👍 Add register (r) to handle register

Author: lambdalisue

denops_std/variable/README.md

@@ -122,3 +122,22 @@ export async function main(denops: Denops): Promise<void> {
   await environment.remove(denops, "DENOPS_HELLO");
 }
 ```
+
+### register (alias r)
+
+Use `register` (or `r`) to access register like:
+
+```typescript
+import { Denops } from "https://deno.land/x/denops_std/mod.ts";
+import { register } from "https://deno.land/x/denops_std/variable/mod.ts";
+
+export async function main(denops: Denops): Promise<void> {
+  // Set register
+  await register.set(denops, "a", "world");
+
+  // Get register
+  console.log(await register.get(denops, "a"));
+}
+```
+
+Note that `register.get()` returns `defaultValue` when the register is falsy.

denops_std/variable/mod.ts

@@ -1,2 +1,3 @@
 export * from "./variable.ts";
 export * from "./environment.ts";
+export * from "./register.ts";

denops_std/variable/register.ts

@@ -0,0 +1,46 @@
+import { Denops } from "../deps.ts";
+import { Getter, Setter } from "./types.ts";
+
+/**
+ * Register
+ */
+export const register: Getter & Setter = {
+  /**
+   * Get register value
+   */
+  async get<T = string>(
+    denops: Denops,
+    prop: string,
+    defaultValue?: T,
+  ): Promise<T | null> {
+    if (prop.length >= 2) {
+      throw new Error(
+        "The 'prop' must be a single character which indicates register",
+      );
+    }
+    const name = `@${prop}`;
+    const result = await denops.eval(name) || defaultValue;
+    // deno-lint-ignore no-explicit-any
+    return result as any ?? null;
+  },
+
+  /**
+   * Set register value
+   */
+  async set<T = string>(
+    denops: Denops,
+    prop: string,
+    value: T,
+  ): Promise<void> {
+    if (prop.length >= 2) {
+      throw new Error(
+        "The 'prop' must be a single character which indicates register",
+      );
+    }
+    const name = `@${prop}`;
+    await denops.cmd(`let ${name} = value`, {
+      value,
+    });
+  },
+};
+export const r = register;

denops_std/variable/register_test.ts

@@ -0,0 +1,65 @@
+import { assertEquals, assertThrowsAsync, test } from "../deps_test.ts";
+import { register } from "./register.ts";
+
+test({
+  mode: "any",
+  name: "register.get() throws an error when 'prop' is invalid",
+  fn: async (denops) => {
+    await assertThrowsAsync(
+      async () => {
+        await register.get(denops, "aa");
+      },
+      undefined,
+      "must be a single character",
+    );
+  },
+});
+test({
+  mode: "any",
+  name: "register.get() return the value of the variable",
+  fn: async (denops) => {
+    await denops.cmd("let @a = 'hello'");
+    const result = await register.get(
+      denops,
+      "a",
+    );
+    assertEquals(result, "hello");
+  },
+});
+test({
+  mode: "any",
+  name: "register.get() return the defaultValue if the register is empty",
+  fn: async (denops) => {
+    const result = await register.get(
+      denops,
+      "a",
+    );
+    assertEquals(result, null);
+  },
+});
+test({
+  mode: "any",
+  name: "register.set() throws an error when 'prop' is invalid",
+  fn: async (denops) => {
+    await assertThrowsAsync(
+      async () => {
+        await register.set(denops, "aa", "world");
+      },
+      undefined,
+      "must be a single character",
+    );
+  },
+});
+test({
+  mode: "any",
+  name: "register.set() replace the value of the variable",
+  fn: async (denops) => {
+    await denops.cmd("let @a = 'hello'");
+    await register.set(denops, "a", "world");
+    const result = await register.get(
+      denops,
+      "a",
+    );
+    assertEquals(result, "world");
+  },
+});