feat: WIP

clap_complete/src/dynamic/fish.rs

@@ -0,0 +1,47 @@
+//! Complete commands within fish
+
+// For fish the behaviour should match the default as close as possible
+// 1. grouping shorthand completions i.e. -a<TAB> should show other shorthands to end up with
+//    -ams...
+// 2. only complete options when one - is typed
+// Due to https://github.com/fish-shell/fish-shell/issues/7943 we need to implement this our self
+//
+
+use std::ffi::OsString;
+
+use clap::Args;
+
+use super::Completer;
+
+/// Dynamic completion for Fish
+pub struct Fish;
+
+impl Completer for Fish {
+    type CompleteArgs = CompleteArgs;
+
+    fn completion_script(cmd: &mut clap::Command) -> Vec<u8> {
+        let name = cmd.get_bin_name().unwrap_or_else(|| cmd.get_name());
+        format!(
+            r#"complete -x -c {name} -a "{name} complete --commandline (commandline) --cursor (commandline -C)""#
+        ).into_bytes()
+    }
+
+    fn file_name(name: &str) -> String {
+        format!("{name}.fish")
+    }
+
+    fn try_complete(args: &Self::CompleteArgs, cmd: &mut clap::Command) -> clap::error::Result<()> {
+        todo!()
+    }
+}
+
+#[derive(Args, Clone, Debug)]
+/// Arguments for Fish Completion
+pub struct CompleteArgs {
+    /// current commandline
+    #[arg(long)]
+    commandline: OsString,
+    /// cursor position
+    #[arg(long)]
+    cursor: usize,
+}

clap_complete/src/dynamic/mod.rs

@@ -1,12 +1,14 @@
 //! Complete commands within shells
 
 pub mod bash;
+pub mod fish;
 
 use std::{io::Write, path::PathBuf};
 
 use clap::{Args, Command, Subcommand, ValueEnum};
 
-use crate::dynamic::bash::Bash;
+use bash::Bash;
+use fish::Fish;
 
 #[derive(Subcommand, Clone, Debug)]
 #[command(hide = true)]
@@ -23,6 +25,7 @@ pub enum CompleteCommand {
 /// Subcommand for all the shells, so each can have their own options
 pub enum CompleteShell {
     Bash(bash::CompleteArgs),
+    Fish(fish::CompleteArgs),
     /// Only exception is Register, which outputs the completion script for a shell
     Register(RegisterArgs),
 }
@@ -44,19 +47,23 @@ pub struct RegisterArgs {
 pub enum Shell {
     /// Bourne Again SHell (bash)
     Bash,
+    /// Friendly Interactive SHell (fish)
+    Fish,
 }
 
 impl Shell {
     /// Return completion script
     fn completion_script(&self, cmd: &mut Command) -> Vec<u8> {
         match self {
             Shell::Bash => Bash::completion_script(cmd),
+            Shell::Fish => Fish::completion_script(cmd),
         }
     }
     /// The recommended file name for the registration code
     fn file_name(&self, name: &str) -> String {
         match self {
             Shell::Bash => Bash::file_name(name),
+            Shell::Fish => Fish::file_name(name),
         }
     }
 }
@@ -88,6 +95,7 @@ impl CompleteCommand {
         let CompleteCommand::Complete(complete) = self;
         match complete {
             CompleteShell::Bash(args) => Bash::try_complete(args, cmd),
+            CompleteShell::Fish(args) => Fish::try_complete(args, cmd),
             CompleteShell::Register(RegisterArgs { path, shell }) => {
                 let script = shell.completion_script(cmd);
                 if path == std::path::Path::new("-") {