feat(source): add command source for listing user-defined commands

Implements a new source that lists all user-defined Vim commands with
their definitions, attributes, and completion settings. Optionally
includes buffer-local and builtin commands.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: lambdalisue

builtin/source/command.ts

@@ -0,0 +1,178 @@
+import * as fn from "@denops/std/function";
+
+import { defineSource, type Source } from "../../source.ts";
+
+type Detail = {
+  /**
+   * Command name
+   */
+  name: string;
+
+  /**
+   * Command definition/replacement text
+   */
+  definition: string;
+
+  /**
+   * Command attributes (bang, range, etc.)
+   */
+  attributes: string;
+
+  /**
+   * Whether the command is buffer-local
+   */
+  bufferLocal: boolean;
+
+  /**
+   * Number of arguments the command accepts
+   */
+  nargs: string;
+
+  /**
+   * Completion type
+   */
+  complete?: string;
+};
+
+export type CommandOptions = {
+  /**
+   * Whether to include buffer-local commands.
+   * @default true
+   */
+  includeBufferLocal?: boolean;
+
+  /**
+   * Whether to include builtin commands.
+   * @default false
+   */
+  includeBuiltin?: boolean;
+};
+
+/**
+ * Creates a Source that generates items from user-defined Vim commands.
+ *
+ * This Source retrieves all user-defined commands and generates items
+ * for each one, showing their definition and attributes.
+ *
+ * @param options - Options to customize command listing.
+ * @returns A Source that generates items representing commands.
+ */
+export function command(
+  options: Readonly<CommandOptions> = {},
+): Source<Detail> {
+  const includeBufferLocal = options.includeBufferLocal ?? true;
+  const includeBuiltin = options.includeBuiltin ?? false;
+
+  return defineSource(async function* (denops, _params, { signal }) {
+    // Get user commands
+    const commandOutput = await denops.call("execute", "command") as string;
+    signal?.throwIfAborted();
+
+    // Parse command output
+    const lines = commandOutput.trim().split("\n").filter((line) =>
+      line.trim()
+    );
+    let items: Array<{
+      id: number;
+      value: string;
+      detail: Detail;
+    }> = [];
+
+    let id = 0;
+    for (const line of lines) {
+      // Skip header line
+      if (line.includes("Name") && line.includes("Args")) {
+        continue;
+      }
+
+      // Parse command line
+      // Format: "    Name              Args       Address   Complete  Definition"
+      const match = line.match(
+        /^\s*(\S+)\s+(\S+)\s+(\S+)\s+(\S*)\s+(.*)$/,
+      );
+      if (!match) {
+        continue;
+      }
+
+      const [, name, nargs, address, complete, definition] = match;
+
+      // Check if it's a buffer-local command
+      const bufferLocal = name.startsWith("b:");
+
+      // Skip buffer-local commands if not included
+      if (bufferLocal && !includeBufferLocal) {
+        continue;
+      }
+
+      // Skip builtin commands if not included (they start with uppercase)
+      if (!includeBuiltin && /^[A-Z]/.test(name) && !name.includes(":")) {
+        continue;
+      }
+
+      // Build attributes string
+      const attributes: string[] = [];
+      if (nargs !== "0") {
+        attributes.push(`nargs=${nargs}`);
+      }
+      if (address !== ".") {
+        attributes.push(`addr=${address}`);
+      }
+      if (complete) {
+        attributes.push(`complete=${complete}`);
+      }
+
+      // Format display value
+      const attrStr = attributes.length > 0
+        ? ` (${attributes.join(", ")})`
+        : "";
+      const localStr = bufferLocal ? " [buffer]" : "";
+      const truncatedDef = definition.length > 50
+        ? definition.substring(0, 47) + "..."
+        : definition;
+
+      items.push({
+        id: id++,
+        value: `:${name}${localStr}${attrStr} → ${truncatedDef}`,
+        detail: {
+          name,
+          definition,
+          attributes: attrStr,
+          bufferLocal,
+          nargs,
+          complete: complete || undefined,
+        },
+      });
+    }
+
+    // Get completion list if needed
+    if (includeBuiltin) {
+      const builtinCommands = await fn.getcompletion(
+        denops,
+        "",
+        "command",
+      ) as string[];
+
+      for (const cmd of builtinCommands) {
+        // Skip if already in the list
+        if (items.some((item) => item.detail.name === cmd)) {
+          continue;
+        }
+
+        items.push({
+          id: id++,
+          value: `:${cmd} [builtin]`,
+          detail: {
+            name: cmd,
+            definition: "(builtin command)",
+            attributes: "",
+            bufferLocal: false,
+            nargs: "?",
+            complete: undefined,
+          },
+        });
+      }
+    }
+
+    yield* items;
+  });
+}

builtin/source/mod.ts

@@ -1,6 +1,7 @@
 // This file is generated by gen-mod.ts
 export * from "./buffer.ts";
 export * from "./colorscheme.ts";
+export * from "./command.ts";
 export * from "./file.ts";
 export * from "./helptag.ts";
 export * from "./highlight.ts";