clidispatch: support command name aliases

Summary:
Support command name aliases like `config|debugconfig` in Python command
definition.

Reviewed By: sfilipco

Differential Revision: D18108170

fbshipit-source-id: eeb9ec273960d7bd4e4278e55ef8122f200b2f60

lib/clidispatch/src/command.rs

@@ -8,8 +8,9 @@
 use crate::{io::IO, repo::Repo};
 use cliparser::parser::{Flag, ParseOutput, StructFlags};
 use failure::Fallible;
+use std::collections::BTreeMap;
 use std::convert::{TryFrom, TryInto};
-use std::{collections::BTreeMap, ops::Deref};
+use std::ops::Deref;
 
 pub enum CommandFunc {
     NoRepo(Box<dyn Fn(ParseOutput, &mut IO) -> Fallible<u8>>),
@@ -56,15 +57,36 @@ impl CommandDefinition {
     }
 }
 
+#[derive(Default)]
 pub struct CommandTable {
     commands: BTreeMap<String, CommandDefinition>,
+
+    /// Alias name -> Command name.
+    alias: BTreeMap<String, String>,
 }
 
 impl CommandTable {
     pub fn new() -> Self {
-        CommandTable {
-            commands: BTreeMap::new(),
+        Default::default()
+    }
+
+    /// Insert aliases to `alias` field.
+    ///
+    /// For example, `insert_aliases("config|cfg")` will insert
+    /// `{"config": "config|cfg", "cfg": "config|cfg"}` to `alias`.
+    fn insert_aliases<'a>(&mut self, names: &'a str) {
+        if !names.contains("|") {
+            return;
         }
+        for name in names.split("|") {
+            self.alias.insert(name.to_string(), names.to_string());
+        }
+    }
+
+    /// Look up a command by name. Consider aliases.
+    pub fn get(&self, name: &str) -> Option<&CommandDefinition> {
+        let name = self.alias.get(name).map(AsRef::as_ref).unwrap_or(name);
+        self.commands.get(name)
     }
 }
 
@@ -87,6 +109,7 @@ where
     FN: Fn(S, &mut IO) -> Fallible<u8> + 'static,
 {
     fn register(&mut self, f: FN, name: &str, doc: &str) {
+        self.insert_aliases(name);
         let func = move |opts: ParseOutput, io: &mut IO| f(opts.try_into()?, io);
         let func = CommandFunc::NoRepo(Box::new(func));
         let def = CommandDefinition::new(name, doc, S::flags, func);
@@ -101,6 +124,7 @@ where
     FN: Fn(S, &mut IO, Option<Repo>) -> Fallible<u8> + 'static,
 {
     fn register(&mut self, f: FN, name: &str, doc: &str) {
+        self.insert_aliases(name);
         let func =
             move |opts: ParseOutput, io: &mut IO, repo: Option<Repo>| f(opts.try_into()?, io, repo);
         let func = CommandFunc::OptionalRepo(Box::new(func));
@@ -116,6 +140,7 @@ where
     FN: Fn(S, &mut IO, Repo) -> Fallible<u8> + 'static,
 {
     fn register(&mut self, f: FN, name: &str, doc: &str) {
+        self.insert_aliases(name);
         let func = move |opts: ParseOutput, io: &mut IO, repo: Repo| f(opts.try_into()?, io, repo);
         let func = CommandFunc::Repo(Box::new(func));
         let def = CommandDefinition::new(name, doc, S::flags, func);

lib/clidispatch/src/dispatch.rs

@@ -234,16 +234,17 @@ pub fn dispatch(command_table: &CommandTable, args: Vec<String>, io: &mut IO) ->
     let command_name = first_arg.to_string();
     let (expanded, _first_arg_index) = expand_aliases(alias_lookup, &args[first_arg_index..])?;
     let (command_name, command_arg_len) =
-        find_command_name(|name| command_table.contains_key(name), &expanded)
+        find_command_name(|name| command_table.get(name).is_some(), &expanded)
             .ok_or_else(|| errors::UnknownCommand(command_name))?;
 
     let mut new_args = Vec::with_capacity(args.len());
     new_args.extend_from_slice(&args[..first_arg_index]);
     new_args.push(command_name.clone());
     new_args.extend_from_slice(&expanded[command_arg_len..]);
+
     let full_args = new_args;
 
-    let def = &command_table[&command_name];
+    let def = command_table.get(&command_name).unwrap();
     let parsed = parse(&def, &full_args)?;
 
     let global_opts: HgGlobalOpts = parsed.clone().try_into()?;

lib/hgcommands/src/commands.rs

@@ -39,7 +39,7 @@ pub fn table() -> CommandTable {
         "debugstore",
         "print information about blobstore",
     );
-    table.register(debugpython, "debugpython", "run python interpreter");
+    table.register(debugpython, "debugpython|debugpy", "run python interpreter");
     table.register(debugargs, "debug-args", "print arguments received");
     table.register(
         debugindexedlogdump,