👍 Add environment (e) to handle environment variables

Author: lambdalisue

denops_std/variable/README.md

@@ -102,3 +102,23 @@ export async function main(denops: Denops): Promise<void> {
   console.log(await vim.get(denops, "version"));
 }
 ```
+
+### environment (alias e)
+
+Use `environment` (or `e`) to access environment variables like:
+
+```typescript
+import { Denops } from "https://deno.land/x/denops_std/mod.ts";
+import { environment } from "https://deno.land/x/denops_std/variable/mod.ts";
+
+export async function main(denops: Denops): Promise<void> {
+  // Set environment variable
+  await environment.set(denops, "DENOPS_HELLO", "world");
+
+  // Get environment variable
+  console.log(await environment.get(denops, "DENOPS_HELLO"));
+
+  // Remove environment variable
+  await environment.remove(denops, "DENOPS_HELLO");
+}
+```

denops_std/variable/environment.ts

@@ -0,0 +1,50 @@
+import { Denops } from "../deps.ts";
+import { Getter, Remover, Setter } from "./types.ts";
+
+/**
+ * Environment variables
+ */
+export const environment: Getter & Setter & Remover = {
+  /**
+   * Get environment variable
+   */
+  async get<T = string>(
+    denops: Denops,
+    prop: string,
+    defaultValue?: T,
+  ): Promise<T | null> {
+    const name = `\$${prop}`;
+    const result = await denops.eval(`exists(n) ? ${name} : v`, {
+      n: name,
+      v: defaultValue ?? null,
+    });
+    // deno-lint-ignore no-explicit-any
+    return result as any;
+  },
+
+  /**
+   * Set environment variable
+   */
+  async set<T = string>(
+    denops: Denops,
+    prop: string,
+    value: T,
+  ): Promise<void> {
+    const name = `\$${prop}`;
+    await denops.cmd(`let ${name} = value`, {
+      value,
+    });
+  },
+
+  /**
+   * Remove environment variable
+   */
+  async remove(
+    denops: Denops,
+    prop: string,
+  ): Promise<void> {
+    const name = `\$${prop}`;
+    await denops.cmd(`unlet ${name}`);
+  },
+};
+export const e = environment;

denops_std/variable/environment_test.ts

@@ -0,0 +1,53 @@
+import { assertEquals, test } from "../deps_test.ts";
+import { environment } from "./environment.ts";
+
+test({
+  mode: "any",
+  name: "environment.get() return the value of the environment variable",
+  fn: async (denops) => {
+    await denops.cmd("let $DENOPS_STD_VARIABLE_ENVIRONMENT = 'hello'");
+    const result = await environment.get(
+      denops,
+      "DENOPS_STD_VARIABLE_ENVIRONMENT",
+    );
+    assertEquals(result, "hello");
+  },
+});
+test({
+  mode: "any",
+  name:
+    "environment.get() return the defaultValue when the environment variable does not exist",
+  fn: async (denops) => {
+    const result = await environment.get(
+      denops,
+      "DENOPS_STD_VARIABLE_ENVIRONMENT",
+    );
+    assertEquals(result, null);
+  },
+});
+test({
+  mode: "any",
+  name: "environment.set() replace the value of the environment variable",
+  fn: async (denops) => {
+    await denops.cmd("let $DENOPS_STD_VARIABLE_ENVIRONMENT = 'hello'");
+    await environment.set(denops, "DENOPS_STD_VARIABLE_ENVIRONMENT", "world");
+    const result = await environment.get(
+      denops,
+      "DENOPS_STD_VARIABLE_ENVIRONMENT",
+    );
+    assertEquals(result, "world");
+  },
+});
+test({
+  mode: "any",
+  name: "environment.remove() remove the environment variable",
+  fn: async (denops) => {
+    await denops.cmd("let $DENOPS_STD_VARIABLE_ENVIRONMENT = 'hello'");
+    await environment.remove(denops, "DENOPS_STD_VARIABLE_ENVIRONMENT");
+    const result = await environment.get(
+      denops,
+      "DENOPS_STD_VARIABLE_ENVIRONMENT",
+    );
+    assertEquals(result, null);
+  },
+});

denops_std/variable/mod.ts

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