Command mapping with get_commands()

The cmd module now takes responsibility for collecting all the StGit
commands.

The new StGitCommand struct defines a common function call interface for
commands. Each command module defines a get_command() function that
returns its StGitCommand instance.

In main(), the clap::App can now be setup more generically, without
main() having to have knowledge of each individual command.

Author: jpgrayson

src/cmd/id.rs

@@ -3,7 +3,11 @@ use git2::Repository;
 
 use crate::revspec::parse_stgit_revision;
 
-pub(crate) fn get_subcommand<'help>() -> App<'help> {
+pub(super) fn get_command() -> (&'static str, super::StGitCommand) {
+    ("id", super::StGitCommand { get_app, run })
+}
+
+fn get_app() -> App<'static> {
     App::new("id")
         .about("Print git hash of StGit revision")
         .long_about("Long about for 'id'.") // TODO
@@ -19,7 +23,7 @@ pub(crate) fn get_subcommand<'help>() -> App<'help> {
         .arg(Arg::new("revision").about("StGit revision"))
 }
 
-pub(crate) fn run(matches: &ArgMatches) -> super::Result {
+fn run(matches: &ArgMatches) -> super::Result {
     let opt_branch = matches.value_of("branch");
     let opt_spec = matches.value_of("revision");
 

src/cmd/init.rs

@@ -1,13 +1,17 @@
-use clap::App;
+use clap::{App, ArgMatches};
 use git2::Repository;
 
 use crate::stack::Stack;
 
-pub(crate) fn get_subcommand() -> App<'static> {
+pub(super) fn get_command() -> (&'static str, super::StGitCommand) {
+    ("init", super::StGitCommand { get_app, run })
+}
+
+fn get_app() -> App<'static> {
     App::new("init").about("Initialize StGit stack on current branch")
 }
 
-pub(crate) fn run() -> super::Result {
+fn run(_: &ArgMatches) -> super::Result {
     let repo = Repository::open_from_env()?;
     let branch_name = None;
     Stack::initialize(&repo, branch_name)?;

src/cmd/mod.rs

@@ -1,3 +1,5 @@
+use std::collections::BTreeMap;
+
 pub(crate) mod branch;
 pub(crate) mod clean;
 pub(crate) mod clone;
@@ -42,3 +44,19 @@ pub(crate) mod unhide;
 pub(crate) mod version;
 
 pub(crate) type Result = std::result::Result<(), crate::error::Error>;
+
+pub(crate) struct StGitCommand {
+    pub get_app: fn() -> clap::App<'static>,
+    pub run: fn(&clap::ArgMatches) -> Result,
+}
+
+pub(crate) fn get_commands() -> BTreeMap<&'static str, StGitCommand> {
+    BTreeMap::from([
+        id::get_command(),
+        init::get_command(),
+        new::get_command(),
+        refresh::get_command(),
+        series::get_command(),
+        version::get_command(),
+    ])
+}

src/cmd/new.rs

@@ -11,7 +11,11 @@ use crate::{
     stack::{ConflictMode, Stack, StackTransaction},
 };
 
-pub(crate) fn get_subcommand() -> App<'static> {
+pub(super) fn get_command() -> (&'static str, super::StGitCommand) {
+    ("new", super::StGitCommand { get_app, run })
+}
+
+fn get_app() -> App<'static> {
     App::new("new")
         .about("Create a new patch at top of the stack")
         .long_about(
@@ -49,7 +53,7 @@ pub(crate) fn get_subcommand() -> App<'static> {
         )
 }
 
-pub(crate) fn run(matches: &ArgMatches) -> super::Result {
+fn run(matches: &ArgMatches) -> super::Result {
     let repo = Repository::open_from_env()?;
     let branch_name: Option<&str> = None;
     let stack = Stack::from_branch(&repo, branch_name)?;

src/cmd/refresh.rs

@@ -2,7 +2,11 @@ use clap::{App, Arg, ArgGroup, ArgMatches, ArgSettings, ValueHint};
 
 use crate::argset;
 
-pub(crate) fn get_subcommand() -> App<'static> {
+pub(super) fn get_command() -> (&'static str, super::StGitCommand) {
+    ("refresh", super::StGitCommand { get_app, run })
+}
+
+fn get_app() -> App<'static> {
     App::new("refresh")
         .about("Incorporate worktree changes into current patch")
         .long_about(
@@ -111,7 +115,7 @@ pub(crate) fn get_subcommand() -> App<'static> {
         .arg(&*argset::DIFF_OPTS_ARG)
 }
 
-pub(crate) fn run(_matches: &ArgMatches) -> super::Result {
+fn run(_matches: &ArgMatches) -> super::Result {
     println!("refresh!");
     Ok(())
 }

src/cmd/series.rs

@@ -6,9 +6,15 @@ use termcolor::WriteColor;
 
 use crate::{patchname::PatchName, stack::Stack};
 
+use super::StGitCommand;
+
 const UNPRINTABLE: &str = "???";
 
-pub(crate) fn get_subcommand() -> App<'static> {
+pub(super) fn get_command() -> (&'static str, StGitCommand) {
+    ("series", StGitCommand { get_app, run })
+}
+
+fn get_app() -> App<'static> {
     App::new("series")
         .about("Print the patch series")
         .long_about(
@@ -121,7 +127,7 @@ pub(crate) fn get_subcommand() -> App<'static> {
         .group(ArgGroup::new("all-short-group").args(&["all", "short"]))
 }
 
-pub(crate) fn run(matches: &ArgMatches) -> super::Result {
+fn run(matches: &ArgMatches) -> super::Result {
     let repo = Repository::open_from_env()?;
     let opt_branch = matches.value_of("branch");
     let stack = Stack::from_branch(&repo, opt_branch)?;

src/cmd/version.rs

@@ -1,10 +1,14 @@
-use clap::App;
+use clap::{App, ArgMatches};
 
-pub(crate) fn get_subcommand() -> App<'static> {
+pub(super) fn get_command() -> (&'static str, super::StGitCommand) {
+    ("version", super::StGitCommand { get_app, run })
+}
+
+fn get_app() -> App<'static> {
     App::new("version").about("Print version information and exit")
 }
 
-pub(crate) fn run() -> super::Result {
+fn run(_: &ArgMatches) -> super::Result {
     println!("Stacked Git {}", env!("CARGO_PKG_VERSION"));
     std::process::Command::new("git")
         .arg("--version")

src/main.rs

@@ -23,6 +23,7 @@ use pyo3::prelude::*;
 use termcolor::WriteColor;
 
 fn main() {
+    let commands = crate::cmd::get_commands();
     let app = App::new("stg")
         .about("Maintain a stack of patches on top of a Git branch.")
         .global_setting(AppSettings::DeriveDisplayOrder)
@@ -34,27 +35,21 @@ fn main() {
         .license(crate_license!())
         .max_term_width(88)
         .subcommand_placeholder("command", "COMMANDS")
-        .subcommand(cmd::init::get_subcommand())
-        .subcommand(cmd::new::get_subcommand())
-        .subcommand(cmd::series::get_subcommand())
-        .subcommand(cmd::refresh::get_subcommand())
-        .subcommand(cmd::id::get_subcommand())
-        .subcommand(cmd::version::get_subcommand());
+        .subcommands(commands.values().map(|command| (command.get_app)()));
 
     // TODO: alias subcommands from config (stgit.alias.)
     // TODO: add top-level -C option
     // TODO: get repository and/or stack handle for subcommand
 
     let matches = app.get_matches();
-
-    let result: cmd::Result = match matches.subcommand() {
-        Some(("id", cmd_matches)) => cmd::id::run(cmd_matches),
-        Some(("init", _)) => cmd::init::run(),
-        Some(("new", cmd_matches)) => cmd::new::run(cmd_matches),
-        // Some(("refresh", cmd_matches)) => cmd::refresh::run(cmd_matches),
-        Some(("series", cmd_matches)) => cmd::series::run(cmd_matches),
-        Some(("version", _)) => cmd::version::run(),
-        _ => punt_to_python(),
+    let result: cmd::Result = if let Some((command_name, cmd_matches)) = matches.subcommand() {
+        if let Some(command) = commands.get(command_name) {
+            (command.run)(cmd_matches)
+        } else {
+            punt_to_python()
+        }
+    } else {
+        panic!("no subcommand?")
     };
 
     if let Err(e) = result {