
 
 /// Print an application-level error (independent from a source file).
@@ -144,6 +181,55 @@ fn print_error(msg: &str) -> io::Result<()> {
     writeln!(w, ": {msg}.")
 }
 
+/// Dispatch a command.
+fn dispatch(command: Command) -> StrResult<()> {
+    match command {
+        Command::Typeset(command) => typeset(command),
+        Command::Highlight(command) => highlight(command),
+        Command::Fonts(command) => fonts(command),
+    }
+}
+
+/// Execute a typesetting command.
+fn typeset(command: TypesetCommand) -> StrResult<()> {
+    let mut builder = Context::builder();
+    if let Some(root) = &command.root {
+        builder.root(root);
+    } else if let Some(dir) = command.input.parent() {
+        builder.root(dir);
+    }
+
+    // Create a loader for fonts and files.
+    let loader = FsLoader::new().with_system();
+
+    // Create the context which holds loaded source files, fonts, images and
+    // cached artifacts.
+    let mut ctx = builder.build(loader.wrap());
+
+    // Load the source file.
+    let id = ctx
+        .sources
+        .load(&command.input)
+        .map_err(|_| "failed to load source file")?;
+
+    // Typeset.
+    match ctx.typeset(id) {
+        // Export the PDF.
+        Ok(frames) => {
+            let buffer = export::pdf(&ctx, &frames);
+            fs::write(&command.output, buffer).map_err(|_| "failed to write PDF file")?;
+        }
+
+        // Print diagnostics.
+        Err(errors) => {
+            print_diagnostics(&ctx.sources, *errors)
+                .map_err(|_| "failed to print diagnostics")?;
+        }
+    }
+
+    Ok(())
+}
+
 /// Print diagnostics messages to the terminal.
 fn print_diagnostics(
     sources: &SourceStore,
@@ -173,3 +259,34 @@ fn print_diagnostics(
 
     Ok(())
 }
+
+/// Execute a highlighting command.
+fn highlight(command: HighlightCommand) -> StrResult<()> {
+    let input = std::fs::read_to_string(&command.input)
+        .map_err(|_| "failed to load source file")?;
+
+    let html = syntax::highlight_html(&input, TokenMode::Markup, &THEME);
+    fs::write(&command.output, html).map_err(|_| "failed to write HTML file")?;
+
+    Ok(())
+}
+
+/// Execute a font listing command.
+fn fonts(command: FontsCommand) -> StrResult<()> {
+    let loader = FsLoader::new().with_system();
+    let fonts = FontStore::new(loader.wrap());
+
+    for (name, infos) in fonts.families() {
+        println!("{name}");
+        if command.variants {
+            for &FaceInfo { variant, .. } in infos {
+                println!(
+                    "- Style: {:?}, Weight: {:?}, Stretch: {:?}",
+                    variant.style, variant.weight, variant.stretch,
+                );
+            }
+        }
+    }
+
+    Ok(())
+}