super basic zsh completion

complete/src/lib.rs

@@ -2,6 +2,7 @@
 // file that was distributed with this source code.
 
 mod fish;
+mod zsh;
 
 pub struct Command {
     pub name: String,
@@ -31,7 +32,8 @@ pub enum ValueHint {
 pub fn render(c: &Command, shell: &str) -> String {
     match shell {
         "fish" => fish::render(c),
-        "sh" | "zsh" | "bash" | "csh" | "elvish" | "powershell" => panic!("shell '{shell}' completion is not supported yet!"),
+        "zsh" => zsh::render(c),
+        "sh" | "bash" | "csh" | "elvish" | "powershell" => panic!("shell '{shell}' completion is not supported yet!"),
         _ => panic!("unknown shell '{shell}'!"),
     }
 }

complete/src/zsh.rs

@@ -0,0 +1,58 @@
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use crate::{Command, Arg};
+
+pub fn render(c: &Command) -> String {
+    template(&c.name, &render_args(&c.args))
+}
+
+fn render_args(args: &[Arg]) -> String {
+    let mut out = String::new();
+    let indent = " ".repeat(8);
+    for arg in args {
+        let help = &arg.help;
+        for short in &arg.short {
+            out.push_str(
+                &format!("{indent}'-{short}[{help}]' \\\n")
+            );
+        }
+        for long in &arg.long {
+            out.push_str(
+                &format!("{indent}'--{long}[{help}]' \\\n")
+            );
+        }
+    }
+    out
+}
+
+fn template(name: &str, args: &str) -> String {
+    format!(
+        "\
+#compdef {name}
+
+autoload -U is-at-least
+
+_{name}() {{
+    typeset -A opt_args
+    typeset -a _arguments_options
+    local ret=1
+
+    if is-at-least 5.2; then
+        _arguments_options=(-s -S -C)
+    else
+        _arguments_options=(-s -C)
+    fi
+
+    local context curcontext=\"$curcontext\" state line
+    _arguments \"${{_arguments_options[@]}}\" \\\n{args}
+&& ret=0
+}}
+
+if [ \"$funcstack[1]\" = \"_{name}\" ]; then
+    {name} \"$@\"
+else
+    compdef _{name} {name}
+fi"
+    )
+}