feat(shell): provide which utility for finding binaries

imhoffd · imhoffd · commit 4dbe922233aa · 2018-09-27T17:21:30.000-05:00
diff --git a/packages/@ionic/cli-framework/src/utils/array.ts b/packages/@ionic/cli-framework/src/utils/array.ts
@@ -49,9 +49,11 @@ export async function map<T, U>(array: T[] | ReadonlyArray<T>, callback: (curren
 
 export async function reduce<T>(array: T[], callback: (accumulator: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<T>): Promise<T>;
 export async function reduce<T>(array: T[], callback: (accumulator: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<T>, initialValue: T): Promise<T>;
+export async function reduce<T, R>(array: T[], callback: (accumulator: R, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<R>): Promise<R>;
 export async function reduce<T, U>(array: T[], callback: (accumulator: U, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<U>, initialValue: U): Promise<U>;
 export async function reduce<T>(array: ReadonlyArray<T>, callback: (accumulator: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<T>): Promise<T>;
 export async function reduce<T>(array: ReadonlyArray<T>, callback: (accumulator: T, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<T>, initialValue: T): Promise<T>;
+export async function reduce<T, R>(array: ReadonlyArray<T>, callback: (accumulator: R, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<R>): Promise<R>;
 export async function reduce<T, U>(array: ReadonlyArray<T>, callback: (accumulator: U, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<U>, initialValue: U): Promise<U>;
 export async function reduce<T, U>(array: T[] | ReadonlyArray<T>, callback: (accumulator: T | U, currentValue: T, currentIndex: number, array: ReadonlyArray<T>) => Promise<T | U>, initialValue?: T | U): Promise<T | U> {
   const hadInitialValue = typeof initialValue === 'undefined';
diff --git a/packages/@ionic/cli-framework/src/utils/shell.ts b/packages/@ionic/cli-framework/src/utils/shell.ts
@@ -1,10 +1,12 @@
+import { statSafe } from '@ionic/utils-fs';
 import { ChildProcess, ForkOptions, SpawnOptions, fork as _fork } from 'child_process';
 import * as os from 'os';
 import * as path from 'path';
 
 import * as crossSpawn from 'cross-spawn';
 
 import { ERROR_SHELL_COMMAND_NOT_FOUND, ERROR_SHELL_NON_ZERO_EXIT, ShellCommandError } from '../errors';
+import { reduce } from '../utils/array';
 import { createProcessEnv } from '../utils/process';
 import { WritableStreamBuffer } from '../utils/streams';
 
@@ -157,3 +159,44 @@ export function spawn(command: string, args: ReadonlyArray<string> = [], options
 export function fork(modulePath: string, args: ReadonlyArray<string> = [], options: ForkOptions & Pick<SpawnOptions, 'stdio'> = {}): ChildProcess {
   return _fork(modulePath, [...args], options);
 }
+
+export interface WhichOptions {
+  PATH?: string;
+}
+
+export async function which(command: string, { PATH = process.env.PATH || '' }: WhichOptions = {}): Promise<string> {
+  if (command.includes(path.sep)) {
+    return command;
+  }
+
+  const pathParts = PATH.split(path.delimiter);
+
+  // tslint:disable:no-null-keyword
+
+  const value = await reduce<string, string | null>(pathParts, async (acc, v) => {
+    // acc is no longer null, so we found the first match already
+    if (acc) {
+      return acc;
+    }
+
+    const p = path.join(v, command);
+    const stats = await statSafe(p);
+
+    if (stats && stats.isFile()) {
+      // TODO: check if file is executable
+      return p;
+    }
+
+    return null;
+  }, null);
+
+  // tslint:enable:no-null-keyword
+
+  if (!value) {
+    const err: NodeJS.ErrnoException = new Error(`${command} cannot be found within PATH`);
+    err.code = 'ENOENT';
+    throw err;
+  }
+
+  return value;
+}
