parcel-query tool (#8478)

packages/dev/query/README.md

@@ -0,0 +1,42 @@
+# `parcel-query`
+
+A REPL to investigate the Parcel graphs in the cache ("offline", after the build).
+
+## Installation
+
+Clone and run `yarn`, then `cd packages/dev/query && yarn link` to make the `parcel-query` binary
+globally available.
+
+## Usage
+
+Call `.help` to view a list of commands.
+
+In a project root containing a `.parcel-cache` folder:
+
+```sh
+$ parcel-query
+> .findBundleReason 27494aebac508bd8 TJbGI
+# Asset is main entry of bundle: false
+# Asset is an entry of bundle: false
+# Incoming dependencies contained in the bundle:
+{
+  id: '3fd182662e2a6fa9',
+  type: 'dependency',
+  value: {
+    specifier: '../../foo',
+    specifierType: 0,
+...
+```
+
+In the `.getAsset 3Xzt5` variant, no quotes/parenthesis are
+needed. Alternatively, you can use proper JS: `getAsset("3Xzt5")`.
+
+The variables `assetGraph` and `bundleGraph` contain the deserialized objects.
+
+For a single query, the command (which has to be a JS call) can be specified as a CLI parameter (the
+disadvantage here is that the graphs have to be loaded on every call as opposed to once when
+starting the REPL):
+
+```sh
+$ parcel-query 'findBundleReason("b0696febf20b57ce", "bNAUZ")'
+```

packages/dev/query/package.json

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+{
+  "name": "parcel-query",
+  "version": "2.8.1",
+  "private": true,
+  "bin": "src/bin.js",
+  "main": "src/index.js",
+  "dependencies": {
+    "@parcel/core": "2.8.1",
+    "@parcel/graph": "2.8.1",
+    "nullthrows": "^1.1.1",
+    "v8-compile-cache": "^2.0.0"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.0.0",
+    "@parcel/babel-register": "2.8.1"
+  }
+}

packages/dev/query/src/bin.js

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+#!/usr/bin/env node
+
+'use strict';
+
+if (
+  process.env.PARCEL_BUILD_ENV !== 'production' ||
+  process.env.PARCEL_SELF_BUILD
+) {
+  require('@parcel/babel-register');
+}
+
+require('v8-compile-cache');
+require('./cli');