Process source maps in Rust instead of JS (#1280)

- Improves speed and binary size significantly.
- Makes deno_last_exception() output a JSON structure.
- Isolate::execute and Isolate::event_loop now return
  structured, mapped JSError objects on errors.
- Removes libdeno functions:
  libdeno.setGlobalErrorHandler()
  libdeno.setPromiseRejectHandler()
  libdeno.setPromiseErrorExaminer()

In collaboration with Ryan Dahl.

7 files changed, 9 insertions, 429 deletions

diff --git a/js/compiler.ts b/js/compiler.ts
index c9fa4611c..e0bfb77bb 100644
--- a/js/compiler.ts
+++ b/js/compiler.ts
@@ -3,10 +3,8 @@ import * as ts from "typescript";
 import { MediaType } from "gen/msg_generated";
 
 import { assetSourceCode } from "./assets";
-import { libdeno } from "./libdeno";
 import * as os from "./os";
 import { CodeProvider } from "./runner";
-import { RawSourceMap } from "./types";
 import { assert, log, notImplemented } from "./util";
 
 const EOL = "\n";
@@ -71,7 +69,7 @@ export class ModuleMetaData implements ts.IScriptSnapshot {
     public readonly mediaType: MediaType,
     public readonly sourceCode: SourceCode = "",
     public outputCode: OutputCode = "",
-    public sourceMap: SourceMap | RawSourceMap = ""
+    public sourceMap: SourceMap = ""
   ) {
     if (outputCode !== "" || fileName.endsWith(".d.ts")) {
       this.scriptVersion = "1";
@@ -131,8 +129,6 @@ export class Compiler
     ContainingFile,
     Map<ModuleSpecifier, ModuleFileName>
   >();
-  // Keep track of state of the last module requested via `getGeneratedContents`
-  private _lastModule: ModuleMetaData | undefined;
   // A reference to the log utility, so it can be monkey patched during testing
   private _log = log;
   // A map of module file names to module meta data
@@ -369,19 +365,15 @@ export class Compiler
       moduleMetaData.outputCode = `${
         outputFile.text
       }\n//# sourceURL=${fileName}`;
-      moduleMetaData.sourceMap = JSON.parse(sourceMapFile.text);
+      moduleMetaData.sourceMap = sourceMapFile.text;
     }
 
     moduleMetaData.scriptVersion = "1";
-    const sourceMap =
-      moduleMetaData.sourceMap === "string"
-        ? moduleMetaData.sourceMap
-        : JSON.stringify(moduleMetaData.sourceMap);
     this._os.codeCache(
       fileName,
       sourceCode,
       moduleMetaData.outputCode,
-      sourceMap
+      moduleMetaData.sourceMap
     );
     return moduleMetaData.outputCode;
   }
@@ -398,36 +390,10 @@ export class Compiler
   }
 
   /** Given a fileName, return what was generated by the compiler. */
-  getGeneratedContents = (fileName: string): string | RawSourceMap => {
-    this._log("compiler.getGeneratedContents", fileName);
-    if (fileName === "gen/bundle/main.js") {
-      assert(libdeno.mainSource.length > 0);
-      return libdeno.mainSource;
-    } else if (fileName === "main.js.map") {
-      return libdeno.mainSourceMap;
-    } else if (fileName === "deno_main.js") {
-      return "";
-    } else if (!fileName.endsWith(".map")) {
-      const moduleMetaData = this._moduleMetaDataMap.get(fileName);
-      if (!moduleMetaData) {
-        this._lastModule = undefined;
-        return "";
-      }
-      this._lastModule = moduleMetaData;
-      return moduleMetaData.outputCode;
-    } else {
-      if (this._lastModule && this._lastModule.sourceMap) {
-        // Assuming the the map will always be asked for after the source
-        // code.
-        const { sourceMap } = this._lastModule;
-        this._lastModule = undefined;
-        return sourceMap;
-      } else {
-        // Errors thrown here are caught by source-map.
-        throw new Error(`Unable to find source map: "${fileName}"`);
-      }
-    }
-  };
+  getGeneratedSourceMap(fileName: string): string {
+    const moduleMetaData = this._moduleMetaDataMap.get(fileName);
+    return moduleMetaData ? moduleMetaData.sourceMap : "";
+  }
 
   /** Get the output code for a module based on its filename. A call to
    * `.getFilename()` should occur before attempting to get the output code as
diff --git a/js/libdeno.ts b/js/libdeno.ts
index c61027324..5448165a1 100644
--- a/js/libdeno.ts
+++ b/js/libdeno.ts
@@ -1,5 +1,4 @@
 // Copyright 2018 the Deno authors. All rights reserved. MIT license.
-import { RawSourceMap } from "./types";
 import { globalEval } from "./global_eval";
 
 // The libdeno functions are moved so that users can't access them.
@@ -39,9 +38,6 @@ interface Libdeno {
   ) => void;
 
   setPromiseErrorExaminer: (handler: () => boolean) => void;
-
-  mainSource: string;
-  mainSourceMap: RawSourceMap;
 }
 
 const window = globalEval("this");
diff --git a/js/main.ts b/js/main.ts
index 241e8d7d1..818713593 100644
--- a/js/main.ts
+++ b/js/main.ts
@@ -11,22 +11,9 @@ import { Runner } from "./runner";
 import { libdeno } from "./libdeno";
 import { args } from "./deno";
 import { sendSync, handleAsyncMsgFromRust } from "./dispatch";
-import { promiseErrorExaminer, promiseRejectHandler } from "./promise_util";
 import { replLoop } from "./repl";
-import * as sourceMaps from "./v8_source_maps";
 import { version } from "typescript";
 
-// Install the source maps handler and do some pre-calculations so all of it is
-// available in the snapshot
-const compiler = Compiler.instance();
-sourceMaps.install({
-  installPrepareStackTrace: true,
-  getGeneratedContents: compiler.getGeneratedContents
-});
-const consumer = sourceMaps.loadConsumer("gen/bundle/main.js");
-assert(consumer != null);
-consumer!.computeColumnSpans();
-
 function sendStart(): msg.StartRes {
   const builder = flatbuffers.createBuilder();
   msg.Start.startStart(builder);
@@ -39,27 +26,9 @@ function sendStart(): msg.StartRes {
   return startRes;
 }
 
-function onGlobalError(
-  message: string,
-  source: string,
-  lineno: number,
-  colno: number,
-  error: any // tslint:disable-line:no-any
-) {
-  if (error instanceof Error) {
-    console.log(error.stack);
-  } else {
-    console.log(`Thrown: ${String(error)}`);
-  }
-  os.exit(1);
-}
-
 /* tslint:disable-next-line:no-default-export */
 export default function denoMain() {
   libdeno.recv(handleAsyncMsgFromRust);
-  libdeno.setGlobalErrorHandler(onGlobalError);
-  libdeno.setPromiseRejectHandler(promiseRejectHandler);
-  libdeno.setPromiseErrorExaminer(promiseErrorExaminer);
 
   // First we send an empty "Start" message to let the privileged side know we
   // are ready. The response should be a "StartRes" message containing the CLI
@@ -68,6 +37,8 @@ export default function denoMain() {
 
   setLogDebug(startResMsg.debugFlag());
 
+  const compiler = Compiler.instance();
+
   // handle `--types`
   if (startResMsg.typesFlag()) {
     const defaultLibFileName = compiler.getDefaultLibFileName();
diff --git a/js/promise_util.ts b/js/promise_util.ts
deleted file mode 100644
index 3c789124d..000000000
--- a/js/promise_util.ts
+++ /dev/null
@@ -1,50 +0,0 @@
-// Copyright 2018 the Deno authors. All rights reserved. MIT license.
-import { PromiseRejectEvent } from "./libdeno";
-
-/* tslint:disable-next-line:no-any */
-const rejectMap = new Map<Promise<any>, string>();
-// For uncaught promise rejection errors
-
-/* tslint:disable-next-line:no-any */
-const otherErrorMap = new Map<Promise<any>, string>();
-// For reject after resolve / resolve after resolve errors
-
-export function promiseRejectHandler(
-  error: Error | string,
-  event: PromiseRejectEvent,
-  /* tslint:disable-next-line:no-any */
-  promise: Promise<any>
-) {
-  switch (event) {
-    case "RejectWithNoHandler":
-      rejectMap.set(promise, (error as Error).stack || "RejectWithNoHandler");
-      break;
-    case "HandlerAddedAfterReject":
-      rejectMap.delete(promise);
-      break;
-    case "ResolveAfterResolved":
-      // Should not warn. See #1272
-      break;
-    default:
-      // error is string here
-      otherErrorMap.set(promise, `Promise warning: ${error as string}`);
-  }
-}
-
-// Return true when continue, false to die on uncaught promise reject
-export function promiseErrorExaminer(): boolean {
-  if (otherErrorMap.size > 0) {
-    for (const msg of otherErrorMap.values()) {
-      console.log(msg);
-    }
-    otherErrorMap.clear();
-  }
-  if (rejectMap.size > 0) {
-    for (const msg of rejectMap.values()) {
-      console.log(msg);
-    }
-    rejectMap.clear();
-    return false;
-  }
-  return true;
-}
diff --git a/js/unit_tests.ts b/js/unit_tests.ts
index 4863b7ac4..55877091e 100644
--- a/js/unit_tests.ts
+++ b/js/unit_tests.ts
@@ -35,5 +35,4 @@ import "./text_encoding_test.ts";
 import "./timers_test.ts";
 import "./truncate_test.ts";
 import "./url_search_params_test.ts";
-import "./v8_source_maps_test.ts";
 import "./write_file_test.ts";
diff --git a/js/v8_source_maps.ts b/js/v8_source_maps.ts
deleted file mode 100644
index dcdde16c7..000000000
--- a/js/v8_source_maps.ts
+++ /dev/null
@@ -1,285 +0,0 @@
-// Copyright 2014 Evan Wallace
-// Copyright 2018 the Deno authors. All rights reserved. MIT license.
-// Originated from source-map-support but has been heavily modified for deno.
-
-import { SourceMapConsumer, MappedPosition } from "source-map";
-import { CallSite, RawSourceMap } from "./types";
-import { atob } from "./text_encoding";
-
-const consumers = new Map<string, SourceMapConsumer>();
-
-interface Options {
-  // A callback the returns generated file contents.
-  getGeneratedContents: GetGeneratedContentsCallback;
-  // Usually set the following to true. Set to false for testing.
-  installPrepareStackTrace: boolean;
-}
-
-interface Position {
-  source: string; // Filename
-  column: number;
-  line: number;
-}
-
-type GetGeneratedContentsCallback = (fileName: string) => string | RawSourceMap;
-
-let getGeneratedContents: GetGeneratedContentsCallback;
-
-// @internal
-export function install(options: Options) {
-  getGeneratedContents = options.getGeneratedContents;
-  if (options.installPrepareStackTrace) {
-    Error.prepareStackTrace = prepareStackTraceWrapper;
-  }
-}
-
-// @internal
-export function prepareStackTraceWrapper(
-  error: Error,
-  stack: CallSite[]
-): string {
-  try {
-    return prepareStackTrace(error, stack);
-  } catch (prepareStackError) {
-    Error.prepareStackTrace = undefined;
-    console.log("=====Error inside of prepareStackTrace====");
-    console.log(prepareStackError.stack.toString());
-    console.log("=====Original error=======================");
-    throw error;
-  }
-}
-
-// @internal
-export function prepareStackTrace(error: Error, stack: CallSite[]): string {
-  const frames = stack.map(
-    frame => `\n    at ${wrapCallSite(frame).toString()}`
-  );
-  return `${error.toString()}${frames.join("")}`;
-}
-
-// @internal
-export function wrapCallSite(frame: CallSite): CallSite {
-  if (frame.isNative()) {
-    return frame;
-  }
-
-  // Most call sites will return the source file from getFileName(), but code
-  // passed to eval() ending in "//# sourceURL=..." will return the source file
-  // from getScriptNameOrSourceURL() instead
-  const source = frame.getFileName() || frame.getScriptNameOrSourceURL();
-
-  if (source) {
-    const line = frame.getLineNumber() || 0;
-    const column = (frame.getColumnNumber() || 1) - 1;
-    const position = mapSourcePosition({ source, line, column });
-    frame = cloneCallSite(frame);
-    Object.assign(frame, {
-      getFileName: () => position.source,
-      getLineNumber: () => position.line,
-      getColumnNumber: () => Number(position.column) + 1,
-      getScriptNameOrSourceURL: () => position.source,
-      toString: () => CallSiteToString(frame)
-    });
-    return frame;
-  }
-
-  // Code called using eval() needs special handling
-  let origin = (frame.isEval() && frame.getEvalOrigin()) || undefined;
-  if (origin) {
-    origin = mapEvalOrigin(origin);
-    frame = cloneCallSite(frame);
-    Object.assign(frame, {
-      getEvalOrigin: () => origin,
-      toString: () => CallSiteToString(frame)
-    });
-    return frame;
-  }
-
-  // If we get here then we were unable to change the source position
-  return frame;
-}
-
-function cloneCallSite(
-  frame: CallSite
-  // mixin: Partial<CallSite> & { toString: () => string }
-): CallSite {
-  const obj = {} as CallSite;
-  const props = Object.getOwnPropertyNames(
-    Object.getPrototypeOf(frame)
-  ) as Array<keyof CallSite>;
-  for (const name of props) {
-    obj[name] = /^(?:is|get)/.test(name)
-      ? () => frame[name].call(frame)
-      : frame[name];
-  }
-  return obj;
-}
-
-// Taken from source-map-support, original copied from V8's messages.js
-// MIT License. Copyright (c) 2014 Evan Wallace
-function CallSiteToString(frame: CallSite): string {
-  let fileLocation = "";
-  if (frame.isNative()) {
-    fileLocation = "native";
-  } else {
-    const fileName = frame.getScriptNameOrSourceURL();
-    if (!fileName && frame.isEval()) {
-      fileLocation = frame.getEvalOrigin() || "";
-      fileLocation += ", "; // Expecting source position to follow.
-    }
-
-    if (fileName) {
-      fileLocation += fileName;
-    } else {
-      // Source code does not originate from a file and is not native, but we
-      // can still get the source position inside the source string, e.g. in
-      // an eval string.
-      fileLocation += "<anonymous>";
-    }
-    const lineNumber = frame.getLineNumber();
-    if (lineNumber != null) {
-      fileLocation += `:${lineNumber}`;
-      const columnNumber = frame.getColumnNumber();
-      if (columnNumber) {
-        fileLocation += `:${columnNumber}`;
-      }
-    }
-  }
-
-  let line = "";
-  const functionName = frame.getFunctionName();
-  let addSuffix = true;
-  const isConstructor = frame.isConstructor();
-  const isMethodCall = !(frame.isToplevel() || isConstructor);
-  if (isMethodCall) {
-    let typeName = frame.getTypeName();
-    // Fixes shim to be backward compatible with Node v0 to v4
-    if (typeName === "[object Object]") {
-      typeName = "null";
-    }
-    const methodName = frame.getMethodName();
-    if (functionName) {
-      if (typeName && functionName.indexOf(typeName) !== 0) {
-        line += `${typeName}.`;
-      }
-      line += functionName;
-      if (
-        methodName &&
-        functionName.indexOf("." + methodName) !==
-          functionName.length - methodName.length - 1
-      ) {
-        line += ` [as ${methodName} ]`;
-      }
-    } else {
-      line += `${typeName}.${methodName || "<anonymous>"}`;
-    }
-  } else if (isConstructor) {
-    line += `new ${functionName || "<anonymous>"}`;
-  } else if (functionName) {
-    line += functionName;
-  } else {
-    line += fileLocation;
-    addSuffix = false;
-  }
-  if (addSuffix) {
-    line += ` (${fileLocation})`;
-  }
-  return line;
-}
-
-// Regex for detecting source maps
-const reSourceMap = /^data:application\/json[^,]+base64,/;
-
-export function loadConsumer(source: string): SourceMapConsumer | null {
-  let consumer = consumers.get(source);
-  if (consumer == null) {
-    const code = getGeneratedContents(source);
-    if (!code) {
-      return null;
-    }
-    if (typeof code !== "string") {
-      throw new Error("expected string");
-    }
-
-    let sourceMappingURL = retrieveSourceMapURL(code);
-    if (!sourceMappingURL) {
-      throw Error("No source map?");
-    }
-
-    let sourceMapData: string | RawSourceMap;
-    if (reSourceMap.test(sourceMappingURL)) {
-      // Support source map URL as a data url
-      const rawData = sourceMappingURL.slice(sourceMappingURL.indexOf(",") + 1);
-      sourceMapData = atob(rawData);
-      sourceMappingURL = source;
-    } else {
-      // TODO Support source map URLs relative to the source URL
-      // sourceMappingURL = supportRelativeURL(source, sourceMappingURL);
-      sourceMapData = getGeneratedContents(sourceMappingURL);
-    }
-
-    const rawSourceMap =
-      typeof sourceMapData === "string"
-        ? (JSON.parse(sourceMapData) as RawSourceMap)
-        : sourceMapData;
-    consumer = new SourceMapConsumer(rawSourceMap);
-    consumers.set(source, consumer);
-  }
-  return consumer;
-}
-
-// tslint:disable-next-line:max-line-length
-const sourceMapUrlRe = /(?:\/\/[@#][ \t]+sourceMappingURL=([^\s'"]+?)[ \t]*$)|(?:\/\*[@#][ \t]+sourceMappingURL=([^\*]+?)[ \t]*(?:\*\/)[ \t]*$)/gm;
-
-function retrieveSourceMapURL(fileData: string): string | null {
-  // Keep executing the search to find the *last* sourceMappingURL to avoid
-  // picking up sourceMappingURLs from comments, strings, etc.
-  let lastMatch, match;
-  while ((match = sourceMapUrlRe.exec(fileData))) {
-    lastMatch = match;
-  }
-  if (!lastMatch) {
-    return null;
-  }
-  return lastMatch[1];
-}
-
-export function mapSourcePosition(position: Position): MappedPosition {
-  const consumer = loadConsumer(position.source);
-  if (consumer == null) {
-    return position;
-  }
-  return consumer.originalPositionFor(position);
-}
-
-const stackEvalRe = /^eval at ([^(]+) \((.+):(\d+):(\d+)\)$/;
-const nestedEvalRe = /^eval at ([^(]+) \((.+)\)$/;
-
-// Parses code generated by FormatEvalOrigin(), a function inside V8:
-// https://code.google.com/p/v8/source/browse/trunk/src/messages.js
-function mapEvalOrigin(origin: string): string {
-  // Most eval() calls are in this format
-  let match = stackEvalRe.exec(origin);
-  if (match) {
-    const position = mapSourcePosition({
-      source: match[2],
-      line: Number(match[3]),
-      column: Number(match[4]) - 1
-    });
-    const pos = [
-      position.source,
-      position.line,
-      Number(position.column) + 1
-    ].join(":");
-    return `eval at ${match[1]} (${pos})`;
-  }
-
-  // Parse nested eval() calls using recursion
-  match = nestedEvalRe.exec(origin);
-  if (match) {
-    return `eval at ${match[1]} (${mapEvalOrigin(match[2])})`;
-  }
-
-  // Make sure we still return useful information if we didn't find anything
-  return origin;
-}
diff --git a/js/v8_source_maps_test.ts b/js/v8_source_maps_test.ts
deleted file mode 100644
index 90c123431..000000000
--- a/js/v8_source_maps_test.ts
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2018 the Deno authors. All rights reserved. MIT license.
-import { test, assert, assertEqual } from "./test_util.ts";
-
-// This test demonstrates a bug:
-// https://github.com/denoland/deno/issues/808
-test(function evalErrorFormatted() {
-  let err;
-  try {
-    eval("boom");
-  } catch (e) {
-    err = e;
-  }
-  assert(!!err);
-  // tslint:disable-next-line:no-unused-expression
-  err.stack; // This would crash if err.stack is malformed
-  assertEqual(err.name, "ReferenceError");
-});