docs: Auto generate command list

xtask/Cargo.toml

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+[package]
+name = "xtask"
+version = "0.5.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+helix-term = { version = "0.5", path = "../helix-term" }

xtask/src/main.rs

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+use std::env;
+
+pub mod md_gen {
+    use super::path;
+    use std::fs;
+
+    use helix_term::commands::cmd::TYPABLE_COMMAND_LIST;
+
+    pub const TYPABLE_COMMANDS_MD_OUTPUT: &str = "typable-cmd.md";
+
+    pub fn typable_commands() -> String {
+        let mut md = String::new();
+        md.push_str("| Name | Description |\n");
+        md.push_str("| ---  | ---         |\n");
+
+        let cmdify = |s: &str| format!("`:{}`", s);
+
+        for cmd in TYPABLE_COMMAND_LIST {
+            let names = std::iter::once(&cmd.name)
+                .chain(cmd.aliases.iter())
+                .map(|a| cmdify(a))
+                .collect::<Vec<_>>()
+                .join(", ");
+
+            let entry = format!("| {} | {} |\n", names, cmd.doc);
+            md.push_str(&entry);
+        }
+
+        md
+    }
+
+    pub fn write(filename: &str, data: &str) {
+        let error = format!("Could not write to {}", filename);
+        let path = path::book_gen().join(filename);
+        fs::write(path, data).expect(&error);
+    }
+}
+
+pub mod path {
+    use std::path::{Path, PathBuf};
+
+    pub fn project_root() -> PathBuf {
+        Path::new(env!("CARGO_MANIFEST_DIR"))
+            .parent()
+            .unwrap()
+            .to_path_buf()
+    }
+
+    pub fn book_gen() -> PathBuf {
+        project_root().join("book/src/generated/")
+    }
+}
+
+pub mod tasks {
+    use super::md_gen;
+
+    pub fn bookgen() {
+        md_gen::write(
+            md_gen::TYPABLE_COMMANDS_MD_OUTPUT,
+            &md_gen::typable_commands(),
+        );
+    }
+
+    pub fn print_help() {
+        println!(
+            "
+Usage: Run with `cargo xtask <task>`, eg. `cargo xtask bookgen`.
+
+    Tasks:
+        bookgen: Generate files to be included in the mdbook output.
+"
+        );
+    }
+}
+
+fn main() -> Result<(), String> {
+    let task = env::args().nth(1);
+    match task {
+        None => tasks::print_help(),
+        Some(t) => match t.as_str() {
+            "bookgen" => tasks::bookgen(),
+            invalid => return Err(format!("Invalid task name: {}", invalid)),
+        },
+    };
+    Ok(())
+}