Add support for -shell-script-* completion in :prompt

Fixes #2754

doc/pages/commands.asciidoc

@@ -247,6 +247,15 @@ but not really useful in that context.
     will have this command executed whenever the prompt content changes
     or the prompt is aborted, respectively.
 
+    Completion support can be controlled with the same switches provided
+    by the *define-command* command, see
+    <<declaring-new-commands,Declaring new commands>>.
+
+    For *-shell-script-completions* and *-shell-script-candidates*
+    completions, token_to_complete will always be 1, and the full
+    prompt content will be passed as a single token. In other words,
+    word splitting does not take place.
+
 *on-key* <command>::
     wait for next key from user, then execute <command>, the key is
     available through the `key` value, accessible through `$kak_key`

src/commands.cc

@@ -272,6 +272,21 @@ private:
     int m_token = -1;
 };
 
+template<typename Completer>
+struct PromptCompleterAdapter
+{
+    PromptCompleterAdapter(Completer completer) : m_completer{completer} {}
+
+    Completions operator()(const Context& context, CompletionFlags flags,
+                           StringView prefix, ByteCount cursor_pos)
+    {
+        return m_completer(context, flags, {String{String::NoCopy{}, prefix}}, 0, cursor_pos);
+    }
+
+private:
+    Completer m_completer;
+};
+
 Scope* get_scope_ifp(StringView scope, const Context& context)
 {
     if (prefix_match("global", scope))
@@ -1862,6 +1877,8 @@ const CommandDesc prompt_cmd = {
           { "buffer-completion", { false, "use buffer completion for prompt" } },
           { "command-completion", { false, "use command completion for prompt" } },
           { "shell-completion", { false, "use shell command completion for prompt" } },
+          { "shell-script-completion", { true, "use shell command completion for prompt" } },
+          { "shell-script-candidates", { true, "use shell command completion for prompt" } },
           { "on-change", { true, "command to execute whenever the prompt changes" } },
           { "on-abort", { true, "command to execute whenever the prompt is canceled" } } },
         ParameterDesc::Flags::None, 2, 2
@@ -1899,6 +1916,10 @@ const CommandDesc prompt_cmd = {
             };
         else if (parser.get_switch("shell-completion"))
             completer = shell_complete;
+        else if (auto shell_script = parser.get_switch("shell-script-completion"))
+            completer = PromptCompleterAdapter{ShellScriptCompleter{shell_script->str()}};
+        else if (auto shell_script = parser.get_switch("shell-script-candidates"))
+            completer = PromptCompleterAdapter{ShellCandidatesCompleter{shell_script->str()}};
 
         const auto flags = parser.get_switch("password") ?
             PromptFlags::Password : PromptFlags::None;

test/shell/prompt-shell-script-candidates/cmd

@@ -0,0 +1 @@
+:foo<ret>b<tab><tab><ret>

test/shell/prompt-shell-script-candidates/in

@@ -0,0 +1 @@
+

test/shell/prompt-shell-script-candidates/out

@@ -0,0 +1 @@
+bar

test/shell/prompt-shell-script-candidates/rc

@@ -0,0 +1,3 @@
+define-command foo %{
+    prompt -shell-script-candidates %{ printf 'foo\nbar\nhaz\n' } ': ' %{exec i %val{text} <esc>}
+}

test/shell/prompt-shell-script-completion/cmd

@@ -0,0 +1 @@
+:foo<ret>b<tab><tab><ret>

test/shell/prompt-shell-script-completion/in

@@ -0,0 +1 @@
+

test/shell/prompt-shell-script-completion/out

@@ -0,0 +1 @@
+foo

test/shell/prompt-shell-script-completion/rc

@@ -0,0 +1,3 @@
+define-command foo %{
+    prompt -shell-script-completion %{ printf 'foo\nbar\nhaz\n' } ': ' %{exec i %val{text} <esc>}
+}