implement fish completion with metadata

src/click/shell_completion.py

@@ -30,8 +30,10 @@
 
     for completion in $response; do
         IFS=',' read type value <<< "$completion"
+        COMPREPLY+=($type)
+        COMPREPLY+=($value)
         if [[ $type == 'dir' ]]; then
-            COMREPLY=()
+            # COMREPLY=()
             compopt -o dirnames
         elif [[ $type == 'file' ]]; then
             COMREPLY=()
@@ -86,12 +88,31 @@
 compdef %(complete_func)s %(script_names)s
 """
 
-COMPLETION_SCRIPT_FISH = (
-    "complete --no-files --command %(script_names)s --arguments"
-    ' "(env %(autocomplete_var)s=complete_fish'
-    " COMP_WORDS=(commandline -cp) COMP_CWORD=(commandline -t)"
-    ' %(script_names)s)"'
-)
+
+COMPLETION_SCRIPT_FISH = """
+function %(complete_func)s_complete;
+    set -l response;
+    for value in (env %(autocomplete_var)s=complete_fish \
+        COMP_WORDS=(commandline -cp) COMP_CWORD=(commandline -t) \
+        %(script_names)s);
+        set response $response $value;
+    end;
+
+    for completion in $response;
+        set -l metadata (string split "," $completion);
+        if test $metadata[1] = "dir";
+            __fish_complete_directories $metadata[2];
+        else if test $metadata[1] = "file";
+            __fish_complete_path $metadata[2];
+        else if test $metadata[1] = "none";
+            echo $metadata[2];
+        end;
+    end;
+end;
+
+complete --no-files --command %(script_names)s --arguments \
+    "(%(complete_func)s_complete)"
+"""
 
 _invalid_ident_char_re = re.compile(r"[^a-zA-Z0-9_]")
 
@@ -133,7 +154,15 @@ def source(self):
         return COMPLETION_SCRIPT_BASH
 
     def complete(self):
-        completions = do_completion(self.cli, self.prog_name)
+        cwords = split_arg_string(os.environ["COMP_WORDS"])
+        cword = int(os.environ["COMP_CWORD"])
+        args = cwords[1:cword]
+        try:
+            incomplete = cwords[cword]
+        except IndexError:
+            incomplete = ""
+
+        completions = do_complete(self.cli, self.prog_name, args, incomplete)
         for item in completions:
             echo(f"{item[0]},{item[1]}")
 
@@ -147,7 +176,15 @@ def source(self):
         return COMPLETION_SCRIPT_ZSH
 
     def complete(self):
-        completions = do_completion(self.cli, self.prog_name)
+        cwords = split_arg_string(os.environ["COMP_WORDS"])
+        cword = int(os.environ["COMP_CWORD"])
+        args = cwords[1:cword]
+        try:
+            incomplete = cwords[cword]
+        except IndexError:
+            incomplete = ""
+
+        completions = do_complete(self.cli, self.prog_name, args, incomplete)
         for item in completions:
             echo(item[1])
             echo(item[2] if item[2] else "_")
@@ -162,25 +199,26 @@ def source(self):
         return COMPLETION_SCRIPT_FISH
 
     def complete(self):
-        completions = do_completion(self.cli, self.prog_name)
+        cwords = split_arg_string(os.environ["COMP_WORDS"])
+        incomplete = os.environ["COMP_CWORD"]
+        args = cwords[1:]
+
+        # Fish is weird in that a partially completed path is registered in
+        # both `COMP_WORDS` and `COMP_CWORD`.
+        if incomplete and args and args[-1] == incomplete:
+            args.pop()
+
+        completions = do_complete(self.cli, self.prog_name, args, incomplete)
         for item in completions:
             if item[2]:
-                echo(f"{item[1]}\t{item[2]}")
+                echo(f"{item[0]},{item[1]}\t{item[2]}")
             else:
-                echo(item[1])
+                echo(f"{item[0]},{item[1]}")
 
         return True
 
 
-def do_completion(cli, prog_name):
-    cwords = split_arg_string(os.environ["COMP_WORDS"])
-    cword = int(os.environ["COMP_CWORD"])
-    args = cwords[1:cword]
-    try:
-        incomplete = cwords[cword]
-    except IndexError:
-        incomplete = ""
-
+def do_complete(cli, prog_name, args, incomplete):
     all_args = copy.deepcopy(args)
     ctx = resolve_ctx(cli, prog_name, args)
     if ctx is None: