feat(clap_complete): add native completion support for elvish

    There is appending a space that isn't being handled.

clap_complete/src/dynamic/shells/elvish.rs

@@ -0,0 +1,62 @@
+use unicode_xid::UnicodeXID as _;
+
+/// Completion support for Bash
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct Elvish;
+
+impl crate::dynamic::Completer for Elvish {
+    fn file_name(&self, name: &str) -> String {
+        format!("{name}.elv")
+    }
+    fn write_registration(
+        &self,
+        name: &str,
+        bin: &str,
+        completer: &str,
+        buf: &mut dyn std::io::Write,
+    ) -> Result<(), std::io::Error> {
+        let bin = shlex::quote(bin);
+        let completer = shlex::quote(completer);
+
+        let script = r#"
+use str
+
+set edit:completion:arg-completer[BIN] = { |@words|
+    set E:_CLAP_IFS = "\n"
+
+    var index = (count $words)
+    set index = (- $index 1)
+    set E:_CLAP_COMPLETE_INDEX = (to-string $index)
+
+    put (COMPLETER complete --shell elvish -- $@words) | to-lines
+}
+"#
+        .replace("COMPLETER", &completer)
+        .replace("BIN", &bin);
+
+        writeln!(buf, "{script}")?;
+        Ok(())
+    }
+    fn write_complete(
+        &self,
+        cmd: &mut clap::Command,
+        args: Vec<std::ffi::OsString>,
+        current_dir: Option<&std::path::Path>,
+        buf: &mut dyn std::io::Write,
+    ) -> Result<(), std::io::Error> {
+        let index: usize = std::env::var("_CLAP_COMPLETE_INDEX")
+            .ok()
+            .and_then(|i| i.parse().ok())
+            .unwrap_or_default();
+        let ifs: Option<String> = std::env::var("_CLAP_IFS").ok().and_then(|i| i.parse().ok());
+        let completions = crate::dynamic::complete(cmd, args, index, current_dir)?;
+
+        for (i, (completion, _)) in completions.iter().enumerate() {
+            if i != 0 {
+                write!(buf, "{}", ifs.as_deref().unwrap_or("\n"))?;
+            }
+            write!(buf, "{}", completion.to_string_lossy())?;
+        }
+        Ok(())
+    }
+}

clap_complete/src/dynamic/shells/mod.rs

@@ -1,10 +1,12 @@
 //! Shell support
 
 mod bash;
+mod elvish;
 mod fish;
 mod shell;
 
 pub use bash::*;
+pub use elvish::*;
 pub use fish::*;
 pub use shell::*;
 

clap_complete/src/dynamic/shells/shell.rs

@@ -12,6 +12,8 @@ pub enum Shell {
     Bash,
     /// Friendly Interactive `SHell` (fish)
     Fish,
+    /// Elf `SHell` (elvish)
+    Elvish,
 }
 
 impl Display for Shell {
@@ -39,13 +41,14 @@ impl FromStr for Shell {
 // Hand-rolled so it can work even when `derive` feature is disabled
 impl ValueEnum for Shell {
     fn value_variants<'a>() -> &'a [Self] {
-        &[Shell::Bash, Shell::Fish]
+        &[Shell::Bash, Shell::Fish, Shell::Elvish]
     }
 
     fn to_possible_value(&self) -> Option<PossibleValue> {
         Some(match self {
             Shell::Bash => PossibleValue::new("bash"),
             Shell::Fish => PossibleValue::new("fish"),
+            Shell::Elvish => PossibleValue::new("elvish"),
         })
     }
 }
@@ -55,6 +58,7 @@ impl Shell {
         match self {
             Self::Bash => &super::Bash,
             Self::Fish => &super::Fish,
+            Self::Elvish => &super::Elvish,
         }
     }
 }

clap_complete/tests/snapshots/home/static/exhaustive/bash/.bashrc

@@ -245,7 +245,7 @@ _exhaustive() {
             fi
             case "${prev}" in
                 --shell)
-                    COMPREPLY=($(compgen -W "bash fish" -- "${cur}"))
+                    COMPREPLY=($(compgen -W "bash fish elvish" -- "${cur}"))
                     return 0
                     ;;
                 --register)

clap_complete/tests/snapshots/home/static/exhaustive/fish/fish/completions/exhaustive.fish

@@ -110,7 +110,7 @@ complete -c exhaustive -n "__fish_seen_subcommand_from hint" -l email -r -f
 complete -c exhaustive -n "__fish_seen_subcommand_from hint" -l global -d 'everywhere'
 complete -c exhaustive -n "__fish_seen_subcommand_from hint" -s h -l help -d 'Print help'
 complete -c exhaustive -n "__fish_seen_subcommand_from hint" -s V -l version -d 'Print version'
-complete -c exhaustive -n "__fish_seen_subcommand_from complete" -l shell -d 'Specify shell to complete for' -r -f -a "{bash	'',fish	''}"
+complete -c exhaustive -n "__fish_seen_subcommand_from complete" -l shell -d 'Specify shell to complete for' -r -f -a "{bash	'',fish	'',elvish	''}"
 complete -c exhaustive -n "__fish_seen_subcommand_from complete" -l register -d 'Path to write completion-registration to' -r -F
 complete -c exhaustive -n "__fish_seen_subcommand_from complete" -l global -d 'everywhere'
 complete -c exhaustive -n "__fish_seen_subcommand_from complete" -s h -l help -d 'Print help (see more with \'--help\')'

clap_complete/tests/snapshots/home/static/exhaustive/zsh/zsh/_exhaustive

@@ -325,7 +325,7 @@ _arguments "${_arguments_options[@]}" : \
 ;;
 (complete)
 _arguments "${_arguments_options[@]}" : \
-'--shell=[Specify shell to complete for]:SHELL:(bash fish)' \
+'--shell=[Specify shell to complete for]:SHELL:(bash fish elvish)' \
 '--register=[Path to write completion-registration to]:REGISTER:_files' \
 '--global[everywhere]' \
 '-h[Print help (see more with '\''--help'\'')]' \