perf: skip visual studio components installation if not needed

src/utils/visual_studio/base.ts

@@ -0,0 +1,74 @@
+import * as os from 'os'
+import * as path from 'path'
+import {getExecOutput} from '@actions/exec'
+
+export class VisualStudio {
+  private constructor(
+    readonly installationPath: string,
+    readonly installationVersion: string,
+    readonly catalog: VisualStudioCatalog,
+    readonly properties: VisualStudioProperties
+  ) {}
+
+  // eslint-disable-next-line no-explicit-any
+  static createFromJSON(json: any) {
+    return new VisualStudio(
+      json.installationPath,
+      json.installationVersion,
+      json.catalog,
+      json.properties
+    )
+  }
+
+  async env() {
+    /// https://docs.microsoft.com/en-us/cpp/build/building-on-the-command-line?view=msvc-170
+    const nativeToolsScriptx86 = path.join(
+      this.installationPath,
+      'Common7',
+      'Tools',
+      'VsDevCmd.bat'
+    )
+    const {stdout} = await getExecOutput(
+      'cmd',
+      [
+        '/k',
+        nativeToolsScriptx86,
+        `-arch=${os.arch()}`,
+        '&&',
+        'set',
+        '&&',
+        'exit'
+      ],
+      {failOnStdErr: true}
+    )
+    return Object.fromEntries(
+      stdout
+        .split(os.EOL)
+        .filter(s => s.indexOf('='))
+        .map(s => s.trim())
+        .map(s => s.split('=', 2))
+        .filter(s => s.length === 2)
+        .map(s => [s[0].trim(), s[1].trim()] as const)
+    ) as VisualStudioEnv
+  }
+}
+
+export interface VisualStudioCatalog {
+  productDisplayVersion: string
+}
+
+export interface VisualStudioProperties {
+  setupEngineFilePath: string
+}
+
+export interface VisualStudioRequirement {
+  version: string
+  components: string[]
+}
+
+export interface VisualStudioEnv {
+  readonly UniversalCRTSdkDir?: string
+  readonly UCRTVersion?: string
+  readonly VCToolsInstallDir?: string
+  readonly [name: string]: string | undefined
+}

src/utils/visual_studio/index.ts

@@ -1,2 +1,3 @@
+export * from './base'
 export * from './setup'
 export * from './update'