feat: new "name" subcommand

Add a "stg name" command that works like "stg id" but returns the patch
name instead of the revision. This can be useful for scripting and some
command aliases. This is a generalization of the "stg next" command:
"stg next" is now equivalent to "stg name +1".

Author: fbenkstein

src/cmd/mod.rs

@@ -25,6 +25,7 @@ pub(crate) mod id;
 pub(crate) mod import;
 pub(crate) mod init;
 pub(crate) mod log;
+pub(crate) mod name;
 pub(crate) mod new;
 pub(crate) mod next;
 pub(crate) mod patches;
@@ -101,6 +102,7 @@ pub(crate) const STGIT_COMMANDS: &[StGitCommand] = &[
     import::STGIT_COMMAND,
     init::STGIT_COMMAND,
     log::STGIT_COMMAND,
+    name::STGIT_COMMAND,
     new::STGIT_COMMAND,
     next::STGIT_COMMAND,
     patches::STGIT_COMMAND,

src/cmd/name.rs

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+//! `stg name` implementation.
+
+use std::io::Write;
+
+use anyhow::{anyhow, Result};
+use clap::{Arg, ArgMatches};
+use termcolor::WriteColor;
+
+use crate::{
+    argset,
+    branchloc::BranchLocator,
+    ext::RepositoryExtended,
+    patch::SingleRevisionSpec,
+    stack::{InitializationPolicy, Stack, StackAccess, StackStateAccess},
+};
+
+pub(super) const STGIT_COMMAND: super::StGitCommand = super::StGitCommand {
+    name: "name",
+    category: super::CommandCategory::PatchInspection,
+    make,
+    run,
+};
+
+fn make() -> clap::Command {
+    clap::Command::new(STGIT_COMMAND.name)
+        .about("Print patch name of a StGit revision")
+        .long_about(
+            "Print the patch name of a StGit revision.\n\
+             \n\
+             Try to get the name of the patch in the current \
+             branch as specified by a StGit revision. Revisions \
+             can be specified in the all the forms accepted by \
+             \"stg id\" command.",
+        )
+        .arg(argset::branch_arg())
+        .arg(
+            Arg::new("show-branch")
+                .long("showbranch")
+                .help("Display the branch name with the patch")
+                .action(clap::ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("no-show-branch")
+                .long("no-showbranch")
+                .help("Do not display branch name")
+                .hide(true)
+                .action(clap::ArgAction::SetTrue)
+                .overrides_with("show-branch"),
+        )
+        .arg(
+            Arg::new("stgit-revision")
+                .value_name("revision")
+                .allow_hyphen_values(true)
+                .value_parser(clap::value_parser!(SingleRevisionSpec))
+                .help("StGit revision"),
+        )
+}
+
+fn run(matches: &ArgMatches) -> Result<()> {
+    let repo = gix::Repository::open()?;
+
+    let stack = Stack::from_branch_locator(
+        &repo,
+        matches.get_one::<BranchLocator>("branch"),
+        InitializationPolicy::RequireInitialized,
+    )?;
+
+    let oid = matches
+        .get_one::<SingleRevisionSpec>("stgit-revision")
+        .map(|spec| spec.resolve_object(&repo, &stack).map(|object| object.id))
+        .transpose()?
+        .unwrap_or_else(|| stack.get_branch_head().id);
+
+    let Some(patch_name) = (oid == stack.base().id).then_some("{base}").or_else(|| {
+        stack
+            .all_patches()
+            .find(|name| oid == stack.get_patch_commit_id(name))
+            .map(|name| name.as_ref())
+    }) else {
+        return Err(anyhow!("patch name not found for revision `{oid}`"));
+    };
+
+    let mut stdout = crate::color::get_color_stdout(matches);
+    let mut color_spec = termcolor::ColorSpec::new();
+    color_spec.set_bold(true);
+    stdout.set_color(&color_spec)?;
+
+    if matches.get_flag("show-branch") {
+        write!(stdout, "{}:", stack.get_branch_name())?;
+    }
+
+    write!(stdout, "{patch_name}")?;
+    color_spec.clear();
+    stdout.set_color(&color_spec)?;
+    writeln!(stdout)?;
+
+    Ok(())
+}

t/t3700-name.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+
+test_description="Test 'stg name'"
+
+. ./test-lib.sh
+
+test_expect_success 'Test on uninitialized repo' '
+    command_error stg name 2>err &&
+    grep "stack not initialized" err
+'
+
+test_expect_success 'Init repo' '
+    echo "foo" >foo.txt &&
+    git add foo.txt &&
+    git commit -m "initial" &&
+    git commit --allow-empty -m "base" &&
+    git branch nostack &&
+    for i in 1 2; do
+        echo "line $i" >>foo.txt &&
+        stg new -m "patch-$i" &&
+        stg refresh || return 1
+    done &&
+    stg branch -C cloned &&
+    stg branch -c forked &&
+    stg branch master
+'
+
+test_expect_success 'Get patch names' '
+  test "$(stg name)" = "patch-2" &&
+  test "$(stg name -1)" = "patch-1" &&
+  test "$(stg name 0~1)" = "{base}" &&
+  test "$(stg name --showbranch)" = "master:patch-2" &&
+  test "$(stg name -b cloned --showbranch)" = "cloned:patch-2" &&
+  test "$(stg name -b forked --showbranch)" = "forked:{base}"
+'
+
+test_expect_success 'Fail to get patch names' '
+  command_error stg name -b nostack --showbranch 2>err &&
+  grep "stack not initialized" err &&
+  command_error stg name 0~2  2>err &&
+  grep "patch name not found" err
+'
+
+test_done