feat(cli): Add Deno.mainModule

cli/js/lib.deno.unstable.d.ts

@@ -1245,4 +1245,7 @@ declare namespace Deno {
    *  Requires `allow-env` permission.
    */
   export function hostname(): string;
+
+  /** **UNSTABLE**: The URL of the file that was originally executed from the command-line. */
+  export const mainUrl: URL;
 }

cli/js/ops/runtime.ts

@@ -1,6 +1,7 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
 import { sendSync } from "./dispatch_json.ts";
+import { URLImpl } from "../web/url.ts";
 
 export interface Start {
   args: string[];
@@ -21,6 +22,10 @@ export function opStart(): Start {
   return sendSync("op_start");
 }
 
+export function opMainUrl(): URLImpl {
+  return new URLImpl(sendSync("op_main_url"));
+}
+
 export interface Metrics {
   opsDispatched: number;
   opsDispatchedSync: number;

cli/js/runtime_main.ts

@@ -9,6 +9,7 @@
 
 import * as denoNs from "./deno.ts";
 import * as denoUnstableNs from "./deno_unstable.ts";
+import { opMainUrl } from "./ops/runtime.ts";
 import { exit } from "./ops/os.ts";
 import {
   readOnly,
@@ -106,6 +107,7 @@ export function bootstrapMainRuntime(): void {
   if (unstableFlag) {
     Object.defineProperties(globalThis, unstableMethods);
     Object.defineProperties(globalThis, unstableProperties);
+    Object.defineProperty(denoNs, "mainUrl", getterOnly(opMainUrl));
     Object.assign(denoNs, denoUnstableNs);
   }
 

cli/ops/runtime.rs

@@ -6,11 +6,13 @@ use crate::state::State;
 use crate::version;
 use crate::DenoSubcommand;
 use deno_core::CoreIsolate;
+use deno_core::ModuleSpecifier;
 use deno_core::ZeroCopyBuf;
 use std::env;
 
 pub fn init(i: &mut CoreIsolate, s: &State) {
   i.register_op("op_start", s.stateful_json_op(op_start));
+  i.register_op("op_main_url", s.stateful_json_op(op_main_url));
   i.register_op("op_metrics", s.stateful_json_op(op_metrics));
 }
 
@@ -39,6 +41,18 @@ fn op_start(
   })))
 }
 
+fn op_main_url(
+  state: &State,
+  _args: Value,
+  _zero_copy: &mut [ZeroCopyBuf],
+) -> Result<JsonOp, OpError> {
+  let main = &state.borrow().main_module.to_string();
+  let main_url = ModuleSpecifier::resolve_url_or_path(&main)?;
+  let main_path = std::env::current_dir().unwrap().join(main_url.to_string());
+  state.check_read_blind(&main_path, "main_url")?;
+  Ok(JsonOp::Sync(json!(&main)))
+}
+
 fn op_metrics(
   state: &State,
   _args: Value,

cli/tests/integration_tests.rs

@@ -500,7 +500,7 @@ fn ts_dependency_recompilation() {
     function print(str: string): void {
         console.log(str);
     }
-    
+
     print(foo);",
   )
   .unwrap();
@@ -1703,6 +1703,11 @@ itest!(import_meta {
   output: "import_meta.ts.out",
 });
 
+itest!(main_url {
+  args: "run --quiet --unstable --allow-read --reload main_url.ts",
+  output: "main_url.ts.out",
+});
+
 itest!(lib_ref {
   args: "run --quiet --unstable --reload lib_ref.ts",
   output: "lib_ref.ts.out",

cli/tests/main_url.ts

@@ -0,0 +1,3 @@
+console.log("main_url", Deno.mainUrl.pathname);
+
+import "./main_url2.ts";

cli/tests/main_url.ts.out

@@ -0,0 +1,2 @@
+main_url2 [WILDCARD]tests/main_url.ts
+main_url [WILDCARD]tests/main_url.ts

cli/tests/main_url2.ts

@@ -0,0 +1 @@
+console.log("main_url2", Deno.mainUrl.pathname);